Validating satellite-derived land surface temperature over mountainous area with in situ measurements

Validating satellite-derived land surface temperature over mountainous area with in

situ measurements

Imlil Valley (High Atlas) - Morocco

Yoann Malbéteau CESBIO / Toulouse [email protected]

http://rec.isardsat.com

Merlin O., Gascoin S., Gastellu J.P., Mattar, C. Olivera L., Khabba S., Jarlan L.

Validació de dades teletransportades en camp; Aplicacions agrícoles i hidrogeològiques 1 of 15

Temperature of Earth's lands during the daytime

April 2016 marks 12th consecutive month of record warmth for globe (NOAA)

Climatic scale

Land & Ocean temperature Percentiles Jan-April 2016 NOAA’s National centers for Environmental Information

Data Source: GHCN-M version 3.3.0 & ERSST version 4.0.0

Record Warmest

Much Warmer than

average

Warmer than average

Near average

Much Cooler than

average

Cooler than average

Record Coldest

Over land: +2.33°C Over land and ocean: +1.11°C

above the 20th century average


Land surface temperature for agriculture….

Evapotranspiration estimation / Soil moisture downscaling amongst of others…

Regional and parcel scale

ASTER temperature (90 m)

ET (mm/day)

0 10 8 6 4 2

Olivera-Guerra L. et al. (2014)


Land surface temperature for agriculture….

Evapotranspiration estimation / Soil moisture downscaling amongst of others…

Regional and parcel scale

SMOS Product

Soil moisture Disaggregated

82 000 km2

ASTER temperature (90 m) MODIS land surface temperature (1 km)

ET (mm/day)

0 10 8 6 4 2

Olivera-Guerra L. et al. (2014)

Malbeteau Y. et al. (2016)

6050 km2

Validació de dades teletransportades en camp; Aplicacions agrícoles i hidrogeològiques

What’s land surface temperature ?

LST (Land Surface Temperature)

NDVI

Soil Moisture

Albedo

texture

ET

Meteo

Topo

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What’s land surface temperature ?

LST (Land Surface Temperature)

NDVI

Soil Moisture

Albedo

texture

ET

Meteo

Topo

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LST landsat at 100m resolution 05 Septembre 2014

Lake

Mountains

Clouds

55

40

30

25

50

45

35

T °C


What’s land surface temperature over mountains?

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Illumination

Elevation


Land surface temperature over mountains

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Aremd station

Northing

Easting

Elevation

1400

0

W.m-2

Net Radiation at 8m (from DART model) at 11h21, the 05th of September

6 km


Land surface temperature over mountains

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45

30

20

15

40

35

25

T °C Sun-exposed slope

Shadowed slope

Vegetation

River

Land surface temperature observed by ASTER satellite

6 km


Scheme placement …

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Temperature sensors/loggers

Different illumination and elevation Spacing: ~100m (ASTER/landsat resolution) 6 months

45

30

20

15

40

35

25

T °C


How can we validate surface temperature ?

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Temperature sensors/loggers

ibutton sensor

135 ibuttons Set up over 45 points

Locations of the 45 ibutton plates, each of them containing 3 ibutton sensors. Red cross indicate plates not used for the study.


Results: sample of in situ surface temperature

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Date (mm/dd/2014)

Surf

ace

tem

pera

ture

(°C

)

Sun exposed shadow exposed



Date (mm/dd/2014)

Surf

ace

tem

pera

ture

(°C

)

Sun exposed shadow exposed 14°C 5°C

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Date (mm/dd/2014)

Surf

ace

tem

pera

ture

(°C

)

lag time

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Sun exposed shadow exposed



Date (mm/dd/2014)

Surf

ace

tem

pera

ture

(°C

)

Cloudy day

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Energy balance

Transpiration

Evaporation

land surface

temperature

𝑻𝑬𝑩 = 𝒇𝒗 𝑻𝒗𝑬𝑩 + 𝟏 − 𝒇𝒗 𝑻𝒔 𝑬𝑩

Based on double source (vegetation/soil) energy

balance model

𝑻𝒔𝑬𝑩 = 𝒇𝒔𝒔 𝑻𝒔, 𝒅𝒓𝒚𝑬𝑩 + 𝟏 − 𝒇𝒔𝒔 𝑻𝒔, 𝒘𝒆𝒕 𝑬𝑩

𝑻𝒗𝑬𝑩 = 𝒇𝒔𝒗 𝑻𝒗, 𝒅𝒓𝒚𝑬𝑩 + 𝟏 − 𝒇𝒔𝒗 𝑻𝒗, 𝒘𝒆𝒕 𝑬𝑩


Modeling topographic effect over mountains

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Modeling topographic effect over mountains

ASTER LST simulated LST

45

30

20

15

40

35

25

T °C

90 m resolution 8 m resolution

Representativeness

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6 km 6 km


Useful for model and observed data validation

14th April 2014 30th April 2014 05th September 2014

Simulated LST

ASTER LST

R (correlation) 14th April 30th April 05th September

Simulated LST 0.75 0.68 0.64

Observed LST 0.64 0.68 0.67

Scatterplots of ASTER and simulated LST at 90m resolution versus ibutton measurements

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Useful for model and observed data validation

14th April 2014 30th April 2014 05th September 2014

Simulated LST

ASTER LST

R (correlation) 14th April 30th April 05th September

Simulated LST 0.75 0.68 0.64


B (bias) 14th April 30th April 05th September

Simulated LST 1.48 2.74 -0.43


Scatterplots of ASTER and simulated LST at 90m resolution versus ibutton measurements

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Additional slide…. for future application over mountains

45

30

20

15

40

35

25

T °C

Before correction After correction

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Conclusion

Challenges: Representativeness of in situ measurement for remote sensing data validation solution ? very dense in situ measurement aggregation few in situ measurement disaggregation (downscaling) in situ measurement representative at the scale resolution

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Conclusion

Challenges: Representativeness of in situ measurement for remote sensing data validation solution ? very dense in situ measurement aggregation few in situ measurement disaggregation (downscaling) in situ measurement representative at the scale resolution intercomparison between remotely sensed data

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Conclusion

Challenges: Representativeness of in situ measurement for remote sensing data validation solution ? very dense in situ measurement aggregation few in situ measurement disaggregation (downscaling) in situ measurement representative at the scale resolution intercomparison between remotely sensed data Terrain accessibility … “When science goes messy”

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Conclusion


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Conclusion


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Conclusion


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Conclusion

Challenges: Representativeness of in situ measurement for remote sensing data validation solution ? very dense in situ measurement aggregation few in situ measurement disaggregation (downscaling) in situ measurement representative at the scale resolution intercomparison between remotely sensed data Terrain accessibility

But it is great …

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Validating satellite-derived land surface temperature over mountainous area with in situ

measurements

Science

Validating satellite-derived land surface temperature over mountainous area with in situ measurements