Decade-Scale Precipitation Increase in Great Plains at End of 20th Century

Abstract

During the 1980-1999 period, many regions in the Central and Southern Great Plains experienced the longest and strongest increase in average annual precipitation of the century. The size of the increase ranged from 6% to 12% of mean annual precipitation, and from 25% to 60% of inter-annual precipitation variability. Precipitation increased for dry, average and wet years, though not equally for each category. Generally precipitation in very wet years increased less than in average and dry years. The probability of occurrence of dry years was greatly reduced compared to earlier in the century, whereas the probability of average years remained about the same and the probability of wet years increased. The observed decade-scale precipitation increase is attributed to a reduction in the number and severity of dry years, as well as to an increase in the number of wet years, though very wet years did not increase as much. The seasonal distribution of the increase in precipitation showed no statistically significant prevalence during any one particular month, yet qualitative considerations suggest that early summer and autumn months capture more of the annual precipitation increase. In the northern and northwestern Great Plains, a similar precipitation increase, but of smaller proportions, was observed during the 1990-1999 period.

Climate trends of the North American prairie pothole region 1906–2000

“…Annual temperature and precipitation data for each station were smoothed at 3-year periods to reduce year-to-year variability and to help detect trends in magnitude and duration. Similar approaches have been used by others in cases where high temporal variability in weather data exists (Karl et al 1995;Hansen et al 1998;Garbrecht and Rossel 2002;NCDC 2008). Estimates from regression equations for the year 1906 were subtracted from those for the year 2000 for each weather station to show the magnitude of change and the sign (positive or negative trend) over the 95-year period.…”

Mapping and attribution of change in streamflow in the coterminous United States

“…For example, part of the increase in streamflow observed in the Great Plains that our regression analysis attributed to increasing atmospheric CO2 could instead be due to reduced interannual precipitation variability (Garbrecht and Rossel, 2002) or to a disproportionate increase in cold-season (as compared with summer) precipitation (Garbrecht et al, 2004). Our interpolation technique could equally well be applied to seasonal or monthly as well as annual mean streamflow, and thus distinguish the hydrologic impacts of these as well as other seasonally specific factors as advances in spring snowmelt and changing vegetation phenology.…”

Linking Climate Change and Groundwater

“…Rosenberg et al (1999) noted that this turn-around occurred despite a very large increase in the total acreage of irrigated agriculture between the early 1980s and mid-1990s. McGuire (2011) attributed the changes in water tables over this period to more efficient irrigation methods and economic factors, but also to the fact that precipitation in the High Plains was well above normal between 1980 and 1999 (Garbrecht and Rossel 2002).…”

“…The above-normal precipitation across the High Plains aquifer region between 1980 and the late-1990s can be attributed to teleconnections from natural variations in sea-surface temperatures and atmospheric pressures across the Atlantic and Pacific Oceans (Garbrecht and Rossel 2002). During the 1980s and early 1990s, the Pacific Decadal Oscillation (PDO) (Mantua and Hare 2002) was in the positive phase of variability and the Atlantic Multidecadal Oscillation (AMO) (Kerr 2000) was in the negative phase of variability, which generally results in wetter conditions and lower frequency of drought for the High Plains region (McCabe et al 2004).…”