Simulating carbon, water and heat fluxes at the Changbaishan tower site using hourly BEPS

1. Simulating carbon, water and heat fluxes at the Changbaishan tower site using hourly BEPS Wang Qiufeng, Yu Guirui Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

2. Outline • Introduction • Materials and methods • Overview of ChinaFLUX • Site description of Changbaishan • Data collection and process • Model description • Preliminary Results • Conclusions

3. Introduction • Carbon cycle and carbon cycle modeling are of great concerns in recent years • Eddy covariance technique provide a feasible way to model validation • The objective of this research is to validate NEP, LE, and Hs simulated by hourly BEPS with flux data of Changbaishan site from ChinaFLUX

4. Materials and methods

5. Overview of ChinaFLUX

6. Changbaishan Site description 42°24′0 9″N , 128°05′45″E , elevation 738m Fetch: 500m-60km Height: 62.8 m

7. Site description

8. Open path/Closed Path EC

9. Sensors of Routine Meteorological elements

10. List of instruments

11. Data collection • Flux data Sampling frequency 10Hz Half-hour fluxes are calculated on-line and collected by data logger (CR5000 Campbell, USA). • Meteorological and soil data are collected every 2 s and stored as half-hour statistics (CR23X, Campbell, USA)

12. Data process • The 3-D Sonic anemometer tilt correction (coordinate rotation) was carried out monthly with the planar fit (PFT) method • Webb–Pearman–Leuning corrections (Webb et al., 1980) was applied to the eddy fluxes.

13. Data process • Remove carbon flux data beyond the range -1.5<Fc<1.0 mg CO2 m-2 s-1 • Remove nighttime data with a friction velocity less than 0.2 m s-1 • Calculate NEP NEP= - NEE

14. Model description

15. Major vegetation parameters

16. Preliminary Results

17. Variations of Meteorological variables(in 2003)

18. Soil temperature

19. Soil moisture

20. Statistical comparison of simulated versus measured soil temperatures and soil moistures

21. Measured VS. Modelled NEP

22. NEP simulated and measured for three periods during growing season

23. simulated VS. measured LE

24. LE simulated and measured for 3 periods during growing season

25. Simulated VS. measured Hs

26. a) b) c) Hs simulated and measured for 3 periods during growing season

27. Sensitivity to climate variability

28. Responses of NEP and ET to climate variability

29. Sensitivity to physiological parameters

30. Conclusions • The results simulated by hourly version BEPS is reasonable, which suggested that the model could be used to simulate the fluxes of C, water and heat flux in China • Results from sensitivity analysis showed that the model is sensitive to climate variability, meanwhile, plant physiological parameters (gmax and Vmax) are also important

31. Conclusions • Although the model could capture the main patterns of the variations in NEP, LE and Hs, discrepancy still exists. The causes is still uncertain. • Much work still needs to be done in the future, such as model application in different types of ecosystems

32. Acknowledgement • Thanks should be given to Prof. Chen J M for giving me the chance to study the BEPS model in UT and his useful advices • I am grateful to the kindly help provided by Dr. Ju W M in model debugging • I appreciate Prof. Shi XZ for providing the soil data

33. Thank you!