Cross Validation of Thermal Infrared Remotely Sensed Data In-Flight Using Automated Validation Sites © 2010 California Institute of Technology. Government

Cross Validation of Thermal Infrared Remotely Sensed Data In-Flight

Using Automated Validation Sites

© 2010 California Institute of Technology. Government sponsorship acknowledged.

Dr Simon J. Hook

William Johnson, Robert Radocinski, Glynn Hulley

Jet Propulsion Laboratory, California Institute of Technology.

Outline• Location and Characteristics

– Lake Tahoe, CA/NV

– Salton Sea, CA

• Measurements and Field Radiometer Calibration• Data Reduction Methodology and Error Budgets• Results from various sensors

– MODIS, ASTER, Landsat

• Summary and Conclusions

Why Lake Tahoe?

• Large 35 km x 16 km• High 2 km• Available year round (does not freeze in winter).• Homogenous compared with land.• Large annual temperature range 5-25 C.• Freshwater (kind to instruments!)• Good infrastructure and easy access.

2000-09-20-D

Measurements

• Offshore– bulk temperature, skin temperature, air

temperature, wind speed, wind direction, relative humidity, net radiation.

• Onshore– air temperature, wind speed, wind direction,

relative humidity, short and longwave radiation (up and down), sky imager, aerosols, total column water.

Site Layout and Measurement

Stations

TB3 Installed 11-04-2002

Skin temperature

Air temperature & Rel. Humidity

Wind Speed & Direction

LoggingSystem

BatteriesBulk WaterTemperature

3m

8

Salton Sea, Platform

Temperatures up to 35 C!

9

Radiometer Calibration and Cross-Cal

10

Cross Comparison of Radiometers at MiamiTime 150.50 to 152.00 150.50 to 151.25 151.25 to 152.00

Radiometer Pair

Mean (K)

Std.Dev (K)

N Mean (K)

Std.Dev (K)

N Mean (K)

Std.Dev (K)

N

MAE-ISA 0.002 0.135 80 0.005 0.135 69 –0.015 0.135 11 MAE-SIS 0.046 0.066 144 0.046 0.066 74 0.045 0.068 70 MAE-JPL 0.007 0.114 148 0.052 0.111 77 -0.042 0.096 71

MAE-DAR -0.008 0.076 149 0.022 0.071 78 -0.041 0.067 71 ISA-SIS 0.038 0.101 79 0.030 0.101 67 0.085 0.093 12 ISA-JPL 0.026 0.142 81 0.027 0.141 70 0.018 0.150 11

ISA-DAR 0.007 0.114 80 0.019 0.112 69 -0.064 0.107 11 SIS-JPL -0.048 0.099 144 -0.009 0.103 74 -0.088 0.078 70

SIS-DAR -0.053 0.074 144 -0.019 0.054 74 -0.088 0.076 70 JPL-DAR -0.014 0.103 148 -0.028 0.102 77 0.000 0.102 71

JPL Rad

Data Reduction: Methodology For Radiance at Sensor Validation

• Extract the bulk temperatures. • Extract the radiometric temperature.• Correct the radiometric temperature to skin kinetic

temperature.• Propagate the skin temperature to the satellite using a radiative

transfer model and interpolated atmospheric profile.• Convolve the propagated at-sensor radiance to the instrument

response function to obtain the Vicarious Radiance (VR).• Extract the image radiance derived using the On Board

calibrator (OBC).• Compare and contrast the OBC and VR Radiance values.

Error BudgetsPerturbation Kinetic Temperature (degrees C) Difference from no perturbation (degrees C)

None 5.634 20.762 0 0

90% Water Vapor 5.640 20.767 0.006 0.005

110% Water Vapor 5.628 20.758 -0.006 -0.005

-1 deg C 5.640 20.767 0.006 0.005

+1 deg C 5.628 20.758 -0.006 -0.005

Ozone Factor 50% 5.640 20.767 0.006 0.005

Ozone factor 150% 5.629 20.759 -0.005 -0.004

-0.5 um SRF shift 5.561 20.717 -0.073 -0.045

+0.5 um SRF shift 5.673 20.815 0.039 0.053

Change from Nominal Temperature in Kelvin

Channel 14 (center 8.55 um)

Channel 15 (center 10.763)

Channel 16 (center 12.013)

