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• 11. [Article] Evaluation of a Regional Climate Modeling Effort for the Western United States Using a Superensemble from Weather@home

  This is the publisher’s final pdf. The published article is copyrighted by American Meteorological Society and can be found at: https://www2.ametsoc.org/ams/index.cfm/publications/journals/journal-of-c...

  Citation × Citation Citation Abstract Copy Title: Evaluation of a Regional Climate Modeling Effort for the Western United States Using a Superensemble from Weather@home Author: Rupp, David E., Vickers, Dean, Allen, Myles, Mote, Philip W., Mera, Roberto, Li, Sihan This is the publisher’s final pdf. The published article is copyrighted by American Meteorological Society and can be found at: https://www2.ametsoc.org/ams/index.cfm/publications/journals/journal-of-climate/ Title: Evaluation of a Regional Climate Modeling Effort for the Western United States Using a Superensemble from Weather@home Author: Rupp, David E., Vickers, Dean, Allen, Myles, Mote, Philip W., Mera, Roberto, Li, Sihan This is the publisher’s final pdf. The published article is copyrighted by American Meteorological Society and can be found at: https://www2.ametsoc.org/ams/index.cfm/publications/journals/journal-of-climate/ Close

• 12. [Article] Evaluation of CMIP5 20th century climate simulations for the Pacific Northwest USA

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-8996.

  Citation × Citation Citation Abstract Copy Title: Evaluation of CMIP5 20th century climate simulations for the Pacific Northwest USA Author: Hegewisch, Katherine C., Rupp, David E., Abatzoglou, John T., Mote, Philip W. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-8996. Title: Evaluation of CMIP5 20th century climate simulations for the Pacific Northwest USA Author: Hegewisch, Katherine C., Rupp, David E., Abatzoglou, John T., Mote, Philip W. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-8996. Close

• 13. [Article] Intraseasonal variations of water vapor in the tropical upper troposphere and tropopause region

  We show the signature of the tropical intraseasonal oscillation (TIO) in upper tropospheric moisture and dynamical fields, roughly between 200 and 100 hPa. Relationships among these fields are examined ...

  Citation × Citation Citation Abstract Copy Title: Intraseasonal variations of water vapor in the tropical upper troposphere and tropopause region Author: Clark, Hannah L., Dunkerton, Timothy J., Mote, Philip W., Harwood, Robert S., Pumphrey, Hugh C. We show the signature of the tropical intraseasonal oscillation (TIO) in upper tropospheric moisture and dynamical fields, roughly between 200 and 100 hPa. Relationships among these fields are examined using lag-correlation analysis and using multivariate extended empirical orthogonal functions (MEEOFs), which maximize the shared explained variance among several fields for both spatial and temporal variations. The MEEOFs show that all of the fields respond to the TIO and that the TIO is the dominant factor influencing each of the fields on these timescales. Convection associated with the TIO moistens the upper troposphere up to about 150 hPa, as expected; the behavior at 100 hPa is more complex. Over the longitude range where the TIO is associated with convection, roughly 60°-180°E, 100-hPa temperature and water vapor tend to be reduced above convection on TIO timescales. East of 180°, though, the temperature and water vapor variations at 100 hPa become decoupled. The water vapor variations, like those of 200-hPa velocity potential, appear to speed up at about 180°E. Title: Intraseasonal variations of water vapor in the tropical upper troposphere and tropopause region Author: Clark, Hannah L., Dunkerton, Timothy J., Mote, Philip W., Harwood, Robert S., Pumphrey, Hugh C. We show the signature of the tropical intraseasonal oscillation (TIO) in upper tropospheric moisture and dynamical fields, roughly between 200 and 100 hPa. Relationships among these fields are examined using lag-correlation analysis and using multivariate extended empirical orthogonal functions (MEEOFs), which maximize the shared explained variance among several fields for both spatial and temporal variations. The MEEOFs show that all of the fields respond to the TIO and that the TIO is the dominant factor influencing each of the fields on these timescales. Convection associated with the TIO moistens the upper troposphere up to about 150 hPa, as expected; the behavior at 100 hPa is more complex. Over the longitude range where the TIO is associated with convection, roughly 60°-180°E, 100-hPa temperature and water vapor tend to be reduced above convection on TIO timescales. East of 180°, though, the temperature and water vapor variations at 100 hPa become decoupled. The water vapor variations, like those of 200-hPa velocity potential, appear to speed up at about 180°E. Close

• 14. [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

• 15. [Article] Tropical tropopause layer

  Observations of temperature, winds, and atmospheric trace gases suggest that the transition from troposphere to stratosphere occurs in a layer, rather than at a sharp ‘‘tropopause.’’ In the tropics, this ...

