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• 21. [Article] The effect of precipitation variation on soil moisture, soil nitrogen, nitrogen response and winter wheat yields in eastern Oregon

  The semi-arid regions of the Pacific Northwest are characterized by a high degree of annual temperature and precipitation variation. As a result of this climatic variation, dryland nitrogen fertilizer ...

  Citation × Citation Citation Abstract Copy Title: The effect of precipitation variation on soil moisture, soil nitrogen, nitrogen response and winter wheat yields in eastern Oregon Author: Glenn, D. M. (David Michael) The semi-arid regions of the Pacific Northwest are characterized by a high degree of annual temperature and precipitation variation. As a result of this climatic variation, dryland nitrogen fertilizer trials on fallow- ,wheat rotations typically demonstrate a variable response. Wheat growers in the area must not only cope with this climatic variation and its sundry effects upon their livelihood, they must also make decisions regarding the future level of anticipated climatic variation. The specific objectives were to: 1) develop a climatically responsive yield potential prediction model for soft white winter wheat from historical data at the Sherman Branch Experiment Station (Moro, OR); 2) modify this model for use on commercial fields; 3) field simulate five fallow-crop precipitation patterns characteristic of the variation found in the Sherman county area of eastern Oregon in order to test the yield potential model: 4) examine the effects of precipitation variation on nitrogen fertilizer responses, moisture storage and depletion and nitrogen mineralization; and 5) establish a quantitative relationship between precipitation/ soil moisture and nitrate accumulation in both the fallow and crop seasons. Two interacting regression models were developed to estimate grain yield levels in the 250-350 mm precipitation zone of eastern Oregon. The first model estimates yield potential from monthly precipitation and temperature values. The second model estimates the percent grain reduction due to delayed crop emergence. The grain yield model was adapted to commercial fields using a Productivity Index factor (PI). The PI is a measure of the productivity of other locations in relation to the Sherman Branch Experiment Station, using water-use-efficiency (WUE) as the basis of comparison. The field simulation of five fallow-crop precipitation patterns demonstrated that the maximum grain yield response occurred at 40 kg N (soil + fertilizer)/metric ton. The grain yield model demonstrated a 15% level of accuracy on a commercial field basis in both field trials and a survey of past production levels (1972-1980). It was hypothesized that the distribution of precipitation in the fallow and crop periods had an effect on both the amount and distribution of stored soil moisture. The field simulation demonstrated that more soil moisture was stored at the 90-240 cm depths by the patterns with more fallow season precipitation when measured in March of the crop year. Soil moisture storage and storage efficiencies fluctuated throughout the fallow and crop periods. At the cessation of the winter precipitation season in both the fallow and crop periods (March), the storage efficiency was highest when low levels of precipitation occurred. At this point in time, the mean crop period storage efficiency was 10% below the mean fallow period storage efficiency (34 and 44%, respectively) in both simulation studies. Soil moisture, temperature and immobilization requirements of crop residues interact to affect the net amount of nitrogen mineralization. The mineralization model proposed by Stanford and Smith (1972) was tested under field conditions. When the nitrogen immobilization requirement of the crop residues was included, the actual and predicted values were in agreement at the close of the 1978 fallow period. A nitrogen deficit was predicted at the 0-30 cm depth at the close of the 1980 fallow; however, the actual levels indicated a net accumulation of nitrate-nitrogen. Crop season mineralization, inferred from Mitscherlick and a-value extrapolations, in 1979 demonstrated that there was a decreasing amount of net mineralization during the crop season with increasing amounts of both fallow and crop season precipitation. Crop season mineralization in 1980 indicated that there was no net accumulation of nitrogen, rather a tie-up of 14 kg N/ha. This result reflects both the unsatisfied immobilization requirement predicted for the 1979 fallow season and crop season denitrification. Title: The effect of precipitation variation on soil moisture, soil nitrogen, nitrogen response and winter wheat yields in eastern Oregon Author: Glenn, D. M. (David Michael) The semi-arid regions of the Pacific Northwest are characterized by a high degree of annual temperature and precipitation variation. As a result of this climatic variation, dryland nitrogen fertilizer trials on fallow- ,wheat rotations typically demonstrate a variable response. Wheat growers in the area must not only cope with this climatic variation and its sundry effects upon their livelihood, they must also make decisions regarding the future level of anticipated climatic variation. The specific objectives were to: 1) develop a climatically responsive yield potential prediction model for soft white winter wheat from historical data at the Sherman Branch Experiment Station (Moro, OR); 2) modify this model for use on commercial fields; 3) field simulate five fallow-crop precipitation patterns characteristic of the variation found in the Sherman county area of eastern Oregon in order to test the yield potential model: 4) examine the effects of precipitation variation on nitrogen fertilizer responses, moisture storage and depletion and nitrogen mineralization; and 5) establish a quantitative relationship between precipitation/ soil moisture and nitrate accumulation in both the fallow and crop seasons. Two interacting regression models were developed to estimate grain yield levels in the 250-350 mm precipitation zone of eastern Oregon. The first model estimates yield potential from monthly precipitation and temperature values. The second model estimates the percent grain reduction due to delayed crop emergence. The grain yield model was adapted to commercial fields using a Productivity Index factor (PI). The PI is a measure of the productivity of other locations in relation to the Sherman Branch Experiment Station, using water-use-efficiency (WUE) as the basis of comparison. The field simulation of five fallow-crop precipitation patterns demonstrated that the maximum grain yield response occurred at 40 kg N (soil + fertilizer)/metric ton. The grain yield model demonstrated a 15% level of accuracy on a commercial field basis in both field trials and a survey of past production levels (1972-1980). It was hypothesized that the distribution of precipitation in the fallow and crop periods had an effect on both the amount and distribution of stored soil moisture. The field simulation demonstrated that more soil moisture was stored at the 90-240 cm depths by the patterns with more fallow season precipitation when measured in March of the crop year. Soil moisture storage and storage efficiencies fluctuated throughout the fallow and crop periods. At the cessation of the winter precipitation season in both the fallow and crop periods (March), the storage efficiency was highest when low levels of precipitation occurred. At this point in time, the mean crop period storage efficiency was 10% below the mean fallow period storage efficiency (34 and 44%, respectively) in both simulation studies. Soil moisture, temperature and immobilization requirements of crop residues interact to affect the net amount of nitrogen mineralization. The mineralization model proposed by Stanford and Smith (1972) was tested under field conditions. When the nitrogen immobilization requirement of the crop residues was included, the actual and predicted values were in agreement at the close of the 1978 fallow period. A nitrogen deficit was predicted at the 0-30 cm depth at the close of the 1980 fallow; however, the actual levels indicated a net accumulation of nitrate-nitrogen. Crop season mineralization, inferred from Mitscherlick and a-value extrapolations, in 1979 demonstrated that there was a decreasing amount of net mineralization during the crop season with increasing amounts of both fallow and crop season precipitation. Crop season mineralization in 1980 indicated that there was no net accumulation of nitrogen, rather a tie-up of 14 kg N/ha. This result reflects both the unsatisfied immobilization requirement predicted for the 1979 fallow season and crop season denitrification. Close