90% Water Vapor 0.149 0.094 0.159110% Water Vapor -0.146 -0.100 -0.167-1 deg C -0.062 -0.028 -0.049+1 deg C 0.064 0.028 0.04950% Ozone 0.249 0.047 0.012150% Ozone -0.241 -0.041 -0.01150% Visibility (11.5 km) -0.323 -0.284 -0.235150% Visibility (34.5 km) 0.113 0.095 0.080-0.5 um SRF shift -0.041 -0.043 -0.042+0.5 um SRF shift 0.048 0.051 0.049

MODIS Terra Vicarious and OBC Thermal Infrared Derived Radiances at Lake Tahoe and Salton Sea CY2000-2009, v4-5.x

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

Vicarious Radiance (W/m2.µm.sr)

OB

C R

adia

nce

(W

/m2.

µm

.sr)

Band 28 (7.43 µm)Band 29 (8.53 µm)Band 30 (9.73 µm)Band 31 (11.01 µm)Band 32 (12.03 µm)Band 33 (13.37 µm)1x1 line

Several hundred matchups per year. MODIS OBC radiance agrees with Vicarious radiance in clear parts of spectrum

MODIS Terra Vicarious and OBC Thermal Infrared Derived Radiances at Lake Tahoe and Salton Sea CY2000-2009, v4-5.x

y = 1.0194x - 0.1460

R2 = 0.9911y = 1.0219x - 0.1986

R2 = 0.9888

y = 1.0361x - 0.3085

R2 = 0.9815

5.0

6.0

7.0

8.0

9.0

10.0

5.0 6.0 7.0 8.0 9.0 10.0


OB

C R

adia

nce

(W

/m2.

µm

.sr)

Band 29 (8.53 µm)Band 31 (11.01 µm)Band 32 (12.03 µm)1x1 lineLinear (Band 29 (8.53 µm))Linear (Band 31 (11.01 µm))Linear (Band 32 (12.03 µm))

Band 29 Band 31 Band 32

MODIS land and water bands show excellent agreement with vicarious radiance. R2 typically 0.99

% Radiance Change in TIR Channels for MODIS Terra with Instrument Zenith at Lake Tahoe and Salton Sea CY2000-2009, v4-5.x

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

0-7 7-18 18-28 28-37 37-43 43-51 51-56

Instrument Zenith

Avg

% R

adia

nce

Dif

f (v

-o)/

v *

100

b29 b31 b32

Poly. (b29) Poly. (b31) Poly. (b32)

Band 31: 11.01 μm 1% radiance change ≈ 0.65K

Validation process works well for angles up to 30 degrees off nadir

% Radiance Change in TIR Channels for MODIS Terra at Lake Tahoe and Salton Sea CY2000-2009, vz0-30 v4-5.x

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 All Years

Year

Avg

% R

adia

nce

Dif

f (v

-o)/

v *

100

b29 b31 b32

b31,32 spec

other MODIS tir bands


10 years of validation! Values for each year from several hundred matchups. MODIS-Terra has performed within specification for duration of mission. Proof necessary for climate change studies

MODIS Aqua Night Only Vicarious and OBC Mid Infrared Derived Radiances at Lake Tahoe and Salton Sea CY2000-2009, VZ0-30, v4-5.x

y = 0.9938x - 0.0007

R2 = 0.9956

y = 0.9948x + 0.0007

R2 = 0.9965

y = 0.9912x - 0.0004

R2 = 0.9971

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Vicarious Radiance (W/m2.µm.sr)

OB

C R

adia

nce

(W

/m2.

µm

.sr)



Validation measurements are made 24x7, validate mid infrared (3-5 um) at night to avoid reflected solar. Results shown for Aqua

% Radiance Change in MIR Channels for MODIS Aqua at Lake Tahoe and Salton Sea CY2000-2009, vz0-30, v4-5.x

-4

-3

-2

-1

0

1

2

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 All Years

Year

Avg

% R

adia

nce

Dif

f (v

-o)/

v *

100

b20 b22 b23

Aqua MIR performance meets preflight specification

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

(1/1

4/20

02n

)

(2/6

/200

2no

os)

(6/6

/200

2d)

(6/7

/200

2n)

(6/2

2/20

02d

)

(9/2

/200

2no

os)

(9/1

0/20

02d

)

