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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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”.