SCD2 SATELLITE FROM INPE MONITORS THE PLANETARY REFLECTIVITY OVER SOUTH AMERICA

The solar radiation reflected by the system Earth.s surface and atmosphere is known as Albedo. The value of the albedo depends on the nature or quality of the Atmosphere and on the type of surface (Land or Ocean) and cloud cover. Various natural and man-made phenomena (Greenhouse effect, Heat exchange, Aerosols, Deforestation, Volcanic eruption, etc.) change the value of Reflectivity (Veissid, 2003, 2011 and 2012). Therefore the variation of the planetary albedo values can be used to monitor climate chang

Experimento ALBEDO do satélite SCD2 do INPE estabelece base de dados decenal para monitorar mudança climática global

The second satellite of the Brazilian Space Mission of the National Institute of Space Researches (SCD2/MECB) launched on October 23, 1998 carries on board an ALBEDO experiment that use space solar cell produced in Brazil. The device acts as a sensor of light and it allows measure the direct solar radiation and the portion of this radiation that it is reflected outside of Earth. This way, the experiment measures the global albedo through the relationship between these two values after spherical angular corrections. The SCD2 has a circular orbit of 750 km high. Albedo data are transmitted in real time and received by the ground station of Cuiabá, MT-Brazil (16S; 56W), which limits its spatial coverage on South America. Statistics done in the data allowed establish a decanal pattern albedo map, on South America, to the four season periods: DJF (december, january and february), MAM (march, april and may), JJA (june, july and august) and SON (september, october and november). This work shows this pattern and use it to determine the annomaly variation map at the period DJF of 2009 year.Pages: 8767-877

Taxa de absorção atmosférica sobre as cidades de Botucatu-SP e Rio de Janeiro-RJ

O segundo satélite da Missão Espacial Completa Brasileira (SCD2/MECB) foi colocado em órbita em 23 de Outubro de 1998 e carrega a bordo um experimento de células solares. Célula solar de silício é um dispositivo semicondutor, que pode medir a intensidade da radiação visível e parte da radiação infravermelha (400-1100 nm). O experimento permite medir simultaneamente a insolação direta e parte da radiação solar que é refletida pela Terra para o espaço. Os dados do experimento célula solar são transmitidos em tempo real pela telemetria do satélite e recebidos pela estação terrestre em Cuiabá, MT-Brasil (16°S; 56°W). Este fato limita a cobertura espacial para um círculo sobre a América do Sul. O albedo planetário é obtido dentro desta cobertura e seus valores podem ser agrupados em períodos temporais (anual, sazonal ou mensal), ou podem ser estudados para várias localizações (latitude e longitude) durante a vida do satélite. O coeficiente de transmissão atmosférica ou índice de claridade (Kt), medido em estações meteorológicas na superfície da Terra, junto com o valor medido simultaneamente do albedo planetário, permite calcular o coeficiente de absorção atmosférica (Ka). O método desenvolvido neste trabalho para avaliar Ka considera que o albedo planetário é composto por duas partes: uma refletividade local e uma refletividade não local. Considerando este novo conceito, é definida uma taxa de absorção atmosférica (denominada Ra) que é a razão entre Ka e a potência de irradiância solar líquida, que não atravessou a atmosfera (100%-Kt). A taxa de absorção atmosférica assim definida é independente da cobertura de nuvens. O histograma de freqüência de Ra mostra os valores de 0,86±0,07 e 0,88±0,09 sobre as cidades de Botucatu-SP e do Rio de Janeiro-RJ, durante os anos de 1999 até 2006, respectivamente.The second satellite of the Brazilian Complete Space Mission (SCD2/MECB) was launched on October 23, 1998 and it hosts on board a solar cell experiment. Silicon solar cell is a semiconductor device that senses visible and near infrared (400-1100 nm) radiations. The experiment permits the simultaneous inference of direct insolation and the insolation that is reflected outside of Earth. The data of the solar cell experiment are transmitted in real time by the satellite telemetry and are received by the ground station of Cuiabá, MT-Brazil (16°S, 56°W). This fact limits their spatial coverage to a circle on the South America. The planetary albedo is obtained inside this coverage area and the data can be grouped into periods of time (annual, seasonal or monthly) or studied for several places (latitude and longitude) during the life of the satellite. Atmospheric transmission coefficient or clearness index (Kt), measured at meteorological stations around the Earth surface, together with simultaneous measured of the planetary albedo permits to calculate the atmospheric absorption coefficient (Ka). The developed method in this work for evaluating the Ka considers that the planetary albedo is composed by two parts: the local and the non local reflectivity. Considering this new concept, an atmospheric absorption ratio (called here Ra) is defined as the quotient between Ka and the net solar irradiance power that is not transmitted through the atmosphere (100%-Kt). The atmospheric absorption ratio defined by this way is not cloud cover dependent. The frequency histogram of Ra indicates the values of 0.86±0.07 and 0.88±0.09 on the cities of Botucatu-SP and Rio de Janeiro-RJ respectively, during the years of 1999 to 2006