Spectroscopic Measurements of Tropospheric Composition from Satellite Measurements in the Ultraviolet And Visible: Steps Toward Continuous Pollution Monitoring from Space

This chapter reviews the current capabilities for ultraviolet and visible spectroscopic measurements of the Earth’s troposphere, and discusses what remains to be achieved in the short term to enable global, continuous measurements of atmospheric pollution from space to be undertaken. Challenges in instrumentation, spectroscopy, radiative transfer modeling, and retrievals are discussed. Current and planned satellite instruments with the capability to make tropospheric measurements in the ultraviolet and visible, with their measurement properties, spectral coverage, and target molecules, are presented. Measurement examples are taken from recent work done at the Harvard-Smithsonian Center for Astrophysics, together with our colleagues at a number of institutions. The examples include global tropospheric ozone (O3) measurements from the nadir geometry; global tropospheric nitrogen dioxide (NO2); bromine oxide (BrO) in the polar spring, and from salt lakes and volcanoes; global tropospheric formaldehyde (HCHO); and preliminary measurements of glyoxal (CHOCHO). Except for a few remaining developments, the field is shown to be sufficiently mature that global measurements of atmospheric pollution from space may be undertaken.