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摘要
The Arabian Gulf (Gulf) and the surrounding regions are centers of intense economic activity. The precipitating weather systems that form over the Gulf are important for this predominantly arid region. It is suggested that El Nino-Southern Oscillation (ENSO) influences the Middle East precipitation variability through an equatorward shift of the subtropical jet. Here we present compelling evidence to illustrate the role of ENSO in modulating the local dynamics and moisture transport in initiating precipitation during different ENSO phases using satellite and reanalysis data. It is found that the moisture transport from the Red and Arabian Seas toward the Gulf is stronger during El Nino years. The pattern and strength of moisture transport toward the Gulf is weakened during La Nina and neutral years, with most of the transport directed toward the northern Gulf. Using a 120 h back trajectory analysis, it is found that while the air parcels coming toward the Gulf from the Arabian and Red Seas side originate at lower tropospheric levels, the air parcels from the Mediterranean originate at middle and upper tropospheric levels during El Nino years. In contrast, upper tropospheric air parcels originating over the southern Arabian Sea plays a dominant role on Gulf precipitation during La Nina and neutral years. The seasonal mean transients of zonal winds show a robust ENSO signature over the Gulf, indicating a favorable (less favorable) condition for the penetration of midlatitude eddies over the region during El Nino (La Nina) winters.
Plain Language Summary The Arabian Gulf and the surrounding regions are centers of intense economic activity. The precipitating weather systems that form over the Arabian Gulf are important for this predominantly arid region. A major portion of the Middle East precipitation variability is known to be associated with the El Nino-Southern Oscillation (ENSO) phenomenon. The sources of moisture for the heavy precipitation events over the Arabian Gulf are the Arabian and Red Seas. In this study, it is found that the local dynamics that favor precipitation differs during El Nino, La Nina, and neutral years. The moisture transport from the Red and Arabian Seas toward the Arabian Gulf is stronger and covers the entire Gulf during El Nino years. The pattern and strength of moisture transport toward the Gulf are similar during La Nina and neutral years, with most of the transport directed toward the northern Gulf. The air parcels that come from the Mediterranean side originate at middle and upper tropospheric levels during El Nino years. However, during La Nina and neutral years, air parcels primarily originate at the upper tropospheric levels over the southern Arabian Sea.
- 出版日期2018-1-16
