Oxford MIPAS meeting#133
12 Feb 08

Present

Oxford: Anu Dudhia, Jane Hurley, Luis Millan-Valle, Randall Skelton, Claire Waymark, Joanne Walker

Instrument Status [Prev] [Next]

Operating continuously since 1st Dec 2007 in standard cycle of 8 days NOM, 1 day MA, 1 day UA.

Currently in NOM sequence (28Jan-04Feb)

L1B Data (JH) [Prev] [Next]

[L1B Data Coverage] - updated as far as Jan 26th

L1B data available on ESA server approximately 2 weeks after acquisition

No data received for 27 Jan 2008 (should have been UA mode operations)

Oxford L2 Processing (AD) [Prev] [Next]

Running MORSE to retrieve our own L2 data

[Oxford L2 Data Coverage] - most recent day: 20 Jan 08

[Recent & Long-Term Trends] - most recent month: Dec 07

Processing all new data currently with a lag of around 3 weeks (2 weeks for L1B data to appear, 1 week to process L2 locally)
Processing all previous Feb/Mar data (2002-2006) in parallel to provide comparison with recent data

Cloud Detection (JH) [Prev] [Next]

Comparing different methods of cloud detection (current CI, alternative CI microwindows, 2 different SVD methods)

Plan to use MORSE L2 retrievals eg of CH4 as test of whether cloud-contamination is present, assuming that cloud contaminated spectra result in CH4 values significantly different from climatology
However, as well as correctly identifying cloud-contaminated spectra, also require a 'good' detection method to avoid rejecting cloud-free spectra
So the first step is to set thresholds for the different techniques so that they all reject the same percentage of spectra
[Plot] showing % spectra rejected as cloudy for current CI microwindows, different lines indicating different nominal altitudes (based on 2 days of FR17 data)

CO Retrievals (JW) [Prev] [Next]

Investigating how to incorporate non-LTE effects into a practical (i.e. operational) scheme to retrieve CO

Still problems tuning the vibrational temperature a priori covariance to provide better constraint on joint CO-VT retrieval
Plan to write up results as an ACPD paper

Comparing MIPAS and TES limb-viewing radiances from 28 Jan 2005 (one of the few days when TES and MIPAS were both taking limb-view observations)

Convert spectra from TES 0.06cm-1 grid to 0.0625cm-1 grid for direct compatibility with MIPAS & MORSE
Deciding where to set spike-detection thresholds to remove spikes evident in TES spectra
After that, run pT, H2O, O3 and HNO3 retrievals using MORSE.

2007/8 Arctic Winter (AD) [Prev] [Next]

From the [Recent Trend] plots of Oxford L2 data for Oct/Nov/Dec/Jan 10mb, averaged from 65N to 90N for 2007 (black) compared to recent years:

[Temperature] another warming in mid-January has raised average temperature to 210K, still significantly below previous years' values (generally >220K) and more recently cooled again down to 200K.

Mesospheric Water Vapour [Prev] [Next]

MORSE retrievals of MA mode data show significant day-night variability in H2O.

[Plot] showing correlation with CH4 (19Dec07)

solid line shows expected correlation (2CH4+H2O=constant).
well-correlated apart from polar winter vortex (60N-90N) where relationship expected to break down
conclude that the MA mode retrievals for H2O (and CH4) are well-behaved in the stratosphere

[Plot] showing comparison with Aura/MLS retrieval for one day (19Sep06)

Left plots are zonal means, MIPAS on top, MLS underneath. MIPAS higher than MLS around 0.1mb
Right plots are day-night differences (MLS assumed to be free of non-LTE effects. Enhancement in MIPAS day-time H2O at 0.1mb looks like a non-LTE effect (not present in MLS) but enhancements in nighttime H2O above 0.1mb surface seem to match some MLS features (colour scales are not the same)

NB: MLS data have not been screened for large a priori contributions

ACE Retrievals (RS) [Prev] [Next]

Trying out alternative optimal-estimation retrieval code for pT from ACE-FTS and MIPAS-like microwindow selection.

Found a large number of missing CO2 lines in HITRAN in the regions of interest (>2000cm-1) for pT microwindows.
Problem fitting H2O lines in troposphere
Using SABER as comparison for high altitudes, but SABER temperatures have changed by up to 20K (!) in new version (1.07) (although this does improve agreement with ACE)

Note that a couple of validation papers for the 'official' ACE products have recently appeared on ACPD.

ACPD Papers [Prev] [Next]

Papers selected from the ACPD website for discussion

"Technical Note: Continuity of MIPAS-ENVISAT ozone data quality from full- to reduced-spectral-resolution operation mode": S. Ceccherini et al. (published 16 Jan 2008, open until 12 Mar 2008).; Introduced by JW.
"Modelling of cirrus clouds - Part 1: Model description and validation": P. Spichtinger and K. M. Gierens (published 11 Jan 2008, open until 07 Mar 2008); Comments being collected by JH
"Measurement of the water vapour vertical profile and of the Earth's outgoing far infrared flux": L. Palchetti et al. (published 10 Dec 2007, open until 04 Feb 2008); Comments submitted by LMV.
"Inversion analysis of carbon monoxide emissions using data from the TES and MOPITT satellite instruments": D. B. A. Jones et al (published 05 Dec 2007, open until 30 Jan 2008); Comments being collected by JW.

Other MIPAS-related papers in the Open Discussion phase, which may be adopted at a future meeting

"Validation and data characteristics of methane and nitrous oxide profiles observed by MIPAS and processed with Version 4.61 algorithm": S. Payan et al. (published 17 Dec 2007, open until 11 Feb 2008).