Oxford MIPAS meeting#113
06 March 07

Present

Oxford: Anu Dudhia, Michael Holmes, Jane Hurley, Luis Millan-Valle, Chiara Piccolo, Joanne Walker, Claire Waymark

Instrument Status [Prev] [Next]

Currently operating for 3 orbits/day, ascending/descending over Plateau Rose (near Zermatt) in support of the ECOWAR campaign.

Begin 3 full days of nominal mode on 10 March

Mission Planning Document for 2007 [XLS] [HTML].
Currently defined measurement modes
Envisat Web-Site

Software Updates (L1C) (AD) [Prev] [Next]

New version of our local IDL l1c.pro software (to apodise L1B spectra and extract microwindows) in /home/crun/eodg/mipas/l1c/l1c.pro

02MAR07: AD/CP Allow for 'batch mode' to process sequence of L1B files

L1B Anomalies (AD) [Prev]

The second of the two anomalies reported in the last meeting seems to have been resolved (continuum-like emission at high altitude) - see message below.

L2 Data [Prev] [Next]

ESA has now started to release RR27 L2 data for validation

This is processed with ML2PP (basically a prototype of the operational processor) however, somewhat confusingly, the files are all labelled as processed with SOFTWARE_VER="ML2PP/4.0" although these are actually newer than the v4.61, v4.62, v4.65 L2 data generated using the operational processor which are labelled SOFTWARE_VER="MIPAS/4.61" etc (v4.0 of the ML2PP approximately corresponds to v5.0 of the operational processor).
Priority is to retrieve L2 data for days when MIPAS was in 'campaign' mode, ie mostly UTLS1 data, a few orbits a day, during 2005/2006.
The file-format has now changed, but new version of BEAT (v4.2.0) should be able to cope with it.
We have managed to download the new data and will eventually update our MIPAS L2 Profile Maps to show the new data coverage, but first have to make some changes to our reading/plotting software.

Precision Validation (CP) [Prev] [Next]

Paper now on the ACPD web-site

Responses to referees comments have been sent.
Still an query over whether the day/night variations between some of the profile pairs contribute to the scatter:
To answer this, here are the equivalent plots to Figs 7 & 8 having removed profile pairs with a day/night variation have been removed:
- Fig.7 (Stratosphere) [EPS] [PDF]
- Fig.8 (Troposphere) [EPS] [PDF]
(our conclusion is that there is not much difference)

TES Radiance Comparison (CW) [Prev] [Next]

Now have the TES limb spectra (from 28Jan05) despiked and regridded to 0.0625cm^-1 to match the MIPAS data, ready to move on to MIPAS-TES differences.

NOx (JW) [Prev] [Next]

Constructing monthly mean maps of NOx to examine the stratospheric variability at middle and low latitudes

Discovered that BEAT II is very useful for ingesting large amounts of data - much better to use BEAT II to find the data rather than load every L2 file explicitly.
Also including retrieved HNO3 to see if there is evidence of conservation of NOy in MIPAS data.

Cloud Parameters (JH) [Prev] [Next]

Calculated Cloud Effective Fraction and Cloud Index for a number of simulated spectra with different combinations of cloud top height and cloud extinction:

[CEF]
[CI]

The fact the contours in the two plots are not parallel illustrates the difficulty in using the current pair of microwindows that define the CI to uniquely identify the CEF as a priori information for a cloud parameter retrieval.

Mesospheric Retrievals (LMV) [Prev] [Next]

Trying a linear least-squares fit retrieval for pT for altitudes 52, 60 and 68km using entire A band (screening out lines affected by non-LTE effects and gases other than CO2). If this works, intend to apply it to MA mode data.

Single initial guess based on mid-latitude day-time atmosphere does not produce useful accuracy
However, taking the nearest match from 3 different initial guess atmospheres (mid-lat day, polar winter and polar summer) produces results much closer to the ESA L2 pT values for these 3 altitudes.
[Results] Top panels show zonal mean of T,p retrievals based on the linear retrieval method, lower panels are ESA L2 data for the same day (chi sq of difference is ~ 2.5)

Next steps: see if linearity is improved by retrieving Planck function instead of temperature, and also including engineering relative pointing as a priori information.

Aircraft Emissions (MH) [Prev]

Trying to detect aircraft emission signatures in MIPAS spectra from AE mode measurements in Dec06

Most promising feature appears to be the NO2 lines around 1580-1610 cm^-1 where there is a gap in the H2O lines, although H2O continuum emission is still significant in the troposphere in this region.
[Plot] shows simulated RFM spectra (top) v actual spectra (bottom) for various tangent altitudes in mid-latitude conditions (these are nominal mode rather than AE mode).
Actual radiances in upper troposphere in 1580-1610 cm^-1 region are much larger than modelled - not yet found reason for this.

ACPD Papers [Prev] [Next]

Papers selected from the ACPD website for discussion

"Validation of MIPAS-ENVISAT NO2 operational data": G. Wetzel et al. (published 02.03.2007, open until 27.04.2007); Introduced by CW
"Global peroxyacetyl nitrate (PAN) retrieval in the upper troposphere from limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)": N. Glatthor et al. (published 29.01.2007, open until 26.03.2007); Comments being collected by LMV.
"HDO measurements with MIPAS": J. Steinwagner et al. (published 19.01.2007, open until 16.03.2007); Comments being collected by AD
"Three years of global carbon monoxide from SCIAMACHY: comparison with MOPITT and first results related to the detection of enhanced CO over cities": M. Buchwitz et all. (published 11.1.07, open until 08.03.2007); Comments being collected by JW.
"A twenty-year study on natural and manmade global interannual fluctuations of cirrus cloud cover": K. Eleftheratos et al. (published 05.01.07, open until 02.03.07); Comments submitted by JH (should be closed by now, but apparently still open).

There are other MIPAS-related papers currently open, which may be adopted for group discussion in future meetings.

"Retrieval of temperature profiles from CHAMP for climate monitoring: intercomparison with Envisat MIPAS and GOMOS and different atmospheric analyses": A. Gobiet et al. (published 27.02.2007, open until 24.04.2007)
"Precision validation of MIPAS-Envisat products": C. Piccolo & A. Dudhia (published 18.01.2007, open until 15.03.2007) - OK, we're not going to discuss this one!

From F. Niro (ESRIN) 21 Feb 2007.

I confirm that the L1 product archived at D-PAC corresponding to orbit 6192 is affected by the same calibration problem observed by Manuel, the product name is: MIP_NL__1PODPA20030507_153442_000060272016_00126_06192_1887.N1
After discussion with Ginette we found that the problem is due to the usage of a wrong offset calibration file (MIP_CO1_AX). The adjacent orbits were processed with correct auxiliary files and they don't show any problem as reported by Bianca. A similar anomaly was observed on Oct 2005 (see §3.5.4 of the MR).
The affected L1 product will be deleted from D-PAC server and reprocessed with correct auxiliary file.

Oxford MIPAS meeting#113 06 March 07

Oxford MIPAS meeting#113
06 March 07