Comparison of AMSR-2 wind speed and sea surface temperature with moored buoy observations over the Northern Indian Ocean

Abstract

The Northern Indian Ocean (NIO) is unique due to seasonal reversal of wind patterns, the formation of vortices and eddies which make satellite observations arduous. The veracity of sea surface wind (SSW) and sea surface temperature (SST) products of sun-synchronous AMSR-2 satellite are compared with high-temporal moored buoy observations over the NIO. The two year-long (2013-2014) comparisons reveal that the root-mean-square-error (RMSE) of AMSR-2 SST and SSW is <0.4 • C and <1.5 ms −1 , respectively, which are within the error range prescribed for the AMSR-2 satellite (±0.8 • C, ±1.5 ms −1). The SST-wind relation is analyzed using data both from the buoy and satellite. As a result, the low-SST is associated with low-wind condition (positive slope) in the northern part of the Bay of Bengal (BoB), while low SST values are associated with high wind conditions (negative slope) over the southern BoB. Moreover, the AMSR-2 displayed larger slope for SST-wind relation and could be mainly due to overestimation of SST and underestimation of wind as compared to the buoy. The AMSR-2 SSW exhibited higher error during post-monsoon followed by monsoon season and could be attributed to the high wind conditions associated with intense oceanic vortices. The study suggests that the AMSR-2 products are reliable and can be used in tropical air-sea interactions, meso-scale features, and weather and climate studies.

Significance of Mesoscale Warm Core Eddy on Marine and Coastal Environment of the Bay of Bengal

“…Figure 5b shows the SST-wind speed relation over the central BoB region, i.e., BD10. Here, the relation displays a positive linear trend, addressing SST increases with an increase in wind speed [23]. Moreover, the deviation of SST and wind speed values of the fitted line is higher (lower) for the low (high) wind conditions.…”

“…The correlation and bias are varying in between 0.7-0.8 and 0.07-0.13°C, respectively (Figure 1c and d). As stated in Reddy et al [23], the AMSR-2 mean SST error over the BoB is limited to $0.3°C. In this situation, the observed RMSE ($0.5-0.6°C) in the WCE period is doubled as that of mean RMSE ($0.3°C) over the BoB.…”

“…The observed slope of the fitted line is high for the AMSR-2 with an SST difference of 3.4°C and is limited to 2°C in case of BD08. However, the long time period (2013-2014) analyses at the same location shows a contradictory relation indicating SST increases with an increase in wind speed [23]. Figure 5b shows the SST-wind speed relation over the central BoB region, i.e., BD10.…”

Long-term forecasting of tropical cyclones over Bay of Bengal using linear and non-linear statistical models

“…The minimum sustained pressure is strongly correlated with the intensities of the strongest tropical cyclones, which can be explained by thermodynamics and the effects of water substance on density (Emanuel, 1988(Emanuel, , 1995. Surface wind speed and sea-surface pressure affect airsea interactions in the Bay of Bengal (Emanuel, 1995;Reddy et al, 2018). This leads to a very active bed for cyclonic disturbances and consequently, maximum tropical cyclones are formed in the Bay of Bengal region .…”

Complexity and periodicity of daily mean temperature and dew-point across India

“…Weather parameters such as temperature, dew-point, rainfall, atmospheric pressure, and wind speed are complicated in nature (Byakatonda et al 2018;Reddy et al 2018). The time series of these parameters need to be analyzed carefully as the dynamics of processes generating these time series are priory unknown.…”