Global Studies of our Planet’s Vegetation

New SeaWiFS Land NDVI and Channels 9/97->now…

Precursor Land Data sets to MODISaka the “warm-up act” for the main event

NOAA AVHRR -- July 1981 to the present…

SeaWiFS -- September 1997 to the present …

SPOT Vegetation -- May 1998 to the present …

MODIS -- early 2000 to the present…

NOAA 11AVHRR

1980 200019901985 201020051995

NOAA 7AVHRR

NOAA 9AVHRR

NOAA 14AVHRR

SeaWiFS

SPOT

MODISes

NOAA-16

NPOESNPOES

1982-20021992-2002

NOAA9NOAA9

Decadal trends in Decadal trends in terrestrialterrestrial vegetation vegetation

N-16N-16

NOAA Advanced Very High Resolution Radiometer (AVHRR)

1981-now…

Visible, near IR,

Thermal IR

1-km & 4-km data

Only pre-Seawifs global time series

data (<late 1997)

NOAA AVHRR 8-km NDVI Data Set

20

NOAA AVHRR 8-km NDVI Data Set

NOAA AVHRR 8-km NDVI Data Set

NOAA AVHRR 8-km NDVI Data SetSimple, few improvements since 1978

NOAA AVHRR 8-km NDVI Data SetSimple, few improvements since 1978

~80 kg, costs ~70 M$ each, ~20 built, also flies on TRMM

AVHRR flies on the Polar-orbiting Meteorological Satellites

0730/1930 equator crossing

series “early morning” satellites; and

1330/0130 equator crossing

series “afternoon” satellites

NOAA AVHRR 8-km NDVI Data Set

Radiation

NOAA AVHRR Channels 1 & 2

Ch 1 Ch 2

(Very broad or wide spectral bands)

VIS/NIR/SWIR Band Comparison

AVHRR

MISR

SeaWiFS

POLDER

VGT

MODIS

Ex post facto AVHRR Absolute Calibration

NOAA AVHRR 8-km NDVI Data Set

Ozone0.247-0.48

[cm/ atm]

Water Vapor0.54.1

[g/ cm2]

Rayleigh1013 mb

aerosolV: 60 km-10

kmContinental

Ch. 1

4.2% to12%

0.7% to 4.4% 0.02 to 0.06 0.005 to 0.12

Ch. 2 _

7.7% to 25% 0.01 to 0.02 0.003 to 0.083NDVI

(bare soil)r1=0.19,

r2=0.22

0.02 to0.06

0.011 to0.12

0.04 to 0.09 0.006 to 0.085

NDVI(deciduou

s forest)r1=0.03

r2=0.36

0.01 to0.02

0.036 to0.038

0.086 to0.23

0.022 to 0.035

Aerosol, O3, Water Vapor, and Rayleigh Effects on AVHRR Ch1 & Ch 2

Maximum Value Compositing No Assumptions

NDVI Maximum Value Composites

8-km output bin from 4-km spatial resolution data at subpoint

All orbits, all data processed, equal area map projection

Scan Angle Restriction to +/- 40 degrees

Maximum Value Compositing

8-km, equal-area, maximum value ndvi composites, “seamless”

residual clouds

Navigation Considerations

July 1, 2, and 3, 1981 NOAA-7 8-km grid cells

Velocity = ~ 7 km/sec; thus a 0.15 second time error = ~1 km

“Migration” of Dakar

Dakar

“Three Cities of Dakar”

7/1

7/2

7/3

Solar Zenith Angle Effects Solar Zenith Angle Effects 25N-25S25N-25S

African Tropical Forest(lat 1.4 N x long. 18 E)

0.3

0.35

0.4

0.45

0.5

0.55

1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

Year

NDVI

GIMMS

GIMMS-Corrected

Jorge’s new solar zenith angle correction

Range w/o SZA Correction: 0.12 ndvi units

Range w/ SZA correction: 0.05 ndvi units

Wavelet decomposition/reconstruction technique Requires no land cover information a priori

Stratospheric Aerosol correction also required

NOAA AVHRR 8-km NDVI Data Set

Mt. Pinatubo, Philippines

June 1991

0.00

0.05

0.10

0.15

0.20

0.25

0 100 200 300 400 500 600

1991

NDVI

1990

1991 corrected

1989

Max. NDVI Effect 0.1-0.15

1991 corrected

Stratospheric Aerosol correction also required

NOAA AVHRR 8-km NDVI Data Set

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

Jul-81 Jul-83 Jul-85 Jul-87 Jul-89 Jul-91 Jul-93 Jul-95 Jul-97 Jul-99 Jul-01

Time

Stratospheric Optical Depth

(550 nm)

Equator

40 N

60 N

30 SEl Chichon

Mt. Pinatubo

Space Shuttle Limb Photographs

Before Mt. Pinatubo Eruption

After Mt. Pinatubo Eruption

NOAA AVHRR 8-km NDVI Data Set

El Chichon (1982-1984) Mt. Pinatubo (1991-1994)

New and improved 8-km AVHRR NDVI data set

NOAA AVHRR 8-km NDVI Data Set

Ready for Prime time:Ready for Prime time: AVHRR NDVI match up to AVHRR NDVI match up to MODIS NDVIMODIS NDVI

NOAA AVHRR 8-km NDVI Data Set May-September NDVI trends

Warmer Earth Greener North Compton Tucker, Dan Slayback, Jorge Pinzon NASA/GSFC

Ranga Myneni, Robert Kaufmann, Liming Zhou, Jiarui Dong BU

Satellite record

Recent work using this new AVHRR data setWarmer Earth Greener North

•Zhou et al. 2001. Variations in Northern Vegetation Activity Inferred from Satellite Data of Vegetation Index During 1981 to 1999. J. Geophys. Res. 106:20069-20083.

•Tucker et al. 2001/2002. Higher Northern Latitude NDVI and Growing Season Trends from 1982 to 1999. Int. J. Biometeorology (in press)

•Myneni et al. 2001. A large carbon sink in the woody biomass of northern forests. Proc. Nat. Acad. Sci. (in press: 12/18/01).

Boston University