Krishnamurti T. N., Jana S., Krishnamurti R., Kumar V., Deepa R., Papa Fabrice, Bourassa M. A., Ali M. M. (2017). Monsoonal intraseasonal oscillations in the ocean heat content over the surface layers of the Bay of Bengal. Journal of Marine Systems, 167, p. 19-32. ISSN 0924-7963.
Titre du document
Monsoonal intraseasonal oscillations in the ocean heat content over the surface layers of the Bay of Bengal
Krishnamurti T. N., Jana S., Krishnamurti R., Kumar V., Deepa R., Papa Fabrice, Bourassa M. A., Ali M. M.
Source
Journal of Marine Systems, 2017,
167, p. 19-32 ISSN 0924-7963
Two major findings of this study are i) the presence of a robust intraseasonal oscillation (ISO) signal in the Bay of Bengal (BOB) subsurface ocean heat content (OHC) anomaly, this ISO signal propagates northward at the rate of roughly one degree latitude per day and ii) a lag of roughly 4 to 6 days between the appearance of this signal in the surface wind speed and followed by the OHC anomaly. The availability of long-term daily data sets for the OHC made it possible to examine the presence of ISO over the BOB. This study also examines the possible relationship of ISO signal in the OHC with other parameters, such as surface wind (wind speed, wind stress curl and related upwelling/downwelling), sea surface temperature (SST), net surface heat flux into the ocean and surface rain. This study confirms the finding of a robust signal for the OHC anomaly over the BoB, on the time scale of ISO, using daily data sets for a 17 years period covering each of the summer monsoon seasons. Also included is an analysis of rainfall and river runoff variability over north of the BoB. The river runoff and the precipitation data sets also show a robust ISO time scale. The mutual relationships among precipitation, SST, net heat flux and OHC are also examined in this study. This work addresses the lag relationship between the surface wind speed and the OHC, a lag of roughly 4 days relates to strong winds impacting a cooling of the ocean. The ranges of spread of all the above parameters for the total field and for the ISO time scale are expressed as percentage variability of the ISO time scale. Those show that the OHC anomaly over the Bay of Bengal is quite a robust feature. This study does not address modeling issues.
