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• 1. [Article] Precipitation characteristics for landslide hazard assessment for the central Oregon Coast Range

  Precipitation data from 1988-1995 for 13 rain gauges of the Department of Forest Engineering rain gauge network, and a longer precipitation record, 1976-1995, at Mapleton were analyzed. The objectives ...

  Citation × Citation Citation Abstract Copy Title: Precipitation characteristics for landslide hazard assessment for the central Oregon Coast Range Author: Surfleet, Christopher G. Precipitation data from 1988-1995 for 13 rain gauges of the Department of Forest Engineering rain gauge network, and a longer precipitation record, 1976-1995, at Mapleton were analyzed. The objectives were to assess the spatial and temporal distribution of precipitation intensity and antecedent precipitation, and understand the role of these characteristics for triggering debris slides from headwalls in the central Oregon Coast Range. Frequency distribution curves and recurrence intervals using a partial-duration series were calculated for the maximum 5-minute, 30 minute, 1 hour, 2 hour, 6 hour precipitation durations and antecedent precipitation index (API) for the rain gauge network and the maximum 1 hour and 2 hour precipitation durations for Mapleton. Isohyet lines showing selected 2-year precipitation intensities and API were used to characterize the spatial distribution of precipitation intensity and API across the central Oregon Coast Range. The effect of elevation on this spatial distribution was investigated. An attempt to quantify the occurrence of high intensity precipitation occurring with high antecedent precipitation, which is hypothesized to trigger debris slides, was done by testing if the highest precipitation intensities (greater than a 1 -year recurrence interval) occurred during the storms with the highest API. API and precipitation intensity were tested for correlation to discern if a particular precipitation duration could be used to predict API, thus make it possible to use a precipitation intensity based threshold to assess the general hazard of landslides. Precipitation intensities associated with selected recurrence intervals vary considerably over the study area. Precipitation values for selected durations and recurrence intervals could vary as much as 50% or larger for selected rain gauge locations. Precipitation intensities are higher in the central portion of the study area, centered around the ridges of the Siuslaw River watershed, with decreasing intensity toward the northern and southern boundaries possibly due to topographic influences. Higher API values are found more frequent where the high precipitation intensity spatial trends exists. Relationships between short duration precipitation intensities with elevation, and API with elevation, within the rain gauge network could not be determined. No single precipitation intensity, including total storm precipitation, showed a strong positive correlation with high API for the entire rain gauge network. It appears that any attempts to predict the precipitation characteristics which trigger headwall failure by a precipitation intensity threshold in the central Oregon Coast Range is not possible. Attempts to assess the risk of headwall failure by high API may be possible. High precipitation intensities occurred with high antecedent precipitation conditions and they occur at the highest antecedent precipitation conditions. Title: Precipitation characteristics for landslide hazard assessment for the central Oregon Coast Range Author: Surfleet, Christopher G. Precipitation data from 1988-1995 for 13 rain gauges of the Department of Forest Engineering rain gauge network, and a longer precipitation record, 1976-1995, at Mapleton were analyzed. The objectives were to assess the spatial and temporal distribution of precipitation intensity and antecedent precipitation, and understand the role of these characteristics for triggering debris slides from headwalls in the central Oregon Coast Range. Frequency distribution curves and recurrence intervals using a partial-duration series were calculated for the maximum 5-minute, 30 minute, 1 hour, 2 hour, 6 hour precipitation durations and antecedent precipitation index (API) for the rain gauge network and the maximum 1 hour and 2 hour precipitation durations for Mapleton. Isohyet lines showing selected 2-year precipitation intensities and API were used to characterize the spatial distribution of precipitation intensity and API across the central Oregon Coast Range. The effect of elevation on this spatial distribution was investigated. An attempt to quantify the occurrence of high intensity precipitation occurring with high antecedent precipitation, which is hypothesized to trigger debris slides, was done by testing if the highest precipitation intensities (greater than a 1 -year recurrence interval) occurred during the storms with the highest API. API and precipitation intensity were tested for correlation to discern if a particular precipitation duration could be used to predict API, thus make it possible to use a precipitation intensity based threshold to assess the general hazard of landslides. Precipitation intensities associated with selected recurrence intervals vary considerably over the study area. Precipitation values for selected durations and recurrence intervals could vary as much as 50% or larger for selected rain gauge locations. Precipitation intensities are higher in the central portion of the study area, centered around the ridges of the Siuslaw River watershed, with decreasing intensity toward the northern and southern boundaries possibly due to topographic influences. Higher API values are found more frequent where the high precipitation intensity spatial trends exists. Relationships between short duration precipitation intensities with elevation, and API with elevation, within the rain gauge network could not be determined. No single precipitation intensity, including total storm precipitation, showed a strong positive correlation with high API for the entire rain gauge network. It appears that any attempts to predict the precipitation characteristics which trigger headwall failure by a precipitation intensity threshold in the central Oregon Coast Range is not possible. Attempts to assess the risk of headwall failure by high API may be possible. High precipitation intensities occurred with high antecedent precipitation conditions and they occur at the highest antecedent precipitation conditions. Close

• 2. [Article] A stochastic precipitation event model for use in erosion simulations

  Mathematical models of the precipitation process are needed to effectively use historical precipitation data in the design and planning of engineering projects and for analysis of watershed runoff behavior. ...

