The Impacts of Global Scale Climate Variations on Southwest Asia
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
Pagination or Media Count:
We have examined the impacts of global scale intraseasonal and interannual climate variations on Southwest Asia SWA. The variations of primary interest are El Nino-La Nina ENLN the Indian Ocean Zonal Mode IOZM the Madden-Julian Oscillation MJO and the North Atlantic Oscillation NAO. The impacts of primary interest are on fall-winter precipitation and temperature in SWA and associated lower and upper level circulation anomalies in the eastern hemisphere. Our primary data sets are National Centers for Environmental Prediction NCEP reanalysis fields and indices of ENLN IOZM MJO and NAO activity. We have identified several upper and lower level circulation anomaly patterns that are directly linked to both the primary climate variations and to anomalous precipitation and temperature in SWA. The circulation anomalies associated with these SWA anomalies are similar for ENLN IOZM MJO and NAO periods. For the tropical climate variations1 the mechanisms for these circulation anomalies involve equatorial Rossby-Kelvin wave dynamics and related alterations of the southwesterly and northeasterly monsoon flows tropical easterly jet and subtropical jet in northeast Africa and SWA and the tropical Africa - Indian Ocean - western tropical Pacific region. Much of the impact on precipitation occurs through 1 anomalous moisture advection over the tropical northwest Indian Ocean and tropical and subtropical North Africa and 2 anomalous moisture convergence over SWA.