Trends and temperature sensitivity of moisture conditions in the conterminous United States

Climate Research

Gregory J. McCabe¹  David M. Wolock¹ 

关键词: Moisture index;    Climate change;    Global warming;   

DOI  :  10.3354/cr020019

来源: Inter-Research Science Publishing

【 摘 要 】

ABSTRACT: Observed (1895-1999) trends in climatic moisture conditions in the conterminous United States (US) characterized by (1) annual precipitation minus annual potential evapotranspiration (PMPE), (2) annual surplus (water that eventually becomesstreamflow), and (3) annual deficit (the amount of water that must be supplied by irrigation to grow vegetation at an optimum rate) are examined. The sensitivity of moisture conditions across the conterminous US to increases in temperature also areexamined. Results indicate that there have been statistically significant trends in PMPE, annual surplus, and annual deficit for some parts of the conterminous US. Most of the significant trends in PMPE have been increasing trends primarily in the easternUS. Annual surplus also has increased over the eastern US, whereas the magnitudes of annual deficit have decreased. For the conterminous US as a whole, there has been a statistically significant increase in PMPE and annual surplus; however, there is nosignificant trend in annual deficit. Results also indicate that PMPE and annual deficit in the warmest regions of the conterminous US are most sensitive to increases in temperature. The high sensitivity of PMPE and annual deficit in these regions toincreases in temperature is related to the relation between temperature and the saturation vapor pressure of air. The increases in potential evapotranspiration for a given change in temperature are larger for high temperatures than for low temperatures.The regions with the highest sensitivity of annual surplus to increases in temperature are the humid regions of the country. In these regions, annual surplus is large and increased potential evapotranspiration, resulting from increased temperature, has asignificant effect on reducing annual surplus. In the dry regions of the country, annual surplus is so low that increases in potential evapotranspiration only result in small decreases in annual surplus.

【 授权许可】

Unknown