Oxford MIPAS meeting#135
11 Mar 08

Present

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

Instrument Status [Prev] [Next]

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

Currently (11Mar) in NOM mode.

L1B Data (JH) [Prev] [Next]

[L1B Data Coverage] - updated as far as Feb 11th

"Off-line" L1B data available on ESA server approximately 2 weeks after acquisition,

(Since Feb08) NRT data available within hours from Kiruna and ESRIN ftp sites

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

Running MORSE to retrieve our own L2 data

Now added processing of all NOM mode NRT data - using same L2 algorithm but restricted to pT, H2O and O3. Usually available a couple of days after acquisition.
Processing all new "off-line" 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 Mar/Apr data (2002-2007) in parallel to provide comparison with recent data and eventually providing a complete L2 dataset

Cloud Studies (JH) [Prev] [Next]

Working on presentations for upcoming progress meeting of the MIPClouds Study (Thursday, 13th Mar)

CO Retrievals (JW) [Prev] [Next]

Comparing nighttime (LTE assumption) CO retrieval with MLS data

New MLS data (v2.2) agrees better with MIPAS, although still a few odd features (eg spike at 20mb in MLS) and MLS mesospheric CO lower than MIPAS.

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

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

A series of warmings [Tem] at approximately 10 day intervals throughout January and February have raised the temperature from the coldest in the past 5 years (end Dec, beginning of January) to the warmest (February).
Tropospheric tracers show peaks coinciding with warmings, particularly [CFC-11], while [H2O] (mesospheric tracer) is anticorrelated, suggesting warmings are period of weak descent/large horizontal mixing.

Mesospheric Temperatures [Prev] [Next]

Analysing MORSE retrievals of MA mode data (using dedicated set of microwindows derived for polar winter conditions but applied globally)

[MA Mode Tem] 2007 zonal mean temperature data as altitude v time for polar and equatorial regions (see L2 Coverage Maps)
[NOM Mode Tem] for similar days - good agreement within overlapping altitude range
[MLS Tem] superficially similar but, for example, warmer stratopause than MIPAS
[SABER Tem] - not so good polar coverage but equatorial mesopause cooler than MIPAS

Despiking TES Spectra (CW) [Prev] [Next]

TES limb spectra have a number of spikes (corresponding to oscillating interferences during the interferometer acquisition).

Most of these are removed by TES L1B processing
Additional SD test applied to averaged spectra to identify and remove remaining spikes
[Plot] showing spectral points in TES 2A4 filter sorted by SD/NESR for an orbit of data - spike threshold set at discontinuity in curve to exclude ~ 10 points
[Plot] of average TES spectra for 2A4 filter for one orbit (top) with SD (bottom), 2nd page shows effect of removing points flagged as spikes by L1B processing (SD set to 0) and 3rd page shows additional despiking after removing points with high SD.

ACPD Papers [Prev] [Next]

Papers selected from the ACPD website for discussion

"Spatiotemporal variations of NOy species in the northern latitudes stratosphere measured with the balloon-borne MIPAS instrument": A. Wiegele et al. (published 05 Mar 2008, open until 30 Apr 2008).; Introduced by AD.
"Chemistry of sprite discharges through ion-neutral reactions": Y. Hiraki et al. (published 08 Feb 2008, open until 04 Apr 2008).; Comments being collected by LMV.
"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).; Comments being collected 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 were being collected by JH but nothing submitted before deadline.

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

"Envisat MIPAS measurements of CFC-11: retrieval, validation, and climatology": L. Hoffmann et al. (published 04 Mar 2008, open until 29 Apr 2008)
"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 31 Mar 2008).