On the relationships between ENSO and autumn rainfall in Iran

Abstract

An investigation of the relationships between Iranian autumn rainfall and the El Niño–Southern Oscillation (ENSO) phenomenon was explored for the period 1951–1990. A negative correlation between the Troup Southern Oscillation Index (SOI) and rainfall data was found for almost all of Iran. The relationships were found to be stronger and more consistent over some regions comprising the southern foothills of the Alborz Mountains, northwestern districts and central areas. For the other parts of the country, correlations were found to be either less significant or non‐stationary. It was determined that the associations between SOI and rainfall over central parts of Iran have persistently improved for the recent period studied. The impacts of ENSO on rainfall amounts during low and high phases of the SO index were also studied. It was found that during El Niño episodes, the amount of rainfall over various parts of the country was several times more than during La Niña periods. The associations between SOI and surface air pressure data were found to be poor and insignificant. The possibility of rainfall forecasting was also explored and the results suggest that autumn rainfall could be predicted a season ahead for some parts of the country. A mechanism for the influence of the ENSO cycle on Iranian rainfall is suggested. Copyright © 2000 Royal Meteorological Society

Qualitative rainfall prediction models for central and southern Sudan using El Niño–southern oscillation and Indian Ocean sea surface temperature Indices

“…Several studies have indicated that the ENSO is teleconnected to the rainfall variability in different parts of the world (Parthasarathy and Pant, 1984;Janowiak, 1988;Parthasarathy et al, 1988;Allan and Pariwono, 1990;Tapley and Waylen, 1990;Lough, 1992Lough, , 1997Hastenrath et al, 1993Hastenrath et al, , 1995Allan et al, 1995;Camberlin, 1995Camberlin, , 1997Gingras and Adamowski, 1995;Seleshi and Demaree, 1995;Glantz, 1996;Piechota and Dracup, 1996;Sun and Furbish, 1997;Chiew et al, 1998;Nazemosadat andCordery, 2000, Sewell andLandman, 2001). A brief historical review about the development of the ENSO teleconnections can be found in Goddard et al (2001).…”

“…The term 'El Niño' is used to describe the quasi-cyclic heating of the Pacific Ocean, and the term 'southern oscillation' is used to describe the undulations in the atmospheric pressure at sea level across the Pacific Ocean. The warm phase of the ENSO is known as El Niño and its cold phase is known as La Niña (Nazemosadat and Cordery, 2000). The ENSO is usually described by numerical indices, which utilize the changes in the sea-level pressure or anomalies of the SST in the Pacific Ocean (Kawamura et al, 1998).…”

Seasonal precipitation forecast skill over Iran

“…However, other parts of the globe, such as the Middle East, are not as strongly associated with the ENSO phenomenon (Ropelewski and Halpert, 1987;Ropelewski and Halpert, 1989). Notwithstanding, Nazemosadat and Coredy (2000) have documented an ENSO signal in Iran during the OND season, and Barlow et al (2002) reported that severe droughts that occurred in central south Asia from 1998 to 2001 are related to a combination of the La Niña and the unusually warm SSTs in the west Pacific, which may have enhanced the regional dynamics of the warm pool. Nazemosadat and Ghasemi (2004) reported that warm ENSO phases reduce the intensity and probability of drought while the cold ENSO phases increase the intensity and probability of severe drought during OND, particularly over the southern parts of Iran.…”

Rainfall: Features and Variations over Saudi Arabia, A Review

“…A central source of inter-annual climate variability over much of the globe is the ENSO events [e.g., 47,48,50]. In recent decades [50,[59][60][61][62][63] it has been indicated that the teleconnection of ENSO has indeed extended its reach into the Middle East region. They noted an increase in the impact of El Niño on rainfall patterns in the middleeast.…”