  Citation × Citation Citation Abstract Copy Title: A stochastic precipitation event model for use in erosion simulations Author: Istok, J. D. Mathematical models of the precipitation process are needed to effectively use historical precipitation data in the design and planning of engineering projects and for analysis of watershed runoff behavior. Existing simple models based on the assumptions of independent, identically-distributed random variables are insufficient to describe several features of the historical precipitation process. The objective of this research was to develop a stochastic model of hourly precipitation that preserves the pattern of occurrence of precipitation events throughout the year as well as several characteristics of the duration, amount, and intensity of precipitation within events. Historical precipitation data for Salem, Oregon were analyzed to identify the patterns of occurrence of precipitation events and the dependence structure of the precipitation during events. The results of this analysis were used to guide the development of a general model of the precipitation process, based on the theory of stochastic cluster processes. The developed model consists of several parts. A Poisson cluster process is used to describe the pattern of occurrence of precipitation events. In this process, the time between clusters and the number of events within clusters are exponentially distributed random variables. The duration of events and the time between events within clusters are described with identical Logarithmic Negative Mixture distributions. The hourly precipitation amounts within events are described with a nonstationary, first-order autoregression model. To test the precipitation model, parameters were estimated for each month using 31 years of hourly precipitation data for Salem and Pendleton, Oregon, two stations from very different climatic regimes. The results of Monte Carlo simulations showed that the model accurately reproduces the seasonal pattern of event occurrence and the marginal and conditional distributions of the magnitude, duration, and intensity of precipitation during events. Autocorrelation functions for the historical and simulated data were also similar. It is concluded that the model has potential for use in many hydrologic applications that use historical precipitation data. Title: A stochastic precipitation event model for use in erosion simulations Author: Istok, J. D. Mathematical models of the precipitation process are needed to effectively use historical precipitation data in the design and planning of engineering projects and for analysis of watershed runoff behavior. Existing simple models based on the assumptions of independent, identically-distributed random variables are insufficient to describe several features of the historical precipitation process. The objective of this research was to develop a stochastic model of hourly precipitation that preserves the pattern of occurrence of precipitation events throughout the year as well as several characteristics of the duration, amount, and intensity of precipitation within events. Historical precipitation data for Salem, Oregon were analyzed to identify the patterns of occurrence of precipitation events and the dependence structure of the precipitation during events. The results of this analysis were used to guide the development of a general model of the precipitation process, based on the theory of stochastic cluster processes. The developed model consists of several parts. A Poisson cluster process is used to describe the pattern of occurrence of precipitation events. In this process, the time between clusters and the number of events within clusters are exponentially distributed random variables. The duration of events and the time between events within clusters are described with identical Logarithmic Negative Mixture distributions. The hourly precipitation amounts within events are described with a nonstationary, first-order autoregression model. To test the precipitation model, parameters were estimated for each month using 31 years of hourly precipitation data for Salem and Pendleton, Oregon, two stations from very different climatic regimes. The results of Monte Carlo simulations showed that the model accurately reproduces the seasonal pattern of event occurrence and the marginal and conditional distributions of the magnitude, duration, and intensity of precipitation during events. Autocorrelation functions for the historical and simulated data were also similar. It is concluded that the model has potential for use in many hydrologic applications that use historical precipitation data. Close

• 3. [Article] Evaluation of precipitation data applied to hydrological simulation using MMS-PRMS for the Whitewater River Basin in Kansas

  Precipitation is one of the most important components contributing to hydrological dynamics. Spatially distributed precipitation data can be obtained by satellite, radar, rain gages, etc, to serve various ...

  Citation × Citation Citation Abstract Copy Title: Evaluation of precipitation data applied to hydrological simulation using MMS-PRMS for the Whitewater River Basin in Kansas Author: Lin, Wei Precipitation is one of the most important components contributing to hydrological dynamics. Spatially distributed precipitation data can be obtained by satellite, radar, rain gages, etc, to serve various purposes. Currently, the most commonly used precipitation data still rely on gage-based measurement techniques that provide timely precipitation information with high quality and reliability. The National Oceanic and Atmospheric Administration (NOAA) and its cooperative climate stations are the primary resources of this form of precipitation data at the federal level. For hydrological simulation of precipitation-runoff for a watershed, precipitation is a critical model input that has a significant impact on the certainty and accuracy of simulation. To better understand the hydrological process within Whitewater River Basin in Kansas, the Precipitation-Runoff Model System (PRMS) was applied to this area, where the Cooperative Atmosphere-Surface Exchange Study (CASES) has set up an intensively instrumented site managed by Hydrologic Science Team (HST) of Oregon State University for rainfall data collection. Two rainfall data sources, NOAA and HST, were used in this study to simulate the stream response to rainfall within the basin. Different simulation results were acquired compared and analyzed. The study concluded that better simulation results were obtained with MMS-PRMS using integrated spatially distributed precipitation data, which was not available as a standard NOAA product. For a large basin, it is necessary to collect precipitation data within the area of interest in addition to standard NOAA data to produce an accurate hydrological model. It was suggested that to guarantee the quality of precipitation-runoff simulation using MMS-PRMS, the coverage of each rain gage should not be larger than 40 to 50 square kilometers (about 15-20 square miles). It was also learned that the precipitation data from local supplementary measurements are unlikely to be a satisfactory substitute for current NOAA data in hydrological simulation due to the short time period of measurement. The combination of standard NOAA data and additional data from an intensively measured site, such as CASES, or from radar, would allow more for better simulation. Title: Evaluation of precipitation data applied to hydrological simulation using MMS-PRMS for the Whitewater River Basin in Kansas Author: Lin, Wei Precipitation is one of the most important components contributing to hydrological dynamics. Spatially distributed precipitation data can be obtained by satellite, radar, rain gages, etc, to serve various purposes. Currently, the most commonly used precipitation data still rely on gage-based measurement techniques that provide timely precipitation information with high quality and reliability. The National Oceanic and Atmospheric Administration (NOAA) and its cooperative climate stations are the primary resources of this form of precipitation data at the federal level. For hydrological simulation of precipitation-runoff for a watershed, precipitation is a critical model input that has a significant impact on the certainty and accuracy of simulation. To better understand the hydrological process within Whitewater River Basin in Kansas, the Precipitation-Runoff Model System (PRMS) was applied to this area, where the Cooperative Atmosphere-Surface Exchange Study (CASES) has set up an intensively instrumented site managed by Hydrologic Science Team (HST) of Oregon State University for rainfall data collection. Two rainfall data sources, NOAA and HST, were used in this study to simulate the stream response to rainfall within the basin. Different simulation results were acquired compared and analyzed. The study concluded that better simulation results were obtained with MMS-PRMS using integrated spatially distributed precipitation data, which was not available as a standard NOAA product. For a large basin, it is necessary to collect precipitation data within the area of interest in addition to standard NOAA data to produce an accurate hydrological model. It was suggested that to guarantee the quality of precipitation-runoff simulation using MMS-PRMS, the coverage of each rain gage should not be larger than 40 to 50 square kilometers (about 15-20 square miles). It was also learned that the precipitation data from local supplementary measurements are unlikely to be a satisfactory substitute for current NOAA data in hydrological simulation due to the short time period of measurement. The combination of standard NOAA data and additional data from an intensively measured site, such as CASES, or from radar, would allow more for better simulation. Close

• 4. [Article] An analysis of the distribution of precipitation and runoff from the historical record for the continental United States

  Characterizing the distribution of precipitation at regional scales is a requirement for the development of regional scale, spatially distributed hydrologic water balance models. This study performs a ...

