Transcript
Page 1: Hui-Lu-improving-flux.ppt

IGARSS 2011, Jul. 26, Vancouver 1

Improving Land Surface Energy and Water Fluxes Simulation over the Tibetan Plateau with Using a Land

Data Assimilation System

Hui Lu (Tsinghua University)Toshio Koike, Hiroyuki Tsutsui, Katsunori Tamagawa

(The University of Tokyo)Kun Yang, Xin Li (Chinese Academy of Science)

Xiangde Xu (Chinese Meteorological Admistration)

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Contents

• Background and Objective• Land Data Assimilation System• Application Region and Data

– Simulation domain and ground sites– Used Data

• Results– Surface soil moisture– Land surface energy fluxes

• Remarks

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Background and objective• Tibetan Plateau is important in the progress of the

Asian summer monsoon – land surface processes – direct Orographic and thermal effects

• Land-atmosphere interaction in T-P is the key to– improve the understanding of Asian monsoon – improve the accuracy of numerical weather prediction in

east Asia – mitigate weather disaster in this region

• Objectives of this research– To identify the potential of LDAS to improve the modeling

of land surface fluxes.– To generate reliable regional distribution of soil moisture

and energy fluxes

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Land Data Assimilation System• Why LDAS

– Shortage of model• Maybe biased, can not correct errors from forcing, parameter setting

and model physics – Shortage of satellite remote sensing

• Limited information, both temporal and spatial

• Structure of LDAS: three parts of a variational system – Dynamic model: Land surface scheme :

• SiB2– TB observation:

• RTM: Advanced Integral Equation Method (AIEM)– Optimization scheme:

• Shuffled Complex Evolution (SCE)

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LSM

lEH τP

↓lR ↓

sR

Radiation transferin canopy

Interception

↑↑sl RR

Roff

Base flow

Infiltrate and Diffuse

Transpira-tion

vqTU lEH τ

P↓lR ↓

sR

Radiation transferin canopy

Interception

↑↑sl RR

Roff

Base flow

Infiltrate and Diffuse

Transpira-tion

vqTU

Minimization schemeF(Tbobs-Tbsim)

Tg, Tc, Mv

Tbsim

Mv

Vegetation layer

Surface

Surface radiation Vegetation emission

RTM

Tbobs

MicrowaveTMI/AMSR/AMSR-E

(6.9/10.6 and 18.7 GHz)

SiB2/New SiB

DMRT-AIEM

Shuffled Complex Evolution

Optimization + Assimilation LDAS

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Introduction of LDAS-UT: Input and Output

LDAS-UT

Meteorological ForcingMeteorological Forcing: Wind, Temp., Humidity, Pressure, Precipitation, Radiation

In situ observation, Satellite Products,

model outputs,

Default Parameters:Default Parameters:Land Cover Type,

Soil Type,……

ISLSCP

Output Status Output Status VariablesVariables:

Energy fluxesSoil Moisture profile

Soil Temp. profileCanopy Temperature

……

Semi-dynamic Vegetation informationSemi-dynamic Vegetation information:

MODIS, LAI VWCMODIS, NDVI Vegetation

Fractional coverage:

Observation:Observation:Microwave TBMicrowave TB

TMI/AMSR/AMSR-E

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Application Region

• Domain:– Lat: 25-40N– Lon: 70-105E

• Simulated Period – May. - Sep., 2008

• Two local sites– West: Gaize– East: Naqu

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Used Data

• In situ observation– Soil moisture at two sites– AWS observation– Energy fluxes derived from AWS observation by Bowen Ratio

• Reanalysis data from NCEP– Meteorological forcing for region simulation– Biases in radiation and precipitation, but not corrected for regional

application.

• Satellite remote sensing data– Soil moisture retrieval from AMSR-E (JAXA)– Brightness temperature from AMSR-E

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ResultsSoil Moisture

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0

10

20

30

40

50

60

5/ 1 5/ 31 6/ 30 7/ 30 8/ 29 9/ 28

Sur

face

soi

l moi

stur

e(%)

Obs AMSR LDAS NCEP

Result: Soil moisture at Gaize

0.44226.1325.28NCEP

0.6016.13-3.01AMSR-E

0.3618.462.74LDAS

RRMSEMBE 

0

100

200

300

400

500

600

700

5/ 1 5/ 31 6/ 30 7/ 30 8/ 29 9/ 28

Acc

umul

ated

pre

cipi

tatio

n (m

m)

Obs NCEP

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0

10

20

30

40

50

60

70

5- 1 5- 31 6- 30 7- 30 8- 29 9- 28

Sur

face

Soi

l Moi

stur

e (%

)

Ob s AMSR LDAS NCEP

Result: Soil moisture at Naqu

0.41712.1510.02NCEP

0.56221.2510.16AMSR-E

0.8533.88-0.17LDAS

RRMSEMBE 

0

100

200

300

400

500

600

5/ 1 5/ 31 6/ 30 7/ 30 8/ 29 9/ 28

Acc

umul

ated

pre

cipi

tatio

n (m

m)

Obs NCEP

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Result: Energy flux:Bowen Ratio

Clean wet/dry division is showed by LDAS result, while NCEP failed to represent such a feature.

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Result: energy fluxes at GaizeMonthly Averaged Diurnal Cycle of lE at Gaize

-50

0

50

100

150

200

250

300

La

tent

Hea

t

Obs LDAS NCEP

May Jun Jul Aug Sep

0.94977.19-15.09G0

0.87831.0512.88lE

0.87954.2143.38Hs

RRMSEMBE 

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Result: energy fluxes at NaquMonthly Averaged Diurnal Cycle of lE at Naqu

-100

0

100

200

300

400

Late

nt H

eat

[W/m

/m]

NCEP Obs LDAS

May Jun Jul Aug Sep

0.96768.853.72G0

0.97535.146.93lE

0.93442.3635.64Hs

RRMSEMBE 

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Result: Dynamic variation

Cyclonic brings moisture from the Bay of Bengal to the SE of T-P, and brings dry air mass from Taklamagan desert

LDAS-UT is able to provide more realistic land surface status for research in other principles

LDAS-UT NCEP

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Remark

• Land-atmosphere interaction in T-P is very important for Asian monsoon development.

• Combining MW remote sensing and LSM, LDAS could improve the land surface fluxes simulation.

• LDAS produce more realistic land surface status, which is in good agreement with monsoon development.

• Feeding LDAS fluxes into atmosphere model is expected

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Acknowledgments

• The data is get from “Japan-China JICA project”. Colleges contribute to this project are:– UT: T. Koike, K. Tamagawa, H. Tutsui, L.

Wang– Tsukuba U.: K. Ueno– ITP: K. Yang, Y.M. Mao– CAREERI: X. Li, Z.Y. Hu, W.Q. Ma, M.S.Li– CAMS: X.D. Xu, H. Peng

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Thank you for your attention!


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