A note on modeling mixing in the upper layers of the Bay of Bengal: Importance of water type, water column structure and precipitation

Atmospheric Cold Pools and Their Influence on Sea Surface Temperature in the Bay of Bengal

“…Following Paulson and Simpson (1977), the Q pen in the model water column is parameterized by the expression where z is depth in m, ζ 1 is the attenuation depth (m) of the infrared and red part of shortwave radiation, and ζ 2 is the attenuation depth of the remaining part of shortwave radiation. Constant values 0.62, 0.6, and 20 m were used for parameters R , ζ 1 , and ζ 2 , respectively, and this selection is based on Jerlov (1968) type 1A water classification, representing typical open ocean conditions in the BoB (Babu et al., 2004; Kantha et al., 2019). However, different values for ζ 1 (0.6–1.5 m) have been used in the previous studies in the BoB (Babu et al., 2004; Buckley et al., 2019; Lotliker et al., 2016).…”

“…In addition, ζ 2 estimated by an 8‐days composite of chlorophyll data at a spatial resolution of 5 km from Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua satellite from January 2003 to March 2020 using the expression ( ζ 2 = [0.027 + 0.0518* chlorophyll 0.428 ] −1 ) proposed by Morel (1988) shows a mean value around 19.9 ± 0.02 m at 15°N, 90°E in the BoB. The choice of these parameters is important to accurately simulate SST in an ocean model (Buckley et al., 2019; Kantha et al., 2019). However, the main goal of our study is to explore the sensitivity for SST responses to ACPs under different initial conditions and forcing scenarios, so the exact choice of parameters to estimate the Q pen in the model is not critical to understanding our results.…”

Multi‐Scale Temporal Variability of Turbulent Mixing During a Monsoon Intra‐Seasonal Oscillation in the Bay of Bengal: An LES Study

“…In contrast, the solar heat flux is concentrated in the near surface layer in the nine-term model. Lotliker et al (2016) and Kantha et al (2019) suggested that the water type during the summer months in the BoB (see blue curve in Figure A1a) is better modeled with the two-term model using water type I. Results from our LES indicate no significant difference between the two models with respect to the ML properties.…”

“…It has been shown that the misalignment between wind and waves can affect LT (Kukulka et al, 2011;Shrestha et al, 2019;Van Roekel et al, 2012;Wang & Kukulka, 2021;Wang et al, 2019;Webb & Fox-Kemper, 2015); however, the effect of misalignment is excluded in the present study. Based on the observation of penetrative radiative heat flux in the BoB between 2009 and 2014 in Lotliker et al (2016), Kantha et al (2019) found that the optical water property during the summer season is closest to water type I (Jerlov, 1968). Thus, the transmissive short-wave heat flux (Q sw ) in our LES is represented using the two-term exponential parameterization of Paulson and Simpson (1977) adjusted for water type I.…”

Freshwater transport by eddies within the Bay of Bengal's central axis

“…The monsoonal forcing also results in seasonal reversal of the Eastern Indian Coastal Current (EICC). The BoB and the Arabian Sea are linked in maintaining the salt balance between the two seas, as freshwater is exported from the BoB and saline water is imported from the Arabian Sea by monsoonal driven currents around the southern rim of Sri Lanka (Kantha et al, 2019). Sengupta et al (2006) found the annual precipitation minus evaporation (P-E) over the BoB (2.17 × 10 12 m 2 , including the Andaman Sea) yields a net freshwater input of 0.5 m/year, with the annual river input of 0.094 Sv spread throughout the BoB amounting to 1.37 m/year.…”