  Citation × Citation Citation Abstract Copy Title: An analysis of the distribution of precipitation and runoff from the historical record for the continental United States Author: Dolph, Jayne Ellen Characterizing the distribution of precipitation at regional scales is a requirement for the development of regional scale, spatially distributed hydrologic water balance models. This study performs a preliminary assessment of the utility and limitations of historical hydro-meteorological data for providing spatially distributed precipitation estimates over large areas. The historical data are used in a spatial analysis to characterize regional patterns of precipitation and runoff across the conterminous United States. Precipitation and runoff "surfaces" generated from interpolation of point measurements capture broad regional patterns. A distributed water balance is calculated over the continent using long-term (1948 -1988) and seven-year (1982 -1988) annual average values to check the reliability of precipitation estimates. The resulting "input-output surfaces" illustrate the deficiency (low elevation bias) of historical precipitation measurements in the mountainous western United States where snowmelt is an important component of the annual runoff. The incorporation of high elevation snow measurements into the precipitation record for the seven-year average significantly improves the water budget estimates in these regions and enhances the utility of historical data for providing spatially distributed precipitation estimates at regional and continental scales. Title: An analysis of the distribution of precipitation and runoff from the historical record for the continental United States Author: Dolph, Jayne Ellen Characterizing the distribution of precipitation at regional scales is a requirement for the development of regional scale, spatially distributed hydrologic water balance models. This study performs a preliminary assessment of the utility and limitations of historical hydro-meteorological data for providing spatially distributed precipitation estimates over large areas. The historical data are used in a spatial analysis to characterize regional patterns of precipitation and runoff across the conterminous United States. Precipitation and runoff "surfaces" generated from interpolation of point measurements capture broad regional patterns. A distributed water balance is calculated over the continent using long-term (1948 -1988) and seven-year (1982 -1988) annual average values to check the reliability of precipitation estimates. The resulting "input-output surfaces" illustrate the deficiency (low elevation bias) of historical precipitation measurements in the mountainous western United States where snowmelt is an important component of the annual runoff. The incorporation of high elevation snow measurements into the precipitation record for the seven-year average significantly improves the water budget estimates in these regions and enhances the utility of historical data for providing spatially distributed precipitation estimates at regional and continental scales. Close

• 5. [Article] Fallow-cropping systems in the Pacific Northwest

  Information contained within documents may be obsolete. Please check for recent information at the OSU Extension Service website: http://extension.oregonstate.edu/catalog/results.php?cat=Agriculture

  Citation × Citation Citation Abstract Copy Title: Fallow-cropping systems in the Pacific Northwest Author: Glenn, David Michael, Bolton, Floyd E. Information contained within documents may be obsolete. Please check for recent information at the OSU Extension Service website: http://extension.oregonstate.edu/catalog/results.php?cat=Agriculture Title: Fallow-cropping systems in the Pacific Northwest Author: Glenn, David Michael, Bolton, Floyd E. Information contained within documents may be obsolete. Please check for recent information at the OSU Extension Service website: http://extension.oregonstate.edu/catalog/results.php?cat=Agriculture Close

• 6. [Article] Century-Long Variability and Trends in Daily Precipitation Characteristics at Three Finnish Stations

  Long-term variations and trends in a wide range of statistics for daily precipitation characteristics in terms of intensity, frequency and duration in Finland were analysed using precipitation records ...

  Citation × Citation Citation Abstract Copy Title: Century-Long Variability and Trends in Daily Precipitation Characteristics at Three Finnish Stations Author: Irannezhad, Masoud, Marttila, Hannu, De-liang, Chen, Kløve, Bjørn Year: 2016 Long-term variations and trends in a wide range of statistics for daily precipitation characteristics in terms of intensity, frequency and duration in Finland were analysed using precipitation records during 1908－2008 from 3 meteorological stations in the south (Kaisaniemi), center (Kajaani) and north (Sodankylä). Although precipitation days in northern part were more frequent than in central and southern parts, daily precipitation intensity in the south was generally higher than those in the centre and north of the country. Annual sum of very light precipitation (0 mm < daily precipitation ≤ long-term 50th percentile of daily precipitation more than 0 mm) significantly (p Title: Century-Long Variability and Trends in Daily Precipitation Characteristics at Three Finnish Stations Author: Irannezhad, Masoud, Marttila, Hannu, De-liang, Chen, Kløve, Bjørn Year: 2016 Long-term variations and trends in a wide range of statistics for daily precipitation characteristics in terms of intensity, frequency and duration in Finland were analysed using precipitation records during 1908－2008 from 3 meteorological stations in the south (Kaisaniemi), center (Kajaani) and north (Sodankylä). Although precipitation days in northern part were more frequent than in central and southern parts, daily precipitation intensity in the south was generally higher than those in the centre and north of the country. Annual sum of very light precipitation (0 mm < daily precipitation ≤ long-term 50th percentile of daily precipitation more than 0 mm) significantly (p Close

• 7. [Article] The late spring secondary precipitation maximum in the interior Pacific Northwest

  The Late Spring Secondary Precipitation Maximum in the Interior Pacific Northwest results from a complex system of climatic controls. The Secondary Maximum is most strongly developed over the high plateau ...

  Citation × Citation Citation Abstract Copy Title: The late spring secondary precipitation maximum in the interior Pacific Northwest Author: Quinn, Robert The Late Spring Secondary Precipitation Maximum in the Interior Pacific Northwest results from a complex system of climatic controls. The Secondary Maximum is most strongly developed over the high plateau of Oregon immediately in the lee of the Cascade Mountains. Local topographic organization exerts strong control over the magnitude and timing of the secondary maximum in the inter-montane region. There is a detectable poleward shift of the precipitation maximum in the interior Northwest from April to June. A synoptic precipitation climatology was developed for the Pacific Northwest for the months of February to July. Surface and 500 millibar circulation maps indicate reorganization of atmospheric flow from strongly zonal flow in midwinter to more highly meridional flow in May and June. Precipitation producing synoptic disturbances manifest a decided evolution from those dominated by warm advection in winter to those dominated by strong, cool advection in May and June. Spokane radiosonde data indicate that increased destabilization of the atmosphere accompanied by increased precipitable moisture is primarily responsible for the increase in average rainfall in May and June. The Secondary Precipitation Maximum is characterized by an increase in precipitation intensity, but is not accompanied by an increase in precipitation frequency. A case history of an early and late spring precipitation producing synoptic sequence is presented. Seasonal changes in precipitation intensity west and east of the Cascades must be related to corresponding changes in the sensible and latent heat budget of the region. Average monthly equivalent potential temperature data indicate pronounced reorganization of the surface temperature field west and east of the Cascades during the period of February to July. Large sensible and latent heat additions occur east of the Cascades in May and June and should be effective in destabilizing maritime polar air masses moving across the interior. Title: The late spring secondary precipitation maximum in the interior Pacific Northwest Author: Quinn, Robert The Late Spring Secondary Precipitation Maximum in the Interior Pacific Northwest results from a complex system of climatic controls. The Secondary Maximum is most strongly developed over the high plateau of Oregon immediately in the lee of the Cascade Mountains. Local topographic organization exerts strong control over the magnitude and timing of the secondary maximum in the inter-montane region. There is a detectable poleward shift of the precipitation maximum in the interior Northwest from April to June. A synoptic precipitation climatology was developed for the Pacific Northwest for the months of February to July. Surface and 500 millibar circulation maps indicate reorganization of atmospheric flow from strongly zonal flow in midwinter to more highly meridional flow in May and June. Precipitation producing synoptic disturbances manifest a decided evolution from those dominated by warm advection in winter to those dominated by strong, cool advection in May and June. Spokane radiosonde data indicate that increased destabilization of the atmosphere accompanied by increased precipitable moisture is primarily responsible for the increase in average rainfall in May and June. The Secondary Precipitation Maximum is characterized by an increase in precipitation intensity, but is not accompanied by an increase in precipitation frequency. A case history of an early and late spring precipitation producing synoptic sequence is presented. Seasonal changes in precipitation intensity west and east of the Cascades must be related to corresponding changes in the sensible and latent heat budget of the region. Average monthly equivalent potential temperature data indicate pronounced reorganization of the surface temperature field west and east of the Cascades during the period of February to July. Large sensible and latent heat additions occur east of the Cascades in May and June and should be effective in destabilizing maritime polar air masses moving across the interior. Close

