MIPAS Monitoring at Oxford Anu Dudhia, Alastair Burgess, Chiara Piccolo & Vivienne Payne Page 1

MIPAS Monitoring at Oxford Daily Means Monthly Means Occupation Matrix Statistics (monthly) REC Analyses (monthly) Results on web http://www.atm.ox.ac.uk/group/mipas/ and selected results provided for monthly reports Page 2

Daily Mean Plots BIRA reported depressed CH4 values following Envisat switch-on 7th Sep 03 indicated a need for day-by-day monitoring Started generating daily zonal mean plots of NRT data at Oxford from 22nd Sep 03 Key findings 3-day pointing oscillation Change in HNO3 following LUT upgrade Step change in concentrations Nov 4th 03 Page 3

Monthly Mean Plots Main aims are: Key Findings Monitoring monthly changes in mean value Comparison with climatology Comparison of latitude structure Check for (un)expected diurnal variability Check on scatter about mean Key Findings Tangent altitudes generally up to 1km higher than nominal Persistent equatorial anomaly at 12/15km CH4, N2O Most retrievals are within 10% of climatology Not much change compared to 12 months ago Page 7

Occupation Matrix Statistics Main aims are to monitor: L2 NRT profile count Latitude distribution of retrievals Frequency of corrupt bands Frequency of cloud detection Key Findings Missing S.Polar data Jan 2003 (due to fringe count error) L2 file format bug with profile counter (fixed in v3.57 but not in 3.59) Unidentified OMs (due to altitude bands being too narrow and accidental use of old OM data at ESRIN in May03) Decreasing frequency of cloudy OMs in October 2003 Page 18

Nov 02

Nov 03

REC Analysis Main aims are to monitor: Key Findings Additional Work Residuals of key species Residuals of error sources Spectral derivative signatures Key Findings Spectral shift with wavelength Possible underestimate of AILS width Problems with NO2 microwindows Additional Work Oxford ‘OPTIMO’ retrieval of OCS Check Spectral Calibration including D Band Page 21

REC Analysis Extended Into The D Band Zeroth (Gain) Non-Operational Microwindows: [PT, H2O], NH3, OCS, SF6, SO2

First (Shift) No spectral calibration applied. These residuals originate with OPTIMO. A Linear Trend?

Second (Spread)

Conclusions Results stable with time Specific points Problems with NO2 microwindows? Persistent equatorial anomaly at 12/15km CH4, N2O Decrease of a few percent in trace gases since 3rd November 2003 Increase in HNO3 of the order of 10% since 23rd July 2003 Page 35