Importance of Precipitation on the Upper Ocean Salinity Response to Typhoon Kalmaegi (2014)

Abstract

Using multiple-satellite datasets, in situ observations, and numerical simulations, the influence of typhoon-induced precipitation on the oceanic response to Typhoon Kalmaegi has been discussed. It is found that the convective system and precipitation distribution of Kalmaegi was asymmetric, which leaded to the asymmetric rainfall at observational stations. The sea surface salinity (SSS) of the buoy to the right of storm track increased with a 0.176 practical salinity units (psu) maximal positive anomaly, while the two buoys on the left side underwent several desalination processes, with a maximum decreases of 0.145 psu and 0.278 psu. Numerical simulations with and without precipitation forcing were also performed. Model results showed that typhoon-induced precipitation can weaken sea surface cooling by approximately 0.03–0.40 °C and suppress the SSS increase by approximately 0.074–0.152 psu. The effect of precipitation can be divided into the direct effect and indirect effect. On one hand, freshwater from precipitation directly dilutes the salinity. On the other hand, when salinity decreases, the ocean stratification will be enhanced, the vertical mixing will be restrained, and then the temperature and salinity can be further affected by weakened vertical mixing.

Satellite Observations of the Sea Surface Salinity Response to Tropical Cyclones

“…In line with the thermal wake signature, a rightward SSS asymmetry is also anticipated from storm‐induced inertial currents in the Northern Hemisphere (Price, 1981). However, heavy precipitations under TCs may lead to poststorm upper ocean freshening, as reported from in situ observations (Bond et al., 2011; Hsu and Ho, 2019; Kil et al., 2013; Lin & Oey, 2016; Lin et al., 2017; Liu et al., 2007, 2020; Pudov & Petrichenko, 2000; Steffen & Bourassa, 2018; Zhang et al., 2016), and numerical simulations (Jacob & Koblinsky, 2007; Robertson & Ginis, 2002).…”

“…Poststorm SSS salinification in the trail of TCs has already been extensively reported both from in situ and satellite observations (e.g., see Bond et al., 2011 ; Chaudhuri et al., 2019; Domingues et al., 2015; Grodsky et al., 2012; Lin et al., 2017; Liu et al., 2020; McPhaden et al., 2009; Price, 1981; Reul et al., 2014; Sanford et al., 1987; Steffen & Bourassa, 2018; Venkatesan et al., 2014; Vinayachandran et al., 2003; Yue et al., 2018; Zhang et al., 2016, 2018). SSS is generally expected to increase in the wakes of cyclones because subsurface water is on average saltier than surface water in the convective regions associated with cyclonic activity (Jourdain et al., 2013).…”

Upper ocean response to tropical cyclones: a review

“…Similar to temperature response, TCs usually increase sea surface salinity and decrease subsurface salinity both within 1 psu, which bias to the right (left) side of TC track in Northern (Southern) Hemisphere (Bond et al 2011;Girishkumar et al 2014;Domingues et al 2015;Zhang et al 2016a;Abernathey and Haller 2018); the positive sea surface salinity sometimes even reaches 1.5-3 psu (Chaudhuri et al 2019). However, TC precipitation usually weakens positive sea surface salinity anomaly (Girishkumar et al 2014;Liu et al 2020) and causes negative sea surface salinity anomaly to the left (right) side of TC track in the Northern (Southern) Hemisphere (Grodsky et al 2012;. The freshness of the sea surface by precipitation increases the upper ocean stratification and weakens the TC-induced mixing (Jourdain et al 2013;Vissa et al 2013;Liu et al 2015Liu et al , 2020, which restricts the sea surface cooling and the negative TCocean feedback (Balaguru et al 2016).…”

“…However, TC precipitation usually weakens positive sea surface salinity anomaly (Girishkumar et al 2014;Liu et al 2020) and causes negative sea surface salinity anomaly to the left (right) side of TC track in the Northern (Southern) Hemisphere (Grodsky et al 2012;. The freshness of the sea surface by precipitation increases the upper ocean stratification and weakens the TC-induced mixing (Jourdain et al 2013;Vissa et al 2013;Liu et al 2015Liu et al , 2020, which restricts the sea surface cooling and the negative TCocean feedback (Balaguru et al 2016). There is a barrier layer if the upper ocean isosaline layer is shallower than the isothermal layer, which also prohibits the deepening of the upper ocean mixed layer caused by a TC (Balaguru et al 2012;Liu et al 2015;Yan et al 2017).…”

Oceanic response to the consecutive Hurricanes Dorian and Humberto (2019) in the Sargasso Sea

“…Ye et al, 2013;Chacko, 2017;Chakraborty et al, 2018;Jayaram et al, 2019). A DCM typically occurs in stratified and oligotrophic marine environments where phytoplankton are not evenly distributed throughout the water column (Liccardo et al, 2013;Macías et al, 2013). In this case, the shape of the vertical profiles of chl a concentration can be considered Gaussian according to the classification of Mignot et al (2011Mignot et al ( , 2014.…”