  Citation × Citation Citation Abstract Copy Title: Tropical tropopause layer Author: Fu, Q., Desller, A.E., Fueglistaler, S., Folkins, I., Mote, Philip W., Dunkerton, T.J. Observations of temperature, winds, and atmospheric trace gases suggest that the transition from troposphere to stratosphere occurs in a layer, rather than at a sharp ‘‘tropopause.’’ In the tropics, this layer is often called the ‘‘tropical tropopause layer’’ (TTL). We present an overview of observations in the TTL and discuss the radiative, dynamical, and chemical processes that lead to its timevarying, three-dimensional structure. We present a synthesis definition with a bottom at 150 hPa, 355 K, 14 km (pressure, potential temperature, and altitude) and a top at 70 hPa, 425 K, 18.5 km. Laterally, the TTL is bounded by the position of the subtropical jets. We highlight recent progress in understanding of the TTL but emphasize that a number of processes, notably deep, possibly overshooting convection, remain not well understood. The TTL acts in many ways as a ‘‘gate’’ to the stratosphere, and understanding all relevant processes is of great importance for reliable predictions of future stratospheric ozone and climate. Title: Tropical tropopause layer Author: Fu, Q., Desller, A.E., Fueglistaler, S., Folkins, I., Mote, Philip W., Dunkerton, T.J. Observations of temperature, winds, and atmospheric trace gases suggest that the transition from troposphere to stratosphere occurs in a layer, rather than at a sharp ‘‘tropopause.’’ In the tropics, this layer is often called the ‘‘tropical tropopause layer’’ (TTL). We present an overview of observations in the TTL and discuss the radiative, dynamical, and chemical processes that lead to its timevarying, three-dimensional structure. We present a synthesis definition with a bottom at 150 hPa, 355 K, 14 km (pressure, potential temperature, and altitude) and a top at 70 hPa, 425 K, 18.5 km. Laterally, the TTL is bounded by the position of the subtropical jets. We highlight recent progress in understanding of the TTL but emphasize that a number of processes, notably deep, possibly overshooting convection, remain not well understood. The TTL acts in many ways as a ‘‘gate’’ to the stratosphere, and understanding all relevant processes is of great importance for reliable predictions of future stratospheric ozone and climate. Close

• 16. [Article] An atmospheric tape recorder: the imprint of tropical tropopause temperatures on stratospheric water vapor

  Citation × Citation Citation Abstract Copy Title: An atmospheric tape recorder: the imprint of tropical tropopause temperatures on stratospheric water vapor Author: Mote, Philip W., Waters, Joe W., Pumphrey, Hugh C., Kinnersley, Jonathan S., Russell, James M., Carr, Ewan S, Rosenlof, Karen H., McIntyre, Michael E., Gille, John C., Holton, James R. Title: An atmospheric tape recorder: the imprint of tropical tropopause temperatures on stratospheric water vapor Author: Mote, Philip W., Waters, Joe W., Pumphrey, Hugh C., Kinnersley, Jonathan S., Russell, James M., Carr, Ewan S, Rosenlof, Karen H., McIntyre, Michael E., Gille, John C., Holton, James R. Close

• 17. [Article] The Response of Northern Hemisphere Snow Cover to a Changing Climate

  A snowpack model sensitivity study, observed changes of snow cover in the NOAA satellite dataset, and snow cover simulations from the Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel dataset ...

