# Presentation: 174889

## CONSISTENCY among                                  MOPITT, SCIA, AIRS and TES measurements of CO using the             GEOS-Chem model as a comparison platform

*Michael Buchwitz, Iryna Khlystova, John Burrows, (SCIA Bremen)    Annemieke Gloudemans, Jos de Laat (SCIA SRON), W. Wallace McMillan (AIRS)*

**IWGGMS**
**Pasadena, June 24, 2008**

- Funding provided by

- MOPITT and TES data provided by the respective retrieval teams for data

**Monika Kopacz**, Jenny Fisher, Daniel Jacob, Jennifer Logan, Lin Zhang, Meghan Purdy

## Carbon Monoxide (CO)

**Carbon Monoxide (CO)**

-  important and uncertain indirect greenhouse gas
-  correlations between CO and CO2 can help improve CO2 flux estimates *(H. Wang’s talk during OCO STM)*

- ...*as relevant to IWGGMS*

- Accurate CO estimates AND  experience with measuring CO from space are very valuable

- Suntharalingam et al.* *[2004]

- IPCC [2007]

- observing CO from space is much easier than CO2 !

## Satellite instruments providing (daytime) CO column measurements

**validated data product**, global coverage every 3 days, used in inversions and comparisons previously

- 4.7 μm

**sensitive throughout the column****, **large errors, relatively unexplored

**extremely dense coverage** (daily global!), v5 retrieval not used so far

**relatively unexplored**, provides collocated information on tropospheric O3

- 4.7 μm

- 4.7 μm

- 2.3 μm

## Available satellite CO (column) data

**MOPITT**

**SCIA Bremen**

**TES (2006)**

**AIRS**

***CO columns expected to be different due to different vertical sensitivity***

- May 2004

- 0           0.88          1.75           2.62         3.50

- 1018molec/cm2

## ?=

- Scientific questions:                   (1) Are the satellite datasets consistent? (Can we treat them as one big dataset for flux inversion etc?)
- (2) What are the biases and how can we account for them?

- Data selection: May 1, 2004 - May 1, 2005

-  MOPITT: 1999 – 2007 (aircraft validation during summer 2004, Emmons   et al. [2007])
-  SCIAMACHY: 2 retrievals for 2003 –  2005 (2004 unbiased, 2005 increasing loss of pixels)
-  AIRS: 2002 – present (v5 retrieval)
-  TES: August 2004 – present

## GEOS-Chem CTM: the comparison platform

- TRUTH

**SATELLITE DATA**

- biased?

- biased?

- biased?

- biased?

- (global) Chemical Transport Model, CTM GEOS-Chem, **comparison platform**

- biased?

**in situ observations**

- validate

- validate

*but very sparse in time and space*

**compute model-satellite correlations for each dataset**

- ?

## Model: satellite correlations

- AIRS

**May 2004 – May 2005 global daytime columns (averaged to 2x2.5 resolution)**

-  r2 = 0.731

-  r2  = 0.832

- TES*

- SCIA SRON

-  r2 = 0.294

- SCIA Bremen

-  r2 = 0.243

-  r2  = 0.645

- MOPITT

**TES data start at the end of August 2004*

- 0              1                2               3              4

- 0              1                2               3              4

- 0                1                2               3               4

- GEOS-Chem CTM

- GEOS-Chem CTM

- Unit: 1018 molec/cm2

- Red line: Reduced Major Axis regression

- 4
- 3
- 2
- 1

- 4
- 3
- 2
- 1

## Temporal variations in data and GEOS-Chem CTM

-  averaging kernels decrease the amplitude of seasonal cycle
-  MOPITT and AIRS appear consistent

**Lines:** GEOS-Chem + averaging kernels
**Symbols:** daily averaged satellite data

- GEOS-Chem columns over N. America

- May 1, 2004

- Nov. 1, 2004

- May 1, 2005

- ___SCIA SRON

- ___SCIA Bremen

- ___AIRS

- ___MOPITT

- ___ no AK

- ___AIRS

- ___MOPITT

- ___SCIA Bremen

- ___SCIA SRON

## Satellite bias based on sat-model correlations

**TES data starts in late August 2004   SCIAMACHY  r**2** too low to compute bias*

- AIRS bias slightly lower than MOPITT
- SCIA Bremen and SRON not correlate with the model due to scatter (r2 = 0.062 and 0.164 respectively)

- Conclusions:

- Latest **MOPITT** **validation** during summer 2004: **5% high**, Emmons et al. [2007]

- MOPITT – GC bias consistent throughout time and space, and values of MOPITT bias alone can be extrapolated from Emmons at al. [2008]

|  | GEOS-Chem/satellite slope (Correlation coefficient r2) |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  |   | global |  |   | NH |   |   |   | 0-60N |
| Satellite | year | year/land |  | year | year/land | spring | no spring | year | no spring |
| MOPIT | .76(.65) | .78(.69) |  | .64(.46) | .75(.53) | .59(.46) | .70(.50) | .65(.51) | .73(.54) |
| AIRS | .71(.73) | .74(.70) |  | .70(.52) | .78(.56) | .68(.49) | .76(.57) | .69(.56) | .76(.61) |
| TES* | .89(.83) |   |  | .93(.50) |   |   |   | .83(.42) | .88(.46) |

## END

- Next: Adjoint inversion using MOPITT, SCIAMACHY and AIRS data to estimate CO sources (**COSPAR July 2008**)