Evolution and features of global land June–August dry/wet periods during 1920–2000

Abstract

Dry/wet features for the globe and the Northern and Southern Hemispheres are investigated in terms of 1920-2000 June-August (JJA) global land precipitation data. The weighted mean JJA precipitation anomaly index and the weighted mean JJA dry/wet area index are used to describe the extent of global dryness/wetness. It is pointed out that 1988 (1930) was the globally wettest (driest) year in 1920-2000, and 1954 (1976) was the second wettest (driest). The dryness/wetness of the globe and Northern and Southern Hemispheres has shown distinctive interdecadal changes: during the 1920s, global dryness occurred in JJA frequently; from the 1920s to the 1940s global wetness occurred infrequently in JJA; the 1950s-1960s was a period of frequent global JJA wetness; and the 1970s to 2000 was a period of frequent global JJA dryness/wetness, with the number of dry years greater than that of wet years. The dry/wet features of the Northern Hemisphere are comparatively consistent with those of the globe, but there is no obvious relation between JJA mean precipitation anomalies of the two hemispheres. The analyses of the simultaneous and last winter sea-surface temperature anomalies of global dry/wet years reveal that there is clear correlation of JJA global dry/wet change with sea-surface temperature variations and El Niño-southern oscillation (ENSO) events. Global JJA dryness occurs when the summer ENSO (El Niño) is weaker, and global JJA wetness occurs when the summer ENSO is strong. The largest difference between the last winter sea-surface temperature fields for global dry and wet years is that the sea-surface temperature in the North Pacific and North Atlantic for wet years is substantially higher than that for dry years.

Inter‐annual and inter‐decadal variability of early‐ and late‐summer precipitation over northeast China and their background circulation

“…The large variability of precipitation in northeast China (NEC) is of great importance to the local agriculture and ecosystems (Sun et al, ; Shi and Chen, ; Gao et al, ). Located in the mid to high latitudes, the summer precipitation in NEC is affected by the atmospheric circulation anomalies both in the tropical and extra‐tropical regions, such as blockings in the high latitudes (Yao and Dong, ; Feng et al, ; He et al, ; Zhao et al, ), the northeast cold vortex (NHCV) (He et al, ; Hu et al, ; Zhao et al, ), the East Asian summer monsoon (EASM) (Shi and Zhu, ; Li and Zeng, ; ; Wang, ; Lian et al, ; Sun et al, ), and the western Pacific subtropical high (WPSH) (Shen et al, ; Ding and Chen, ).…”

Western Indian Ocean marine and terrestrial records of climate variability: a review and new concepts on land–ocean interactions since AD 1660

“…Interannual to multidecadal variations have been found in drought and precipitation records around the globe (Dai et al 1998;Shi and Chen 2004;D'Arrigo et al 2005;Meehl and Hu 2006). The possible forcing factors for such variations were identified to originate from the Indo-Pacific and North-Atlantic oceans including the Pacific Decadal Oscillation (PDO, Mantua et al 1997;Deser et al 2004), the El Nino-Southern Oscillation (ENSO; McPhaden et al 2006) and the Atlantic Multidecdal Oscillation (AMO) (McCabe and Palecki 2006).…”

Multidecadal climate variability of global lands and oceans

“…Multiyear to multidecadal variations have been found in the drought or precipitation records of many global regions (Dai et al, 1997(Dai et al, , 1998Shi and Chen, 2004). Work done to reconstruct drought status or seasonal precipitation from tree-ring analysis in North America clearly demonstrates the existence of several periodic and quasi-periodic drought cycles as well as of individual events of great severity within the last two millennia (Woodhouse and Overpeck, 1998;Cook et al, 2004).…”