The Middle East (ME) is threatened by severe air pollution due to human-induced sulfur dioxide (SO2) emissions from the oil and gas industry, power, and desalination plants. SO2 emissions contribute to sulfate aerosol generation, impacting cloud formation and climate. This study refines OMI-HTAP SO2 point source emissions using inverse modeling with OMPS SO2 observations and FLEXPART-WRF simulations. This model used hourly meteorological data from the WRF-Chem run with OMI-HTAP SO2 emissions at a 10 km resolution for 2016. In particular, we ported the WRF-Chem’s code for simulating major SO2 sinks (dry deposition, oxidation by OH and H2O2) into the FLEXPART-WRF model. This enabled the exclusion of ’background’ SO2  column loadings caused by the spatially distributed emissions from OMPS observations and allowed the inversion of daily emission rates for 134 point sources mainly in the ME. The annual mean RMSE for column loadings relative to OMPS observations decreased by ~16%, and the total point emissions rate in the OMI-HTAP inventory dropped by ~23%. We found that this overestimation of prior emissions from point sources is inherent to data-driven emission quantification methods (for example, the Gaussian plume fitting method), which are incapable of ’background’ column loadings removal in areas with a high density of strong point sources. In turn, the approach proposed here avoids this deficiency. Seasonal fluctuations in inverted emissions are observed for point sources categorized as ’power plant’ and ’unknown’ types. The enhanced OMI-HTAP dataset will be applied in ME air-quality modeling. The framework can also extend to other gases.

We modeled the radiative forcing (RF) of sulfate aerosols and water vapor (WV) clouds generated by the explosive eruption of the Hunga volcano on January 15, 2022, using the WRF-Chem meteorology–chemistry model. We injected 150 Mt of WV and 0.45 Mt of SO2 at a height of 35 km. The resulting volcanic WV layer was cooled through thermal radiation and descended to 27 km in two weeks. The WV mixing ratio within the plume exceeded 30 ppmV after the eruption, gradually reducing after that. Within three weeks, SO2 had been converted to SO4 with a 1.0 µm global stratospheric aerosol optical depth (SAOD) of 0.0025. To fit the observed SAOD, the SO2 mass should be scaled to 0.73–1.46 Mt. The six-month-average global mean net instantaneous RF (IRF) of volcanic sulfate aerosols (SAs) at the top of the atmosphere (TOA) reaches −0.381 W/m2 for 1.46-Mt SO2 emission. The negative WV net IRF at TOA is at least one order of magnitude smaller than that from SAs. The WV IRF at the bottom of the atmosphere is negligibly small and cannot cause discernable long-term effects on climate. Broadband WV calculations overestimate IRF by 30% relative to line-by-line calculations. Cooling in the lower stratosphere within the WV plume exceeds −1 K, and the WV adjusted (to stratospheric temperature) RF (ARF) is positive at TOA and the tropopause but overwhelmed by negative SA forcing. The patchy tropospheric temperature response does not show systematic changes.

In desert regions like the Middle East (ME), dust has a profound impact on the environment, climate, air quality, and solar devices. The size of dust particles determines the extent of these effects. Dust deposition (DD) measurements show that coarse dust particles with geometric radius r > 10 μm comprise most of the deposited mass. Still, these particles are not represented in the current models that are tuned to fit the observed aerosol visible optical depth (AOD). As a result, the existing models and reanalysis products underestimate DD and dust emission (DE) almost three times. This is the first study to constrain the dust simulations by both AOD and DD measurements to quantify the effect of coarse and fine dust using the WRF-Chem model. We found that, on average, coarse dust contributes less than 10% to dust shortwave (SW) radiative forcing (RF) at the surface but comprises more than 70% of DE. Annual mean net RF over the Arabian Peninsula and regional seas locally reaches -25 W m-2. Airborne fine dust particles with radii r < 3 μm are mainly responsible for the significant dimming (5-10%) of solar radiation, cooling the surface and hampering solar energy production. However, dust mass deposition is primarily linked to coarse particles, decreasing the efficiency of Photovoltaic panels by 2-5% per day. Therefore, incorporating coarse dust in model simulations and data assimilation would improve the overall description of the dust mass balance and its impact on environmental systems and solar devices.