• 8. [Article] An investigation of precipitation from solid solution in an aluminum-magnesium-silicon alloy using x-ray diffraction techniques

  The thesis was an investigation into the mechanism of precipitation from solid solution in an Aluminum-0.7% Magnesium-0.6% Silicon alloy containing iron impurities. Laue x-ray diffraction patterns were ...

  Citation × Citation Citation Abstract Copy Title: An investigation of precipitation from solid solution in an aluminum-magnesium-silicon alloy using x-ray diffraction techniques Author: Guthrie, J. L. (James Leonard), 1937- The thesis was an investigation into the mechanism of precipitation from solid solution in an Aluminum-0.7% Magnesium-0.6% Silicon alloy containing iron impurities. Laue x-ray diffraction patterns were obtained from solution heat treated and aged single crystal specimens in various crystallographic orientations. Precipitation related streaking was detected on some of the patterns from aged specimens. From an analysis of the streaking it was concluded that precipitate stringlets formed during the early stages of precipitation and that the stringlets were coherent with the solid solution in the <100> directions. From the experimental results it was not possible to determine the degree of strengthening due to coherency. Title: An investigation of precipitation from solid solution in an aluminum-magnesium-silicon alloy using x-ray diffraction techniques Author: Guthrie, J. L. (James Leonard), 1937- The thesis was an investigation into the mechanism of precipitation from solid solution in an Aluminum-0.7% Magnesium-0.6% Silicon alloy containing iron impurities. Laue x-ray diffraction patterns were obtained from solution heat treated and aged single crystal specimens in various crystallographic orientations. Precipitation related streaking was detected on some of the patterns from aged specimens. From an analysis of the streaking it was concluded that precipitate stringlets formed during the early stages of precipitation and that the stringlets were coherent with the solid solution in the <100> directions. From the experimental results it was not possible to determine the degree of strengthening due to coherency. Close

• 9. [Article] Frequency Modes of Monsoon Precipitation in Arizona and New Mexico

  The interannual and intraseasonal variability of the North American monsoon is of great interest because a large proportion of the annual precipitation for Arizona and New Mexico arrives during the summer ...

  Citation × Citation Citation Abstract Copy Title: Frequency Modes of Monsoon Precipitation in Arizona and New Mexico Author: Hall-McKim, Eileen A., Nolin, Anne W. The interannual and intraseasonal variability of the North American monsoon is of great interest because a large proportion of the annual precipitation for Arizona and New Mexico arrives during the summer monsoon. Forty-one years of daily monsoon season precipitation data for Arizona and New Mexico were studied using wavelet analysis. This time-localized spectral analysis method reveals that periodicities of less than 8 days are positively correlated with mean daily precipitation during the 1 July–15 September monsoon period. Roughly 17% of the years indicate no significant periodicity during the monsoon period for either region and are associated with low monsoon precipitation. High- and low-frequency modes explain an equivalent percentage of the variance in monsoon precipitation in both Arizona and New Mexico, and in many years concurrent multiple periodicities occur. Wavelet analysis was effective in identifying the contribution of high-frequency modes that had not been discerned in previous studies. These results suggest that precipitation processes during the monsoon season are modulated by phenomena operating at synoptic (2–8 days) and longer (>8 days) time scales and point to the need for further studies to better understand the associated atmospheric processes. Title: Frequency Modes of Monsoon Precipitation in Arizona and New Mexico Author: Hall-McKim, Eileen A., Nolin, Anne W. The interannual and intraseasonal variability of the North American monsoon is of great interest because a large proportion of the annual precipitation for Arizona and New Mexico arrives during the summer monsoon. Forty-one years of daily monsoon season precipitation data for Arizona and New Mexico were studied using wavelet analysis. This time-localized spectral analysis method reveals that periodicities of less than 8 days are positively correlated with mean daily precipitation during the 1 July–15 September monsoon period. Roughly 17% of the years indicate no significant periodicity during the monsoon period for either region and are associated with low monsoon precipitation. High- and low-frequency modes explain an equivalent percentage of the variance in monsoon precipitation in both Arizona and New Mexico, and in many years concurrent multiple periodicities occur. Wavelet analysis was effective in identifying the contribution of high-frequency modes that had not been discerned in previous studies. These results suggest that precipitation processes during the monsoon season are modulated by phenomena operating at synoptic (2–8 days) and longer (>8 days) time scales and point to the need for further studies to better understand the associated atmospheric processes. Close

• 10. [Article] Paired stable isotopologues in precipitation and vapor: A case study of the amount effect within western tropical Pacific storms

  Access to this item has been restricted by repository administrators at the request of the publisher until October 16, 2016.

  Citation × Citation Citation Abstract Copy Title: Paired stable isotopologues in precipitation and vapor: A case study of the amount effect within western tropical Pacific storms Author: Noone, David, Cobb, Kim M., Conroy, Jessica L., Konecky, Bronwen L., Moerman, Jessica W. Access to this item has been restricted by repository administrators at the request of the publisher until October 16, 2016. Title: Paired stable isotopologues in precipitation and vapor: A case study of the amount effect within western tropical Pacific storms Author: Noone, David, Cobb, Kim M., Conroy, Jessica L., Konecky, Bronwen L., Moerman, Jessica W. Access to this item has been restricted by repository administrators at the request of the publisher until October 16, 2016. Close

• 11. [Article] Investigating the Impact of Remotely Sensed Precipitation and Hydrologic Model Uncertainties on the Ensemble Streamflow Forecasting

  In the past few years sequential data assimilation (SDA) methods have emerged as the best possible method at hand to properly treat all sources of error in hydrological modeling. However, very few studies ...

