The El Niño–Southern Oscillation and daily temperature extremes in east Asia and the west Pacific

Abstract

The numbers of warm nights and hot days, across most of the east Asia – west Pacific region, increase substantially in the year after the onset of an El Niño event. The number of cool days and cold nights tend to decrease, although the relationship with El Niño is weaker for these variables. The relationship is confounded, for warm nights and hot days, by a strong increasing trend in the numbers of extremes not matched by a trend in the El Niño. Removal of this trend leads to even stronger correlations with the El Niño. Strong correlations exist between some of the extremes indices and an index of the El Niño – Southern Oscillation in months prior to the occurrence of the extremes, indicating that predictions of the frequency of extreme temperatures across the region should be feasible.

Role of El Niño/La Niña in temperature extremes over India

“…The existence of strong correlations with substantial lead time (significant at 5% level for cold events, and 1% level for hot events) indicates potentially useful prediction skills. These results are similar to those reported by Nicholls et al (2005) who showed that the ENSO has strong links with variations in the annual frequency of temperature extremes in East Asia-West Pacific Region and the predictions of frequencies of hot and cold events could be made with some skill from NINO3.4 SSTs as early as May in the preceding year. They have also shown that the annual number of cool days tends to be lower in the year following the onset of El Niño event, whereas the annual number of hot days tends to be higher.…”

“…As strong trends have been identified by earlier studies in the temperature extremes over Indian region (Kothawale et al, 2006), the correlations between NINO3.4 SSTs and indices are calculated on linearly detrended data as well as on the 'raw' data. Similar approach was used by Nicholls et al (2005) while examining the relationship between ENSO and daily temperature extremes in East Asia and West Pacific. However, it has been found that the detrending approach made very little difference to the correlation results.…”

“…Trewin (2001) also observed similar relationship for many parts of Australian region and suggested that the relationship was strong enough to allow prediction of extremes. Nicholls et al (2005) have shown that the onset of El Niño leads to increased numbers of warm extremes (and fewer cool extremes) in East Asia and western Pacific. While analysing the annual extremes, they have pointed out that further work is necessary to examine seasonal variations in the relationships between extremes and ENSO.…”

The El Nino‐Southern Oscillation and winter precipitation extremes over India

“…Hence continuous wet days are substantially decreasing in recent period. A Similar type of analysis has been done by Nicholls et al (2005) for hot/cool days and warm/cold nights. …”

The link between the Barents Sea and ENSO events simulated by NEMO model

“…Many publications provide evidence of correlations between El Niño events and atmospheric circulations in the Northern Hemisphere (e.g. see Lau et al, 2005;Nicholls et al, 2005;Mokhov and Smirnov, 2006;Müller and Roecker, 2006), as the sea surface temperature anomalies in the tropics can cause a remote teleconnection response in the atmospheric circulation. It is therefore not unrealistic to expect that atmospheric teleconnections during warm ENSO events lead to an anomalous anticyclonic atmospheric circulation pattern (higher atmospheric pressure) developing over the Barents Sea, instead of the more usual cyclonic conditions observed during winter months (e.g.…”