Upwelling along the East and West Coast of India

摘要

Goastal upwelling signals along the east and west coast of India are inferred from the monthly mean climatologies of wind, sea level anomalies and temperature. Since wind reports from the coastal regions are sparse, we have considered the wind observed in the coastal stations. For knowing the oceani cresponses we have used three data sets from the coastal regions. These are monthly mean sea level, (TOPEX/POSEIDON) sea surface height and monthly mean temperature sections. Along the south-west coast of India, upwelling occurs during southwest monsoon season. PSMSL (Permanent Service for Mean Sea Level) and TOPEX POSEIDON sea level anomaly and the temperature sections demonstrate this seasonal upwelling signals. Regarding forcing, upwelling indices were found to be in phase and significant in magnitude only off the southernmost station, Thiruvananthapuram. Along the east coast, while the upwelling indices show maximum in south-west monsoon season, the negative sea level anomalies are observed in both PSML and altimetry data in winter season. In case of the west coast upwelling the wind forcing appears to be a regular modifier of the remote forcing, demonstrated by McCreary et al. (1993). However, for the east coast, the wind is totally out of phase with the observed upwelling, suggesting the dominance of shelf waves, generated by both local and remote forcing.