Retrieval of spectrally-resolved dust direct radiative effects over desert regions from hyperspectral observations of EMIT mission: Preliminary results

Mineral dust is one of the most abundant types of atmospheric aerosols in terms of dry mass. Dust directly interacts with both solar shortwave (SW) and thermal infrared (IR) longwave (LW) radiation and thereby influences the Earth’s radiative energy budget, which is known as the direct radiative effects (DRE) of dust. Despite significant progress made over the last few decades, there are still significant uncertainties in both model- and observation-based estimates of dust DRE, which are particularly large in the desert regions. NASA’s Earth Surface Mineral Dust Source Investigation (EMIT) mission launched in 2022 provides unique hyperspectral observations that cover most of the solar spectrum (381 nm to 2493 nm) and corresponding surface reflectance retrievals over the dust source regions. Our research is motivated to provide a unique observation-based, spectrally-resolved clear-sky SW dust DRE at the top of atmosphere (TOA) in the desert regions based on a novel method enabled by the hyperspectral observations of EMIT instrument.

In this paper, we will first show a comparison of the upwelling broadband SW flux derived from the EMIT hyperspectral observations with the collocated CERES flux product. Then we will present a few case studies to demonstrate our spectrally-resolved dust DRE retrievals.