Regional Carbon Fluxes in WI:
Moving towards synthesis
Cheas IX, June 2006
Ankur R. Desai
Pennsylvania State University, Dept. of Meteorology
National Center for Atmospheric Research, Advanced Study Program
University of Wisconsin, Atmospheric & Oceanic Sciences Dept.
Question
• One of several overarching ChEAS
questions is:
What is the regional
carbon flux?
Do we have to study its ursprache?
Pardon?
• WHAT -> define? quantify? explain?
• IS -> present? past? future?
• THE -> only one answer?
• REGIONAL -> scale?
• CARBON -> CO2, CH4, VOC?
• FLUX? -> Vertical, horizontal, NBP?
Approaches
• Biometric / FIA
• Ecophysiological
• Tall tower + footprint models
• Stand scale eddy covariance towers
• Tall tower ABL budgets
• Multi-tower mesoscale inversion
• Remote sensing (MODIS, LiDAR)
• Modeling (ED, SiB, Biome-BGC)
A Bit About ED
• Ensemble-average canopy gap model
(Moorcroft et al., 2001; Albani et al.,
in press; Desai et al, submitted)
– Conditioned on stand age and plant
height (modifies light environment)
– Multiple competing plants
– Disturbance, mortality, harvest,
reproduction control dynamics
– Traditional soil/leaf biogeochemistry
A Bit About ED
• For ChEAS: 40 km radius of WLEF
• Forcing:
– Pre-European settlement vegetation
– Ecophysiological and allometric
growth/respiration parameters
– Long-term climate data
– Forest harvest statistics
– FIA to tune forest structure and params.
• 3 “grid cells” / subregions
ED MODEL PFTS
Mesic Upland / N. Hardwoods
GR
Grass
AS
Aspen
BI
Birch
SM
Sugar maple/basswood
HE
Hemlock/Spruce
Xeric Upland / Mixed conifer
GR
Shrub/Pine Barren
JP
Jack Pine
RP
Red Pine
WP
White Pine/Fir
RM
Red maple/Oak/Ash
Lowland / Wetland
GR
Meadow grass
AW
Alder/Willow shrub
TM
Tamarack
CE
Cedar
BS
Black spruce
What Have We Learned
• When you’re up you’re up
• When you’re down you’re down
• And when you’re only halfway up,
you’re neither up nor down
– Puzzling results when comparing upscaled estimates from one approach to
another at a larger scale
– You’re asking for trouble if you try to
measure something more than once or
in more than one way
What Have We Learned
• Stand age and species matter
– Within site IAV < Across-site variability
What Have We Learned
• Climate explains much of interannual
variability of CO2 flux
– We’re doing a better job at modeling it
What Have We Learned
• But it’s harder to model indiv. stands
What Have We Learned
• Over the long term, forest dynamics
matter
What Have We Learned
• Scale matters
What Have We Learned
• Tree biophysics matter
What Have We Learned
• Animals and pests matter
What Have We Learned
• People matter
What Have We Learned
• There’s a lot of things to worry about
when answering “What is the
regional carbon flux?”
• We’re making good progress in spite
of that
• Starting to put together some of our
top-down and bottom-up flux
estimates
– Need your help
Some Numbers
• NEE, several methods (gC m-2 yr-1)
– better in Jun-Aug than all year
LEF
tall tower
Year
Decomp.
Multisite
ED
Bakwin, Helliker,
2004
2004
2003
2000
1997
2003
2003
2003
1997
2000
Jun-Aug
-76
-149
-124
-258
-298
-177
-140
-174
Annual
80
95
44
-119
N/A
-143
77
-40
Some Numbers
• NPP (gC m-2 yr-1):
– FIA 553 (1996-2004 biomass
increment) – litter (~100)
– MODIS NPP (MOD17) 2002: ~600
– Ahl et al, RSOE, 05 (ATLAS 15 m): 403
– ED model: 423
Moving Toward Synthesis?
• Maybe
• More observations, more models,
more processes
– Will it help?
– When is it enough?
– What’s the next step?
• Working on paper this summer at
PSU on regional synthesis
Moving Toward Cuteness!