1. WP2300 – Space Segment Concepts Paul S. Monks, John J. Remedios, Gary K. Corlett and Simon Good Space Research Centre University of Leicester

2. Aims The objective of this work within the CAPACITY study is to –Identify the requirements for an integrated observing system focussed on the target applications The aims of this work within the CAPACITY study are –To provide a vision of integrated observing systems for the target applications –To identify ground-based, airborne and space-based components to the system that would add value (information) to observables directly required/measured by existing/potential new systems, –To consider the most pressing application questions and make recommendations as to potential elements of appropriate space-based observing systems.

3. Broad recommendations With respect to a space segment of a measuring system for operational monitoring, it is clear there are three overall requirements that cannot be met by current or planned systems –High temporal/spatial resolution space-based measurements of tropospheric (PBL) composition for application to AQ –High vertical resolution measurements in the UT/LS region for ozone and climate applications –High spatial/high precision monitoring of tropospheric climate gases (CO 2, CH 4 and CO) and aerosol with sensitivity to PBL concentrations

4. How do we arrive at this? a)Air Quality (B) b)Climate Applications (C) c)Ozone and UV (A)

5. From GMES-BICEPS-AQ-Fiche Information requirements

6. Air quality Management and Forecast Existing satellite observations O 3, NO 2, CO Dedicated satellite observations ++ + Data assimilation Applications Reduction of uncertainties Ground based measurements O 3, NO 2, CO CAPACITY (ESA) PROMOTE (ESA) GEMS (CE) End user requirements Chemical Transport models System Concept for AQ PROMOTE (ESA)

7. Current Capabilities EMEP – ground based network EARLINET - LIDAR network MOSAIC - in-service aircraft Satellite – Science and operational AQ forecasts

8. AQ Simplified Requirements Instruments should be sensitive to the Planetary Boundary Layer (PBL). Re-visit times of 2 hours are threshold requirements Horizontal resolutions should ideally be better than 20 km with a target of 5 km. Night-time measurements would be ideal, as well as daytime measurements. Both trace gases and aerosol information are required [major trace gases are O 3, CO, NO 2, SO 2, HCHO, H 2 O and nitrogen species]  AQ rapid-revisit time mission

9. AQ Mission Analysis Metop provides a basic set of measurements through GOME-2 (O 3, NO 2, SO 2, HCHO) and IASI (CO). Aerosol information is likely to be available from GOME-2 and AVHRR but with caveats on uncertainty and spatial resolution achieved. Combination of O 3 data from GOME-2 and IASI could provide greater height resolution in the PBL and free troposphere. Development work to support this product is highly recommended. Similar work could be performed for CO with advantage if a shortwave infra-red (SWIR) instrument could be flown to complement MetoP. Re-flight of an existing aerosol instrument could deliver required aerosol information at 550 nm. A new instrument achieving better uncertainty performance is highly desirable. Re-flight of an ice-free SCIAMACHY nadir near infra-red instrument could give better information on CO. The greatest requirement for the mission is frequent re-visit time (< 2 hours) as well as high spatial resolution (<20 km). This is not met by existing orbital elements such as MetOp and is necessary to meet existing basic operational modes.

10. AQ consolidated requirements (with ability to meet them mapped on) Order of importance

11. AQ Mission Concept Frequent re-visit time and high spatial resolution (<20 km) Options could be GEO or LEO or a combination of both. If LEO, then an enhancement of the Metop/NPOESS systems would be necessary both for complement of species and for coverage/spatial resolutions. Species: O 3, NO 2, SO 2, HCHO, CO, aerosol AOD (550 nm), multi- spectral AOD for aerosol size. Instruments are likely to be UV-visible (O 3, NO 2, SO 2, HCHO, aerosol) and mid infra-red (MIR) or SWIR for CO. The MIR can also supply complementary information for O 3 and possibly nitrogen species. There is a requirement for an enhanced aerosol instrument/system delivering uncertainties of < 0.05 in aerosol optical depth at 10 km spatial resolution and enhancing our ability to discriminate aerosol type. Limb instruments would enable better correction for upper parts of NO 2, O 3, CO columns.

