Upload
scot
View
29
Download
1
Embed Size (px)
DESCRIPTION
FACTORS GOVERNING THE SEASONAL VARIABILITY OF ATMOSPHERIC CARBONYL SULFIDE. Parv Suntharalingam Harvard/Univ. of East Anglia A.J. Kettle, S. Montzka, D. J. Jacob. GEOS-Chem Meeting April 12 th , 2007. - PowerPoint PPT Presentation
Citation preview
FACTORS GOVERNING THE SEASONAL VARIABILITY OF ATMOSPHERIC CARBONYL SULFIDE
Parv Suntharalingam
Harvard/Univ. of East Anglia
A.J. Kettle, S. Montzka, D. J. Jacob
GEOS-Chem Meeting
April 12th, 2007
Carbonyl Sulfide (COS) Uptake by Leaf During Photosynthesis
Can Carbonyl Sulfide help in Constraining Estimates of Global Primary Production ?
COSCO2
COS and CO2 are taken up through leaf stomata during photosynthesis
CO2
COS
GPP : Gross flux of CO2
converted to organic matter during photosynthesis
SEASONAL CYCLES OF COS and CO2
COS measurements : S. Montzka (NOAA-GMD)
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.00 0.20 0.40 0.60 0.80 1.00
(X I
- X
mea
n)
/ X m
ean
-0.05
-0.04
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
0.00 0.20 0.40 0.60 0.80 1.00
BRW
ALT
MHD
LEF
HFM
NWR
MLO
KUM
CGOCO2 SH
COS
J F M A M J J A S O N D J F M A M J J A S O N D
Seasonal cycles of COS and CO2 are correlated, especially at forested sites.
CAN COS MEASUREMENTS CONSTRAIN BIOSPHERIC CO2 UPTAKE ?
Significant uncertainties remain on aspects of COS budget
SOURCES AND SINKS OF ATMOSPHERIC CARBONYL SULFIDE
COS
Mean atmospheric conc. ~ 500 ppt
SOURCES AND SINKS OF ATMOSPHERIC CARBONYL SULFIDE
ANTHROPOGENIC
OCEAN
CS2
DMS
COSOxidation
SOURCES AND SINKS OF ATMOSPHERIC CARBONYL SULFIDE
SOILS PLANTS ANTHROPOGENIC
OCEAN
CS2
DMS
COS
Tropospheric Oxidation, Stratospheric Photolysis
Oxidation
SOURCES AND SINKS OF ATMOSPHERIC CARBONYL SULFIDE
SOILS PLANTS ANTHROPOGENIC
OCEAN
CS2
DMS
COS
Tropospheric Oxidation, Stratospheric Photolysis
Oxidation
Biomass Burning
????
????
Uncertainty remains on source/sink fluxes
ATMOSPHERIC COS BUDGETKettle et al. [2002] : Gridded Fields
Not included here
Biomass Burning : 35 Tg S (8%) Stratospheric Photolysis : 16 Tg (3.5%) Minor sources : < 3%
ANNUALLY BALANCED BUDGET Total sources/sinks : 460 Gg S/year
-238 -130 -92
-180280
Also based on :