  Citation × Citation Citation Abstract Copy Title: Investigating the Impact of Remotely Sensed Precipitation and Hydrologic Model Uncertainties on the Ensemble Streamflow Forecasting Author: Moradkhani, Hamid, Hsu, K., Hong, Y., Sorooshian, S. Year: 2006 In the past few years sequential data assimilation (SDA) methods have emerged as the best possible method at hand to properly treat all sources of error in hydrological modeling. However, very few studies have actually implemented SDA methods using realistic input error models for precipitation. In this study we use particle filtering as a SDA method to propagate input errors through a conceptual hydrologic model and quantify the state, parameter and streamflow uncertainties. Recent progress in satellite-based precipitation observation techniques offers an attractive option for considering spatiotemporal variation of precipitation. Therefore, we use the PERSIANN-CCS precipitation product to propagate input errors through our hydrologic model. Some uncertainty scenarios are set up to incorporate and investigate the impact of the individual uncertainty sources from precipitation, parameters and also combined error sources on the hydrologic response. Also probabilistic measures are used to quantify the quality of ensemble prediction. Title: Investigating the Impact of Remotely Sensed Precipitation and Hydrologic Model Uncertainties on the Ensemble Streamflow Forecasting Author: Moradkhani, Hamid, Hsu, K., Hong, Y., Sorooshian, S. Year: 2006 In the past few years sequential data assimilation (SDA) methods have emerged as the best possible method at hand to properly treat all sources of error in hydrological modeling. However, very few studies have actually implemented SDA methods using realistic input error models for precipitation. In this study we use particle filtering as a SDA method to propagate input errors through a conceptual hydrologic model and quantify the state, parameter and streamflow uncertainties. Recent progress in satellite-based precipitation observation techniques offers an attractive option for considering spatiotemporal variation of precipitation. Therefore, we use the PERSIANN-CCS precipitation product to propagate input errors through our hydrologic model. Some uncertainty scenarios are set up to incorporate and investigate the impact of the individual uncertainty sources from precipitation, parameters and also combined error sources on the hydrologic response. Also probabilistic measures are used to quantify the quality of ensemble prediction. Close

• 12. [Article] Three Recent Flavors of Drought in the Pacific Northwest

  In common with much of the western United States, the Pacific Northwest (defined in this paper as Washington and Oregon) has experienced an unusual number of droughts in the past decade. This paper describes ...

  Citation × Citation Citation Abstract Copy Title: Three Recent Flavors of Drought in the Pacific Northwest Author: Bumbaco, Karin A., Mote, Philip W. In common with much of the western United States, the Pacific Northwest (defined in this paper as Washington and Oregon) has experienced an unusual number of droughts in the past decade. This paper describes three of these droughts in terms of the precipitation, temperature, and soil moisture anomalies, and discusses different drought impacts experienced in the Pacific Northwest (PNW). For the first drought, in 2001, low winter precipitation in the PNW produced very low streamflow that primarily affected farmers and hydropower generation. For the second, in 2003, low summer precipitation in Washington (WA), and low summer precipitation and a warm winter in Oregon (OR) primarily affected streamflow and forests. For the last, in 2005, a lack of snowpack due to warm temperatures during significant winter precipitation events in WA, and low winter precipitation in OR, had a variety of different agricultural and hydrologic impacts. Although the proximal causes of droughts are easily quantified, the ultimate causes are not as clear. Better precipitation observations in the PNW are required to provide timely monitoring of conditions leading to droughts to improve prediction in the future Title: Three Recent Flavors of Drought in the Pacific Northwest Author: Bumbaco, Karin A., Mote, Philip W. In common with much of the western United States, the Pacific Northwest (defined in this paper as Washington and Oregon) has experienced an unusual number of droughts in the past decade. This paper describes three of these droughts in terms of the precipitation, temperature, and soil moisture anomalies, and discusses different drought impacts experienced in the Pacific Northwest (PNW). For the first drought, in 2001, low winter precipitation in the PNW produced very low streamflow that primarily affected farmers and hydropower generation. For the second, in 2003, low summer precipitation in Washington (WA), and low summer precipitation and a warm winter in Oregon (OR) primarily affected streamflow and forests. For the last, in 2005, a lack of snowpack due to warm temperatures during significant winter precipitation events in WA, and low winter precipitation in OR, had a variety of different agricultural and hydrologic impacts. Although the proximal causes of droughts are easily quantified, the ultimate causes are not as clear. Better precipitation observations in the PNW are required to provide timely monitoring of conditions leading to droughts to improve prediction in the future Close

• 13. [Article] Estimating the economic net returns of Oregon & Washington forests with regard to climate change

  Little work has been conducted regarding the net returns of forest lands. The Ricardian model is ripe with potential to estimate the effects of climate on net returns to forestry. Multiple linear regression ...

  Citation × Citation Citation Abstract Copy Title: Estimating the economic net returns of Oregon & Washington forests with regard to climate change Author: Johnson, Zoe I. Little work has been conducted regarding the net returns of forest lands. The Ricardian model is ripe with potential to estimate the effects of climate on net returns to forestry. Multiple linear regression allows each climate variable to measure its effect of net returns with the assumption of all other factors being fixed. Independent variables of average temperature (°C), average temperature squared (°C²), average precipitation (mm), average precipitation squared (mm2), maximum August temperature (°C), and minimum December temperature (°C) were scaled by year using dummy variables to output the dependent variable of real net returns (USD 2010) per county of tree species. This OLS linear regression showed annual precipitation, marginal precipitation, and maximum temperature experienced by forests to affect the net returns they produced. Increased precipitation is expected to increase net returns to forests while higher maximum temperatures will negatively impact net returns in Douglas Fir regions and positively affect pine regions. Precipitation is linearly related to forest net returns, while temperature is not linearly related. With this finding, various areas of Oregon and Washington that are expected to experience heavier precipitation due to climate change should expect more net returns from their forestlands. Title: Estimating the economic net returns of Oregon & Washington forests with regard to climate change Author: Johnson, Zoe I. Little work has been conducted regarding the net returns of forest lands. The Ricardian model is ripe with potential to estimate the effects of climate on net returns to forestry. Multiple linear regression allows each climate variable to measure its effect of net returns with the assumption of all other factors being fixed. Independent variables of average temperature (°C), average temperature squared (°C²), average precipitation (mm), average precipitation squared (mm2), maximum August temperature (°C), and minimum December temperature (°C) were scaled by year using dummy variables to output the dependent variable of real net returns (USD 2010) per county of tree species. This OLS linear regression showed annual precipitation, marginal precipitation, and maximum temperature experienced by forests to affect the net returns they produced. Increased precipitation is expected to increase net returns to forests while higher maximum temperatures will negatively impact net returns in Douglas Fir regions and positively affect pine regions. Precipitation is linearly related to forest net returns, while temperature is not linearly related. With this finding, various areas of Oregon and Washington that are expected to experience heavier precipitation due to climate change should expect more net returns from their forestlands. Close

• 14. [Article] Characterizing Rain/snow Partitioning in Mountain Watersheds for Present-day and Future Projected Climates

  Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR.