12. GOME-2 Column O3, NO2, SO2, H2CO Column AOD B1 (Consolidated): Air Quality Protocol Monitoring Satellite Component Evolution Ultimate Specification Minimum Specification IASI CO Col/Profile NEW Combined CO Profiles (Data) Combined UV/VIS & IR O3 Profiles B2 H2O Profiles (Data) B1 SPECIES Improved Revisit Times Improved Horizontal Resolution < 2 hrs < 20 km Meets Significant Capacity Capability NEW AEROSOL Type <10% mis-assign SCIA NADIR NIR CO MODIS,MISR, POLDER Column AOD (550 nm) B1 Species: O 3, CO, NO 2, SO 2, H 2 CO [For B2, B3 add H 2 O; Nitrogen species are N 2 O 5, HNO 3, PAN, organic nitrates] Aerosol OD (550 nm) Multi-spectral AOD and type should be < 2 hours re-visit time but accept high spatial resolution (5 km) would be a trade-off. Note: PBL sensitivity is mandatory for all measurements Night-time data are important NEW AEROSOL Multi-spectral Column AOD AOD < 0.05, 10 km PRIORITY IASI B2 H2O Col/Profile NEW Nitrogen B3 Species

13. Recommendation Both GEO and LEO options should be studied. Priority 1 is to achieve the re-visit time with high spatial resolution as the 2 nd priority. A key decision concerns our ability to measure CO. Flight of both a MIR and SWIR instrument would provide the greatest performance but would add to mission complexity. Multi-spectral aerosol information with improved uncertainty (equivalent to <0.05 nm at 550 nm) would be ideal. Aerosol type measurements are also useful.

14. Climate Protocol monitoring is a different genre of mission NRT Climate i.e. H 2 O and Assessment though having different drivers have overlapping solution

15. Reduction of uncertainties Protocol Monitoring CO 2, CH 4, CFC Ground-based monitoring End users requirements Applications + + + ++ + + + Future Missions e.g. OCO, GOSAT Application Unproven EVERGREEN (EC) GEMS (CE) Data Assimilaiton Space-borne profile e.g. H 2 O profiles Current Data AIRS, SCIA System Concept for Climate Protocol Monitoring

16. CO 2 columns (cloud flagged) CO 2 columns with column errors < 3%  ‘A priori’ surface albedo ‘A priori’ surface pressure

17. C1/C2 consolidated requirements (with ability to meet them mapped on)

18. Protocol Monitoring The mission seeks to measure greenhouse gases, CO and aerosols. The mission is intended to be global and have PBL sensitivity for CH 4, CO 2, CO, NO 2. The chief targets are CO 2, CH 4, CO, O 3, NO 2, aerosols Stratospheric aerosol measurements could be important during volcanic loading periods (e.g. Pinatubo) to ensure good tropospheric aerosol data.

19. IASI CH4, CO, CO2, O3 GOME-2 O3, NO2 Column AOD (550 nm) Absorbing aerosol OD C1: Climate Protocol Monitoring Satellite Component Evolution Ultimate Specification Minimum Specification SCIA NADIR NIR CH4, CO, CO2, NEW NADIR UV/VIS O3, NO2 Improved Spatial Resolution10 km Improved re-visit times 12 hours NEW AEROSOL OD 0.05 uncertainty 550 nm Absorbing Aerosol OD 0.01 uncertainty Improved re-visit times 6-12 hours Meets Significant Capacity Capability Combined UV/VIS/NIR & IR O3, CO Profiles (Data) NEW NADIR NIR CH4, CO CH4 error (2%) Improved Spatial Resolution 10 km SAGE equivalent Strat. Aerosol TOMS, MODIS, MISR, POLDER Equivalent Column AOD (550 nm) NEW CO2 CO2 error (PBL) CH 4, CO 2, CO and NO 2 measurements should be PBL sensitive. Note CO 2 : CO 2 (highlighted in red) information does not meet capacity requirements but could be sufficient for some user services PRIORITY

20. Near real-time/ Assessment Near real-time The mission seeks to derive climate information in near real- time This mission concept is driven by NRT system assimilation and the improvement in representation of climate from assimilation of observations for rapidly varying The targets are H 2 O (very important), O 3, aerosols/cirrus, stratospheric tracer information. Stratospheric aerosol is required as well as tropospheric aerosols Assessment The mission seeks to provide a fundamental capability for scientific assessment of the climate system. The mission targets can be sub-divided into radiative forcing, oxidising capacity and stratospheric ozone. There are many target species and domains but the UTLS is particularly important. Vertical resolution and no. of species is more important than re- visit times.

