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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. Menziesand P. Ingmann (ESA)
Outline
• Overview of existing / planned missions
• What is a Lidar?
• Why a CO2 Lidar?
• Instrument requirements
CO2 from space: Existing and planned missions• Thermal IR: NOAA-TOVS, AIRS, IASI
• Near IR: SCIAMACHYOCO (2009), GOSAT
(2009)
• Near IR: A-SCOPE; candidate ESA Earth explorer mission (~2015)
Pas
sive
Act
ive
A-SCOPE payload
• CO2 Lidar
• Contextual camera (TBC)
• Altimeter: Canopy height distribution (TBC)
Measurement Principle
Active: Laser + Receiver
- Differential Absorption Lidar (DIAL)
- 2-3 wavelengths as probe (on) and reference (off)
- Lidar: Light Detection and Ranging
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 tosurface
- Dusk - dawn orbit (diurnal cycle amplitude)
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are needed to see this picture.
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
Path = lPath > lPath = 0Path < l
How do aerosols affect CO2?
Modelled aerosol errorAnnual mean
Houweling et al. (ACP, 2005)
SCIAMACHY CO2
Annual mean
… OCO: Can handle aerosols much better than SCIAMACHY
CO2 Lidar: Accuracy requirements
• Target requirement on surface flux estimation (level 3):
0.02 PgC/yr over 106 km2
(or ~ 50% of the annual flux)
Translation to XCO2 (level 2)• Inverse modelling simulations
Required precision:
0.5 - 1.5 ppm
Systematic error:10% of precision
Canopy Lidar
Harding & Carabajal (GRL, 2005)
Can
op
y heig
ht d
istribu
tion
Supporting activities
• CO2 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
Conclusions
• A-SCOPE is a mission aiming at the monitoring of spatial and temporal gradients of atmospheric CO2 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”.