1. Atmospheric, Oceanic & Planetary Physics, University of Oxford A Dudhia MIPAS QWG13 Firenze 12-14 June 2007 Page 1 Radiometric Offset Impact on L2 Anu Dudhia University of Oxford

2. Atmospheric, Oceanic & Planetary Physics, University of Oxford A Dudhia MIPAS QWG13 Firenze 12-14 June 2007 Page 2  Microwindow selection and error analysis has assumed uncertainty in radiometric offset error which is  fully correlated (i.e., constant) with altitude,  uncorrelated between microwindows, and  of magnitude ±1  = NESR (apodised)  What would be the impact of an additional error which is  uncorrelated (i.e., randomly varying) with altitude,  fully correlated between microwindows, and  of magnitude ±1  = 20% nominal, unapodised NESR  Plots show current error analysis, plus additional systematic error in green with (solid) and without (open) continuum fitted for each microwindow

3. Atmospheric, Oceanic & Planetary Physics, University of Oxford A Dudhia MIPAS QWG13 Firenze 12-14 June 2007 Page 3

4. Atmospheric, Oceanic & Planetary Physics, University of Oxford A Dudhia MIPAS QWG13 Firenze 12-14 June 2007 Page 4

5. Atmospheric, Oceanic & Planetary Physics, University of Oxford A Dudhia MIPAS QWG13 Firenze 12-14 June 2007 Page 5

6. Atmospheric, Oceanic & Planetary Physics, University of Oxford A Dudhia MIPAS QWG13 Firenze 12-14 June 2007 Page 6

7. Atmospheric, Oceanic & Planetary Physics, University of Oxford A Dudhia MIPAS QWG13 Firenze 12-14 June 2007 Page 7  For the assumed amplitudes (e.g., 10nW/etc for A band) altitude-varying, spectrally-correlated radiometric offsets  are effectively removed by the continuum fit,  but would have a significant impact on the retrieval if no continuum fit were applied Conclusions

8. Atmospheric, Oceanic & Planetary Physics, University of Oxford A Dudhia MIPAS QWG13 Firenze 12-14 June 2007 Page 8