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ARS Home » Plains Area » Lubbock, Texas » Cropping Systems Research Laboratory » Wind Erosion and Water Conservation Research » Research » Publications at this Location » Publication #352129

Title: Optimal ranking regime analysis of U.S. summer temperature and degree-days: 1895-2015

item Mauget, Steven

Submitted to: Journal of Applied Meteorology and Climatology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2018
Publication Date: 9/11/2018
Citation: Mauget, S.A. 2018. Optimal ranking regime analysis of U.S. summer temperature and degree-days: 1895-2015. Journal of Applied Meteorology and Climatology. 57:2141-2159.

Interpretive Summary: Increasing global temperatures requires that U.S. agriculture will need to become more proactive if the world is to be clothed and fed adequately in the future. To define the current state of U.S. summer temperature trends, an ARS scientist from Lubbock applied specialized data analysis methods to mean summer maximum and minimum temperature U.S. temperature records during 1895-2015. During that period increasing trends in summer maximum temperatures are found in the west and northeast, but warming trends in summer minimum temperatures are found over almost all of the U.S. During 1970-2015 warming trends in maximum temperature are also found mainly in the west and northeast. But over the key production regions of the midwestern Corn Belt no significant increase in summer temperature was found during 1970-2015. This research shows that, even though warming trends are evident other U.S. areas, the summer temperature of this important agricultural region has been stable in recent decades.

Technical Abstract: The Optimal Ranking Regime (ORR) method was applied to mean summer maximum (TMXS) and minimum (TMNS) temperature, and cumulative summer cooling degree days (CDDS) calculated from U.S. climate division data during 1895-2015. CDDS variation is proposed as a proxy for summer corn growing degree day variation given their high rank correlation in station data during 1950-2014. The TMXS and CDDS ORR analyses show similar regime patterns. Western and northeastern divisions experienced cool periods before 1930 and warm periods after 1990. The 1930’s drought appears as decadal warm regimes over the Midwest and Great Plains. Southeastern multi-decadal TMXS and CDDS cycles are evident, but Midwestern TMXS and CDDS variation over the important Corn Belt agricultural region has been regime-free between the early 1940s and 2015. By contrast, TMNS regime signatures consistent with centennial-scale warming trends are found over most divisions outside of the southeast. Based on the multi-decadal regime patterns detected by the ORR analyses, each climate division’s TMXS, TMNS, and CDDS series was tested for significant linear trends during 1910-2015 and 1970-2015. Although only 48 of 102 divisions show significant positive TMNS trends during 1910-2015, some western trend magnitudes are greater than 15% of 20th century climatology. Positive TMXS trends during 1970-2015 are detected over 39 western and northeastern divisions, but warming TMNS trends are evident nationally. In some cooler western divisions the magnitudes of positive 1970-2015 CDDS trends exceed 90% of climatology. But, consistent with the ORR analyses, Corn Belt TMXS and CDDS trends are insignificant during 1970-2015.