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.

[There is a lack of agreement on the sign and magnitude of the effect of dust-radiative forcing on African easterly waves (AEWs) among past studies. The uncertainty in the dust-radiative forcing associated with the estimation of shortwave absorption is a leading cause of disagreement in the literature. The inability of models to represent various dust–AEW interaction pathways also leads to uncertainty among modeling studies. The present study investigates the sensitivity of AEWs to the observed variability in dust shortwave absorption using a high-resolution atmospheric general circulation model. Global simulations are conducted at a spatial resolution of about 25 km to simulate AEWs and associated circulation features adequately well. The results reveal that AEWs are highly sensitive to dust shortwave absorption. In addition, the AEW activity intensifies and broadens the wave track with a southward shift in response to dust shortwave absorption. There is approximately a 25 \% change in eddy kinetic energy (EKE) associated with AEWs for the range of dust shortwave absorption used. The 6-9–day waves are more sensitive to dust shortwave absorption than the 3-5–day waves, where the response in the former has a stark land–sea contrast. The sensitivity of AEW to dust heating stems from a combination of the response from various energy conversions. Although baroclinic energy conversion is the leading term in the energy cycle, the responses to dust shortwave heating in barotropic and generation terms are comparable to those in baroclinic conversion.]

The global average temperature has increased significantly since the preindustrial era. Translating global warming into regional scales is crucial to formulate effective environmental and climate policies. A realistic assessment of regional climate change requires high-resolution datasets. We present a new high-resolution (9 km) analysis of historical and future regional warming over the Middle East and North Africa (MENA) using observations, reanalysis products, and statistically downscaled global climate models from the Coupled Model Intercomparison Project (CMIP) Phase 5 and 6. The observed regional temperature change over the MENA subregions appears to be up to three times faster than the global average. Regional warming has already surpassed the 1.5 ℃ and is at the brink of exceeding 2 ℃. By the end of the 21st century, the Arabian Peninsula will warm from 2.66 ± 0.57 to 7.61 ± 1.53 ℃ under the low (SSP1–2.6) and high-end (SSP5–8.5) emission scenarios, respectively. We identify spatially distinct summer and winter warming hotspots. The most prominent spots in summer are the Arabian Peninsula Hotspot Region (APHR) and Algerian Hotspot Region. Major winter hotspots appear over Mauritania in West Arica and the Elburz Mountains. Moreover, APHR has already exceeded 2 °C of warming and will warm by about 9 °C under the high-end emission scenario by the end of the century. The 1.5, 2, 3, and 4 ℃ global warming levels are associated with substantial regional warming of 2.1 ± 0.2, 2.76 ± 0.2, 4.19 ± 0.25, and 5.49 ± 0.38 ℃, respectively, over the Arabian Peninsula.

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.