  Citation × Citation Citation Abstract Copy Title: Characterizing Rain/snow Partitioning in Mountain Watersheds for Present-day and Future Projected Climates Author: Sproles, Eric A., Nolin, Anne W. Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Title: Characterizing Rain/snow Partitioning in Mountain Watersheds for Present-day and Future Projected Climates Author: Sproles, Eric A., Nolin, Anne W. Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Close

• 15. [Article] Intraseasonal Variability of the West African Monsoon and Atlantic ITCZ

  Intraseasonal variability of boreal summer rainfall and winds in tropical West Africa and the east Atlantic is examined using daily Tropical Rainfall Measuring Mission (TRMM) precipitation and the NCEP–NCAR ...

  Citation × Citation Citation Abstract Copy Title: Intraseasonal Variability of the West African Monsoon and Atlantic ITCZ Author: Maloney, Eric D., Shaman, Jeffrey Intraseasonal variability of boreal summer rainfall and winds in tropical West Africa and the east Atlantic is examined using daily Tropical Rainfall Measuring Mission (TRMM) precipitation and the NCEP–NCAR reanalysis during 1998–2006. Intraseasonal precipitation variability is dominated by two significant spectral peaks at time scales near 15 and 50 days, accompanied by corresponding peaks in eddy kinetic energy (EKE) and eddy enstrophy. Regional precipitation variability on 30–90-day time scales is significantly correlated (+0.6) with a global Madden–Julian oscillation time series based on equatorial zonal winds, supporting the results of A. J. Matthews. The overall amplitude of the 30–90-day West African monsoon precipitation variability during a given summer, however, does not appear to be strongly regulated by interannual variability in MJO amplitude. Composite analysis and complex empirical orthogonal function analysis shows that 30–90-day precipitation anomalies are generally zonally elongated, grow and decay in place, and have maximum amplitude near the Gulf of Guinea and in the Atlantic ITCZ. Composite 30–90-day enhanced precipitation events are accompanied by a significant suppression of eastern North Atlantic trade winds. Suppressed 30–90-day precipitation events are associated with an enhancement of the Atlantic trade winds. Enhanced (suppressed) EKE occurs just to the north of the east Atlantic ITCZ during positive (negative) 30–90-day precipitation events, with the maximum EKE magnitude lagging precipitation events by about 5 days. East Atlantic tropical cyclone activity is significantly modulated on intraseasonal time scales. The number of tropical cyclones that occur in the Atlantic’s main development region to the east of 60°W is suppressed about 5–10 days before maxima in a regional intraseasonal precipitation time series, and enhanced about 5–10 days after time series maxima. An analysis of east Atlantic tropical cyclone activity based on an equatorial MJO index produces similar results. Consistent with the results of K. C. Mo, variations in vertical shear may help explain this modulation of tropical cyclone activity. Title: Intraseasonal Variability of the West African Monsoon and Atlantic ITCZ Author: Maloney, Eric D., Shaman, Jeffrey Intraseasonal variability of boreal summer rainfall and winds in tropical West Africa and the east Atlantic is examined using daily Tropical Rainfall Measuring Mission (TRMM) precipitation and the NCEP–NCAR reanalysis during 1998–2006. Intraseasonal precipitation variability is dominated by two significant spectral peaks at time scales near 15 and 50 days, accompanied by corresponding peaks in eddy kinetic energy (EKE) and eddy enstrophy. Regional precipitation variability on 30–90-day time scales is significantly correlated (+0.6) with a global Madden–Julian oscillation time series based on equatorial zonal winds, supporting the results of A. J. Matthews. The overall amplitude of the 30–90-day West African monsoon precipitation variability during a given summer, however, does not appear to be strongly regulated by interannual variability in MJO amplitude. Composite analysis and complex empirical orthogonal function analysis shows that 30–90-day precipitation anomalies are generally zonally elongated, grow and decay in place, and have maximum amplitude near the Gulf of Guinea and in the Atlantic ITCZ. Composite 30–90-day enhanced precipitation events are accompanied by a significant suppression of eastern North Atlantic trade winds. Suppressed 30–90-day precipitation events are associated with an enhancement of the Atlantic trade winds. Enhanced (suppressed) EKE occurs just to the north of the east Atlantic ITCZ during positive (negative) 30–90-day precipitation events, with the maximum EKE magnitude lagging precipitation events by about 5 days. East Atlantic tropical cyclone activity is significantly modulated on intraseasonal time scales. The number of tropical cyclones that occur in the Atlantic’s main development region to the east of 60°W is suppressed about 5–10 days before maxima in a regional intraseasonal precipitation time series, and enhanced about 5–10 days after time series maxima. An analysis of east Atlantic tropical cyclone activity based on an equatorial MJO index produces similar results. Consistent with the results of K. C. Mo, variations in vertical shear may help explain this modulation of tropical cyclone activity. Close

• 16. [Article] The relationship of precipitation in the western United States to variations in the outgoing long-wave radiation field over the tropical Pacific : the role of the mid-latitude circulation

  The relationship between the outgoing long-wave radiation (OLR) field over the tropical Pacific and wintertime monthly precipitation for the western U. S. is investigated, using the mid-latitude upper-air ...

