Using longwave HIRS radiances to test climate models

Emma C. Turner*, Simon F. B. Tett

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

A 'model-to-radiance' comparison of simulated brightness temperatures from the Hadley Centre Global Environmental Model 2 with measurements from the High Resolution Infrared Radiation Sounder/4 (HIRS/4) instrument onboard the MetOp-A satellite is presented. For the all-sky, the model overestimates brightness temperatures in the atmospheric window region with the greatest biases over areas associated with deep convective cloud. In contrast to many global climate models, much smaller clear-sky biases are found indicating that model clouds are the dominating source of error. Simulated values in upper atmospheric CO2 channels approximate observations better as a result of compensating cold biases at the poles and warm biases at lower latitudes, due to a poor representation of the Brewer Dobson circulation in the 38 level 'low-top' configuration of the model. Simulated all and clear-sky outgoing longwave radiation (OLR) evaluated against the Clouds and the Earth's Radiant Energy System (CERES) and HIRS OLR products reveal good agreement, in part due to cancellation of positive and negative biases. Through physical arguments relating to the spectral energy balance within a cloud, it is suggested that broadband agreement could be the result of a balance between positive window biases and unseen negative biases originating from the water vapour rotational band in the far infrared (not sampled by HIRS).

Original languageEnglish
Pages (from-to)1103-1127
Number of pages25
JournalClimate Dynamics
Volume43
Issue number3-4
DOIs
Publication statusPublished - Aug 2014

Keywords / Materials (for Non-textual outputs)

  • GCM
  • HadGEM2
  • HIRS
  • Radiation
  • RTTOV
  • Clouds
  • EARTH RADIATION BUDGET
  • GENERAL-CIRCULATION MODEL
  • OFFICE UNIFIED MODEL
  • LOW-TOP VERSIONS
  • SATELLITE-OBSERVATIONS
  • DIURNAL CYCLE
  • WATER-VAPOR
  • CLOUD COVER
  • BRIGHTNESS TEMPERATURE
  • AIR-TEMPERATURE

Fingerprint

Dive into the research topics of 'Using longwave HIRS radiances to test climate models'. Together they form a unique fingerprint.

Cite this