GRWG/GDWG Web Meeting 2012-01-17
GSICS Web Meeting on DCCs for Geostationary Lightning Mapper and Meteosat-HIRS inter-calibration strategy
- Dennis Buechler (UAH) Using Deep Convective Clouds to Monitor the Geostationary Lightning Mapper (GLM)
- Tim Hewison & Rob Roebeling (EUMETSAT) Strategy to inter-calibrate Meteosat archive using HIRS
CMA: Xiuqing ("Scott") Hu
EUMETSAT: Tim Hewison (chair), Rob Roebeling, Sebastien Wagner, Jochen Grandell, Marianne Koenig
JMA: Hiroaki Tsuchiyama, Arata Okuyama, Yoshihiko Tahara, Kenji Date, Riyuicho Nakayama, Yuki Kosaka
NASA: Dave Doelling
NOAA: Fangfang Yu
UAH: Dennis Buechler
Dennis Buechler (University of Alabama, Huntsville) presented an analysis of the use of Deep Convective Cloud as a reference for the calibration of the background images of the TRMM/LIS lightning imager. The results were very stable of 12 years (<0.5% trend), showing the stability of the instrument, as well as confirming the applicability of the DCC method. It was also interesting to note the small differences found between the reflectance and IR brightness over the land and sea. Further investigation was suggested to confirm whether these differences are related to the regional variations observed by Dave Doelling.
Rob Roebeling and Tim Hewison presented a strategy developed at EUMETSAT for generate Fundamental Climate Data Records from the 30 year archive of Meteosat data, based on inter-calibration with data from HIRS instruments operated on different NOAA and Metop polar platforms. This was intended to give an example, which may be considered for adoption by other GSICS developers for the reprocessing of other historic datasets. It highlighted some of the general problems that we face when trying to account for different instruments' spectral responses, proposing a generalised solution. Two different inter-calibration approaches were suggested, based using a homogenised series of HIRS data as a reference, or using double-differences between pairs of LEO reference instruments and GEO monitored instrument to span the whole period. In order to select the best approach it is necessary to quantify the uncertainties introduced by the spectral conversion and calibration transfer (SNO) process, as well as the drift in the calibration of the reference instrument. Approaches were proposed to address each of these.