flux observation: integrating fluxes derived from ground station and satellite remote sensing...
TRANSCRIPT
Flux observation: Integrating fluxes derived from
ground station and satellite remote sensing
王鹤松 Hesong Wang Institute of atmospheric physics, Chinese Academy of Sciences
李正权， 2006
Why integrating ? (precision and scale)
•The fluxes of water, energy and carbon are important variables in climate modeling, are also key processes in land surface–atmosphere interactions.
•Regional extrapolation of field based flux measurements is still a challenging task due to the high spatial and temporal variability of terrestrial ecosystems across complex landscapes and regions. •The application of satellite remote sensing has greatly enhanced global scale observations of flux over heterogeneous landscapes.
Focus on the flux in terrestrial ecosystem
(especially in northern China)
• Observation in station scale (such as EC, TDP, Licor series etc.) and regional scale (such as Landsat, MODIS, MERIS etc.);
• Integration of remote sensing and flux measurements to the generate regional products with high accuracy.
Observation of fluxes in ground stations
Photosynthesis Respiration Sap flow
Eddy covariance (EC) measurement in Tongyu, a CEOP reference station (grassland and cropland)
Regional Integration:Coordinated flux measurements in northern China
Intensive calibration was done weeks before the coordinated enhanced observation period to make those site scale data comparable.
LUEmax derived from our method
LUEmax derived from MOD17
Deriving maximal light use efficiency regional gross primary production modeling
EC measured GPP (g C/m2) in 8-day
Pre
dict
ed
GP
P (
g C
/m2 )
in
8-
day
Grass sites Forest sites
Crop sites All sites
y = 0.9576x + 0.6142R2 = 0.82, p<0.01
y = 1.0732x + 2.4747R2 = 0.57, p<0.05
y = 0.7235x + 13.483R2 = 0.69, p<0.01
y = 0.8564x + 5.9414R2 = 0.79, p<0.01
Simulated GPP VS. Measured GPPSimulated GPP VS. Measured GPP
Spatial pattern of GPP in northern China
Main landcover types and their dynamics of GPP in northern China
For more details, see paper published in RSE (Wang et al., 2010)
DOY 185
DOY 201
DOY 209
DOY 225
NDVI
LST
difference in day and night (K)
Triangle of Ts-VI method to estimate EF and Triangle of Ts-VI method to estimate EF and to calculate ET in northern China to calculate ET in northern China
Simulated EF VS. Measured EFSimulated EF VS. Measured EF
mm/Day
Seasonality of ET in northern China Seasonality of ET in northern China
Main landcover types and their dynamics of ET in northern China
Heterogeneity in simulating flux
谢谢！ Thank you ！