The observations carried out at Lampedusa are directed mainly to study:
- the evolution of the atmospheric concentration of several greenhouse gases;
- the radiative budget of the atmosphere, and the factors that may affect it.
The first activity is aimed at the long term characterization of the atmosphere composition, and in particular to the monitoring of main greenhouse
gases like carbon dioxide (CO2), methane (CH4),
nitrous oxide (N2O), chlorofluorocarbons (CFC-11 and CFC-12).
These species have strong absorption bands in the infrared spectral range; their concentration in the atmosphere has largely increased in the last 200 years due to human activities, and are indicated as capable to affect the global temperature of the Earth. Measurement of concentration of other minor greenhouse gases (SF6, HFCs, HCFCs, some of which are used to substitute CFCs in refrigerators and air conditioning systems) will be added in the near future.
The second research activity is dedicated to the study the radiation balance, and of some important parameters that may affect it. The study is conducted by combining long-term measurements and intensive campaigns. In the long term, basic radiative fluxes (broadband shortwave downward irradiance, spectral ultraviolet irradiance, narrowband global and diffuse irradiance at selected bands) and some relevant quantities (total ozone and water vapour, aerosol optical depth) are measured continuously. During intensive campaigns additional instruments (ballons, lidars, radiometers and spectroradiometers) are added to obtain a more detailed characterization of the atmospheric structure and composition, and of the radiative fluxes at the surface. When available, measurements from satellites or from aircraft are also used. The observations of the radiative quantities are maintained on the same absolute scale through periodical calibrations against NIST traceable lamps, and routine verification of redundant measurements. The collected measurements are analyzed in an integrated effort, also by means of a detailed radiative transfer model. This model was specifically developed to accurately describe the atmospheric vertical structure and the aerosol properties.