Observed and CMIP5 modeled influence of large-scale circulation on summer precipitation and drought in the South-Central United States
- 560 Downloads
Annual precipitation in the largely agricultural South-Central United States is characterized by a primary wet season in May and June, a mid-summer dry period in July and August, and a second precipitation peak in September and October. Of the 22 CMIP5 global climate models with sufficient output available, 16 are able to reproduce this bimodal distribution (we refer to these as “BM” models), while 6 have trouble simulating the mid-summer dry period, instead producing an extended wet season (“EW” models). In BM models, the timing and amplitude of the mid-summer westward extension of the North Atlantic Subtropical High (NASH) are realistic, while the magnitude of the Great Plains Lower Level Jet (GPLLJ) tends to be overestimated, particularly in July. In EW models, temporal variations and geophysical locations of the NASH and GPLLJ appear reasonable compared to reanalysis but their magnitudes are too weak to suppress mid-summer precipitation. During warm-season droughts, however, both groups of models reproduce the observed tendency towards a stronger NASH that remains over the region through September, and an intensification and northward extension of the GPLLJ. Similarly, future simulations from both model groups under a +1 to +3 °C transient increase in global mean temperature show decreases in summer precipitation concurrent with an enhanced NASH and an intensified GPLLJ, though models differ regarding the months in which these decreases are projected to occur: early summer in the BM models, and late summer in the EW models. Overall, these results suggest that projected future decreases in summer precipitation over the South-Central region appear to be closely related to anomalous patterns of large-scale circulation already observed and modeled during historical dry years, patterns that are consistently reproduced by CMIP5 models.
KeywordsPrecipitation Drought Southern Plains South Central U.S. North Atlantic Subtropical High Great Plains low-level jet Global climate models CMIP5
We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modeling groups (listed in Table 1 of this paper) for producing and making available their model output. For CMIP5 the U.S. Department of Energy’s Program for Climate Model Diagnosis and Intercomparison provided coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. This research was supported by USGS Award Number G15AP00137.
- Blackadar AK (1957) Boundary layer wind maxima and their significance for the growth of nocturnal inversions. Bull Amer Meteor Soc 38:283–290Google Scholar
- Dirmeyer PA, Cash BA, Kinter III JL, Jung T, Marx L, Satoh M, Stan C, Hirofumi T, Towers P, Wedi N, Achuthavarier D, Adams JD, Altshuler EL, Huang B, Jin EK, Manganello J (2012) Simulating the diurnal cycle of rainfall in global climate models: resolution versus parameterization. Clim Dyn 39:399–418CrossRefGoogle Scholar
- Fannin B (2012) Updated 2011 Texas agricultural drought losses total $7.62 billion. Texas A&M AgriLife Today. http://today.agrilife.org/2012/03/21/updated-2011-texas-agriculturaldrought-losses-total-7-62-billion/ March 21, 2012
- Garfin G, Franco G, Blanco H, Comrie A, Gonzalez P, Piechota T, Smyth R, Waskom R (2014) Ch. 20: Southwest. In Climate change impacts in the United States: The third national climate assessment, edited by J.M. Melillo, T.C. Richmond, and G.W. Yohe. Washington, DC: U.S. Global Change Research Program, 462–486Google Scholar
- Henderson KG, Vega AJ (1996) Regional precipitation variability in the southern United States. Phys Geogr 17:93–112Google Scholar
- Mesinger et al (2006) North American Regional Reanalysis. Bull Amer Meteor Soc 87:343–360. doi: 10.1175/bams-87-3-343
- NCDC (2013) Billion-dollar weather/climate disasters 1980–2016. Available online: http://www.ncdc.noaa.gov/billions/events.pdf. Accessed 16 Sept 2013
- Shafer M, Ojima D, Antle JM, Kluck D, McPherson RA, Petersen S, Scanlon B, Sherman K (2014) Ch. 19: Great Plains. Climate Change Impacts in the United States: The Third National Climate Assessment, Melillo JM, Richmond TC, Yohe GW, Eds., U.S. Global Change Research Program, 441–461. doi: 10.7930/J0D798BC
- USDA FSA (2015) Secretarial Drought Designations - All Drought. United Stated Department of Agriculture Farm Services Agreement. Washington DC. Jan 28, 2015. http://www.usda.gov/documents/usda-drought-fast-track-designations-012815.pdf
- Walsh J, Coauthors (2014) Ch. 2: Our changing climate. In Climate change impacts in the United States: The third national climate assessment, edited by Melillo JM, Richmond TC, and Yohe GW. Washington, DC: U.S. Global Change Research Program, 19–67Google Scholar