Intercomparisons of MIPAS and SCIAMACHY L1 and L2 Products with GOME and AATSR Authors: B.Kerridge, R.Siddans, J.Reburn, B.Latter and V.Jay (Remote-Sensing Group, Rutherford Appleton Laboratory, UK)  

Progress at RAL on Envisat Cal/Val Project AO1204 Outline Progress at RAL on Envisat Cal/Val Project AO1204 Preliminary MIPAS Intercomparisons: L1B in operational microwindows with calculations using ECMWF T, H2O & O3 L2 H2O and O3 with ECMWF and with RAL GOME O3 profiles Preliminary SCIAMACHY L1B Intercomparisons: Direct-sun spectrum with GOME Sun-normalised radiance spectra in uv/vis with GOME Spectrally-integrated sun-normalised radiances with AATSR 550, 670, 870nm & 1.6mm

Comparisons of MIPAS L1 with Calculated Spectra O3 MW1 24km Tangent-Height Orbit 2081 24/07/02 MIPAS L2 T, O3 & H2O ECMWF T, O3 & H2O

H2O MW1 15km Tangent-Height Orbit 2081 24/07/02 MIPAS L2 T, O3 & H2O ECMWF T, O3 & H2O

Comparisons of MIPAS L2 O3 & H2O ECMWF data for 24/07/02 interpolated to MIPAS L2 grid ECMWF H2O blended with climatology in stratosphere Individual profiles and orbit cross-sections compared Structures in cross-sections broadly similar in stratosphere O3 MIPAS generally higher than ECMWF in stratosphere (by 1-2 ppmv) MIPAS affected by PSCs near S.Pole in stratosphere MIPAS (too) high in equatorial upper troposphere (due to cloud) H2O MIPAS generally higher in stratosphere (~several ppmv) MIPAS (too) high near S.Pole in stratosphere (due to PSCs?)

Comparison of MIPAS L2 O3 Orbit Cross-Section with ECMWF Orbit 2083 on 24/07/02

Comparison of MIPAS L2 H2O Orbit Cross-Section with ECMWF Orbit 2083 on 24/07/02

Comparison of MIPAS L2 H2O Orbit Cross-Section with ECMWF Orbit 2083 on 24/07/02

Correction for GOME Scan-Mirror Degradation - Correction needed for GOME O3 profiles in 2002 to compare with Envisat - Empirical correction scheme devised from calculations assuming climatology - Update to ozonesonde statistical intercomparison in progress Wavelength (nm) Time Wavelength (nm) Time

MIPAS vs GOME O3 24 July 2002 (degradation corrected) Latitude (N)

Comparisons of SCIAMACHY L1 data with GOME in uv/vis Solar irradiance spectrum Sun-normalised radiances Orbit 2509, 11th August 2002 Different SZAs accounted for Co

Comparison of Sun-Normalised Radiances in Band 1

Comparison of Sun-Normalised Radiances in Bands 2-4

Summary of Preliminary Findings MIPAS L1 Example L1 spectra consistent with calculations in O3 & H2O mw’s Registration of tangent-point pressures crucial, but difficult to assess MIPAS L2 O3 and H2O Stratospheric O3 and H2O x-sections quite consistent with ECMWF Stratospheric O3 consistent with GOME (10% for 20-36km at mid-lat); vertical structure smoother than anticipated cf GOME (vert res 4-6km) SCIAMACHY L1 Sun-normalised radiances significantly lower than GOME: ~10-25% in uv (Bands 1 & 2) ~5-20% in vis (Bands 3 & 4)

Planned Further Work on MIPAS & SCIA Cal/Val Assess MIPAS L1 tangent-pressure registration Extend comparison of MIPAS L2 with GOME O3 profiles Comparisons of MIPAS L2 O3 & H2O with other schemes (AMIL2DA) Extend comparison of SCIA-nadir L1 with GOME Comparison of SCIA-nadir L1 with AATSR (cf ERS-2 GOME/ATSR-2) Assess SCIA radiometry cf AATSR 550, 670, 870nm and 1.6mm Assess SCIA pointing cf AATSR (1km x 1km) Comparison of SCIAMACHY L2 O3 profiles, when available, with O3 profiles retrieved by RAL scheme from: GOME SCIA-nadir (when improved L1B available).

Supplementary Slides

Comparison of MIPAS L2 O3 Orbit Cross-Section with ECMWF

Comparison of MIPAS L2 O3 Orbit Cross-Section with ECMWF Orbit 2082 on 24/07/02

Comparison of MIPAS L2 H2O Orbit Cross-Section with ECMWF Orbit 2081 on 24/07/02

Comparison of MIPAS L2 H2O Orbit Cross-Section with ECMWF Orbit 2081 on 24/07/02

Comparison of MIPAS L2 H2O Orbit Cross-Section with ECMWF Orbit 2082 on 24/07/02

Comparison of MIPAS L2 H2O Orbit Cross-Section with ECMWF Orbit 2082 on 24/07/02

MIPAS retrievals from real data

Comparisons of MIPAS L1 with Calculated Spectra O3 MW21 24km Tangent-Height Orbit 2081 24/07/02 MIPAS L2 T, O3 & H2O ECMWF T, O3 & H2O

H2O MW1 21km Tangent-Height Orbit 2081 24/07/02 MIPAS L2 T, O3 & H2O ECMWF T, O3 & H2O

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Co

Key-data

Comparison of SCIA-nadir Sun-Normalised Radiances with AATSR SCIA integrated spectrally over AATSR 550, 670, 870nm and 1.6mm filters Spatial integration over scenes (480km (across) x 512km (along)) viewed in common on Orbit 2338 11/08/02

Ratio to simulation with albedo 0 Comparison in Bands 2-4 Ratio to simulation with albedo 0 Measurement