Effects of the Hunga Tonga-Hunga Ha'apai Eruption on MODIS-Retrieved Sea Surface Temperatures

The eruption of Hunga Tonga-Hunga Ha'apai (HTHH) volcano on 15 January 2022 injected a great amount of H2O and a moderate amount of SO2 into the stratosphere, producing a pronounced and persistent sulfate aerosol layer centered around the mid-stratosphere, mostly confined to Southern Hemisphere (SH) tropics. These aerosols affect the Moderate Resolution Imaging Spectroradiometer (MODIS) retrievals of sea surface temperature (SST) where negative biases reached -0.3 K and an annual mean of -0.1 K north of 40 & DEG;S in the SH. The spatial and temporal evolutions of MODIS SST anomalies are presented. Radiative transfer simulations demonstrate the aerosol effect on MODIS SST retrievals by causing an additional brightness temperature (BT) deficit at 11 & mu;m and a reduction in BT differences since the characteristic of spectral attenuation between 11 and 12 & mu;m is opposite to that of H2O. A correction for HTHH aerosol effects in the retrieval algorithm is therefore desirable.