Observations on Fine Structure in the Northern Arabian Sea

Abstract

Vertical profiles of temperature and salinity, obtained using a STD recorder, from the northern Arabian Sea revealed the presence of fine structures characterized by homogeneous layers separated by interfaces. The layers were generally regions of low stability. Fluctuations of temperature and salinity were maximum in the thermocline (about 0.5° C and 0.2% respectively). Temperature showed an increased fine structure activity with the formation of seasonal thermocline. Deeper waters, below thermocline, showed the fine structure activity with less amplitudes of fluctuations and larger layer thicknesses. Blobs of temperature and salinity at about 180 m observed in the thermocline near the mouth of Persian Gulf may be due to gross overturning of internal waves. Possibility of double-diffusion as a causative factor for the layerings is also discussed.