Ground-based measurements of local cloud cover |
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Authors: | Abel Antônio Silva Mariza Pereira de Souza Echer |
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Institution: | 1. Instituto de Estudos Avan?ados, Rod. dos Tamoios km 5.5, Torr?o de Ouro II, S?o José dos Campos, SP, CEP, 12228-001, Brazil 2. Instituto Nacional de Pesquisas Espaciais, Av. dos Astronautas 1758, Jd. Granja, S?o José dos Campos, SP, CEP, 12227-010, Brazil
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Abstract: | Clouds are believed to reflect temporal climate changes through variations in their amounts, characteristics, and occurrence. In addition, they reflect both weather and climate in a region. In this work, a methodology to determine the local cloud cover (LCC) is proposed using sky images obtained from a ground-based instrument. Three years of sky images from an urban, tropical site were obtained and analyzed through that methodology. Monthly average LCC varied from 3 to 96 %, while seasonal average values were 68 % for summer, 54 % for spring, 46 % for fall, and 23 % for winter. LCC results show a clear seasonal dependence and a fair agreement (r 2 = 0.72) with satellite data, which typically underestimate the cloud cover in relation to LCC. Our analysis also suggests the possibility of a measurable link between LCC and natural events like the El Niño Southern Oscillation. |
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