VALIDATION OF MIPAS-ENVISAT VERSION 4.61 OPERATIONAL DATA WITH BALLOON AND AIRCRAFT MEASUREMENTS: H_2O

摘要

Embedded in the ENVISAT validation programme ofrnthe chemistry instruments GOMOS, MIPAS, andrnSCIAMACHY, a number of remote sensing and in siturntechniques from balloon and aircraft platforms werernemployed since the launch of Envisat on March 1,rn2002. In this paper we will be focusing on thernvalidation of MIPAS-Envisat (MIPAS-E) off-linernproducts, by presenting the results of thernintercomparison between MIPAS-E H_2O verticalrnprofiles as well as aircraft and balloon correlativernmeasurements as obtained within the ESABCrnprogramme [1]. First priority is given to the validationrnof processor v4.61 data. However, to get a morerncomplete picture, individual results of 2002 and 2003rnballoon observations are also compared with earlierrnversions of the MIPAS-E operational processor or withrndata processed with scientific processors run at expertrnsupport laboratories. Some general remarks are finallyrnexpressed, along with specific recommendations tornfully exploit the available ESABC validation dataset.rnUnfortunately, by the date of the ACVE-2 conference,rnre-analyzed operational MIPAS-E data was almostrnonly available for the year 2002 limiting the number ofrnvalidation cases with the new operational version 4.61rn(v4.61). Based on these few cases, the MIPAS-E H_2Ornprofiles as processed with v4.61 are in good agreementrnwith airborne observations between about 15 and 30rnkm altitude in all cases with a good coincidence in timernand space between the MIPAS-E observations and therncorrelative measurements. However, due to the veryrnlimited number of good validation cases available sornfar, this statement cannot yet been regarded asrnconclusive and representative. Low biases in MIPASErnH_2O compared to the correlative measurementsrnappear frequently in the lowermost stratospherernpointing at a retrieval problem in this crucial altitudernregion. Retrievals of MIPAS-E H_2O profiles asrnobtained by different processors appear to be generallyrnrather robust as proven by a statistics of intercomparisonsrnof H2O profiles between the operationalrnv4.61 data and data processed with the IMK scientificrnprocessor, provided that a considerable number ofrnspurious and unphysical data has been removed fromrnthe v4.61 data prior to the statistical assessment. Thisrnpoints at the need for an automatic quality control ofrnthe operationally retrieved H_2O data.rnFurther validation coincidences in differentrngeophysical situations will have to be considered usingrnv4.61 data before a final quantitative assessment on thernquality of the MIPAS-E operational H_2O data can berngiven.