21. C2: Climate Near Real Time Data Satellite Component Evolution Ultimate Specification Minimum Specification IASI O3, H2O, CO2, CH4, N2O GOME-2 AOD 550 nm Absorbing Aerosol OD CURRENT LIMB C2 Species NEW C2 Species Improved revisit times. H2O (1-6 nhrs); O3 (6 hours) Improved Horizontal Spatial Resolution: 50 km NEW LIMB IR or Microwave C2 Species Improved vertical resn: 2 km horizontal resolution; 50 km Meets Significant Capacity Capability C2 Species: H 2 O, O 3, CH 4, N 2 O (SF 6 and CO 2 as alternative tracers) Aerosol OD Cirrus OD Stratospheric Tracers NEW CH4, N2O Tropospheric columns CH4 error 2% Improved spatial resn. 10 km SAGE Strat. Aerosol TOMS, MODIS, MISR, POLDER Column AOD (550 nm) NEW CO2 CO2 error (PBL) PRIORITY NEW AEROSOL OD 0.05 uncertainty 550 nm Absorbing Aerosol OD 0.01 uncertainty Cirrus OD 100% Improved re-visit times 1-6 hours

22. Climate Assessment – consolidated requirements

23. C3: Climate Scientific Assessment Satellite Component Evolution Ultimate Specification Minimum Specification Metop IASI Nadir IR FTS O3, H2O, CO, C2H6, CH4, N2O Nadir UV-VIS O3, H2O, NO2, CH2O, Aerosol, Solar irradiance Meets Significant Capacity Capability CURRENT Limb IR FTS IR species Oxidising Capacity Radiative Forcing Ozone NEW SCIA NIR CH4, CO CH4 error < 2% Horiz resn < 10 km New Occultation or Microwave HCl NEW Trop Aerosol 0.05 nm 10 km Meets Significant Capacity Capability CURRENT Limb Microwave (in addition to Limb IR) O3, H2O (clouds) Cirrus OD, ClO (MS), SO2 (enh.) Meets Significant Capacity Capability Integrated Approach Combination O3 profiles (data) SAGE equivalent Strat. Aerosol IR species: O 3, H 2 O, CO, HNO 3, H 2 O 2, CH 3 COCH 3, PAN, C 2 H 6, CFCs, HCFC, PSCs, CH 4, N 2 O, SF 6, N 2 O 5, ClO (LS), ClONO 2, SO 2 (enh.) PRIORITY

24. Climate Summary Protocol monitoring is a different genre of mission NRT Climate i.e. H 2 O and Assessment though having different drivers have overlapping solution in terms of instrument suite

25. Climate Summary Protocol monitoring is a different genre of mission  GHG monitoring mission  Could be met by additional SWIR channel NRT Climate i.e. H 2 O and Assessment though having different drivers have overlapping solution in terms of instrument suite  Limb viewing-climate gas mission scenario  (Later overlap with Ozone and UV)

26. Ozone and UV Many of the requirements can be met by existing systems But …

27. Reduction of uncertainties Dedicated satellites: O 3 profiles, strat (H)CFCs, H 2 O, CH 4, aerosols T, PSCs, HNO 3, Active Cl/Br Ozone Trend Assessment, Polar O 3 monitoring, U/V forecast Total. O 3, Trop. (H)CFCs Ground-based measurements Existing satellites Total O 3, OClO End users requirements Applications + + + Balloon programme: Cly, NOy [Recommendation] Surface albedo, tropospheric aerosol, tropospheric O 3 European assessment – SCOUT (CE) System concept for O 3 /UV

28. Ozone/UV Satellite (Consolidation) For ozone/UV missions, a system can be consolidated which a)Delivers O 3 columns and UV for Protocol b)Delivers O 3 profiles for NRT c)Delivers trace species and aerosols for assessment. Consolidated system therefore would ideally deliver assessment capabilities at a minimum to provide all 3 services.

29. Ozone/UV Climate NRT/Assessment - Summary of requirements Limb instrument(s) that measures a range of trace species and complements the Nadir measurements made on Metop/NPOESS. Implementation options include a limb-MIR of at least 2 km resolution, potentially in combination with a limb microwave instrument in order to meet the optimal number of requirements. A limb UV/VIS system to measure NO 2 and potentially BrO would be invaluable. Solar occultation instruments require consideration including re-flight of SAGE III. Ground-based systems provide a total ozone verification system, validation and source gas monitoring, but cannot provide the range of height resolved information required.

