OMI follow-on Project Toekomstige missies gericht op troposfeer en klimaat Pieternel Levelt, KNMI
Mar 31, 2015
OMI follow-on Project Toekomstige missies gericht op
troposfeer en klimaat
Pieternel Levelt, KNMI
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 2
Climate Air quality
Anthropogenic influence
Importance of Tropospheric Measurements
Tropospheric chemical science has very strong links to:
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 3
Troposphere
Tropospheric measurements needs:
• higher spatial resolution • improved accuracy for O3, NO2, aerosols,
clouds, HCHO• together with CO, CH4, CO2 and H2O• improve aerosol information• improve time-resolution• preference for daily global coverage
(air quality)
GOME Observations of Formaldehyde over North America
Chance et al., Geo. Res. Let. 27, 3461-3464, 2000.
• Next challenge for satellite instrument development is to map the troposphere for air quality monitoring and climate research:
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 4
Tropospheric Important Trace Species
(tropospheric) Ozone Aerosols (tropospheric) NO2
SO2
Formaldehyde BrO
UV/VIS
CO CH4
CO2
H2O
NIR
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 5
Why these trace species?
• CO indicates combustion; has a chemical role (CO2, CH4)• HCHO indicates VOCs; has role in O3 & aerosols• NO2 indicates NOx; is precursor to O3 & aerosols• SO2 traces combustion, is major aerosol precursor • CO2 is an important greenhouse gas• H2O is an important greenhouse gas
• Ozone is a toxic greenhouse gas.
• Small aerosols are toxic, have direct & indirect global warming effects.
II
II
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 6
Climate Forcing
Source: IPCC
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 7
Few measurements from space to date: except: MOPITT CO, TOMS residual O3, GOME NO2, BrO, HCHO, MODIS for
aerosols and clouds TES and OMI (Aura) and SCIAMACHY (ENVISAT) will provide many
new measurements Selected OCO NASA mission (2007): Measures CO2 with 1 km2 pixels and
10 km swath. However: Tropospheric chemical science needs more and more accurate
measurements
Currently available or selected tropospheric-climate missions
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 8
OMI on EOS Aura Spectrometer in wavelength range 270 – 500 nm
Daily Global Coverage
Small Ground Pixels (13x24 km2)
Polarization Scrambler
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 9
OMI Measurement Principle
Courtesy of Dutch Space
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 10
New Developments for Polar missions
Smaller Ground Pixels (will also improve accuracy) Extending the Wavelength Range (add IR-channel) Multi-Angle Viewing (for improved aerosol detection)
Assumption: Start from current Leo-OMI optical design:
This means that a smaller spatial resolution of 10 x 10 km2 is not feasible, since this is the optical resolution of the instrument in polar orbit!
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 11
Chosen for a module approach:
OMI/SCIAMACHY + instrument is by itself a very complete tropospheric instrument
Depending on missions, channels can be adjusted or skipped
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 12
Requirements UV/VIS Ground pixels: decreased to 12 x 13 km2 (except for UV-1,
40 x 40 km2) Spatial sampling: 3 x 270 - 500 nm, preferred extension to 600 nm (O3 and O2-O2) Spectral resolution: minimal OMI, preferred GOME Spectral sampling: 3 x Daily global coverage S/N ratios same as in OMI SRD, except for O3 and NO2
column
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 13
Requirements NIR Ground pixels: 12 x 13 km2
Spatial sampling: 3 x 1,6 (CH4 and CO2) and 2,4 mm (CO)
O2A band detection for airmass factor (760 nm)
Spectral resolution: 0.08 nm (CO2), 0.15 nm (CO & CH4) and 0.08 nm for O2A band
Spectral sampling: 3 x Daily global coverage for CO, for CH4 and CO2 not necessary (1000
km swath) S/N ratios: see input SRON
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 14
Technical Challenges Identified Size of instrument:
- NIR increases size of instrument - High spectral resolution in combination with high spatial
resolution and broad swath S/N: smaller pixels and same or increased S/N is needed ! CCD’s: CCD with preferred requirements at this moment non-existent; techniques to
built it are however available Scrambler for polarisation insensitivity optimal for UV/VIS and IR Grating: New developed grating needed in order to decrease size of instrument Temperature control of instrument, especially 2,4 mm And more can follow …..Caveat: in case higher spatial resolution is needed for tropospheric trace gases to
obtain needed accuracy.
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 15
6 options UV/VIS and IR now studied by industry
(1) Climate mission: Complete UV/VIS and CO, CO2, CH4 and O2A
(2) Air Quality mission: Complete UV/VIS and CO
(3) Climate mission with 1000 km swath for NIR and O2A
(4) Climate mission as (1), without CO
(5) Same as (3) but with 2 telescopes
(6) Same as (1) but with 1000 km swath
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 16
Mean aerosol optical depth in August 1997 (monthly average). Retrieved from ATSR-2 image (see Gonzalez et al., Geophys. Res. Lett., 27, 955-958, 2000 )
Monitoring Aerosol
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 17
Aerosol retrieval Use dual viewing concept for info on surface albedo for
aerosol retrieval and AMF information for trace gas retrieval
- Current OMI for nadir - Add one viewing angle looking forward - Need for an extra CCD for forward looking
channel, and second telescope Technical Challenge: calibration of those two channels
with high accuracy! Not clear if this is feasible.
Toekomstige Troposfeer Missie, SRON, 18 november 2003
Dr. P.F. Levelt (KNMI) Slide 18
Summary OMI Technology is very suitable for remote sensing of the troposphere
- Spatial resolution can be improved to 10 x 10 km2
- Wavelength range can be extended to NIR High-level instrument requirements for UV/VIS and NIR are decided Currently 6 possible instrument designs are studied on feasibility: many
technical challenges are identified Multi angle viewing seems to be more difficult than expected due to
calibration difficulty Caveat: in case higher spatial resolution is needed: new instrument
design probably needed