Aerosol Retrievals From SPEXone on the NASA PACE Mission: First Results and Validation

We present the first Spectropolarimeter for Planetary EXploration ‐ one (SPEXone) aerosol retrieval results over land and ocean using the Remote sensing of Trace gas and Aerosol Products algorithm, covering the period 23 February–31 August 2024. We validate the retrieved Aerosol Optical Depth (AOD), Angstrom Exponent (AE), and Single Scattering Albedo (SSA) with AErosol RObotic NETwork (AERONET) data. The validation results show that SPEXone provides products of good quality, with comparable performance over land and ocean. For AOD, the Root‐Mean‐Square Error (RMSE) is 0.053 over land and 0.043 over ocean, while respectively 77% and 75% of the retrievals are within the requirement formulated by the Global Climate Observing System (GCOS). For AE, the RMSE is 0.25 over land and 0.26 over ocean. For SSA, the RMSE is 0.036 over land and 0.036 over ocean, with respectively 69% and 69.4% within the GCOS requirement. After a gap of more than 10 years, this is the first new global Multi‐Angle Polarimeter aerosol dataset. Aerosols are small particles in the atmosphere, that affect the climate by reflecting and absorbing sun light (aerosol‐radiation interactions) and by changing the properties of clouds (aerosol‐cloud interactions). The Plankton, Aerosol, Cloud and ocean Ecosystem satellite was successfully launched on 8 February 2024, carrying the SPEXone instrument which is a multi‐angle polarimeter (MAP), as one of its three instruments. The MAP measurements of SPEXone provide a wealth of information on aerosols, after a gap of more than 10 years in the availability of such measurements. This paper shows the first results from measurements by SPEXone over a ∼${\sim} $6‐month period (23 February–31 August 2024), focusing on key aerosol properties like AOD (a measure of the amount of aerosol), AE (an indicator of aerosol size), and SSA (an indicator of the fraction of light absorbed by aerosols). These properties are compared with data from the reference AERONET sunphotometer network to evaluate their accuracy, and good agreement is found between SPEXone and AERONET. Global maps of aerosol properties show distinct regional features of different aerosol types, like anthropogenic pollution, smoke, sea‐salt, and dust. We present the first aerosol retrievals (amount, size, absorption) from Spectropolarimeter for Planetary EXploration ‐ one (SPEXone) on the NASA Plankton, Aerosol, Cloud and ocean Ecosystem mission, launched February 2024SPEXone retrievals agree very well with AErosol RObotic NETwork, showing similar performance over land and oceanThe global distribution of aerosols from SPEXone shows characteristic patterns of man‐made pollution, biomass burning, dust, and sea‐salt We present the first aerosol retrievals (amount, size, absorption) from Spectropolarimeter for Planetary EXploration ‐ one (SPEXone) on the NASA Plankton, Aerosol, Cloud and ocean Ecosystem mission, launched February 2024 SPEXone retrievals agree very well with AErosol RObotic NETwork, showing similar performance over land and ocean The global distribution of aerosols from SPEXone shows characteristic patterns of man‐made pollution, biomass burning, dust, and sea‐salt