Cathy Clerbaux, Geocape meeting, May 2011 The potential of MTG-IRS to detect high pollution events at urban and regional scales 1/ What do we see with IASI for pollution events 2/ What is the potentiel for IRS/MTG?

Cathy Clerbaux, Geocape meeting, May 2011 Fires, Moscow area, summer 2010

Cathy Clerbaux, Geocape meeting, May 2011 CO total columns from the IASI/MetOp observations (FORLI-CO) from July 22 to August 22, Data averaged over 3 days on a 0.5°x0.5° grid – only daytime with CO above molecules/cm 2 Animation by Maya George (LATMOS) CO concentration up to 6 times above safe levels in Moscow IASI-CO July 22  Aug. 22 IASI - CO 2010 Fires in Central Russia

Cathy Clerbaux, Geocape meeting, May 2011 Potential of IRS-MTG to detect high pollution events at urban and regional scales ESA-ESTEC, June 2008 Concentration en ozone fin juillet 2007 Pollution peaks Ozone measurements

Cathy Clerbaux, Geocape meeting, May 2011 October 0-8 km column April 0-8 km column IASI - Ozone

Cathy Clerbaux, Geocape meeting, May 2011 Ammonia hotspots with IASI

Cathy Clerbaux, Geocape meeting, May 2011 Ammonia 2008 average – IASI data … dealing with a signal hardly detectable … Clarisse et al., Nature Geo 2009

Cathy Clerbaux, Geocape meeting, May 2011 Eyjafjöll eruption, Iceland, april-mai 2010

Cathy Clerbaux, Geocape meeting, May 2011 IASI ash detection – first event

Cathy Clerbaux, Geocape meeting, May PM 15 AM 15PM 16 AM 16PM 17 AM17 PM 18 AM IASI ash detection – first event

Cathy Clerbaux, Geocape meeting, May 2011 morning evening Thermal contrast, IASI data -Controlled pollutants are O 3, CO, NO 2, SO 2, PM + NH3 ; Ozone : peaks in the afternoon. Alert levels exceeded several days per year. Current prediction scores around 50%. CO : Alert levels exceeded only when big fire events occur. Detection of pollution peaks with IR instruments Thermal contrast is higher during the day and during the spring/summer, over land.

Cathy Clerbaux, Geocape meeting, May 2011 Spectral resolution and sampling  MOPD  sampling  FWHM of non-apodized ILS  0.8 cm  cm -1  0.75cm -1  IRS-MTG  4.0 cm  cm -1  0.15cm -1  Sentinel 4 (goal)  2.0 cm  cm -1  0.30cm -1  Sentinel 4 (Threshold) Radiometric noise  NEDT (of 280K blackbody)  NESR  0.20 K  W/cm 2 sr cm -1  IRS-MTG  0.05 K  W/cm 2 sr cm -1  Sentinel 4 (goal)  0.10 K  W/cm 2 sr cm -1 IRS-MTG Sentinel 4 (goal) Sentinel 4 (threshold) IRS-MTG IRS3: OPD = 0.8 cm NEDT = 0.2K Ozone with IRS/MTG

Cathy Clerbaux, Geocape meeting, May 2011 OPD = 0.8 cm NEDT = 0.2K OPD = 0.8 cm NEDT = 0.05K OPD = 4 cm NEDT = 0.2 K Varying spectral resolution and noise  = 0.96;  T = 0 K IRS-MTG Relaxing spectral resolution and/or radiometric noise  loss of vertical sensitivity in the lower troposphere Vertical sensitivity Results for ozone

Cathy Clerbaux, Geocape meeting, May 2011 MTG-IRS Sentinel 4 (FWHM threshold) Sentinel 4 ( FWHM goal) DOFS Varying spectral resolution and noise  = 0.96;  T = 0 K Summary Results for ozone a priori variability MTG-IRS PBL (0-2 km) column LT (0-6 km) column a priori variability MTG-IRS MOPD=0.8 cm (IRS-MTG) MOPD = 2.0 cm (Sentinel 4 threshold) MOPD = 4.0 cm (Sentinel 4 goal)

