English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Aerosol perturbations over selected land regions are imposed in Version-4 ofthe Goddard Earth Observing System (GEOS-4) general circulation model (GCM)to assess the influence of increasing aerosol concentrations on regionalcirculation patterns and precipitation in four selected regions: India,Africa, and North and South America. Part 1 of this paper addresses theresponses to aerosol perturbations in India and Africa. This paper presentsthe same for aerosol perturbations over the Americas. GEOS-4 is forced withprescribed aerosols based on climatological data, which interact with cloudsusing a prognostic scheme for cloud microphysics including aerosolnucleation of water and ice cloud hydrometeors. In clear-sky conditions theaerosols interact with radiation. Thus the model includes comprehensivephysics describing the aerosol direct and indirect effects on climate(hereafter ADE and AIE respectively). Each simulation is started fromanalyzed initial conditions for 1 May and was integrated throughJune-July-August of each of the six years: 1982–1987 to provide a 6-ensembleset. Results are presented for the difference between simulations withdouble the climatological aerosol concentration and one-half theclimatological aerosol concentration for three experiments: two where theADE and AIE are applied separately and one in which both the ADE and AIE areapplied. The ADE and AIE both yield reductions in net radiation at the topof the atmosphere and surface while the direct absorption of shortwaveradiation contributes a net radiative heating in the atmosphere. A large netheating of the atmosphere is also apparent over the subtropical NorthAtlantic Ocean that is attributable to the large aerosol perturbationimposed over Africa. This atmospheric warming and the depression of thesurface pressure over North America contribute to a northward shift of theinter-Tropical Convergence Zone over northern South America, an increase inprecipitation over Central America and the Caribbean, and an enhancement ofconvergence in the North American monsoon region

Sensitivity of boreal-summer circulation and precipitation to atmospheric aerosols in selected regions &ndash Part 2: The Americas