Surface Reflectance in the Visible for Improved Satellite Measurements of Near-surface Ozone

Abstract:

We present high spectral resolution calculations of visible surface reflectance as a function of wavelength for use in satellite measurements of ozone using the Chappuis band (400-650 nm) and evaluate the impacts of using this reflectance data in two methods on GOME-2 (Global Ozone Monitoring Experiment–2) ultraviolet + visible ozone profile retrievals. The TEMPO (Tropospheric Emissions: Monitoring of Pollution) instrument is planned to measure backscattered solar radiation in the 290-740 nm range, including the ultraviolet and visible Chappuis ozone bands for increased sensitivity to near-surface ozone. Observation in the weak Chappuis band takes advantage of the relative transparency of the atmosphere in the visible to achieve sensitivity to near-surface ozone. However, due to the weakness of the ozone absorption features this measurement is more sensitive to errors in visible surface reflectance, which is highly variable. We utilize reflectance measurements of individual plant, man-made, and other surface types to calculate the primary modes of variability of visible surface reflectance at a spectral resolution comparable to than that of TEMPO (0.6 nm). Using MODIS (Moderate-resolution Imaging Spectroradiometer) BRDF (Bidirection Reflectance Distribution Function)/albedo product and our derived primary modes we construct a high spatial resolution climatology of wavelength-dependent surface reflectance over all viewing scenes and geometries. In the ozone profile retrieval from visible measurements, we can model the surface reflectance by either fitting a combination of primary modes or using the derived high spatial resolution spectral reflectance. We evaluate the improvement using this new reflectance data in multispectral ultraviolet + visible ozone retrievals from the GOME-2 instrument and compare the retrieval performance of using these two approaches.