On the Relationship Between Northwest-Northcentral Pacific SST and Low-level Jet Over the Arabian Sea
Abstract
This study examines variability in Low-Level Jet (LLJ) over the Indian Ocean (5� N: 15� N; 50� E: 70� E) during June-July-August (JJA), using reanalysis data for the past four decades (1979-2019).A significant positive trend (0.04 ms-1 yr-1) in the intensity of LLJ is observed during the study period.We examined the relationship between LLJ and Sea Surface Temperature (SST) anomalies over the Northern hemisphere using linear regression.On interannual time scales, the significant relationship associated with El Nino-Southern Oscillation (ENSO) events and LLJ intensity anomalies is prominent in the equatorial Pacific Ocean.When the ENSO effects were removed, a strong co-variability is observed between LLJ intensity and SST anomalies over the Northwest-Northcentral Pacific during the JJA season.Our analysis suggests that SST over this region is correlated with the upper-tropospheric geopotential height anomalies.These geopotential anomalies were favourable for easterlies in the upper troposphere, intensifying the low-level westerlies and hence LLJ.
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