Satellite Remote Sensing and Applications in Hydrometeorology

Xubin Zeng

Dept of Atmospheric Sciences University of Arizona Tucson, AZ 85721

http://www.atmo.arizona.edu/~zeng/zeng.html

•Fractional cover (Zeng et al. 2000, 2003) and green vegetation cover (Miller et al. 2006)

•Albedo/BRDF (Wang et al. 2004, 2005, 206) and snow albedo (Barlage et al. 2005, 2006)

•Vegetation root (Zeng et al. 1998; Zeng 2001)

•Precip intensity and freq. (Kursinski and Zeng 2006)

•Precip, water vapor, and monsoon (Zeng and Lu 2004)

•Veget. pattern and growth (X.D. Zeng et al. 2006a,b)

Tucson Landscape

NCAR/CLM3: FVC(x,y), LAI(x,y,t)NCEP/Noah: GVF(x,y,t),LAI=Const

Validation:1-3m spy sat data,1-5m aircraft data,30m Landsat data,Surface survey data

Histogram of evergreenBroadleaf treeNDVIveg = 0.69

FVC vs LAI

FVC (x,y)

LAI (x,y,t)

Versus

FVC (x,y,t)

LAI = 4

Interannual variability and decadal trend ofglobal fractional vegetation cover from1982 to 2000

Global FVC Data

Data Impact

NDSI and NDVI

NLDAS GVF DataNoah 1/8 degree monthly

MODIS 2km 16-day

Application of MODIS Maximum Snow Albedo to WRF-NMM/NOAH

• up to 0.5 C decreases in 2-m Tair in regions of significant albedo change

• > 0.5 C increase in 2-m Tair in several regions

Land Surface albedo and its SZA dependence

ECMWF: no SZA dependenceNCEP: simple formulationNCAR (CLM3): two streamNASA (Catchment): simple fitting to two-stream

In satellite remote sensing retrieval of solar fluxes, including ISCCPFD, UMD (Pinker; ISCCP C1), CERES TRMM: surface albedo adjusted to match computed TOA solar flux with satellite measurements

Tsvetsinskaya et al. (2002)

The comparison of theMODIS blue-sky albedos with CERES/TRMM broadband albedos at 8 locations with differentvegetation types from July 11-26, 1998. The MODIS BSA at 60 SZA for the 16-day period starting fromJulian day 193 averaged from 2000 to 2004 are used.

Maximum snow albedo• Maximum snow albedo is used as an end member of the interpolation from snow- to non-snow covered grids

• Current dataset is based on 1-year of DMSP observations from 1979

• Current resolution of 1°• Create new dataset using 4+ years of MODIS data with much higher resolution

MODIS Albedo Data

(a) 1 km data in 10 deg tiles; global 0.05 deg

(vs. 1 deg in RK)

(b) seven narrow bands, VIS (0.4-0.7 microns),

NIR (0.7-5 microns), SW (0.4-5 microns)

(vs. SW from 0.4-1.1 microns in RK)

(c) Day 49 of 2000 - Day 177 of 2004

(vs. 75 images in 1979 and 5 images in 1978)

(d) Quality flags

(e) MODIS data from both Terra and Aqua

(f) Both albedo and BRDF

NDSI and Snow Albedo

)64.1(6)55.0(4

)64.1(6)55.0(4

NDSI

Current Logic Structure

NDSI > 0.4MODIS QC = good

Global Maximum Snow Albedo

Band 2 > 0.11

0.05o MODISAlbedo

Land Cover

Final 0.05° Maximum Snow Albedo

Application of MODIS Maximum Snow Albedo to NCEP Land Surface

ModelUp to 0.2 difference in high/mid latitudes can greatly affect surface energy balance, snow depth, and snow melt timing*Note: 0.05° maximum albedo dataset downscaled to 1° to compare with NOAH data

*

Application of MODIS Maximum Snow Albedo to WRF-NMM/NOAH

• WRF-NMM Model: 10min(0.144°) input dataset converted from 0.05° by simple average; model run at 12km; initialized with Eta output;

• Winter simulation: 24hr simulation beginning 12Z 31 Jan 2006

Vegetation type-dependent vegetation root distribution

Offline simulation over the Amazon (deep roots maintain dry season ET)

Precipitation intensity and frequency

Gauge Radar

Monsoon Onset/Retreat Indexes

Normalized precipitable water (PW) index:

NPWI = (PW – PWmin)/(PWmax – PWmin)

where PWmax and PWmin are the ten-year averages of the annual max and min daily PW at each grid cell.

Proposed objective criterion:

The monsoon onset (or retreat) date for grid cell G is defined as the first day (d) when NPWI is greater (or less) than the Golden Ratio (0.618) for 3 consecutive days in 7 of the 9cells centered at cell G in day d or d±1.

Explanations: `3 consecutive days’, `9 cells’, `Golden Ratio’

Dynamic vegetation and spatial patterns

Vegetation Pattern and DiversityVegetation Pattern and Diversity

(1) (2) (3) (4) (5) (6) (7)

Annual Precipitation: 342 mm

Annual Precipitation: 297mm

Annual Precipitation: 484mm

Annual Precipitation: 542mm