DETERMINATION OF THE EFFECT OF AEROSOLS ON DIRECT SOLAR RADIATION WITHIN THE GLOBE PROGRAM

The paper explains the operating principle of a hand held Sun photometer with light emitting diodes (LED) that was developed for international scientific and educational program “Global Learning and Observation for the Benefit of the Environment” (GLOBE). The performance of GLOBE LED Sun photometer is described and sensitivity of the hand held LED instrument in relation to the photometer with interference filters is discussed. Using of Langley’s method to determine extraterrestrial constant of GLOBE LED Sun photometer is discussed. More than 120 GLOBE schools around world are conducting aerosol measurements on daily basis and have reported around 80.000 data on atmospheric optical depth. There are four GLOBE Sun photometers operating in Croatia now, which are used by six schools, so our schools made around 5000 measurements. The data collected to date indicates that the GLOBE LED Sun photometer is capable of meeting its dual purpose of ground and space based data comparison and for use of inquiry based approach to science education in schools