VALIDATION OF GOMOS HIGH RESOLUTION TEMPERATURE DATA WITH THE U. BONNLIDAR AT THE ESRANGE DURING JANUARY AND FEBRUARY 2003

摘要

The Bonn University lidar is located at the Esrange (68 N,rn21 E) in northern Sweden, near the city of Kiruna. DuringrnJanuary/February 2003 a measurement campaign forrnthe validation of Mipas, Gomos, and Sciamachy data wasrnperformed. During 27 measurement runs a total of nearlyrn300 hours integration time was accumulated. Most ofrnthe measurements could be used for the calculation ofrntemperature profiles in the aerosol-free part of the atmosphere,rnwhich is above 30 km altitude.rnFor the period August 2002 to February 2003 we receivedrn261 Gomos files containing high-resolution temperaturern(HRT) data, processed with the ESA operational softwarernGOPR LV2/6.0a for the Esrange location. After removingrnall data that are flagged as invalid by the processor,rnwe were left with 103 files. The range of values encounteredrnin these files are: tangent point distances from thernlidar range from 55 km to 752 km, altitudes range fromrn5 km to 46.5 km, temperatures range from 79 K to 432rnK, and temperature errors range from 3 K to 4650 K. Arnnumber of these temperature values and associated errorsrnexceed the expected extremes in the middle atmosphere.rnOut of these 103 Gomos temperature profiles we couldrnuse 25 profiles for validation. Selection criteria were thernsimultaneous spatial and temporal coincidence of the Gomosrnand lidar measurements. The time window was met,rnwhen the lidar measurements started or ended within onernhour around the Gomos measurement time. We used twornspace windows. The first window comprised all datarnwithin 500 km of the Esrange (in total 21 profiles) andrnthe second window consisted of all profiles within 1000rnkm of the Esrange (in total 25 data-sets). We interpolatedrnthe lidar data to the Gomos altitudes.rnThe comparison of all available Gomos-Lidar temperaturernpairs in the altitude range 30 to 40 km showed meanrnvalues for the temperature difference of 10.1 K and 7.4rnK in the 500 km and 1000 km tangent point range windows,rnrespectively. A t-test revealed that these differencesrncannot be attributed to chance, but must be real.rnThe respective median differences are 6.5 K and 4.5 K,rnwhile the modes are 4 K for both ranges. The discrepanciesrnof mean, median, and mode values indicate thatrnthe histogram of differences is asymmetric, which hintsrnat systematic errors as cause for the differences. The Gomosrnhigh-resolution temperatures do not agree on averagernwith the lidar temperatures for the available data-set.