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Remote Sensing: Stratospheric and Tropospheric Ozone

Professor Robert Hudson is leading the effort in this investigation. Ozone plays an important role in the radiative and chemical balance in the atmosphere. Ozone in the stratosphere filters out harmful ultraviolet radiation from reaching the earth, and high levels of ozone near ground level cause respiratory problems for people. In addition, ozone near the tropopause exerts considerable radiative forcing. Dr. Robert D. Hudson is developing algorithms for the derivation of the global picture for total ozone in both the stratosphere and troposphere, from measurents of the ultraviolet albedo of the earth. Instruments which currently measure these albedos are the Total Ozone Mapping Spectrometer (TOMS), the Solar Backscatter Ultraviolet Spectrometer (SBUV), and the Global Ozone Monitoring Experiment (GOME). Algorithms have been developed which retrieve tropospheric column ozone in the tropics, and daily near real-time images of the results are given at the Tropical Troposheric Ozone Home Page. This technique is currently being extended to the Mid-Atlantic region to examine high ground-level ozone events (smog).

Two major interferences in the derivation of total ozone are sulfur dioxide and clouds of aerosol particles. An algorithm was developed to remove these interferences from albedos obtained during periods of major volcanic eruptions, and information was obtained about the nature of the emitted gas and the rate of formation of the resulting sulfate aerosols, which are another major source of climate forcing. A new algorithm is currently being developed to separate the effects of ozone and aerosols on the measured albedos during non-volcanic periods. This algorithm will determine the aerosol type and optical depth. In addition there is a continuing study of improvements to the algorithms used by NASA and NOAA for the retrieval of operational ozone and related data products.