Oxford MIPAS meeting#143
29 Jul 08

Present

Oxford: Anu Dudhia, Jane Hurley, 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.

25/26 Jul 08: most recent MA/UA observations

Recent interruptions in data [MIPAS Availability]

no interruptions in past 2 weeks

General Information

Mission Planning Document for 2008 [XLS] [HTML].
MIPAS Mission Plan v4.3 (March 08) [DOC] [PDF]
Currently defined measurement modes
Envisat Web-Site

L1B Data [Prev] [Next]

[L1B Data Coverage]

"Near Real Time" (NRT) data available on Kiruna or ESRIN ftp sites ~ hours after acquisition.

No current problems, although a delay on 17th July at the ESRIN site [details]

"Off-line" (OFL) L1B data available on D-PAC ftp site approximately 2 weeks after acquisition.

Continued problems acquiring ftp connection from Oxford (unlike NRT data sites)

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

[Oxford L2 Data Coverage]

Running MORSE to retrieve our own L2 data (ESA species plus CFC-11,CFC-12,N2O5,ClONO2 and CO)

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) - most recent day 5th July
Processing all previous Aug data (2002-2007) in parallel to provide comparison with recent data and eventually providing a complete L2 dataset - most recent day completed for all years: 5th August
Processing NOM mode NRT data - same L2 algorithm but restricted to pT, H2O and O3. Usually available a couple of days after acquisition - most recent day 27th July

Antarctic Winter (AD) [Prev] [Next]

From the Oxford L2 [trend plots] for 65S-90S at 10mb

[Temperature] 190K - a few K lower than normal through most of July, but rose to 193 K on July 23rd, more in line with previous years.
[HNO3] lower than usual at the beginning of July but converging to previous years' values
[CFC-11] Still anomalously high at the beginning of July (as in previous years) - probably related to problems with the tabulated absorption coefficients at low temperatures.
[O3] rising throughout July, as in most previous years

CO retrievals (JW) [Prev] [Next]

Revisiting joint (non-LTE) retrieval of CO + VT

Examining various options of setting up the Vibrational Temperature a priori estimate, based on Granada model, which seems to be key in getting a good CO retrieval

Non-LTE Radiances (LMV) [Prev]

Completed analysis of differences between observed day/night differences in MIPAS MA mode spectra and the expected differences from the non-LTE models used for microwindow selection and error budget calculations.

[Tech Note]
Abstract One of the parameters used to determine the best possible subset of spectra, or microwindows, to retrieve temperature and gas concentrations from MIPAS is the vibrational temperature that estimates the nonLTE effects acting upon the radiances. A technique that uses the daytime and nightime MIPAS midlatitude middle atmosphere radiances to evaluate the quality of the vibrational temperatures used on the microwindow selection procedure is described. This technique is applied to the transitions of CO2, O3, H2O, HNO3, CH4, N2O, NO2, NO and CO encountered in the MIPAS spectral range.

Cloud Parameter Retrieval (JH) [Prev]

Investigating behaviour of cloud parameter retrieval when applied to all spectra (including cloud-free) to see if there is a bias in the retrieved extinction

[Plot] shows retrieved values of Cloud Top Height, Cloud Top Temperature and Cloud Extinction in different panels, each plotted as a function of Cloud Index (points to the left of the red line at CI=1.8 are those normally identified as cloudy spectra).
Different colour dots indicate points taken from different nominal tangent altitudes for one day of Full Resolution data - coloured lines in CTH plot also show these altitudes with FOV extent indicated by dashed lines.

Main conclusion is that for "cloud-free" spectra, when the retrieval does converge, it retrieves low values of cloud extinction ~1E-4/km, which is reasonable. However these are significantly above zero, suggesting that there is some a priori bias towards positive values.

TES Limb Retrievals (CW) [Prev] [Next]

Run MORSE to retrieve pT,H2O,O3 and HNO3 from TES limb-spectra (27Jun05) TES limb spectra are acquired in sets of 3 ("scans #4,#5,#6") with different spectral filters.

Scan#4 appears to produce reasonable retrieved profiles, but Scans#5 and #6 diverge significantly from MIPAS
Problem could be related to different microwindows used in Scan#5

ACPD Papers [Prev] [Next]

Papers selected from the ACPD website for discussion

"Cloud's center of gravity - a compact approach to analyze convective cloud development": I. Koren et al (published 23 Jul 2008, open until 17 Sep 2008); Introduced by JH.
"Comparison of CMAM simulations of carbon monoxide (CO), nitrous oxide (N2O), and methane (CH4) with observations from Odin/SMR, ACE-FTS, and Aura/MLS": J. J. Jin et al (published 09 Jul 2008, open until 03 Sep 2008); Comments being collected by AD.
"Mesospheric N2O enhancements as observed by MIPAS on Envisat during the polar winters in 2002-2004": B. Funke et al (published 03 Jun 2008, open until 29 Jul 2008); Comments submitted by LMV.
"Nitric acid in the stratosphere based on Odin observations from 2001 to 2007 - Part 1: A global climatology": J. Urban et al (published 26 May 2008, open until 21 Jul 2008); Comments were being collected by JW but discussion closed before anything was submitted.

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

"Atmospheric tracers during the 2003-2004 stratospheric warming event and impact of ozone intrusions in the troposphere": Y. Liu et al (published 17 Jul 2008, open until 11 Sep 2008)

Oxford MIPAS meeting#143 29 Jul 08

Oxford MIPAS meeting#143
29 Jul 08