Stress Deciduous Phenology in the CLM

Transcription

1 Stress Deciduous Phenology in the CLM Kyla Dahlin & Rosie Fisher February 25, 2014 image credit: Forrest Copeland talesfromthebigcountry.wordpress.com

2 Can we accurately model seasonal changes in vegetation in the semiarid tropics? image credit: Forrest Copeland talesfromthebigcountry.wordpress.com

3 Phenology in CLM 15 non-crop plant functional types 3 phenology algorithms evergreen cold deciduous stress (= drought) deciduous

4 Phenology in CLM 15 non-crop plant functional types 3 phenology algorithms evergreen cold deciduous stress (= drought) deciduous

5 Where is CLM Stress Deciduous?

6 How does stress/drought decidousness work in CLM? (in warm, long-day regions*) CLM4.5 Tech Note from White et al 1997 And stress deciduous plants can turn evergreen if conditions permit! dormant F M A onset M CS leaf t onset A t offset S O offset dormant N D CLM4.5 Tech Note

7 How does stress/drought decidousness work in CLM? (in warm, long-day regions*) CLM4.5 Tech Note from White et al 1997 Start growing leaves if... 3 rd soil layer is wet (soil water potential > -2 MPa) for 15 days dormant F M A onset M CS leaf t onset A t offset S O offset dormant N D CLM4.5 Tech Note

8 How does stress/drought decidousness work in CLM? (in warm, long-day regions*) CLM4.5 Tech Note from White et al 1997 Start growing leaves if... 3 rd soil layer is wet (soil water potential > -2 MPa) for 15 days Onset period fixed at 30 days dormant F M A onset M CS leaf t onset A t offset S O offset dormant N D CLM4.5 Tech Note

9 How does stress/drought decidousness work in CLM? (in warm, long-day regions*) CLM4.5 Tech Note from White et al 1997 Start growing leaves if... 3 rd soil layer is wet (soil water potential > -2 MPa) for 15 days Onset period fixed at 30 days Start dropping leaves if... Onset period is complete 3 rd soil layer is dry (soil water potential < -2 MPa) for 15 days dormant F M A onset M CS leaf t onset A t offset S O offset dormant N D CLM4.5 Tech Note

10 How does stress/drought decidousness work in CLM? (in warm, long-day regions*) CLM4.5 Tech Note from White et al 1997 Start growing leaves if... 3 rd soil layer is wet (soil water potential > -2 MPa) for 15 days Onset period fixed at 30 days Start dropping leaves if... Onset period is complete 3 rd soil layer is dry (soil water potential < -2 MPa) for 15 days Leaf drop period fixed at 15 days And stress deciduous plants can turn evergreen if conditions permit! dormant F M A onset M CS leaf t onset A t offset S O offset dormant N D CLM4.5 Tech Note

11 Questions How well does the stress deciduous phenology algorithm work in CLM? Which SD parameters have the most leverage?

12 Questions How well does the stress deciduous phenology algorithm work in CLM? [Leaf Area Index] (compared to AVHRR-derived LAI3g for ; Zhu et al 2013) Which SD parameters have the most leverage? Can we make it work better? (with relatively simple changes)

13 Questions How well does the stress deciduous phenology algorithm work in CLM? [Leaf Area Index] (compared to AVHRR-derived LAI3g for ; Zhu et al 2013) Can we make it work better? (with relatively simple changes)

14 Obs v. CLM4.5BGC LAI

15 Obs v. CLM4.5BGC LAI

16 Correlations

17 Correlations

18 How well does the stress deciduous phenology algorithm work in CLM across different PFTs? Temperate C3 grasses (NH) C4 grasses (NH) Leaf Area Index Tropical Deciduous Trees BD Shrubs (SH) Leaf Area Index Leaf Area Index Leaf Area Index

19 How well does the stress deciduous phenology algorithm work in CLM across different PFTs? Temperate C3 grasses (NH) C4 grasses (NH) Leaf Area Index Tropical Deciduous Trees BD Shrubs (SH) Leaf Area Index Leaf Area Index Leaf Area Index

20 What about at single points? Leaf Area Index Leaf Area Index Leaf Area Index Leaf Area Index Leaf Area Index

21 Counting Peaks AVHRR LAI3g CLM4.5BGC

22 Leaf Area Index What about daily model output?

23 Leaf Area Index What about daily model output?

24 What s going on? Leaf Area Index Rainfall (mm) Soil Water Potential Stored Carbon

25 What s going on? Leaf Area Index Rainfall (mm) Soil Water Potential Stored Carbon

26 What s going on? Leaf Area Index Rainfall (mm) Soil Water Potential Stored Carbon

27 How does stress decidousness currently work in CLM? (in warm, long-day regions) CLM4.5 Tech Note from White et al 1997 Start growing leaves if... 3 rd soil layer is wet (soil water potential > -2 MPa) for 15 days Onset period fixed at 30 days Start dropping leaves if... Onset period is complete 3 rd soil layer is dry (soil water potential < -2 MPa) for 15 days Leaf drop period fixed at 15 days And stress deciduous plants can turn evergreen if conditions permit! dormant 3 dimensional sensitivity analysis F M A onset M CS leaf t onset A t offset S O offset dormant N D CLM4.5 Tech Note

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29 How does stress decidousness currently work in CLM? (in warm, long-day regions) CLM4.5 Tech Note from White et al 1997 Start growing leaves if... 3 rd soil layer is wet (soil water potential > -2 MPa) for 15 days It RAINS? Onset period fixed at 30 days Start dropping leaves if... Onset period is complete 3 rd soil layer is dry (soil water potential < -2 MPa) for 15 days Leaf drop period fixed at 15 days And stress deciduous plants can turn evergreen if conditions permit! dormant F M A onset M CS leaf t onset A t offset S O offset dormant N D CLM4.5 Tech Note

30 Does adding a rainfall trigger help? 4 dimensional sensitivity analysis with point simulations

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32 How does stress decidousness currently work in CLM? (in warm, long-day regions) CLM4.5 Tech Note from White et al 1997 Start growing leaves if... 3 rd soil layer is wet (soil water potential > -2 MPa) for 15 days It RAINS! (20 mm in the past 10 days) Onset period fixed at 30 days Start dropping leaves if... Onset period is complete 3 rd soil layer is dry (soil water potential < -2 MPa) for 15 days Leaf drop period fixed at 15 days And stress deciduous plants can turn evergreen if conditions permit! dormant F M A onset M CS leaf t onset A t offset S O offset dormant N D CLM4.5 Tech Note

33 Leaf Area Index It works (better)!

34 Leaf Area Index It works (better)!

35 Max LAI

36 Correlations

37 Correlations

38 Correlations

39 Conclusions In CLM leaves come on during the dry season due to unrealistic upwards water movement in the soil profile

40 Conclusions In CLM leaves come on during the dry season due to unrealistic upwards water movement in the soil profile Delaying budburst until some rain has fallen gives better agreement with the data, both for magnitude and seasonal cycle of LAI in savanna regions

41 Next Steps What happens to productivity? What happens to the fire cycle? Does this change matter to the atmosphere?

42 Next Steps What happens to productivity? What happens to the fire cycle? Does this change matter to the atmosphere?

43 Next Steps What happens to productivity? What happens to the fire cycle? Does this change matter to the atmosphere?

44 Thanks! Questions?