Envisat Validation Workshop Atmospheric Chemistry Validation Team GroundBased

Envisat Validation Workshop Atmospheric Chemistry Validation Team Ground-Based Measurements and Campaign Database Subgroup Comparison of other Sciamachy operational products Renske Timmermans, renske. timmermans@knmi. nl Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 1

Contributions from • AOID 427 – Yuri Timofeyev (PI), Dmitry Ionov St. Petersburg State University • AOID 126 – Martine de Maziere (PI), Thierry Coosemans BIRA-IASB • AOID 174 – Hennie Kelder (PI), Renske Timmermans, Jan-Fokke Meirink, Ankie Piters KNMI Bogumil Kois Legionowo, Poland Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 2

Direct solar observations with IR spectrometer Intercomparison of CO columns The nearest SCIAMACHY pixel is selected within a 500 km range from the GB station Constant values found

CO columns Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 4

Direct solar observations with IR spectrometer Intercomparison of CH 4 columns The nearest SCIAMACHY pixel is selected within a 500 km range from the GB station Constant values found

CH 4 columns Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 6

CH 4 columns BIAS_1_CH 4 22 nov Constant value Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 7

H 2 O columns Version 3. 53, 25 October-10 November § BIAS-2 (ch. 8 2360 -2366): all negative values version 4. 0 positive values but orders of magnitude too high § BIAS-1 (ch. 8 2269 -2275): values between 0 en 3 x 10^5 kg m-2 1% of pixels is negative (not counting sza > 85 ) § BIAS-0 (ch 7 2031 -2038): non-physical values, large spread with small given errors, many ‘normal’ values around 10 to 20 kg m-2. 0. 1% of pixels is negative. Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 8

H 2 O columns Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 9

Intercomparison of H 2 O columns Direct solar observations with IR spectrometer The nearest SCIAMACHY pixel is selected within a 500 km range from the GB station COMPARISON OF SCIAMACHY WITH GROUND-BASED MEASUREMENTS-AOID 427 Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 10

Intercomparison of H 2 O columns Sciamachy data * Integrated radiosonde * Closest Sciamachy pixel Mean difference : -33 % St. dev. : 35 % Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 11

Intercomparison of H 2 O columns Sciamachy data * Integrated radiosonde * Closest Sciamachy pixel Mean difference: 90 % St. dev. : 220 % * Integrated radiosonde/ozonesonde Sciamachy data Sonde data from Bogumil Kois, IMWM, Legionowo, Poland Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 12

Intercomparison of H 2 O columns Int. sonde on 29 oct = 15. 4 kg/m 2 Int. sonde on 5 nov = 10. 0 kg/m 2 Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 13

Conclusions • Sciamachy columns of CO, CH 4 and H 2 O show non-physical values, orders of magnitude too high, negative values, large spread, constant values at high sza (close to gb values). • Given the current status of these products, comparing with groundbased measurements does not give any additional information • Br. O, Cl. O, SO 2, H 2 CO: not in the distributed products yet • CO 2, N 2 O: too unrealistic to do any comparisons (CO 2 = 0, N 2 O orders of magnitude too large) Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY ‘other’ products 12/12/2002 Page 14