• 22. [Article] A study of the relation between radar and raingage indicated rainfall over northern California

  The WSR-57 weather radar operated by the National Weather Service at Sacramento, California, plus a network of precipitation gages provided data for this comparison of radar reflectivity with precipitation ...

  Citation × Citation Citation Abstract Copy Title: A study of the relation between radar and raingage indicated rainfall over northern California Author: Strem, Eric Thomas The WSR-57 weather radar operated by the National Weather Service at Sacramento, California, plus a network of precipitation gages provided data for this comparison of radar reflectivity with precipitation rates. Located in a valley with mountains within range of the radar on three sides, this radar has varying sensitivity for precipitation rates as a result of the terrain effects. Variation in the terrain surrounding the radar has led to a very wide scatter in precipitation rates associated with any particular radar reflectivity. The radar failed to detect precipitation up to 77% of the time over the Coast Range at ranges greater than 100 nm. Linear regression analyses revealed very poor correlation between the raingage indicated precipitation rate and the radar reflectivity. These analyses resulted in values of (R²), the coefficient of determination, ranging from zero as a minimum to only 0.502 as a maximum. Such results are generally much poorer than results obtained by others. The poor correlations and both overestimation and underestimation of rainfall resulted from factors such as range, terrain blocking, windward or leeward exposure, freezing level height, beam height and width, and the distribution of water vapor in the vertical. Title: A study of the relation between radar and raingage indicated rainfall over northern California Author: Strem, Eric Thomas The WSR-57 weather radar operated by the National Weather Service at Sacramento, California, plus a network of precipitation gages provided data for this comparison of radar reflectivity with precipitation rates. Located in a valley with mountains within range of the radar on three sides, this radar has varying sensitivity for precipitation rates as a result of the terrain effects. Variation in the terrain surrounding the radar has led to a very wide scatter in precipitation rates associated with any particular radar reflectivity. The radar failed to detect precipitation up to 77% of the time over the Coast Range at ranges greater than 100 nm. Linear regression analyses revealed very poor correlation between the raingage indicated precipitation rate and the radar reflectivity. These analyses resulted in values of (R²), the coefficient of determination, ranging from zero as a minimum to only 0.502 as a maximum. Such results are generally much poorer than results obtained by others. The poor correlations and both overestimation and underestimation of rainfall resulted from factors such as range, terrain blocking, windward or leeward exposure, freezing level height, beam height and width, and the distribution of water vapor in the vertical. Close

