Monitoring Chlorophyll-a and sea surface temperature variations in se Arabian Gulf and NW sea of Oman from MODIS Aqua data

Chlorophyll-a (chl-a) and sea surface temperature (SST) recorded by MODIS-Aqua from 2002-2015 show pronounced monthly, seasonal, interannual and spatial variability and distinct differences between NW Sea of Oman and the adjoining SE Arabian Gulf. The annual average chl-a values in NW Sea of Oman was 1.86 mg m^-3compared to 1.78 mg m^-3in the SE Arabian Gulf, which showed the lowest variability. Seasonal variations consisted of the highest chl-a concentrations in February and March and the lowest in May, June, and July ranging from 0.85 to 2.92 mg m^-3in the SE Arabian Gulf and from 0.37 to 4.96 in mg m^-3NW Sea of Oman. During the spring bloom in February and March, the average chl-a in the NW Sea of Oman was 4.96 and 4.69 mg m^-3and SE Arabian Gulf was 2.92 and 2.19 mg m^-3. In the Arabian Gulf, spring bloom concentrations in the deeper waters were much lower than deeper waters in the Sea of Oman. January to March, which were the coolest months with average SST of 22.6-23.5°C in the Sea of Oman and 21.3-22.4°C in the Arabian Gulf, coincided with the peak months of chl-a concentrations. The Sea of Oman area recorded the highest monthly average of 31.4°C in July and a minimum of 22.6°C in February whereas the highest of 32.5°C was recorded in the Arabian Gulf in July and the minimum of 21.3°C in February. Mean monthly chl-a and SST values were slightly more negatively correlated in the NW Sea of Oman (r = -0.73, p <0.05) than the SE Arabian Gulf (r = -0.56, p <0.05). The variations in chl-a concentrations in the Sea of Oman showed more complexity than the SE Arabian Gulf. The highest chl-a concentrations were observed in November 2008 and continued to March 2009.