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duration if the amount is the same. Drought appears to have increased substantially globally since the 1970s ( Dai et al. 2004 ) in part because of decreased precipitation over land (mainly in the Tropics and subtropics) but also because of warming and increased atmospheric demand for moisture. Drought has increased especially throughout Africa, southern Asia, the southwestern United States, and the Mediterranean region (both southern Europe and northern Africa), and has also influenced the Amazon
duration if the amount is the same. Drought appears to have increased substantially globally since the 1970s ( Dai et al. 2004 ) in part because of decreased precipitation over land (mainly in the Tropics and subtropics) but also because of warming and increased atmospheric demand for moisture. Drought has increased especially throughout Africa, southern Asia, the southwestern United States, and the Mediterranean region (both southern Europe and northern Africa), and has also influenced the Amazon
( Goddard and Dilley 2005 ). For each year and month the fractional coverage of the globe falling outside those percentiles, amounting to 38% of the precipitation values, was calculated (FC p0.38 ). Very arid regions were not included, namely, locations with a monthly median rainfall of zero. Next, FC p0.38 was calculated separately for the globe (67.5°N to 85°S), Northern Hemisphere extratropics (67.5° to 25°N), Southern Hemisphere extratropics (25° to 67.5°S), and Tropics (25°N to 25°S) over ocean
( Goddard and Dilley 2005 ). For each year and month the fractional coverage of the globe falling outside those percentiles, amounting to 38% of the precipitation values, was calculated (FC p0.38 ). Very arid regions were not included, namely, locations with a monthly median rainfall of zero. Next, FC p0.38 was calculated separately for the globe (67.5°N to 85°S), Northern Hemisphere extratropics (67.5° to 25°N), Southern Hemisphere extratropics (25° to 67.5°S), and Tropics (25°N to 25°S) over ocean
. , 54 , 2799 – 2812 . 10.1175/1520-0469(1997)054<2799:MSPITI>2.0.CO;2 Heckley, W. A. , Kelly G. , and Tiedtke M. , 1990 : On the use of satellite-derived heating rates for data assimilation within the tropics. Mon. Wea. Rev. , 118 , 1743 – 1757 . 10.1175/1520-0493(1990)118<1743:OTUOSD>2.0.CO;2 Higgins, R. W. , Shi W. , Yarosh E. , and Joyce R. , 2000 : Improved U.S. Precipitation Quality Control System and Analysis . NCEP/Climate Prediction Center Atlas 7, NOAA/NWS, 40 pp . Hou
. , 54 , 2799 – 2812 . 10.1175/1520-0469(1997)054<2799:MSPITI>2.0.CO;2 Heckley, W. A. , Kelly G. , and Tiedtke M. , 1990 : On the use of satellite-derived heating rates for data assimilation within the tropics. Mon. Wea. Rev. , 118 , 1743 – 1757 . 10.1175/1520-0493(1990)118<1743:OTUOSD>2.0.CO;2 Higgins, R. W. , Shi W. , Yarosh E. , and Joyce R. , 2000 : Improved U.S. Precipitation Quality Control System and Analysis . NCEP/Climate Prediction Center Atlas 7, NOAA/NWS, 40 pp . Hou
small ice particles. b. Precipitation extremes GEWEX precipitation products provide a broad view of the water cycle that includes oceans as well as land areas including the effects of El Niño events on precipitation. Gu et al. (2007) have shown that in the Tropics over 37% of the spatial extent of rainfall extremes over the oceans are explained by sea surface temperature variations associated with ENSO events. In particular, El Niño events are associated with rainfall deficiencies over the oceans
small ice particles. b. Precipitation extremes GEWEX precipitation products provide a broad view of the water cycle that includes oceans as well as land areas including the effects of El Niño events on precipitation. Gu et al. (2007) have shown that in the Tropics over 37% of the spatial extent of rainfall extremes over the oceans are explained by sea surface temperature variations associated with ENSO events. In particular, El Niño events are associated with rainfall deficiencies over the oceans