• 23. [Article] Precipitation-snowmelt timing and snowmelt augmentation of large peak flow events, western Cascades, Oregon

  Despite advances in the understanding of rain-on-snow storms and their resulting peak flows, little is understood about the response of snowmelt to precipitation and the relative timing of the two at multiple ...

  Citation × Citation Citation Abstract Copy Title: Precipitation-snowmelt timing and snowmelt augmentation of large peak flow events, western Cascades, Oregon Author: Jennings, Keith S. Despite advances in the understanding of rain-on-snow storms and their resulting peak flows, little is understood about the response of snowmelt to precipitation and the relative timing of the two at multiple temporal scales within such events. To address this issue, climate, snowmelt, and streamflow data were analyzed for 26 large storms in the H.J. Andrews Experimental Forest in the western Cascades of Oregon. Cumulative net snowmelt was plotted against precipitation for each storm to identify net snowmelt response categories, which were then used to summarize climatic and streamflow data, while the timing of precipitation and net snowmelt was assessed at multiple temporal scales and time ranges with wavelet coherence. Five precipitation-net snowmelt response categories were identified: flat; persistent melt; persistent accumulation; late melt; and late accumulation. Persistent melt events, which were characterized by concomitantly increasing cumulative net snowmelt and precipitation, had the highest mean peak flow and water available for runoff values of the response categories. Large, contiguous regions of significant wavelet coherence at multiple temporal scales were observed in both the persistent melt and persistent accumulation categories, but the phase difference distributions indicated differing snowpack dynamics with pulses of precipitation leading pulses of snowmelt in the former and precipitation being absorbed by the snowpack in the latter. High water available for runoff totals and peak flows were observed in each of the five response categories, but a dewpoint temperature consistently above 0.5°C, elevated wind speeds, and a high fraction of precipitation falling as rain in the persistent melt category facilitated rapid snowmelt rates which were often synchronized with precipitation. Wavelet coherence showed this synchronization to be significant across all temporal scales and time periods for the two largest peak flows in the study, indicating that tightly coupled rainfall-synchrony is essential in generating an extreme rain-on-snow flood. By quantifying the amount and timing of net snowmelt, the categorization scheme provides a means of distinguishing among rain-on-snow events and predicting peak discharge magnitude. Title: Precipitation-snowmelt timing and snowmelt augmentation of large peak flow events, western Cascades, Oregon Author: Jennings, Keith S. Despite advances in the understanding of rain-on-snow storms and their resulting peak flows, little is understood about the response of snowmelt to precipitation and the relative timing of the two at multiple temporal scales within such events. To address this issue, climate, snowmelt, and streamflow data were analyzed for 26 large storms in the H.J. Andrews Experimental Forest in the western Cascades of Oregon. Cumulative net snowmelt was plotted against precipitation for each storm to identify net snowmelt response categories, which were then used to summarize climatic and streamflow data, while the timing of precipitation and net snowmelt was assessed at multiple temporal scales and time ranges with wavelet coherence. Five precipitation-net snowmelt response categories were identified: flat; persistent melt; persistent accumulation; late melt; and late accumulation. Persistent melt events, which were characterized by concomitantly increasing cumulative net snowmelt and precipitation, had the highest mean peak flow and water available for runoff values of the response categories. Large, contiguous regions of significant wavelet coherence at multiple temporal scales were observed in both the persistent melt and persistent accumulation categories, but the phase difference distributions indicated differing snowpack dynamics with pulses of precipitation leading pulses of snowmelt in the former and precipitation being absorbed by the snowpack in the latter. High water available for runoff totals and peak flows were observed in each of the five response categories, but a dewpoint temperature consistently above 0.5°C, elevated wind speeds, and a high fraction of precipitation falling as rain in the persistent melt category facilitated rapid snowmelt rates which were often synchronized with precipitation. Wavelet coherence showed this synchronization to be significant across all temporal scales and time periods for the two largest peak flows in the study, indicating that tightly coupled rainfall-synchrony is essential in generating an extreme rain-on-snow flood. By quantifying the amount and timing of net snowmelt, the categorization scheme provides a means of distinguishing among rain-on-snow events and predicting peak discharge magnitude. Close

