{"id":3428,"date":"2021-04-23T08:57:56","date_gmt":"2021-04-23T08:57:56","guid":{"rendered":"https:\/\/www.icterra.pt\/?p=3428"},"modified":"2021-04-23T08:57:56","modified_gmt":"2021-04-23T08:57:56","slug":"solar-radiation-budget-in-the-atmosphere-under-broken-cloudy-sky-an-analytical-model","status":"publish","type":"post","link":"https:\/\/www.icterra.pt\/legacy\/index.php\/2021\/04\/23\/solar-radiation-budget-in-the-atmosphere-under-broken-cloudy-sky-an-analytical-model\/","title":{"rendered":"Solar radiation budget in the atmosphere under broken cloudy sky. An analytical model"},"content":{"rendered":"

Rosa, R. N., A. M. Silva, 2021<\/span><\/p>\n

\n

This study theoretically investigates the transport of broadband solar radiation in the Earth’s cloudy atmosphere (extended and broken) by considering three plane parallel layers: i) thin bottom layer adjacent to the Earth’s surface; ii) intermediate layer where clouds are most embedded; and iii) upper layer that is essentially cloud-free with possible occurrence of only thin clouds. These three layers are coupled by\u00a0upwelling\u00a0and downwelling radiation exchanges, including multiple retro-diffusion, and both direct beam and diffuse components are considered. The interrelation and relative magnitude of the solar radiation flux cascade across the atmosphere –\u00a0\u03b1<\/strong>P<\/strong><\/sub>, R<\/strong>a<\/strong><\/sub>, R<\/strong>c<\/strong><\/sub>, R<\/strong>g<\/strong><\/sub>\u00a0and\u00a0G\/H<\/strong>\u00a0\u2013 was established and explored as a tool for the present simulations. Two distinct radiation transport regimes through the inter-cloud gaps are identified, with the regime transition occurring when (AR<\/strong>*TAN(\u03b8<\/strong>)+1)*CF<\/strong>\u00a0=\u00a01 where\u00a0AR<\/strong>,\u00a0\u03b8<\/strong>\u00a0and\u00a0CF<\/strong>\u00a0are the cloud aspect ratio, solar\u00a0zenith angle, and cloud fraction, respectively. The variation of the solar radiation fluxes with\u00a0CF<\/strong>\u00a0and\u00a0\u03b8<\/strong>\u00a0exhibit the transition between the two radiation transport regimes, as evidenced in the flux absorbed in the cloudy layer. The effect of\u00a0AR<\/strong>\u00a0upon the\u00a0solar fluxes\u00a0also exhibits the two radiation transport regimes, with one regime having linear dependence of the various fluxes on\u00a0AR<\/strong>\u00a0and the other one having fluxes stay at constant levels independent of\u00a0AR.<\/strong>\u00a0The shape factor\u00a0SF<\/strong>\u00a0of cloud top and bottom boundary \u201csurfaces\u201d is introduced to account for the self-irradiation effect for different cloud types. It is found that increased roughness of one or both boundaries increases the cloud\u00a0absorptance\u00a0in all cases whereas\u00a0transmittance\u00a0and reflectance for upwelling and downwelling can either be diminished or enhanced.<\/span><\/p>\n

With the proposed model the estimated impact of clouds on the enhancement of the\u00a0shortwave radiation\u00a0absorption in the atmospheric column was improved leading to results closer to the cloudy-sky absorptance observations reported in the literature. The ratio of the\u00a0cloud radiative forcing\u00a0at the surface to the cloud radiative forcing at the top of the atmosphere (R<\/strong>net<\/strong><\/sub>), obtained by means of the present model, lead to\u00a0R<\/strong>net<\/strong><\/sub>\u00a0=\u00a01.3, closer to the estimate of 1.5 by Cess et al. than the values reported by other cloud\u00a0radiative transfer models. Read the full article<\/a>.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Rosa, R. N., A. M. Silva, 2021 This study theoretically investigates the transport of broadband solar radiation in the Earth’s cloudy atmosphere (extended and broken) by considering three plane parallel layers: i) thin bottom layer adjacent to the Earth’s surface; ii) intermediate layer where clouds are most embedded; and iii) upper layer that is essentially […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[506,508,507],"_links":{"self":[{"href":"https:\/\/www.icterra.pt\/legacy\/index.php\/wp-json\/wp\/v2\/posts\/3428"}],"collection":[{"href":"https:\/\/www.icterra.pt\/legacy\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.icterra.pt\/legacy\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.icterra.pt\/legacy\/index.php\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.icterra.pt\/legacy\/index.php\/wp-json\/wp\/v2\/comments?post=3428"}],"version-history":[{"count":1,"href":"https:\/\/www.icterra.pt\/legacy\/index.php\/wp-json\/wp\/v2\/posts\/3428\/revisions"}],"predecessor-version":[{"id":3429,"href":"https:\/\/www.icterra.pt\/legacy\/index.php\/wp-json\/wp\/v2\/posts\/3428\/revisions\/3429"}],"wp:attachment":[{"href":"https:\/\/www.icterra.pt\/legacy\/index.php\/wp-json\/wp\/v2\/media?parent=3428"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.icterra.pt\/legacy\/index.php\/wp-json\/wp\/v2\/categories?post=3428"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.icterra.pt\/legacy\/index.php\/wp-json\/wp\/v2\/tags?post=3428"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}