Evaluation and correction of GEOS-5 pressure and temperature profiles between 40 and 70 km using Suomi/OMPS-LP data

Evaluation and correction of GEOS-5 pressure and temperature profiles between 40 and 70 km using Suomi/OMPS-LP data

P. Q. Xu^1,2, P. K. Bhartia¹, M. T. DeLand^1,3, Z. Chen^1,3, and S. Pawson¹

1) NASA Goddard Space Flight Center, Greenbelt, MD, USA

2) Science Applications Intl Corp. (SAIC), Beltsville, MD, USA

3) Science Systems and Applications, Inc. (SSAI), Lanham, MD, USA

[ABSTRACT]

The Ozone Mapping and Profile Suite Limb Profiler (OMPS-LP) on board the NASA Suomi National Polar-orbiting Partnership (Suomi NPP) satellite is a limb-scattering hyperspectral sensor designed to retrieve ozone profiles at 1.5 km vertical resolution.  Radiances are acquired over a wavelength range covering 290 nm to 1000 nm and an altitude range covering 0 km to 80 km for every event.  The OMPS LP retrieval algorithm calculates simulated radiances for each event using a radiative transfer forward model that uses pressure and temperature profiles interpolated from Goddard Earth Observing System Model Version 5 (GEOS-5) products.  The assimilation and forecast procedure used by GEOS-5 yields accurate pressure and temperature profiles up to approximately 5 hPa when compared to ground-based observations.  Above 5 hPa, the GEOS-5 profiles are effectively determined by modeling, and need to be validated against measurements.

The LP radiance residuals are defined as the difference between measured and calculated radiances.  We choose a reference wavelength with minimal atmospheric absorption (353 nm) and a reference altitude with good GEOS-5 accuracy (37.5 km) to create normalized radiance residual (NRR) profiles.  This approach removes diffuse upwelling radiation effects, and also reduces the impact of any LP altitude registration and calibration errors.  The NRR profiles above 37.5 km are then governed primarily by the accuracy of the GEOS-5 pressure profiles (and secondarily by the temperature profiles).  We use an iterative process to reduce the magnitude of the NRR values, and thus improve the accuracy of the GEOS-5 profiles, between 37.5 km and 70 km.  We evaluate these results by comparing to pressure profiles derived from Aura Microwave Limb Sounder (MLS) geopotential height measurements.