  Citation × Citation Citation Abstract Copy Title: The relationship of precipitation in the western United States to variations in the outgoing long-wave radiation field over the tropical Pacific : the role of the mid-latitude circulation Author: Twining, David S. The relationship between the outgoing long-wave radiation (OLR) field over the tropical Pacific and wintertime monthly precipitation for the western U. S. is investigated, using the mid-latitude upper-air circulation as an intermediary. Principal components (PC's) of the 500mb monthly averaged height field over the NE Pacific and western North America are compared with those of the monthly tropical Pacific OLR field. It is found that, of the first 6 PC's of the height field, five are correlated significantly with the first 3 OLR field PC's at lags of between two and six months. Canonical correlations between the two sets of PC's are greatest at a lag of four months and are highly significant. When stratified by different levels of the OLR field PC's, the separations between means of the height field PC's are highly significant as well. Differing distributions of the height field PC ensemble are also found to be associated with different OLR field PC levels. The relationship between the 500mb height field and concurrent western district precipitation is examined. Using a hybrid model including both linear statistical and non-linear physical components it is found that considerably more of the variance in the precipitation can be explained by that of the height field alone than when the precipitation is inferred directly from a linear statistical model. A set of reconstructed height field PC's is predicted from OLR values based on the height field/OLR stratification associations compiled for a period separate from that of the forecast. Applied to the precipitation model, this results in predicted western district precipitation which is better correlated with the observations than is the equivalent precipitation forecast from the linear statistical relationship of precipitation to the Southern Oscillation Index. Title: The relationship of precipitation in the western United States to variations in the outgoing long-wave radiation field over the tropical Pacific : the role of the mid-latitude circulation Author: Twining, David S. The relationship between the outgoing long-wave radiation (OLR) field over the tropical Pacific and wintertime monthly precipitation for the western U. S. is investigated, using the mid-latitude upper-air circulation as an intermediary. Principal components (PC's) of the 500mb monthly averaged height field over the NE Pacific and western North America are compared with those of the monthly tropical Pacific OLR field. It is found that, of the first 6 PC's of the height field, five are correlated significantly with the first 3 OLR field PC's at lags of between two and six months. Canonical correlations between the two sets of PC's are greatest at a lag of four months and are highly significant. When stratified by different levels of the OLR field PC's, the separations between means of the height field PC's are highly significant as well. Differing distributions of the height field PC ensemble are also found to be associated with different OLR field PC levels. The relationship between the 500mb height field and concurrent western district precipitation is examined. Using a hybrid model including both linear statistical and non-linear physical components it is found that considerably more of the variance in the precipitation can be explained by that of the height field alone than when the precipitation is inferred directly from a linear statistical model. A set of reconstructed height field PC's is predicted from OLR values based on the height field/OLR stratification associations compiled for a period separate from that of the forecast. Applied to the precipitation model, this results in predicted western district precipitation which is better correlated with the observations than is the equivalent precipitation forecast from the linear statistical relationship of precipitation to the Southern Oscillation Index. Close

• 17. [Article] Construction of a model organism for performing calcium carbonate precipitation in a porous media reactor

  Aquifers are an important storage location and source of fresh groundwater. They may become polluted by a number of contaminants including mobile divalent radionuclides such as strontium-90 which is a ...

  Citation × Citation Citation Abstract Copy Title: Construction of a model organism for performing calcium carbonate precipitation in a porous media reactor Author: Kaufman, Megan J. Aquifers are an important storage location and source of fresh groundwater. They may become polluted by a number of contaminants including mobile divalent radionuclides such as strontium-90 which is a byproduct of uranium fission. A method for remediating such divalent radionuclides is sequestration through co-precipitation into calcium carbonate. Calcium carbonate precipitation occurs naturally but can be enhanced by the use of ureolytic microorganisms living within the aquifer. The microbial enzyme urease cleaves ammonia from urea (added as a stimulant to the aquifer) increasing the pH and subsequently pushing the bicarbonate equilibrium towards precipitation. Laboratory experimentation is necessary to better predict field scale outcomes of remediation that is driven by ureolytic calcium carbonate co-precipitation. To aid in such laboratory experiments, I constructed two ureolytic organisms which contain green fluorescent protein (GFP) so that the location of the microbes in relation to media flow paths and precipitation can be viewed by microscopy in a 2- dimensional porous medium flow cell reactor. The reactor was operated with a parallel flow regime where the two influent media would not promote microbially induced calcium carbonate precipitation until they were mixed in the flow cell. A demonstration study compared the results of parallel flow and mixing in the reactor operated with and without one of the GFP-containing ureolytic organisms. The growth and precipitation of calcium carbonate within the reactor pore space altered flow paths to promote a wider mixing zone and a more widely distributed overall calcium carbonate precipitation pattern. This study will allow optimization of remediation efforts of contaminants such as strontium-90 in aquifers. Title: Construction of a model organism for performing calcium carbonate precipitation in a porous media reactor Author: Kaufman, Megan J. Aquifers are an important storage location and source of fresh groundwater. They may become polluted by a number of contaminants including mobile divalent radionuclides such as strontium-90 which is a byproduct of uranium fission. A method for remediating such divalent radionuclides is sequestration through co-precipitation into calcium carbonate. Calcium carbonate precipitation occurs naturally but can be enhanced by the use of ureolytic microorganisms living within the aquifer. The microbial enzyme urease cleaves ammonia from urea (added as a stimulant to the aquifer) increasing the pH and subsequently pushing the bicarbonate equilibrium towards precipitation. Laboratory experimentation is necessary to better predict field scale outcomes of remediation that is driven by ureolytic calcium carbonate co-precipitation. To aid in such laboratory experiments, I constructed two ureolytic organisms which contain green fluorescent protein (GFP) so that the location of the microbes in relation to media flow paths and precipitation can be viewed by microscopy in a 2- dimensional porous medium flow cell reactor. The reactor was operated with a parallel flow regime where the two influent media would not promote microbially induced calcium carbonate precipitation until they were mixed in the flow cell. A demonstration study compared the results of parallel flow and mixing in the reactor operated with and without one of the GFP-containing ureolytic organisms. The growth and precipitation of calcium carbonate within the reactor pore space altered flow paths to promote a wider mixing zone and a more widely distributed overall calcium carbonate precipitation pattern. This study will allow optimization of remediation efforts of contaminants such as strontium-90 in aquifers. Close

• 18. [Article] Precipitation efficiency derived from isotope ratios in water vapor distinguishes dynamical and microphysical influences on subtropical atmospheric constituents

  This is the publisher’s final pdf. The article is copyrighted by American Geophysical Union and published by John Wiley & Sons, Inc. It can be found at: http://agupubs.onlinelibrary.wiley.com/agu/jgr/j...

  Citation × Citation Citation Abstract Copy Title: Precipitation efficiency derived from isotope ratios in water vapor distinguishes dynamical and microphysical influences on subtropical atmospheric constituents Author: Bailey, A., Nusbaumer, J., Noone, D. This is the publisher’s final pdf. The article is copyrighted by American Geophysical Union and published by John Wiley & Sons, Inc. It can be found at: http://agupubs.onlinelibrary.wiley.com/agu/jgr/journal/10.1002/%28ISSN%292169-8996/ Title: Precipitation efficiency derived from isotope ratios in water vapor distinguishes dynamical and microphysical influences on subtropical atmospheric constituents Author: Bailey, A., Nusbaumer, J., Noone, D. This is the publisher’s final pdf. The article is copyrighted by American Geophysical Union and published by John Wiley & Sons, Inc. It can be found at: http://agupubs.onlinelibrary.wiley.com/agu/jgr/journal/10.1002/%28ISSN%292169-8996/ Close

• 19. [Article] Sensitivity of Columbia Basin Runoff to Long-Term Changes in Multi-Model CMIP5 Precipitation Simulations

  In this study, we used precipitation elasticity index of streamflow, to reflect on the sensitivity of streamflow to changes in future precipitation. We estimated precipitation elasticity of streamflow ...

