Variational bias correction of satellite radiance data in the ERA‐Interim reanalysis

TLDR

The study evaluates the performance of a variational bias correction system for satellite radiance data in ERA‑Interim and its implications for climate signal representation in reanalysis. The method automatically generates bias estimates when new satellite sensor radiances are introduced, and the authors present results from the first 19 years of ERA‑Interim (1989–2007). Results reveal MSU calibration errors, a response to the 1991 Pinatubo eruption, a long‑term drift in AMSU‑A biases, and support the use of global reanalysis for climate monitoring. © 2009 Royal Meteorological Society.

Abstract

Abstract This article describes the performance of the variational bias correction system for satellite radiance data in ERA‐Interim, and considers implications for the representation of climate signals in reanalysis. We briefly review the formulation of the method and its ability to automatically develop bias estimates when radiance measurements from newly available satellite sensors are first introduced in the reanalysis. We then present several results obtained from the first 19 years (1989–2007) of ERA‐Interim. These include the identification of Microwave Sounding Unit (MSU) instrument calibration errors, the response of the system to the Pinatubo eruption in 1991, and the detection of a long‐term drift in biases of tropospheric AMSU‐A data. We find that our results support the notion that global reanalysis provides an appropriate framework for climate monitoring. Copyright © 2009 Royal Meteorological Society