Stratospheric Infrared Measurements

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9415388 Murcray Infrared remote sensing instruments have provided a wealth of information about the atmosphere. Because nitrogen and oxygen are almost completely transparent in the infrared, radiative transfer is dominated by minor and trace gases. Many of these gases are chemically active, and infrared techniques provide methods of measuring their concentrations. Changes in the chemical balance in the atmosphere also affect the Earth's radiative budget. Since most of the planet's cooling takes place in the mid infrared, accurate measurements are needed both to detect changes, and to verify model calculations. This project will continue infrared measurements of the stratosphere and upper troposphere using balloon and ground-based instruments. The very high resolution solar absorption spectrometer will make one flight per year from the US. This instrument has been flown several times previously to obtain solar absorption spectra. The spectra taken as the balloon ascends show the change in atmospheric transmission with altitude. Once the balloon is at float altitude (approx. 40 km), changing geometry as the sun sets provides very long optical absorption paths entirely at high altitudes. These data allow chemical concentrations of several species to be measured simultaneously as a function of altitude, provide tests for models which calculate atmospheric radiative transfer, and verify the molecular parameters database necessary for the models. Data from a very high resolution ground based solar spectrometer (operated by the DOE) will be used to recover information on chemical concentrations in the stratosphere and upper troposphere. DOE is accumulating a long term data set for the study of clouds and radiation, which will contain a long record of stratospheric and upper tropospheric chemical compounds.