  Citation × Citation Citation Abstract Copy Title: The Response of Northern Hemisphere Snow Cover to a Changing Climate Author: Brown, Ross D., Mote, Philip W. A snowpack model sensitivity study, observed changes of snow cover in the NOAA satellite dataset, and snow cover simulations from the Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel dataset are used to provide new insights into the climate response of Northern Hemisphere (NH) snow cover. Under conditions of warming and increasing precipitation that characterizes both observed and projected climate change over much of the NH land area with seasonal snow cover, the sensitivity analysis indicated snow cover duration (SCD) was the snow cover variable exhibiting the strongest climate sensitivity, with sensitivity varying with climate regime and elevation. The highest snow cover–climate sensitivity was found in maritime climates with extensive winter snowfall—for example, the coastal mountains of western North America (NA). Analysis of trends in snow cover duration during the 1966–2007 period of NOAA data showed the largest decreases were concentrated in a zone where seasonal mean air temperatures were in the range of −5° to +5°C that extended around the midlatitudinal coastal margins of the continents. These findings were echoed by the climate models that showed earlier and more widespread decreases in SCD than annual maximum snow water equivalent (SWEmax), with the zone of earliest significant decrease located over the maritime margins of NA and western Europe. The lowest SCD–climate sensitivity was observed in continental interior climates with relatively cold and dry winters, where precipitation plays a greater role in snow cover variability. The sensitivity analysis suggested a potentially complex elevation response of SCD and SWEmax to increasing temperature and precipitation in mountain regions as a result of nonlinear interactions between the duration of the snow season and snow accumulation rates. Title: The Response of Northern Hemisphere Snow Cover to a Changing Climate Author: Brown, Ross D., Mote, Philip W. A snowpack model sensitivity study, observed changes of snow cover in the NOAA satellite dataset, and snow cover simulations from the Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel dataset are used to provide new insights into the climate response of Northern Hemisphere (NH) snow cover. Under conditions of warming and increasing precipitation that characterizes both observed and projected climate change over much of the NH land area with seasonal snow cover, the sensitivity analysis indicated snow cover duration (SCD) was the snow cover variable exhibiting the strongest climate sensitivity, with sensitivity varying with climate regime and elevation. The highest snow cover–climate sensitivity was found in maritime climates with extensive winter snowfall—for example, the coastal mountains of western North America (NA). Analysis of trends in snow cover duration during the 1966–2007 period of NOAA data showed the largest decreases were concentrated in a zone where seasonal mean air temperatures were in the range of −5° to +5°C that extended around the midlatitudinal coastal margins of the continents. These findings were echoed by the climate models that showed earlier and more widespread decreases in SCD than annual maximum snow water equivalent (SWEmax), with the zone of earliest significant decrease located over the maritime margins of NA and western Europe. The lowest SCD–climate sensitivity was observed in continental interior climates with relatively cold and dry winters, where precipitation plays a greater role in snow cover variability. The sensitivity analysis suggested a potentially complex elevation response of SCD and SWEmax to increasing temperature and precipitation in mountain regions as a result of nonlinear interactions between the duration of the snow season and snow accumulation rates. Close

• 18. [Article] Kelvin wave signatures in stratospheric trace constituents

  Connections, sometimes tenuous, have previously been noted between stratospheric Kelvin waves and several stratospheric trace constituents. The present study finds evidence of Kelvin wave signatures in ...

  Citation × Citation Citation Abstract Copy Title: Kelvin wave signatures in stratospheric trace constituents Author: Dunkerton, Timothy J., Mote, Philip W. Connections, sometimes tenuous, have previously been noted between stratospheric Kelvin waves and several stratospheric trace constituents. The present study finds evidence of Kelvin wave signatures in ozone from the Microwave Limb Sounder (MLS) and Cryogenic Limb Array Etalon Spectrometer (CLAES) instruments aboard the Upper Atmosphere Research Satellite. Predominant variations near 10 days are associated with a Kelvin wave mode previously identified in MLS temperature. Variations in CLAES nitrous oxide also show some evidence of influence by this Kelvin mode. The results presented here show that the observing characteristics of the instrument can influence the derived structure and properties of Kelvin waves. Title: Kelvin wave signatures in stratospheric trace constituents Author: Dunkerton, Timothy J., Mote, Philip W. Connections, sometimes tenuous, have previously been noted between stratospheric Kelvin waves and several stratospheric trace constituents. The present study finds evidence of Kelvin wave signatures in ozone from the Microwave Limb Sounder (MLS) and Cryogenic Limb Array Etalon Spectrometer (CLAES) instruments aboard the Upper Atmosphere Research Satellite. Predominant variations near 10 days are associated with a Kelvin wave mode previously identified in MLS temperature. Variations in CLAES nitrous oxide also show some evidence of influence by this Kelvin mode. The results presented here show that the observing characteristics of the instrument can influence the derived structure and properties of Kelvin waves. Close

• 19. [Article] The annual cycle of stratospheric water vapor in a general circulation model

  The application of general circulation models (GCMs) to stratospheric chemistry and transport both permits and requires a thorough investigation of stratospheric water vapor. The National Center for Atmospheric ...