  Citation × Citation Citation Abstract Copy Title: Sensitivity of Columbia Basin Runoff to Long-Term Changes in Multi-Model CMIP5 Precipitation Simulations Author: Demirel, Mehmet, Moradkhani, Hamid Year: 2014 In this study, we used precipitation elasticity index of streamflow, to reflect on the sensitivity of streamflow to changes in future precipitation. We estimated precipitation elasticity of streamflow from: (1) simulated streamflow by the VIC model using observed precipitation for the current climate (1963–2003); (2) simulated streamflow by the VIC model using simulated precipitation from 10 GCM - CMIP5 dataset for the future climate (2010–2099) including two different pathways (RCP4.5 and RCP8.5) and two different downscaled products (BCSD and MACA). The hydrological model was calibrated at 1/16 latitude-longitude resolution and the simulated streamflow was routed to the subbasin outlets of interest i.e. Hungry Horse subbasin. We used hydrological model simulations from 19063-2003 and calculated streamflow sensitivities and precipitation elasticity for the same period using observed climate (case 1) and simulated climate (case 2). The runoff sensitivity to long-term (e.g., 30-year) average annual changes in precipitation is calculated based on the elasticity of streamflow for three different 30 year blocks (2010-40, 2040-70 and 2070-99), which are of importance to reservoir management in the Columbia River basin. These two cases and different periods are compared to assess the effects of forcing by different climate models and different pathways on the precipitation elasticity of streamflow. Title: Sensitivity of Columbia Basin Runoff to Long-Term Changes in Multi-Model CMIP5 Precipitation Simulations Author: Demirel, Mehmet, Moradkhani, Hamid Year: 2014 In this study, we used precipitation elasticity index of streamflow, to reflect on the sensitivity of streamflow to changes in future precipitation. We estimated precipitation elasticity of streamflow from: (1) simulated streamflow by the VIC model using observed precipitation for the current climate (1963–2003); (2) simulated streamflow by the VIC model using simulated precipitation from 10 GCM - CMIP5 dataset for the future climate (2010–2099) including two different pathways (RCP4.5 and RCP8.5) and two different downscaled products (BCSD and MACA). The hydrological model was calibrated at 1/16 latitude-longitude resolution and the simulated streamflow was routed to the subbasin outlets of interest i.e. Hungry Horse subbasin. We used hydrological model simulations from 19063-2003 and calculated streamflow sensitivities and precipitation elasticity for the same period using observed climate (case 1) and simulated climate (case 2). The runoff sensitivity to long-term (e.g., 30-year) average annual changes in precipitation is calculated based on the elasticity of streamflow for three different 30 year blocks (2010-40, 2040-70 and 2070-99), which are of importance to reservoir management in the Columbia River basin. These two cases and different periods are compared to assess the effects of forcing by different climate models and different pathways on the precipitation elasticity of streamflow. Close

• 20. [Article] Evaluation of a probabilistic quantitative precipitation forecasting experiment

  Forecasts of the likelihood of occurrence of various amounts of precipitation are very important, since excessive precipitation amounts over relatively short time periods can have adverse effects on public ...

  Citation × Citation Citation Abstract Copy Title: Evaluation of a probabilistic quantitative precipitation forecasting experiment Author: Hsu, Wu-ron Forecasts of the likelihood of occurrence of various amounts of precipitation are very important, since excessive precipitation amounts over relatively short time periods can have adverse effects on public safety and economic efficiency, As a result, forecasters at the National Weather Service Forecast Office in San Antonio, Texas were asked to formulate subjective probabilistic quantitative precipitation forecasts on an experimental basis beginning in February 1981. This study describes methods of evaluating probability forecasts of this ordinal variable and presents some results of the first year of the experiment. Scalar and vector evaluation procedures are described. In the case of scalar evaluation, the inclusion of a no-skill line and a no-correlation line on reliability diagrams is helpful in representing the skill, reliability, and resolution qeometrically in two-state situations. Geometrical interpretations of attributes of forecasts can also be accomplished in three-state situations based on vector evaluation procedures. A skill score for subsample forecasts is shown to be useful in identifying systematic errors made by forecasters or forecast systems. A beta model is developed to obtain a forecaster's predictive distributions (i.e., the distribution of use of probability values). The experimental results show that the skill of the subjective forecasts is generally higher than the skill of objective guidance forecasts for measurable precipitation (i.e., precipitation amounts exceeding a threshold of 0.01 inches), but that the opposite is true for threshold associated with larger precipitation amounts. This result is due primarily to the forecaster's tendency to over forecast for the events associated with higher precipitation thresholds. The tendency to over forecast is most pronounced in the nighttime forecasts and in the forecasts for drier stations. The MCS objective guidance forecasts, on the other hand, are quite reliable for both periods and all stations. The vector evaluation approach indicates that the degree of overforecasting is quite high for bimodal forecasts and that the skill contribution from bimodal forecasts is negative in many cases. Title: Evaluation of a probabilistic quantitative precipitation forecasting experiment Author: Hsu, Wu-ron Forecasts of the likelihood of occurrence of various amounts of precipitation are very important, since excessive precipitation amounts over relatively short time periods can have adverse effects on public safety and economic efficiency, As a result, forecasters at the National Weather Service Forecast Office in San Antonio, Texas were asked to formulate subjective probabilistic quantitative precipitation forecasts on an experimental basis beginning in February 1981. This study describes methods of evaluating probability forecasts of this ordinal variable and presents some results of the first year of the experiment. Scalar and vector evaluation procedures are described. In the case of scalar evaluation, the inclusion of a no-skill line and a no-correlation line on reliability diagrams is helpful in representing the skill, reliability, and resolution qeometrically in two-state situations. Geometrical interpretations of attributes of forecasts can also be accomplished in three-state situations based on vector evaluation procedures. A skill score for subsample forecasts is shown to be useful in identifying systematic errors made by forecasters or forecast systems. A beta model is developed to obtain a forecaster's predictive distributions (i.e., the distribution of use of probability values). The experimental results show that the skill of the subjective forecasts is generally higher than the skill of objective guidance forecasts for measurable precipitation (i.e., precipitation amounts exceeding a threshold of 0.01 inches), but that the opposite is true for threshold associated with larger precipitation amounts. This result is due primarily to the forecaster's tendency to over forecast for the events associated with higher precipitation thresholds. The tendency to over forecast is most pronounced in the nighttime forecasts and in the forecasts for drier stations. The MCS objective guidance forecasts, on the other hand, are quite reliable for both periods and all stations. The vector evaluation approach indicates that the degree of overforecasting is quite high for bimodal forecasts and that the skill contribution from bimodal forecasts is negative in many cases. Close