(9/2

6/20

02d

)

(10/

12/2

002d

)

(11/

4/20

02d

oo

s)

(11/

29/2

002d

)

(11/

30/2

002n

)

Overpass Date

% R

adia

nce

Dif

fere

nce

(V

ic-O

BC

)/V

ic*1

00

Band 13 (10.66 µm)

0.007

0.0075

0.008

0.0085

0.009

0.0095

0.01

0 500 1000 1500 2000 2500

C1 measured by LTCC1 estimated by regression

C1

Co

effi

cie

nt

Days Since the Launch

1st Period 2nd Period

Day 1919

ASTER Short and Long-Term Calibration

ASTER calibrates when instrument drifts. Introduces “sawtooth” appearance

For much of mission predictable behavior but recently showed more rapid change

-1

-0.5

0

0.5

0 500 1000 1500 2000 2500 3000 3500

Calibration error (Band 12)

V3_300K V3_320K V3_340KCal

ibra

tion

erro

r [K

]

Days since Launch

ASTER Short and Long-Term Calibration

More frequent drift corrections now required and additional monitoring

If carefully monitor and correct can maintain instrument within specification, If look at mean radiance differences for each year they are typically less than 0.5% or 0.3K. 2005 and 2006 need more examination.

Percent Radiance Change in TIR Channels for ASTER at Lake Tahoe and Salton Sea CY2000-2009, Std Filter, v3.x

-3

-2

-1

0

1

2

3

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 All years

Year

Avg

% R

adia

nce

Dif

f (v

-o)/

v *

100

b10 b11 b12 b13 b14

MODIS other TIR bands


ASTER specification is 1K for at sensor temps between 270-340K

Std FilterBuoy Range < 0.1km Std Dev > 0.2N Good = 9Skin Effect < 1.0

22

Landsat 7, Channel 6 Vicarious and OBC Thermal Infrared Derived Radiances at Lake Tahoe and Salton Sea, CY1999-2009

y = 0.9597x + 0.3235R2 = 0.9891

6.25

6.75

7.25

7.75

8.25

8.75

9.25

9.75

6.25 6.75 7.25 7.75 8.25 8.75 9.25 9.75


OB

C R

adia

nce

(W

/m2.

µm

.sr)

Channel 61x1 lineLinear (Channel 6)

High temperature points from Salton Sea allow evaluation of gain and offset. Landsat required gain and offset adjustment

2009-12-02 23

Difference Between Vicarious and OBC Brightness Temperatures for Landsat 7, Channel 6 at Lake Tahoe and Salton Sea, CY1999-2009

-3

-2

-1

0

1

2

3

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 All years

Year

Tem

per

atu

re D

iffe

ren

ce (

K)

L7B6




After adjustment Landsat 7 meets specification

Summary and Conclusions• Established an automated site for validating thermal infrared data at

Lake Tahoe CA/NV. Site has been operating since 1999. Second site established at Salton Sea CA in 2008. Salton Sea provides very high temperatures.

• Measurements made at the site include skin- bulk- air- temperature, wind speed, wind direction and net radiation at multiple locations every 2 minutes. Multiple locations (4 buoys) allow validation of several points within a scene at Lake Tahoe.

• Validated data from multiple instruments including, ATSR2, AATSR, ASTER, MODIS (Terra, Aqua), Landsat 5 and Landsat ETM+, MTI.

• Results so far indicate:– MODIS-Terra and Aqua LWIR meet specification (no bias, abs. acc. ± 0.2K)– MODIS-Aqua MIR meet specification (Terra MIR does not)– ASTER, Landsat require adjustment but perform to specification

• In-flight validation is a necessity for climate studies!

http://calval.jpl.nasa.gov

Backup

% Radiance Change in TIR Channels for MODIS Terra with Mirror AOI at Lake Tahoe and Salton Sea CY2000-2009 v4-5.x

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

10-20 20-30 30-40 40-50 50-60 60-70

Angle of incidence on Mirror

Av

g %

Ra

dia

nc

e D

iff

(v-o

)/v

* 1

00

b29 b31 b32

Poly. (b29) Poly. (b31) Poly. (b32)

Mirror AOI related to scan angle, validation process works well for angles up to 30 degrees off nadir