Cathy Clerbaux, Geocape meeting, May 2011 Spectral resolution and sampling  MOPD  sampling  FWHM of non-apodized ILS  0.8 cm  cm -1  0.75cm -1  IRS-MTG  4.0 cm  cm -1  0.15cm -1  Sentinel 4 (goal)  2.0 cm  cm -1  0.30cm -1  1.0 cm  cm -1  0.60cm -1  Sentinel 4 (Threshold) Radiometric noise  NEDT (of 280K blackbody)  NESR  0.85 K  W/cm 2 sr cm -1  IRS-MTG  0.05 K  W/cm 2 sr cm -1  Sentinel 4 (goal)  0.15 K  W/cm 2 sr cm -1 IRS-MTG Sentinel 4 (goal) Sentinel 4 (threshold) IRS-MTG IRS7: OPD = 0.8 cm NEDT = 0.85K Carbon monoxide with IRS/MTG

Cathy Clerbaux, Geocape meeting, May 2011 OPD = 0.8 cm NEDT = 0.85K OPD = 4 cm NEDT = 0.05K OPD = 1 cm NEDT = 0.15 K Varying spectral resolution and noise  = 0.96;  T = 0 K IRS-MTGSentinel 4 - GoalSentinel 4 – Thr. Only Sentinel (goal) provides vertically resolved information in the troposphere Lowering the noise (IRS-MTG  Sentinel 4 Threshold increases sensitivity to the lower troposphere Vertical sensitivity Results for carbon monoxide

Cathy Clerbaux, Geocape meeting, May % MTG-IRS Sentinel 4 threshold a priori variability DOFSTotal column error Varying spectral resolution and noise  = 0.96;  T = 0 K NeDT 0.85 K NeDT 0.15 K NeDT 0.05 K Sentinel 4 goal MTG-IRS Sentinel 4 threshold Sentinel 4 goal DOFS of 1 for MTG-IRS Up to 3 for Sentinel 4 - goal 13 % on total CO column for MTG-IRS Down to 5 % for Sentinel 4 - goal A. Sensitivity analyses Summary Results for carbon monoxide

Cathy Clerbaux, Geocape meeting, May 2011 Conclusions The levels of all controlled pollutants (NO 2, SO 2, CO, O 3, PM 10 and PM 2.5 ) are continuously decreasing over Europe, except for O 3. The warning and alert levels of the latter are exceeded every year, and it will be worse in the future. Ozone peaks occur between 12 and 15 pm. Levels of pollution for CO are exceeded when fire events occur. With the current MTG/IRS specifications: Ozone DOFS around 3.5  single information in the troposphere CO DOFS around 1  total column Error on the tropospheric column is around 15 % Impact of thermal contrast : Impact is in the lower troposphere. The error on the tropospheric column reaches ~ 10 % for positive values of  T

Cathy Clerbaux, Geocape meeting, May 2011 Conclusions Although the instrumental specifications for MTG-IRS are not optimized for chemistry, the instrument will provide tropospheric columns of O 3 and CO, with significant improvement on our prior knowledge, for high pollution events (photochemical pollution in the case of ozone; fires in the case of CO). The diurnal variability might be difficult to capture if thermal contrast remains low. However, as ozone pollution mainly occurs along with high temperatures, pollution peaks will likely be monitored. One may expect to take benefit of the high sampling rate of the MTG sounder (0.5 hour over Europe) in order to set-up a specific retrieval strategy that would use the information at different times of the day (hence different thermal contrast) to extract the peak pollution events at the right time and place. Moreover the smaller MTG-IRS pixel size (4 km) would allow to average data in order to increase accuracy. NH3 might also be measurable to some extent. For volcano: main SO2 band missing but ashes detection OK