Oxford-RAL IASI Group Meetings

Meeting#11 (12Jan16)

Oxford: Anu Dudhia, Elisa Carboni, Catherine Hayer, Fred Prata, Lucy Ventress, Tony Vincent

RAL: Brian Kerridge, Diane Knappett (Skype), Richard Siddans, Jo Walker (Skype)

Leicester: David Moore (Skype)

CH4 Retrievals (DK) [Prev] [Next]

Now processed every day of 8 years of IASI CH4 data, being archived at CEDA. Presentation at AGU fall meeting. Time series show steady increase 2007-2015 with seasonal cycle, consistent with MACC.

Running local IASI-MHS for temperature, humidity, emissivity (IASI+MHS+AMSU) for temperature - general gives better CH4 retrieval than using ECMWF+U.Wisconsin. But only processed one month so far.

O3 Retrievals (JW) [Prev] [Next]

Including O3 in local IASI-MHS Processor, comparing results with MACC and sondes. Major effort in moving processor onto CEMS.

CO Retrievals (DM) [Next]

CO retrievals with ULIRS. Using TV's RFM-LUTs. Errors cf LBL < 1% from using LUTs, gives factor 10 improvement in speed. A Priori covariance based on old TOMCAT model data - might need updating.

MORSE (AD) [Prev] [Next]

Rewritten for F90 and seems to be working in standard MIPAS configuration. Faster for pT retrievals by factor 2, but (surprisingly) slower for H2O (and therefore probably other VMR retrievals) - further investigation required.

Ash (LV) [Prev] [Next]

Comparisons of IASI ash optical depth at 11um v ORAC TERRA/MODIS for Eyja eruption. Shows better agreement since ORAC improvements. MODIS values within IASI pixel averaged, but simple averaging of AOD values probably not best. (TERRA, as opposed to AQUA/MODIS, allows combination of data taken within an hour).

NRT Detection (LV) [Prev] [Next]

Looking how to adapt NRT SO2 to detect anomalous concentrations of other species. Looking for suitable test case for NH3. Also quick look at recent Los Angeles CH4 leak - not sure if we can see something or not.

OCS Retrievals (TV) [Prev] [Next]

Previously developed a linear retrieval scheme based on trying different linearisation points from an ensemble of profiles. Now written an unconstrained, RFM-based iterative retrieval which led to modification of state vector to reduce number of H2O points from 2 to 1 (but still handles 4 temperature levels).

Randomly tried out in region of Grimsvotn eruption - residuals show large H2O errors so might try to adapt measurement error covariance matrix to account for these.

SO2 Retrievals (CH) [Prev] [Next]

Looking at Calbuco eruption (Chile, 23 March 2015). IASI NRT and iterative SO2 retrievals show SO2 circling the globe but stopping and circulating over the S Atlantic for a few days. Stratospheric height confirmed by colocated MLS data and ash from CALIOP (both in the few days after the eruption). Estimate 0.3Tg SO2. There seems to be an H2SO4 signature during the S Atlantic circulating period, consistent with expected evolution of stratospheric SO2.

SO2 Retrievals (EC) [Prev] [Next]

Calculate time v height for Calbuco emissions which seem to show an e-folding time around 17 days for stratospheric SO2.