ENSO Teleconnections on Wintertime Precipitation Variability Over UAE

Wednesday, 17 December 2014
Niranjan Kumar Kondapalli and Taha Ouarda, Masdar Institute of Science and Technology, Abu Dhabi, United Arab Emirates
For years, many studies have attempted to detect linkages between seasonal precipitation and remote ocean temperatures (called "teleconnections"). For example, the most widely studied climate phenomenon is the El Nino Southern Oscillation (ENSO). Although ENSO generation primarily occurs in the west-central Pacific it causes short-term climate fluctuations in regions far from there. For instance, a variety of local studies have linked ENSO and Middle Eastern precipitation, although none specifically investigated the United Arab Emirates (UAE). In this study we investigate the role of Equatorial Pacific Sea Surface Temperatures (SSTs) on the winter time precipitation variability over the UAE and adjoining Middle East regions. The UAE is located in the eastern corner of the Arabian Peninsula, dominated by arid to desert climates with low mean precipitation rates ranging from 40 mm/yr in the southern desert region to 160 mm/yr in the northeastern mountainous region with mean spatial annual rainfalls of about 78 mm/yr. Precipitation over the UAE are characterized by high spatial and temporal variability, with standard deviation occasionally exceeding the mean annual precipitation amounts. However, it is observed that statistically significant correlations exist between precipitation over the UAE and the Equatorial Pacific SSTs. The moisture budget analysis reveals the distinct change in the anomalous circulation (cyclonic and anti-cyclonic) associated with strong convergence and divergence of the moisture flux during warm and cold phases of ENSO respectively. Further, the composite analysis of upper troposheric zonal wind shows the equatorward shift (~2º latitude) of subtropical jet stream (STJ) over the Middle East during the warm phase of ENSO affecting the weather in the UAE. The findings suggest that the teleconnection linking ENSO and the precipitation over UAE and adjoining regions is mediated by the response of STJ to Rossby waves.