Oxford MIPAS meeting#19
19 Nov 02

Present

Oxford: Alastair Burgess, Anu Dudhia, Don Grainger, Vivienne Payne, Chiara Piccolo, Clive Rodgers.
RAL: Victoria Jay, Jolyon Reburn

Instrument Status [Prev] [Next]

Envisat payload switched-off 18-20 Nov to minimise risk during Leonid meteor shower.

Software Updates [Prev] [Next]

Software in /home/crun/eodg/mipas/

L2/util/
- mipas_met_plot.pro (VJ) polar plot Meteo data
- polar_o3.pro (VP) polar plots of MIPAS O3 column (Dobson Units) from CDs
- dsd_read.pro (AD) fix bugs
- f_mip_l2rd.pro (AD) fix bugs
L1B/util/
- f_mip_l1rd.pro (JR) read L1B files

Auxiliary Data Updates [Prev] [Next]

New data in /home/crun/eodg/mipas/

MW/ (AD) Update MW database files (including irregular grid data) for hitran pf3.0 for key species
CS/ (AD) Update CS files (LUTs) also (only key species)

L1/L2 Data Delivery [Prev] [Next]

Still no CDs received since 01 Oct - query sent to ESA
CP retrieving MIPAS L2 data via ftp from Kiruna from ftp site ftp-ops.pdk.envisat.esa.int although not updated recently

RAL Retrievals [Prev] [Next]

Joint retrieval of O3 and H2O using ESA pT profiles

(VJ) running forward model with ESA retrieved profiles shows noticeable spectral shift between predicted and observed lines for H2O_0007 MW
(JR) attempting to run retrieval for the AMIL2DA-selected scans.

Minor Species (AB) [Prev] [Next]

Investigating potential to retrieve minor species from MIPAS spectra for orbit 2081 (24 Jul 02) using OPTIMO

Plots of Location v Scan and SZA v scan for orbit 2081

OPTIMO now adapted to work on Linux machines as well as Alphas
Successfully retrieved full orbit for CFC-11, ClONO2, SF6 (CFC-12 in progress)
Successfully retrieved 5 AMIL2DA-selected profiles for OCS, NH3
Retrieval convergence problems with N2O5 and SO2
Results (Scan# in brackets): [Polar Summer (#03)] [Mid-Lat Day (#12)] [Equatorial Day (#20)] [Polar Winter (#36)] [Mid-Lat Night (#68)]
SF6 concentration broadly in line with trend observed from ATMOS data in lower stratosphere, but curious peak in upper stratosphere
Concentrations compared to MIPAS climatologies generally in agreement with sign observed in REC analyses.

Spectral Shifts [Prev] [Next]

REC analysis shows a linear spectral shift varying from -0.001cm^-1 to +0.001cm^-1 from A to C bands

(VP) Using OPTIMO, residuals using realistic AILS show very little difference to those using ideal AILS (`realistic' AILS has now been revised due to new ilspar but large difference not expected).
(CP) ilspar now produces AILS shapes much closer to those produced by ML2PP but still minor differences, possibly due to different interpolation strategies from calibration lines to AILS in microwindows.
(CP) Investigation of switching off the `recentering' option in comp_ils shows shifts varying from -0.004 cm^-1 (A band) to -0.006 cm^-1 (D band), so `recentering' definitely needed. However trend with wavelength is very similar to that observed in the REC analysis, which may be significant.

REC analysis also shows a spectral shift varying from -0.001cm^-1 to +0.001cm^-1 from 68 to 12 km tangent altitude.

IFAC have processed 2081 down to 6 km to investigate trend at lower altitudes, REC analysis shows that 9 km (x symbols) continues the trend but 6 km often reverses it (+ symbols) NB they have also removed the trend with wavenumber
One explanation might be variation in illumnation of FOV with tangent height due to differing vertical radiance gradients. Results are inconclusive (and should be plotted differently).

Gain Oscillation (VP) [Prev] [Next]

OPTIMO-ORM temperature differences showed chequerboard pattern, due to (visible) vertical oscillations in the OPTIMO retrieval rather than the ORM.

Since OPTIMO has no `memory' of the previously retrieved profile, oscillations are thought due to some artifact in the Level 1 spectra.
Plot of the average difference (solid lines) between pairs of adjacent spectra for the PT__0004 microwindow should look like noise, which they do for 18 and 24km, but for 21 and 27km the difference has a similar shape to the average radiance (dotted line, scaled to fit).

To be investigated further.

MWMAKE (CDR) [Prev] [Next]

Adapting MWMAKE to suit TES observations