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Update on El NiñoFocus and perspectives

Authors: 超级管理员 | Edit: zhuliang

5.4 Update on El Niño

La Niña condition prevailed across the Pacific Ocean. Figure 5.8 illustrates the behavior of the standard Southern Oscillation Index (SOI) published by the Australian Bureau of Meteorology (BOM) for the period from October 2019 to October 2020. Sustained positive values of the SOI above +7 typically indicate La Niña while sustained negative values below -7 typically indicate El Niño. Values between about +7 and -7 generally indicate neutral conditions. During this monitoring period, SOI increased from 4.2 in July to 9.8 in July, then increased to 10.5 in September, then decreased to 4.2 in October, indicating a La Niña has developed.

The sea surface temperature anomalies in July 2020 for NINO3, NINO3.4, and NINO4 regions were -0.8°C, -1.0°C, and -0.5°C, respectively, somewhat warmer than the 1961-1990 average according to BOM (see Figure 5.8 and Figure 5.9). La Niña has developed and is expected to last into next year, affecting temperatures, precipitation and storm patterns in many parts of the world, according to the World Meteorological Organization (WMO).(https://public.wmo.int/en/media/press-release/la-ni%C3%B1a-has-developed). CropWatch will keep monitoring the situation (Figure 5.10).


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Figure 5.8 Monthly SOI-BOM time series from October 2019 to October 2020 (Source: http://www.bom.gov.au/climate/current/soi2.shtml)


Figure 5.09 Map of NINO Region (Source: https://www.climate.gov/sites/default/files/Fig3_ENSOindices_SST_large.png)

Figure 5.10 October 2020 sea surface temperature departure from the 1961-1990 average (Source:http://www.bom.gov.au/climate/enso/wrap-up/archive/20201110.ssta_pacific_monthly.png?popup)