Editorial Type:
Article
Article Type:
Research Article

Summertime Potential Evapotranspiration in Eastern Washington State

Nicholas A. Bond Office of the Washington State Climatologist, Joint Institute for the Study of Atmosphere and Ocean, University of Washington, Seattle, Washington

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Karin A. Bumbaco Office of the Washington State Climatologist, Joint Institute for the Study of Atmosphere and Ocean, University of Washington, Seattle, Washington

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Print Publication:
01 May 2015
DOI:
https://doi.org/10.1175/JAMC-D-14-0228.1
Page(s):
1090–1101
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Abstract

The demands for water in agricultural regions depend on the rate of evapotranspiration (ET). Daily records of potential ET (pET) are available from the late 1980s through the present for five stations in eastern Washington State (George, Harrah, LeGrow, Lind, and Odessa) through the Pacific Northwest Cooperative Agricultural Weather Network (AgriMet) under the auspices of the Bureau of Reclamation. These records reveal a secular increase in the summer (June–August) mean pET over the period 1987–2014. This increase can be attributed largely to an increase in solar irradiance of 20–30 W m−2 over the same period. The seasonal mean solar irradiance accounts for approximately 35%–50% of the variance in the interannual variations in seasonal mean pET at the individual stations and for approximately 60% of the variance from a five-station average perspective. The period of analysis includes a mean increase of temperature of about 0.3°C (10 yr)−1, and the variability in temperature relates more to the year-to-year fluctuations in pET than to the overall increase in pET. The time series of surface relative humidity and wind speed exhibit only minor trends. Daily and seasonal mean data for 500-hPa geopotential height and other variables are used to determine aspects of the regional atmosphere associated with periods of high pET. Anomalous ridging aloft and negative anomalies in 925-hPa relative humidity tend to occur over the study area during the summers with the greatest pET. The relationships that are emerging may provide a basis for empirical downscaling of pET from global climate model projections.

Joint Institute for the Study of the Atmosphere and Ocean Contribution Number 2352.

Corresponding author address: Nicholas Bond, Office of the Washington State Climatologist, Joint Institute for the Study of Atmosphere and Ocean, University of Washington, Box 355672, Seattle, WA 98195-5672. E-mail: nab3met@u.washington.edu

Abstract

The demands for water in agricultural regions depend on the rate of evapotranspiration (ET). Daily records of potential ET (pET) are available from the late 1980s through the present for five stations in eastern Washington State (George, Harrah, LeGrow, Lind, and Odessa) through the Pacific Northwest Cooperative Agricultural Weather Network (AgriMet) under the auspices of the Bureau of Reclamation. These records reveal a secular increase in the summer (June–August) mean pET over the period 1987–2014. This increase can be attributed largely to an increase in solar irradiance of 20–30 W m−2 over the same period. The seasonal mean solar irradiance accounts for approximately 35%–50% of the variance in the interannual variations in seasonal mean pET at the individual stations and for approximately 60% of the variance from a five-station average perspective. The period of analysis includes a mean increase of temperature of about 0.3°C (10 yr)−1, and the variability in temperature relates more to the year-to-year fluctuations in pET than to the overall increase in pET. The time series of surface relative humidity and wind speed exhibit only minor trends. Daily and seasonal mean data for 500-hPa geopotential height and other variables are used to determine aspects of the regional atmosphere associated with periods of high pET. Anomalous ridging aloft and negative anomalies in 925-hPa relative humidity tend to occur over the study area during the summers with the greatest pET. The relationships that are emerging may provide a basis for empirical downscaling of pET from global climate model projections.

Joint Institute for the Study of the Atmosphere and Ocean Contribution Number 2352.

Corresponding author address: Nicholas Bond, Office of the Washington State Climatologist, Joint Institute for the Study of Atmosphere and Ocean, University of Washington, Box 355672, Seattle, WA 98195-5672. E-mail: nab3met@u.washington.edu
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  • Abatzoglou, J., D. Rupp, and P. Mote, 2014: Seasonal climate variability and change in the Pacific Northwest of the United States. J. Climate, 27, 2125–2142, doi:10.1175/JCLI-D-13-00218.1.

    • Search Google Scholar
    • Export Citation

  • Allen, R. G., L. S. Pereira, D. Raes, and M. Smith, 1998: Crop evapotranspiration: Guidelines for computing crop water requirements. FAO Irrigation and Drainage Paper 56, Food and Agriculture Organization of the United Nations, 300 pp.

    • Search Google Scholar
    • Export Citation

  • Amatya, D. M., R. W. Skaggs, and J. D. Gregory, 1995: Comparison of methods for estimating REF-ET. J. Irrig. Drain. Eng., 121, 427–435, doi:10.1061/(ASCE)0733-9437(1995)121:6(427).

    • Search Google Scholar
    • Export Citation

  • Brewer, M., C. Mass, and B. Potter, 2012: The West Coast thermal trough: Climatology and synoptic evolution. Mon. Wea. Rev.,140, 3820–3843, doi:10.1175/MWR-D-12-00078.1.