• 24. [Article] Large wood export regulated by the pattern and intensity of precipitation along a latitudinal gradient in the Japanese archipelago

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/wr/.

  Citation × Citation Citation Abstract Copy Title: Large wood export regulated by the pattern and intensity of precipitation along a latitudinal gradient in the Japanese archipelago Author: Ichiyanagi, Hidetaka, Seo, Jung Il, Nakamura, Futoshi, Akasaka, Takumi, Chun, Kun Woo This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/wr/. Title: Large wood export regulated by the pattern and intensity of precipitation along a latitudinal gradient in the Japanese archipelago Author: Ichiyanagi, Hidetaka, Seo, Jung Il, Nakamura, Futoshi, Akasaka, Takumi, Chun, Kun Woo This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/wr/. Close

• 25. [Article] Clouds, Aerosols, and Precipitation in the Marine Boundary Layer: An Arm Mobile Facility Deployment

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by American ...

  Citation × Citation Citation Abstract Copy Title: Clouds, Aerosols, and Precipitation in the Marine Boundary Layer: An Arm Mobile Facility Deployment Author: de Szoeke, Simon P., et al., Wyant, Matthew, Bretherton, Christopher S., Wood, Robert To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by American Meteorological Society and can be found at: http://www2.ametsoc.org/ams/index.cfm/publications/bulletin-of-the-american-meteorological-society-bams/ Title: Clouds, Aerosols, and Precipitation in the Marine Boundary Layer: An Arm Mobile Facility Deployment Author: de Szoeke, Simon P., et al., Wyant, Matthew, Bretherton, Christopher S., Wood, Robert To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by American Meteorological Society and can be found at: http://www2.ametsoc.org/ams/index.cfm/publications/bulletin-of-the-american-meteorological-society-bams/ Close

• 26. [Article] Variability of precipitation in western Oregon as revealed by rado echo patterns

  Citation × Citation Citation Abstract Copy Title: Variability of precipitation in western Oregon as revealed by rado echo patterns Author: Mendenhall, Laurence David Title: Variability of precipitation in western Oregon as revealed by rado echo patterns Author: Mendenhall, Laurence David Close

• 27. [Article] Some characteristics of time and space patterns of fall precipitation in northwest Oregon

  Citation × Citation Citation Abstract Copy Title: Some characteristics of time and space patterns of fall precipitation in northwest Oregon Author: Velthoen, John Richard Title: Some characteristics of time and space patterns of fall precipitation in northwest Oregon Author: Velthoen, John Richard Close

• 28. [Article] Surface observations of the electrical charges retained by precipitation

  Citation × Citation Citation Abstract Copy Title: Surface observations of the electrical charges retained by precipitation Author: Couch, Richard W. Title: Surface observations of the electrical charges retained by precipitation Author: Couch, Richard W. Close

• 29. [Article] Intensity and periodicity of spring precipitation in the Willamette Valley

  Citation × Citation Citation Abstract Copy Title: Intensity and periodicity of spring precipitation in the Willamette Valley Author: Smith, Floyd Harold Title: Intensity and periodicity of spring precipitation in the Willamette Valley Author: Smith, Floyd Harold Close

• 30. [Article] Analysis of microwave back-scattering from precipitation

  Citation × Citation Citation Abstract Copy Title: Analysis of microwave back-scattering from precipitation Author: Hershman, Arthur Lee Title: Analysis of microwave back-scattering from precipitation Author: Hershman, Arthur Lee Close