Effect of desert dust intrusion on the detection of marine heatwaves

Increasing frequency, intensity, and duration of marine heatwaves (MHWs) is an essential indicator of regional warming in the Eastern Mediterranean Sea. Moreover, desert dust intrusions are frequently observed over the sea: they are characterized by the arrival of warm air masses containing dust aerosol from the desert. In this study we found the effect of desert dust intrusion on the detection of marine heatwaves by satellite SST retrievals. This effect has not yet been investigated in previous studies. Our approach was based on the separate use of microwave (MW) and infrared (IR) satellite radiometry of nighttime sea surface temperature (SST). Satellite MW radiometry was represented by a product developed by the GHRSST group: it is based on SST retrievals from multiple satellite MW sensors. On the other hand, satellite IR radiometry was represented by MODIS-Aqua nighttime SST retrievals. Our analysis, for the first time, provides observational evidence that there was no effect of dust intrusion on the detection of MHWs by satellite MW radiometry, despite the fact that the aerosol optical depth (AOD) ranged within an extremely wide interval of 0.3 to 5. As for IR radiometry, we found an inverse correspondence between daily variations in both IR-based SST and AOD. The inverse correspondence indicates that IR-based SST was profoundly influenced by desert dust causing negative biases in daily variations in IR-based SST. This dust-induced artificial "cooling effect" in satellite IR data masked actual MHWs. As a result, in the presence of a strong dust intrusion (AOD of up to 5), satellite IR radiometry was incapable of detecting MHWs. This was in contrast to MW radiometry which was capable of detecting MHWs. An essential point of our study is that, even in the presence of weak dust intrusion (AOD ranged from 0.3 to 0.4), IR-based SST was incapable of detecting MHWs due to the occurrence of erroneous short-term sharp drops in IR-based SST. This failure was because of dust appearance at high altitudes. Dust-related IR radiation, emitted by dust particles at high altitudes was interpreted by satellite IR sensors as SST cooler that it actually was. Our findings highlight the importance of analyzing physical factors responsible for interruptions of MHWs - namely, whether these interruptions are actual SST changes or indeed dust-induced artifacts. The failure of satellite IR radiometry to detect MHWs reduces the capability to detect MHWs by SST datasets integrating MW and IR radiometry. It was proved by the MUR Global Foundation SST analysis developed by the GHRSST group. We found an underestimation in the presence of MHWs in the Eastern Mediterranean Sea.

Reference: Kishcha and Starobinets (2026) Effect of desert dust intrusion on the detection of marine heatwaves. Remote Sensing, https://www.mdpi.com/2072-4292/18/1/48 .