1. A-SCOPE Advanced Space Carbon and Climate Observation of Planet Earth MAG: F.M. Breon, H. Dolman, G. Ehret, P. Flamant, N. Gruber, S. Houweling, M. Scholze, R.T. Menzies and P. Ingmann (ESA)

2. Outline Overview of existing / planned missions What is a Lidar? Why a CO 2 Lidar? Instrument requirements

3. CO 2 from space: Existing and planned missions Thermal IR: NOAA-TOVS, AIRS, IASI Near IR: SCIAMACHY OCO (2009), GOSAT (2009) Near IR: A-SCOPE; candidate ESA Earth explorer mission (~2015) Passive Active

4. A-SCOPE payload CO 2 Lidar Contextual camera (TBC) Altimeter: Canopy height distribution (TBC)

5. Measurement Principle Active: Laser + Receiver - Differential Absorption Lidar (DIAL) - 2-3 wavelengths as probe ( on ) and reference ( off ) - Lidar: Light Detection and Ranging

6. Sampling approach 50km <100m - Measurements accumulated and averaged over a 50 km interval - on in the wing of an absorption line to optimize the sensitivity to surface - Dusk - dawn orbit (diurnal cycle amplitude)

7. Advantage over passive systems versus thermal IR: - high surface sensitivity versus near IR: - eliminates the influence of thin cloud layers and aerosols - measures during nighttime

8. Path = l Path > l Path = 0Path < l How do aerosols affect CO 2 ?

9. Modelled aerosol error Annual mean Houweling et al. (ACP, 2005)

10. SCIAMACHY CO 2 Annual mean … OCO: Can handle aerosols much better than SCIAMACHY

11. CO 2 Lidar: Accuracy requirements Target requirement on surface flux estimation (level 3): 0.02 PgC/yr over 10 6 km 2 (or ~ 50% of the annual flux)

12. Translation to XCO2 (level 2) Inverse modelling simulations Required precision: 0.5 - 1.5 ppm Systematic error: 10% of precision

13. Canopy Lidar Harding & Carabajal (GRL, 2005) Canopy height distribution

14. Supporting activities CO 2 study:‘Observation Techniques and Mission Concepts for Analysis of the Global Carbon Cycle’ Other activities: –study regarding 1.6 and 2.0 micron observations of relevant lidar reflectivities –study regarding the diurnal cycle of carbon dioxide –study addressing instrument requirements for CCDAS

15. Conclusions A-SCOPE is a mission aiming at the monitoring of spatial and temporal gradients of atmospheric CO 2 globally. A potentially complementary objective of the mission is the measurement of canopy height distribution. Cloud and aerosol information will be provided as a “by-product”.