Mapping Evapotranspiration and Drought at Local to Continental Scales Using Thermal Remote Sensing

Transcription

1 Mapping Evapotranspiration and Drought at Local to Continental Scales Using Thermal Remote Sensing M.C. Anderson, W.P. Kustas USDA-ARS, Hydrology and Remote Sensing Laboratory J.M Norman University of Wisconsin - Madison

2 Remote Sensing of Surface Moisture MICROWAVE (10-50 km resolution) THERMAL (60m 10km resolution) Canopy temperature Canopy transpiration Root-zone moisture Microwave emissivity Surface dielectric properties Surface moisture Surface layer: ~5cm Soil temperature Soil evaporation Surface moisture Rootzone: ~1-2m

3 Satellite Thermal Imaging Systems Pixel Scale Spatial Resolution Temporal Resolution Current Sources Future Sources Coarse 5-20 km 15 min AIRS GOES MSG CrIS GOES MSG Moderate 1 km 2-4 times daily MODIS AVHRR ATSR VIIRS AVHRR ATSR Fine m Once every 8-16 days ASTER Landsat Table from S. Hook

4 APPLICATIONS evapotranspiration ALEXI Atmosphere-Land Exchange Inverse Model (Anderson et al, 1997)

5 Two-Source Energy Balance Model (TSEB) Available energy ET = (R NET -G) -H T A H = H C + H S θ T RAD (θ) ~ f c (θ)t c + [1-f c (θ)]t s (two-source approximation) Norman, Kustas et al. (1995) R A H C Treats soil/plant-atmosphere coupling differences explicitly T AERO R S R X T C Accommodates off-nadir thermal sensor view angles T S H S f c (θ) = 1 exp -0.5 Ω(θ) LAI cos (θ)

6 Atmosphere-Land Exchange Inverse (ALEXI) ABL T a Blending height T a Two-Source Model Norman and Kustas et al. (1995) R a T ac R soil H = H c + H s H c T R c x H s R a,i T s T RAD (φ), f c i 5 km ALEXI 30 m DisALEXI Anderson et al. (1997) Norman et al. (2003) T RAD,i (φ i ), f c,i Surface temp: Cover fraction: Regional scale ΔT RAD - GOES -MODIS f c T RAD f c Landscape scale - TM, ASTER, MODIS - TM, ASTER, MODIS

7 Continental (10km) Regional (5km) Watershed (1km) Catchment (60m) Field scale (30m) 30 SURFACE TEMPERATURE EVAPOTRANSPIRATION 500 Latent Heat (Wm -2 ) CORN 300 SOY July :30AM CST DisALEXI (USU aircraft) DisALEXI (Landsat) Temperature (C) ALEXI (GOES Imager) ALEXI (GOES Sounder) DisALEXI (MODIS)

8 GOES Coverage Copyright 2008 EUMETSAT Copyright 2008 EUMETSAT GOES West (Pacific) GOES - East

9 Low EVAPOTRANSPIRATION (Wm -2 ) High (Anderson et al, 2007) SEP AUG JUL JUN MAY APR

10 ALEXI validation sites SMEX04 Fort Peck Black Hills Bushland Sevilleta Audubon SMEX02/05 Bondville SGP97 Goodwin Creek Walker Branch Everglades BARC Gainesville

11 Clear-sky fluxes using Landsat thermal (60m) 800 Modeled flux (Wm -2 ) RN ET H G rangeland pasture corn soybean RMSD: 33 Wm -2 (10%) Tower flux (Wm -2 ) (Anderson et al, 2007)

12 APPLICATIONS drought & stress monitoring AET ESI = 1 PET Evaporative Stress Index

13 Climatological Study: Cumulative areal percentage Palmer Drought Index - NCDC Extreme wet Extreme dry Date 2002: extreme-severe drought conditions covering 40% of the US in July 2003: some improvement (10-25% extreme-severe drought coverage) 2004: extreme drought coverage falls < 5% due to increased late rainfall 2005: wetter than average in western US, drought in east

14 SEP AUG JUL JUN MAY APR MONTHLY ESI ANOMALIES DRY WET

15 ΔESI 2002 ΔZ Evaporative Stress Index Dry 2002 Wet SEP AUG JUL JUN MAY APR 2002

16 ΔESI 2003 ΔZ Dry Evaporative Stress Index 2003 Wet SEP AUG JUL JUN MAY APR 2003

17 ΔESI 2004 ΔZ Dry Evaporative Stress Index 2004 Wet SEP AUG JUL JUN MAY APR 2004

18 ΔESI 2005 ΔZ Dry Evaporative Stress Index 2005 Wet SEP AUG JUL JUN MAY APR 2005

19 ALEXI Precipitation Dry ESI anomaly Wet Precipitation anomaly (mm)

20 Multi-scale Drought Monitoring GOES Evaporative Stress Index JUNE 2002 Palmer Z Index Anomaly

21 Landsat 2/13/02

22 Multi-scale Ecosystem Health Monitoring FLORIDA EVERGLADES GOES (10km) MODIS (1km) L7 (60m) (hourly) (daily) (monthly) Evapotranspiration (Wm -2 )

23 Multi-scale Ecosystem Health Monitoring FLORIDA EVERGLADES GOES (10km) MODIS (1km) L7 (60m) TIR descoped from LDCM (hourly) (daily) (monthly) Evaporative stress (high) (low)

24 Impending data gap in high-resolution TIR Pixel Scale Spatial Resolution Temporal Resolution Current Sources Future Sources Coarse 5-20 km 15 min AIRS GOES MSG CrIS GOES MSG Moderate 1 km 2-4 times daily MODIS AVHRR ATSR VIIRS AVHRR ATSR Fine m Once every 8-16 days ASTER Landsat HyspIRI-TIR? Table from S. Hook

25 APPLICATIONS soil moisture mapping

26 MESONET ALEXI MESONET ALEXI June 19, 2002 August 1, 2003 May 12, 2003 May 7, May 29, 2003 June 2, AWF (% 0-100cm) 0 July 5, 2003 August 3, 2004 (Hain et al., 2008)

27 Volumetric Soil Moisture Retrievals r 2 = 0.53 RMSD = 0.06 Bias = ALEXI ALEXI VSM ALEXI AWF LAI < > Observed AWF Observed VSM (0-100 cm)

28 Improving weather forecast accuracy 2-m temperature bias 2-m dewpoint bias ALEXI SM Control 1800 UTC 1 Aug UTC 2 Aug UTC 1 Aug UTC 2 Aug 2004

29 Assimilation into hydrologic models No Assimilation Assimilation Assimilating thermal-based ET/PET Assimilating surface temperature directly Crow et al., RSE 2007

30 CONCLUSIONS THERMAL REMOTE SENSING DATA HAVE GREAT UTILITY: ET mapping drought monitoring soil moisture mapping NEED TO MAINTAIN MULTI-SCALE THERMAL DATA SOURCES

31 ALEXI_EUROPE and _AFRICA (coming soon) METEOSAT COVERAGE Copyright 2008 EUMETSAT Copyright 2008 EUMETSAT 0 o Operational Indian Ocean

32 METEOSAT Application LEBRIJA, SPAIN Evapotranspiration ESI (low) (high)

33 1.0 Soil evaporation Transpiration Actual/potential ET ET Actual/potential ET ET Soil Available water Available fraction w ater fraction (soil surface) Canopy Available water Available fraction w ater (root zone) 0-5cm 1-2m