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Aerosols significantly affect cloud microphysics and energy budget in different ways. The contribution of the direct, semi‐direct, and indirect effects of aerosols on radiation are here investigated over the North Atlantic tropical ocean under different aerosol loadings. The Weather Research and Forecasting Model is used to perform a set of numerical idealized experiments, which are forced with prescribed aerosol profiles. We evaluate the effects of aerosols on modeled shallow clouds and surface radiative budget. The results indicate that large aerosol loadings are associated with enhanced cloudiness and reduced precipitation. While the change in rainfall is mainly due to the larger number of smaller droplets, the change in cloudiness is attributed to the effects of absorbing aerosols, mainly dust particles, which are responsible for a rise of temperature that feeds back onto specific humidity. As in the boundary layer the increase of moisture dominates, the net effect is a higher relative humidity, which favors the formation of thin low non‐precipitating clouds. The feedback accounts for a dynamical change in the lower troposphere: shortwave radiation absorption increases temperature at the top of the marine atmospheric boundary‐layer and reduces entrainment of warm and dry air, increasing low level moisture content. Despite the overall increase in cloudiness, daytime cloud cover is reduced. The semi‐direct effect of aerosols on clouds results in a warming of the surface, opposite to the indirect effect. [ABSTRACT FROM AUTHOR]

Previous studies indicate that convective heating variability of the western North Pacific summer monsoon (WNPSM) influences strongly weather and climate over East Asia. Based on daily reanalysis data and interpolated outgoing longwave radiation (OLR) data, this study demonstrates that the WNPSM convection can also cause severe weather events remotely over the Antarctic through the exciting of the Australia‐South Pacific‐Atlantic wave train (ASPA pattern). Surface air temperature (SAT) rises over the Ross Sea‐Mawson‐Dumont d'Urville Seas sector and over the Weddell Sea, while the SAT drops over the Amundsen–Bellingshausen Seas. Concurrently, sea ice concentration (SIC) is reduced over the Ross Sea and enhanced over the Amundsen–Bellingshausen Seas. The result suggests that the newly found ASPA pattern may serve as an important bridge linking the WNPSM convection and the weather over the Antarctic region. The dynamics of ASPA's formation and propagation are also investigated comprehensively. Day‐to‐day energy budget analysis suggests that after its initiation by WNPSM convection, the ASPA pattern is driven by the baroclinic energy conversion from the climatological flow and nonlinear term. The barotropic energy conversion from the climatological flow contributes to positive KE tendency before day +1 and negative KE tendency after day +1. It is therefore extremely important to improve the representations of the climatological‐mean sea ice and jet stream, wave‐mean flow interaction and wave‐wave interaction in the mid‐ and high‐latitudes of the Southern Hemisphere, as well as the convection over the WNPSM region of the Northern Hemisphere in numerical model for a better weather prediction for the Antarctic. [ABSTRACT FROM AUTHOR]

The impact of local climate conditions on air temperatures during a hot summer period over the United Kingdom in 2018 is studied using simple sensitivity experiments with a state‐of‐the‐art regional numerical weather prediction system. The experiments are designed to investigate the influence of sea surface temperature (SST) and soil moisture on the air temperatures over land. They involved applying changes to the analysed SST and soil moisture patterns with magnitudes consistent with the differences between forecast analysis and climatology. The results from daily 5‐day forecasts over an 11‐day period show that a 3°C reduction in SSTs reduces the simulated air temperatures averaged over all land points by just over 1°C. Moistening the soil while using the control SSTs reduces the temperatures by a little less than 1°C on average although this can be larger than 3°C locally. While the reduction in SST impacts the daily maximum and minimum temperatures to a similar extent, the increase in soil moisture had little impact on the daily minimum temperatures. [ABSTRACT FROM AUTHOR]

The microwave temperature sounder (MWTS) on board the third FengYun satellite (FY-3C) is well suited for the detection of tropical cyclones because the observed radiance is insignificantly affected by non-precipitating clouds. In this study, a stepwise multiple linear regression technique is proposed to retrieve the atmospheric temperature profiles based on MWTS measurements. Under clear-sky conditions, the root-mean-square error of retrieved temperature is no >1.4 K, which is low enough to monitor the thermal structure within typhoons. An application of this method to the Super Typhoon Rammasun resolves the warm-core eye and temperature gradients across the eye-wall very well. [ABSTRACT FROM AUTHOR]