    • Search Google Scholar
    • Export Citation

  • Bumbaco, K. A., K. D. Dello, and N. A. Bond, 2013: History of Pacific Northwest heat waves: Synoptic pattern and trends. J. Appl. Meteor. Climatol., 52, 1618–1631, doi:10.1175/JAMC-D-12-094.1.

    • Search Google Scholar
    • Export Citation

  • Feng, S., and Q. Fu, 2013: Expansion of global drylands under warming climate. Atmos. Chem. Phys., 13, 10 081–10 094, doi:10.5194/acp-13-10081-2013.

    • Search Google Scholar
    • Export Citation

  • George, B. A., B. R. S. Reddy, N. S. Raghuwanshi, and W. W. Wallender, 2002: Decision support system for estimating reference evapotranspiration. J. Irrig. Drain. Eng., 128, 1–10, doi:10.1061/(ASCE)0733-9437(2002)128:1(1).

    • Search Google Scholar
    • Export Citation

  • Hamlet, A. F., P. W. Mote, M. P. Clark, and D. P. Lettenmaier, 2007: Twentieth-century trends in runoff, evapotranspiration, and soil moisture in the western United States. J. Climate, 20, 1468–1486, doi:10.1175/JCLI4051.1.

    • Search Google Scholar
    • Export Citation

  • Hargreaves, G. H., and Z. A. Samani, 1982: Estimating potential evapotranspiration. J. Irrig. Drain. Eng., 108, 223–230.

  • Hobbins, M. T., J. A. Ramirez, and T. C. Brown, 2001: Trends in regional evapotranspiration across the United States under the complementary relationship hypothesis. 35th Annual Hydrology Days, Fort Collins, CO, Amer. Geophys. Union, 106–121. [Available online at http://www.fs.fed.us/rm/value/docs/et-trends.pdf.]

  • Jensen, M. E., R. D. Burman, and R. G. Allen, Eds., 1990: Evapotranspiration and Irrigations Water Requirements. ASCE Manuals and Reports on Engineering Practice 70, ASCE, 332 pp.

  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77, 437–471, doi:10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Lau, N.-C., and M. J. Nath, 2012: A model study of heat waves over North America: Meteorological aspects and projections for the twenty-first century. J. Climate,25, 4761–4784, doi:10.1175/JCLI-D-11-00575.1.

  • Otkin, J. A., and T. J. Greenwald, 2008: Comparison of WRF model-simulated and MODIS-derived cloud data. Mon. Wea. Rev., 136, 1957–1970, doi:10.1175/2007MWR2293.1.

    • Search Google Scholar
    • Export Citation

  • Palmer, P. L., 2011: AgriMet: A reclamation tool for irrigation water management. Proc. World Environmental and Water Resources Congress 2011, Palm Springs, CA, ASCE, 2682–2691, doi:10.1061/41173(414)279.

  • Palmer, W. C., 1965: Meteorological drought. U.S. Dept. of Commerce Research Paper 45, 58 pp. [Available online at https://www.ncdc.noaa.gov/temp-and-precip/drought/docs/palmer.pdf.]

  • Riihimaki, L. D., F. E. Vignola, and C. N. Long, 2009: Analyzing the contribution of aerosols to an observed increase in direct normal irradiance in Oregon. J. Geophys. Res., 114, D00D02, doi:10.1029/2008JD010970.

    • Search Google Scholar
    • Export Citation

  • Scheff, J., and D. Frierson, 2014: Scaling potential evapotranspiration with greenhouse warming. J. Climate, 27, 1539–1558, doi:10.1175/JCLI-D-13-00233.1.

    • Search Google Scholar
    • Export Citation

  • Tang, Q., and G. Leng, 2013: Changes in cloud cover, precipitation, and summer temperature in North America from 1982 to 2009. J. Climate, 26, 1733–1744, doi:10.1175/JCLI-D-12-00225.1.

    • Search Google Scholar
    • Export Citation

  • Walter, M. T., D. S. Wilks, J.-Y. Parlange, and R. L. Schneider, 2004: Increasing evapotranspiration from the conterminous United States. J. Hydrometeor., 5, 405–408, doi:10.1175/1525-7541(2004)005<0405:IEFTCU>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Wild, M., and Coauthors, 2005: From dimming to brightening: Decadal changes in solar radiation at Earth’s surface. Science, 308, 847–850, doi:10.1126/science.1103215.

    • Search Google Scholar
    • Export Citation

  • Wright, J. L., 1982: New evapotranspiration crop coefficients. J. Irrig. Drain. Div., 108, 57–74. [Available online at http://eprints.nwisrl.ars.usda.gov/382/1/478.pdf.]

    • Search Google Scholar
    • Export Citation

  • Wright, J. L., R. G. Allen, and T. A. Howell, 2000: Conversion between evapotranspiration references and methods. Proc. Fourth Decennial National Irrigation Symp., Phoenix, AZ, Amer. Soc. of Agricultural Engineers, 251–259.

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