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The potential of MTG-IRS to detect high pollution events at urban and regional scales

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?. Fires , Moscow area, summer 2010. IASI - CO. 2010 Fires in Central Russia. IASI-CO July 22  Aug. 22.

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The potential of MTG-IRS to detect high pollution events at urban and regional scales

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  1. 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?

  2. Fires, Moscow area, summer 2010

  3. IASI - CO 2010 Fires in Central Russia IASI-CO July 22  Aug. 22 CO concentration up to 6 times above safe levels in Moscow CO total columns from the IASI/MetOp observations (FORLI-CO) from July 22 to August 22, 2010. Data averaged over 3 days on a 0.5°x0.5° grid – only daytime with CO above 2.2 1018 molecules/cm2 Animation by Maya George (LATMOS)

  4. Potential of IRS-MTG to detect high pollution events at urban and regional scales ESA-ESTEC, June 2008 Pollution peaks Ozone measurements Concentration en ozone fin juillet 2007

  5. IASI - Ozone October 0-8 km column April 0-8 km column

  6. Ammoniahotspots with IASI

  7. Ammonia 2008 average – IASI data … dealing with a signal hardly detectable … Clarisse et al., Nature Geo 2009

  8. Eyjafjöll eruption, Iceland, april-mai 2010

  9. IASI ash detection – first event

  10. IASI ash detection – first event 14 PM 15 AM 15PM 16 AM 16PM 18 AM 17 AM 17 PM

  11. Detection of pollution peaks with IR instruments Thermal contrast, IASI data evening morning Thermal contrast is higher during the day and during the spring/summer, over land. • Controlled pollutants are O3, CO, NO2, SO2, 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.

  12. Ozone with IRS/MTG IRS-MTG IRS3: OPD = 0.8 cm NEDT = 0.2K • Spectral resolution and sampling • MOPDsampling FWHM of non-apodized ILS • 0.8 cm  0.625 cm-1 0.75cm-1  IRS-MTG  4.0 cm  0.125 cm-1 0.15cm-1  Sentinel 4 (goal)  2.0 cm  0.250 cm-1 0.30cm-1  Sentinel 4 (Threshold) IRS-MTG Sentinel 4 (goal) Sentinel 4 (threshold) • Radiometric noise • NEDT (of 280K blackbody) NESR • 0.20 K  2.45 10-8 W/cm2 sr cm-1 IRS-MTG  0.05 K  6.08 10-9 W/cm2 sr cm-1 Sentinel 4 (goal)  0.10 K  1.22 10-8 W/cm2 sr cm-1

  13. Results for ozone OPD = 0.8 cm NEDT = 0.2K OPD = 0.8 cm NEDT = 0.05K OPD = 4 cm NEDT = 0.2 K Vertical sensitivity Varying spectral resolution and noise e = 0.96; DT = 0 K IRS-MTG Relaxing spectral resolution and/or radiometric noise loss of vertical sensitivity in the lower troposphere

  14. Results for ozone PBL (0-2 km) column a priori variability MTG-IRS LT (0-6 km) column Summary a priori variability MOPD=0.8 cm (IRS-MTG) MOPD = 2.0 cm (Sentinel 4 threshold) MOPD = 4.0 cm(Sentinel 4 goal) MTG-IRS DOFS Sentinel 4 (FWHM threshold) Sentinel 4 ( FWHM goal) MTG-IRS Varying spectral resolution and noise e = 0.96; DT = 0 K

  15. Carbon monoxide with IRS/MTG Sentinel 4 (threshold) • Spectral resolution and sampling • MOPDsampling FWHM of non-apodized ILS • 0.8 cm  0.625 cm-1 0.75cm-1  IRS-MTG  4.0 cm  0.125 cm-1 0.15cm-1  Sentinel 4 (goal) • 2.0 cm  0.250 cm-1 0.30cm-1 • 1.0 cm  0.500 cm-1 0.60cm-1  Sentinel 4 (Threshold) IRS-MTG Sentinel 4 (goal) • Radiometric noise • NEDT (of 280K blackbody) NESR • 0.85 K  6.12 10-9 W/cm2 sr cm-1 IRS-MTG  0.05 K  3.60 10-10 W/cm2 sr cm-1 Sentinel 4 (goal)  0.15 K  1.08 10-9 W/cm2 sr cm-1 IRS-MTG IRS7: OPD = 0.8 cm NEDT = 0.85K

  16. Results for carbon monoxide Varying spectral resolution and noise e = 0.96; DT = 0 K Vertical sensitivity OPD = 0.8 cm NEDT = 0.85K OPD = 4 cm NEDT = 0.05K OPD = 1 cm NEDT = 0.15 K IRS-MTG Sentinel 4 - Goal Sentinel 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

  17. Results for carbon monoxide A. Sensitivity analyses Varying spectral resolution and noise e = 0.96; DT = 0 K Summary DOFS Total column error Sentinel 4 goal NeDT 0.85 K NeDT 0.15 K NeDT 0.05 K a priori variability MTG-IRS 10% Sentinel 4 threshold Sentinel 4 threshold MTG-IRS Sentinel 4 goal 13 % on total CO column for MTG-IRS Down to 5 % for Sentinel 4 - goal DOFS of 1 for MTG-IRS Up to 3 for Sentinel 4 - goal

  18. Conclusions The levels of all controlled pollutants (NO2, SO2, CO, O3, PM10 and PM2.5) are continuously decreasing over Europe, except for O3. 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 DT

  19. Conclusions Although the instrumental specifications for MTG-IRS are not optimized for chemistry, the instrument will provide tropospheric columns of O3 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

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