Influence of temperature inversions and barrier layer depth on deepening of Sonic Layer Depth in the Bay of Bengal
K ANNAPURNAIAH*, TVS UDAYA BHASKAR
INCOIS, Ocean valley, Pragathi Nagar Hyderabad, Telangana, India Pincode: 500090 Mobile: 9492032074 E-mail: email@example.com
Seasonal evolution of the sonic layer depth (SLD) in the Bay of Bengal (BoB) is studied. Monthly sonic layer depth climatology is constructed using Argo temperature and salinity. Depth of temperature inversions (TI) (>= 0.2°C), magnitude of temperature compared to surface temperature, magnitude of salinity compared to surface and salinity at depth of inversion are all obtained from Argo temperature profiles. SLD showed semiannual variability with peaks during June August and December February and lows during pre and post monsoon season. SLD is observed to be shallower than mixed layer depth over most of the BoB except in the regions dominated by temperature which usually happens during winter owing to TIs. SLD and mixed layer depth (MLD) is observed to have high correlation (> 0.80) over most of the BoB indicating a good relationship between them, except in regions dominated by TIs. Barrier layer is responsible for formation and sustenance of strong TI in BoB. As sound velocity is sensitive to temperature, SLD is observed to deepen in comparison to MLD. SLD is found to be deeper than MLD during the winter season due to the presence of TI which are common phenomenon in BoB during that period. Advection of cooler low-salinity water over warmer salty water leads to the formation of TI in BoB. Sound velocity being sensitive to temperature, results in deepening of SLD in this region. This can be used to understand relation between them to a great degree of accuracy and estimate one from the other.