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- Title
Impacts of Irrigation on Summertime Temperatures in the Pacific Northwest.
- Authors
Lawston, Patricia M.; Santanello, Joseph A.; Hanson, Brian; Arsensault, Kristi
- Abstract
Irrigation has the potential to modify local weather and regional climate through a repartitioning of water among the surface, soil, and atmosphere with the potential to drastically change the terrestrial energy budget in agricultural areas. This study uses local observations, satellite remote sensing, and numerical modeling to 1) explore whether irrigation has historically impacted summer maximum temperatures in the Columbia Plateau, 2) characterize the current extent of irrigation impacts to soil moisture (SM) and land surface temperature (LST), and 3) better understand the downstream extent of irrigation's influence on near-surface temperature, humidity, and boundary layer development. Analysis of historical daily maximum temperature (TMAX) observations showed that the three Global Historical Climate Network (GHCN) sites downwind of Columbia Basin Project (CBP) irrigation experienced statistically significant cooling of the mean summer TMAX by 0.8°–1.6°C in the post-CBP (1968–98) as compared to pre-CBP expansion (1908–38) period, opposite the background climate signal. Remote sensing observations of soil moisture and land surface temperatures in more recent years show wetter soil (~18%–25%) and cooler land surface temperatures over the irrigated areas. Simulations using NASA's Land Information System (LIS) coupled to the Weather Research and Forecasting (WRF) Model support the historical analysis, confirming that under the most common summer wind flow regime, irrigation cooling can extend as far downwind as the locations of these stations. Taken together, these results suggest that irrigation expansion may have contributed to a reduction in summertime temperatures and heat extremes within and downwind of the CBP area. This supports a regional impact of irrigation across the study area.
- Subjects
COLUMBIA Plateau; LAND surface temperature; ENERGY budget (Geophysics); IRRIGATION; METEOROLOGICAL research; WEATHER forecasting; SUMMER; IRRIGATED soils
- Publication
Earth Interactions, 2020, Vol 24, Issue 1, p1
- ISSN
1087-3562
- Publication type
Article
- DOI
10.1175/EI-D-19-0015.1