Chin and Davis, 1993; Watts, 2000
OUTLINE
1. Model atmospheric COS with recent best estimates of seasonal sources and sinks [Kettle et al. 2002]
2. Evaluate against measurements from global observation network [Montzka et al. 2006]
3. Which processes govern observed seasonal variability ? Can we improve estimates of prior COS fluxes?
AIM : Improved constraints on factors governing COS seasonal variability
COS SURFACE OBSERVATION NETWORK : NOAA-GMD Flask measurements since 2000 [Montzka et al. 2006]
Barrow (BRW)
Mauna Loa (MLO)
South Pole (SPO)
•
•
••
•
• • ••
•cgo
mhd
altbrw
kum mlo
smo
spo
nwr hfmlef
GEOS-Chem COS SIMULATION
INPUT FLUX DISTRIBUTIONS [Kettle et al. 2002]
SOURCES
•Ocean (Direct; CS2 and DMS oxidation to COS)
•Anthropogenic (Direct and CS2 oxidation to COS)
SINKS
•Terrestrial plant uptake
•Soil uptake
•COS oxidation by OH (tropospheric)
To be Implemented • Biomass burning•Stratospheric photolysis
GEOS-Chem Version 7-03-06
Resolution : 2x2.5; 30 vertical levels
Meteorology Year : 2001
COS SINK DISTRIBUTIONS [Kettle et al. 2002]
Plant Uptake (JAN)
Plant Uptake (JUL)
Soil Uptake (JAN)
Soil Uptake (JUL)
Plant fluxes derived from NPP and NDVI fields
Soil uptake based on soil moisture and temperature. (Only 1 soil type)
pmol/m2/sec
Anthropogenic (JAN)
Anthropogenic (JUL)
Ocean (JAN)
Ocean (JUL)
Anthropogenic COS fluxes distributed according to SO2 emissions (GEIA 1985)
Ocean fluxes based on ocean photochemical model and DMS distributions
COS SOURCE DISTRIBUTIONS [Kettle et al. 2002]
pmol/m2/sec
SEASONAL VARIABLITY OF COS FLUXESFlux Distributions : Kettle et al [2002]
AGGREGATED FLUXES
•N Hemisphere variability driven by plant uptake and ocean fluxes
•S Hemisphere variability driven by ocean fluxes
OCEAN
TOTAL SURFACE COS FLUX
PLANTSOILS
ANTH. OCEAN
Northern Hemisphere Southern Hemisphere
Gg
S p
er m
on
th
SEASONAL ANOMALIES AT MEASUREMENT SITESData : S. Montzka (NOAA-GMD)
South Pole Cape Grim, Tasmania
Barrow, Alaska Park Falls, Wisconsin
•Seasonal cycle has similar phase at Southern Hemisphere and Northern Hemisphere sites
•Northern Hemisphere sites show larger seasonal amplitude
Data for years 2001-2005
SEASONAL CYCLE AT REMOTE/OCEAN SITESObservations and Model : Seasonal Anomalies
•Good agreement at Southern Hemisphere remote/ocean sites
X Observations
Model
•Good agreement at Southern Hemisphere remote/ocean sites
•Observed seasonality not well reproduced as move northwards
X Observations
Model
SEASONAL CYCLE AT REMOTE/OCEAN SITESObservations and Model : Seasonal Anomalies
SEASONAL CYCLE AT TERRESTRIAL STATIONS Observations and Model : Seasonal Anomalies
Observed seasonal cycle not well
simulated at Northern Hemisphere terrestrial
sites
X Observations
Model
GLOBAL PLANT UPTAKE OF COS SUMMARY OF ESTIMATES : (Table 4 : Sandoval-Soto et al. 2005)
Units : Tg COS/year
Brown and Bell (1986) 2-5
Goldan et al. 1988 0.2-0.6
Kesselmeier and Merk (1993) 0.93 + 0.07
Chin and Davis (1993) 0.16-0.91
Watts (2000) 0.56 + 0.1
Xu et al. (2002) 2.3 + 0.5
Kettle et al. (2002) 0.39 – 0.5
Sandoval-Soto et al. (2005) 1.37-2.81
Kettle et al. [2002] NPP-based estimate is lower than recent estimates
SEASONAL CYCLE AT TERRESTRIAL SITES Increased Model Plant COS Uptake (Factor of 3)
X Observations
Original Model
Model: Increased
plant uptake
ORIG MODEL
INCREASED UPTAKE MODEL
Increased COS uptake by plants better matches observed seasonality
SEASONAL CYCLE AT TERRESTRIAL SITES Increased Model Plant COS Uptake (Factor of 3)
X Observations
Original Model
Increased
plant uptake
BUT
•Now need an additional source (for balanced annual budget)
SEASONAL CYCLE AT TERRESTRIAL SITES Increased Model Plant COS Uptake (Factor of 3)
X Observations
Original Model
Increased
plant uptake
BUT
•Now need an additional source (for balanced annual budget)
•Phase problems remain
SEASONAL CYCLE AT TERRESTRIAL SITES Increased Model Plant COS Uptake (Factor of 3)
X Observations
Original Model
Increased
plant uptake
BUT
•Now need an additional source (for balanced budget)
•Phase problems remain
•Missing source flux ?
SUMMARY
•Add source and sink for biomass burning and stratospheric photolysis
•Update anthropogenic COS emissions based on latest SO2 inventories.
•Inverse model analysis of COS measurements to improve source/sink flux estimates
•Primary influences on COS seasonal cycle : Ocean fluxes in Southern Hemisphere; Plant uptake and ocean fluxes in Northern Hemisphere.
•Increasing plant uptake of COS by a factor of 3 (to 0.7 Tg S/year) improves model representation of seasonal cycle at terrestrial sites
•But, annual COS budget no longer in balance – missing source ?
ONGOING/PLANNED WORK