Simulating Atmospheric CO2

for 2000: Our Quandary, Our Hypotheses and a Case Study

Using Analyzed Climate, Transport and Satellite Vegetation

Sheri L. Conner Gausepohl

TRANSCOM Meeting13 - 16 June 2005

Paris, France

Introduction

• Research Goals

• Team: NASA/Goddard, CSU, NOAA-CMDL

Oak Ridge Lab

• Models: SiB3 and PCTM

• Experiment Overview

• Our Quandary

• Our Hypotheses

• Case Study

• Next Steps

Goals

• Create a synthetic atmospheric [CO2 ] product with realistic diurnal, synoptic and seasonal variations with quantified error

– Sub-sampling for various observing systems– Testing inverse methods

– Creating lateral boundary [CO2] conditions for mesoscale models (SiB-RAMS)

– Testing flux models and hypotheses of surface exchanges

Team

• NASA/Goddard– Randy Kawa– Steven Pawson– Jim Collatz– Zhengxin Zhu

• CSU– A. Scott Denning– Kevin Gurney– Ian Baker– John Kleist– Ravi Lokupitiya– Andrew Philpott– Lara Prihodko– Owen Leonard– Erin Chorak– Sheri Conner Gausepohl

With many thanks to CMDL and Joe Berry and Steve Montzka

• NOAA - CMDL– Arlyn Andrews– Kevin Schaefer

• Oak Ridge Lab– David Erickson III

Parameterized Chemical Transport Model (PCTM)

U U

PCTM – Previous Results

Thanks to Kevin Gurney and Scott Denning

PCTM TRANSCOM Responses

CO

2 C

on

cen

trat

ion

(p

pm

)

Simple Biosphere Model (SiB3)

Thanks to Piers Sellers, Ian Baker et al.

Experiment Overview

NDVI10

years

3 years

GEOS – 4 DASMeteorology

(core Goddard GCM)

SiB3Biosphere

PCTMTransport

(core Goddard GCM)

IGBP Soils

DeFries Biome Types

Met Fields1º x 1.25º x 55L x 3/6 hours

Met Fields1º x 1.25º x 3 hours

NEE1º x 1.25º x 1 hour

18 years

3 years

NCEP

Takahashi Ocean 1997

Andres Fossil Fuel Emissions

1990

[CO2]2º x 2.5º x 25L x 1 hour

www.noaa.gov

www.e-design.org.uk

www.nws.noaa.gov/rrs/overview.htm

www.noaa.gov

http://www.fas.harvard.edu/~cobra/http://public.ornl.gov/ameriflux/

faculty.law.lsu.edu/ccorcos/biblio/flask.gif

Quandary: Early Drawdown

Hypotheses• Autotrophic Respiration

• Photosynthesis: Normalized Difference Vegetation Index (NDVI)

• Radiation

Case Study: COS• Use carbonyl sulfide (COS)

to quantify error in

photosynthesis

Data: red Model: green

Hypothesis: Respiration

• Heterotrophic Respiration– 50% of annual Net Assimilation (GPP - Respiration leaf maintenance)

– Seasonality defined from Soil Temperature & Soil Moisture

• Autotrophic Respiration– 50% of annual Net Assimilation– Seasonality defined by FPAR (canopy nitrogen)

New Respiration Calculation:

Thanks to Kevin Schaefer

Temperate North America

Old Scheme: red New Scheme blue CASA: green T3L3: black

-60.00

-55.00

-50.00

-45.00

-40.00

-35.00

-30.00

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

5.00

10.00

15.00

20.00

25.00

30.00

1 2 3 4 5 6 7 8 9 10 11 12

Month

Brief Note re: SiB3, CASA

SiB3

• FPAR estimated from mid-month linearly interpolated NDVI, BUT solar zenith angle dependent FPAR

• Single respiring carbon pool generates respiration that varies with soil temperature, soil moisture

CASA

• FPAR estimated from mid-month linearly interpolated NDVI , BUT nadir FPAR

• Multiple respiring carbon pools generate respiration that varies with amount of material in labile pools, air temperature, soil moisture

Hypothesis: NDVINew NDVI Interpolation Schemes:

NDVI at WLEF, Wisconsin

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1 31 61 91 121 151 181 211 241 271 301 331 361

Day of Year (1996)

Normalized Difference Vegetation Index (NDVI)

NDVI at Kenai, Alaska

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1 31 61 91 121 151 181 211 241 271 301 331 361

Day of Year (1996)

Normalized Difference Vegetation Index (NDVI)

Thanks to Andrew Philpott and the Tucker Group (NASA - Goddard)

Data: green Old Scheme: Blue New Scheme: Red

• Assign maximum value composite NDVI values to:- day observed OR

- first day, mid-point, last day of month based on curvature

and linearly interpolate

• Tropics are an issue due to cloud contamination

Hypothesis: Radiation

• Separate treatment of sunlit and shaded leaves – Photosynthesis– Stomatal conductance– Leaf temperature– Transpiration

• Solar zenith angle dependence of canopy shading acts to delay onset of photosynthesis in new scheme

Improved Canopy Radiation Scheme:

Case Study: Assessing Photosynthesis vs. Respiration

• Primary source: oxidation of marine organic matter

• Primary sink: terrestrial biosphere

• Large seasonal variation strongly related to CO2

– Sink process identical to CO2 in photosynthesizing plants

– No source process akin to respiration from biosphere

COS: the Sulfur Analog of CO2

Thanks to CMDL for CO2 data and to Steve Montzka for COS data

[COS]

355.00

375.00

395.00

415.00

435.00

455.00

475.00

495.00

515.00

535.00

1 3 5 7 9 11 13 15 17 19 21 23

Month (2000 - 2001)

ppt[COS] WLEF

[COS] NWR

[CO2]

355.00

360.00

365.00

370.00

375.00

380.00

385.00

1 3 5 7 9 11 13 15 17 19 21 23

Month (2000 - 2001)

ppm

[CO2] WLEF

[CO2] NWR

Case Study: Assessing Photosynthesis vs. Respiration

• Estimate timescale of mixing between mixed layer and free troposphere from water vapor and CO2 gradients

• Calculate COS drawdown using timescale and SiB3

• Compare COS drawdown to observations of COS at WLEF

COS: The PlanFree Troposphere

Mixed Layer

Canopy Air Space

NOTE: SiB3 currently calculates all but one necessary resistance

Next Steps

1. Diagnose why SiB3-PCTM has springtime bias using

COS (carbonyl sulfide)

2. (Improve SiB3 per results of diagnosis)

3. Run SiB3 with new schemes

4. Run PCTM at 1.0º x 1.25º resolution with updated

fossil fuel and ocean fluxes

5. Calculate errors on [CO2] using observations

6. Release hourly global [CO2] product to science

community with quantified errors

Thank you very much for your kind attention.