  Citation × Citation Citation Abstract Copy Title: The annual cycle of stratospheric water vapor in a general circulation model Author: Mote, Philip W. The application of general circulation models (GCMs) to stratospheric chemistry and transport both permits and requires a thorough investigation of stratospheric water vapor. The National Center for Atmospheric Research has redesigned its GCM, the Community Climate Model (CCM2), to enable studies of the chemistry and transport of tracers including water vapor; the importance of water vapor to the climate and chemistry of the stratosphere requires that it be better understood in the atmosphere and well represented in the model. In this study, methane is carried as a tracer and converted to water; this simple chemistry provides an adequate representation of the upper stratospheric water vapor source. The cold temperature bias in the winter polar stratosphere, which the CCM2 shares with other GCMs, produces excessive dehydration in the southern hemisphere, but this dry bias can be ameliorated by setting a minimum vapor pressure. The CCM2's water vapor distribution and seasonality compare favorably with observations in many respects, though seasonal variations including the upper stratospheric semiannual oscillation are generally too small. Southern polar dehydration affects midlatitude water vapor mixing ratios by a few tenths of a part per million, mostly after the demise of the vortex. The annual cycle of water vapor in the tropical and northern midlatitude lower stratosphere is dominated by drying at the tropical tropopause. Water vapor has a longer adjustment time than methane and had not reached equilibrium at the end of the 9 years simulated here. Title: The annual cycle of stratospheric water vapor in a general circulation model Author: Mote, Philip W. The application of general circulation models (GCMs) to stratospheric chemistry and transport both permits and requires a thorough investigation of stratospheric water vapor. The National Center for Atmospheric Research has redesigned its GCM, the Community Climate Model (CCM2), to enable studies of the chemistry and transport of tracers including water vapor; the importance of water vapor to the climate and chemistry of the stratosphere requires that it be better understood in the atmosphere and well represented in the model. In this study, methane is carried as a tracer and converted to water; this simple chemistry provides an adequate representation of the upper stratospheric water vapor source. The cold temperature bias in the winter polar stratosphere, which the CCM2 shares with other GCMs, produces excessive dehydration in the southern hemisphere, but this dry bias can be ameliorated by setting a minimum vapor pressure. The CCM2's water vapor distribution and seasonality compare favorably with observations in many respects, though seasonal variations including the upper stratospheric semiannual oscillation are generally too small. Southern polar dehydration affects midlatitude water vapor mixing ratios by a few tenths of a part per million, mostly after the demise of the vortex. The annual cycle of water vapor in the tropical and northern midlatitude lower stratosphere is dominated by drying at the tropical tropopause. Water vapor has a longer adjustment time than methane and had not reached equilibrium at the end of the 9 years simulated here. Close

• 20. [Article] Declining mountain snowpack in western North America

  In western North America, snow provides crucial storage of winter precipitation, effectively transferring water from the relatively wet winter season to the typically dry summers. Manual and telemetered ...

  Citation × Citation Citation Abstract Copy Title: Declining mountain snowpack in western North America Author: Clark, Martyn P., Lettenmaier, Dennis P., Mote, Philip W., Hamlet, Alan F. In western North America, snow provides crucial storage of winter precipitation, effectively transferring water from the relatively wet winter season to the typically dry summers. Manual and telemetered measurements of spring snow-pack, corroborated by a physically based hydrologic model, are examined here for climate-driven fluctuations and trends during the period of 1916–2002. Much of the mountain West has experienced declines in spring snowpack, especially since midcentury, despite increases in winter precipitation in many places. Analysis and modeling show that climatic trends are the dominant factor, not changes in land use, forest canopy, or other factors. The largest decreases have occurred where winter temperatures are mild, especially in the Cascade Mountains and northern California. In most mountain ranges, relative declines grow from minimal at ridgetop to substantial at snow line. Taken together, these results emphasize that the West's snow resources are already declining as earth's climate warms. Title: Declining mountain snowpack in western North America Author: Clark, Martyn P., Lettenmaier, Dennis P., Mote, Philip W., Hamlet, Alan F. In western North America, snow provides crucial storage of winter precipitation, effectively transferring water from the relatively wet winter season to the typically dry summers. Manual and telemetered measurements of spring snow-pack, corroborated by a physically based hydrologic model, are examined here for climate-driven fluctuations and trends during the period of 1916–2002. Much of the mountain West has experienced declines in spring snowpack, especially since midcentury, despite increases in winter precipitation in many places. Analysis and modeling show that climatic trends are the dominant factor, not changes in land use, forest canopy, or other factors. The largest decreases have occurred where winter temperatures are mild, especially in the Cascade Mountains and northern California. In most mountain ranges, relative declines grow from minimal at ridgetop to substantial at snow line. Taken together, these results emphasize that the West's snow resources are already declining as earth's climate warms. Close