30. A3 (Consolidation): Ozone Layer Scientific Assessment Satellite Component Evolution SCIA Limb BrO, NO2 A1 GOME-2 Column O3 UV Aerosol Solar Irradiance IASI UT H2O Ultimate Specification Minimum Specification OSIRIS NO2 A2 HIRDLS O3 A2 SCIA Limb O3 A2 MLS O3 A2 MIPAS O3 Meets Significant Capacity Capability A3 Species: ClO (LS), HNO 3, H 2 O, tracers MIR: + PSCs, (H)CFCs, ClONO 2 Microwave: + HCl, ClO (MS), SO 2 (enh) SAGE equivalent Strat. Aerosol CURRENT IR A3 SPECIES CURRENT MICROWAVE A2 SPECIES NEW IR or MICROWAVE or UV Limb O3 Ver. Res. 2 km, 50 km Inc. UT NEW UV VIS Limb BrO,NO2 Ver. Res. 2 km NEW IR A3 SPECIES Ver. Res. 2km NEW MICROWAVE A3 SPECIES Ver. Res. 2km New Aerosol Rev. Time 6-24 hours

31. Broad recommendations With respect to a space segment of a measuring system for operational monitoring, it is clear there are three overall requirements that cannot be met by current or planned systems –High temporal/spatial resolution space-based measurements of tropospheric (PBL) composition for application to AQ –High vertical resolution measurements in the UT/LS region for ozone and climate applications –High spatial/high precision monitoring of climate gases (CO 2, CH 4 and CO) and aerosol with sensitivity to PBL concentrations

32. Specific Summaries

33. Stratospheric Ozone/Surface UV Protocol monitoring requirements can be met by the planned MetOp and ground-based systems. The other stratospheric NRT and assessment themes require limb sounding capabilities. –For NRT, only ozone profiles are mandatory but measurements of other species are highly desirable: ClO, polar stratospheric clouds, stratospheric aerosol, HNO 3, H 2 O, tracers, and HCl. –For assessment, all the NRT measurements are required with, in addition, HCFCs, ClONO 2, and SO 2 (enhanced). A limb MIR system is therefore suggested but a limb MM also has significant complementary capabilities, particularly in cloudy regions of the atmosphere. A limb UV-VIS instrument can monitor the important compounds of NO 2 and BrO.

34. Air Quality All AQ requirements are essentially similar with a –prime requirement for high spatial (<20 km) and temporal (<2 hours) resolution –measurements of O 3, CO, NO 2, SO 2, HCHO, and H 2 O –with sensitivity to the PBL. Instruments types are likely to be nadir UV- VIS-NIR with either Short-Wave Infra-Red (SWIR) or Mid Infra-Red (MIR) capability for CO. For aerosol measurements at multiple wavelengths would enhance the system ideally in conjunction with night time measurements.

35. Climate Protocol monitoring system was notably different to those for NRT and assessment. Kyoto protocol monitoring demands high precision measurements of CH 4 and CO (and CO 2 ) –This builds on the SWIR measurements demonstrated by SCIAMACHY. –Improved NO 2 measurements (spatial resolution of 10 km) would also be ideal. It is suggested that climate protocol monitoring systems could be combined with AQ systems in the evolution of a GMES system.

36. Climate (cont’d) NRT & Assessment The priorities are limb sounder measurements for high vertical resolution (<2 km). For NRT, measurements of H 2 O, O 3, CH 4, and N 2 O suggest either limb MM or limb MIR For assessment, limb MIR is more likely to be a priority to measure the large range of necessary species to monitor changes in radiative forcing, oxidising capacity and stratospheric ozone with sensitivity also to the upper troposphere.

37. Broad recommendations With respect to a space segment of a measuring system for operational monitoring, it is clear there are three overall requirements that cannot be met by current or planned systems –High temporal/spatial resolution space-based measurements of tropospheric (PBL) composition for application to AQ –High vertical resolution measurements in the UT/LS region for ozone and climate applications –High spatial/high precision monitoring of climate gases (CO 2, CH 4 and CO) and aerosol with sensitivity to PBL concentrations