% Radiance Change in TIR Channels for MODIS Aqua at Lake Tahoe and Salton Sea CY2000-2009, vz0-30 v4-5.x

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 All Years

Year

Av

g %

Ra

dia

nc

e D

iff

(v-o

)/v

* 10

0

b29 b31 b32

b31,32 spec



8 years of validation! Values for each year from several hundred matchups. MODIS-Aqua has performed within specification for duration of mission. Proof necessary for climate change studies

% Radiance Change in TIR Channels for MODIS Terra at Lake Tahoe and Salton Sea CY2000-2009, vz0-30 v4-5.x

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 All Years

Year

Avg

% R

adia

nce

Dif

f (v

-o)/

v *

100

b29 b31 b32

b31,32 spec



% Radiance Change in TIR Channels for MODIS Aqua at Lake Tahoe and Salton Sea CY2000-2009, vz0-30 v4-5.x

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 All Years

Year

Av

g %

Ra

dia

nc

e D

iff

(v-o

)/v

* 1

00

b29 b31 b32

b31,32 spec



Skin Effect

Diurnal thermocline

Skin cooling

0.1 mm

2 m

Depth

Temperature

Sea surface

Night time

Afternoon

After Minnett et al. 2000

Water surface

MODIS Aqua Vicarious and OBC Thermal Infrared Derived Radiances at Lake Tahoe and Salton Sea CY2000-2009, v4-5.x

y = 1.0172x - 0.1349

R2 = 0.9916y = 1.0152x - 0.1496

R2 = 0.9903y = 1.0291x - 0.2661

R2 = 0.9827

5.0

6.0

7.0

8.0

9.0

10.0

5.0 6.0 7.0 8.0 9.0 10.0


OB

C R

adia

nce

(W

/m2.

µm

.sr)



MODIS Terra Night Only Vicarious and OBC Mid Infrared Derived Radiances at Lake Tahoe and Salton Sea CY2000-2009, VZ0-30, v4-5.x

y = 0.9993x + 0.0017

R2 = 0.9963y = 1.0048x + 0.0038

R2 = 0.9966y = 0.9972x + 0.004

R2 = 0.9974

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Vicarious Radiance (W/m2.µm.sr)

OB

C R

adia

nce

(W

/m2.

µm

.sr)



% Radiance Change in MIR Channels for MODIS Terra at Lake Tahoe and Salton Sea CY2000-2009, vz0-30, v4-5.x

-4

-3

-2

-1

0

1

2

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 All Years

Year

Avg

% R

adia

nce

Dif

f (v

-o)/

v *

100

b20 b22 b23

Matchup Count for MODIS Terra at Lake Tahoe and Salton Sea CY2000-2009 v4-5.x

0

200

400

600

800

1000

1200

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009Year

Nu

mb

er o

f M

atch

up

s

All data, cloud and standard filter onlyVZ0-30 cloud and std filterVZ0-30 day only cloud and standard filterVZ0-30 night only cloud and standard filter

Standard Filter1. Buoy must be with 1km of center value2. All 9 values (3x3) must be good quality3. Std Dev. Of Band 31 3x3 must be < 0.2K

2009-12-02 35

Difference Between Vicarious and OBC Brightness Temperatures for Landsat 5, Channel 6 at Lake Tahoe and Salton Sea CY1999-2009

-3

-2

-1

0

1

2

3

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 All years

Year

Tem

per

atu

re D

iffe

ren

ce (

K)

L5B6




Similar issue with Landsat 5. After adjustment Landsat 5 meets specification. Landsat 5 data are slightly noisier than Landsat 7

MODERATE RESOLUTION IMAGING SPECTRORADIOMETER

Orbit: 705 km, 10:30 a.m. descending node (AM-1) or 1:30 p.m. ascending node (PM-1), sun-synchronous, near-polar, circular.Swath dimensions: 2330 km (cross track) by 10 km (along track at nadir). Spatial Resolution 250 m (bands 1-2), 500 m (bands 3-7)1000 m (bands 8-36).

Application Band Bandwidth (nm) SNR Application Band Bandwith (um) NEdT

1 620-670 128 20 3.660-3.840 0.05Land/CloudBoundaries 2 841-876 201 21 3.929-3.989 2.00

3 459-479 243 22 3.929-3.989 0.074 545-565 228

Surface/CloudTemperature

23 4.020-4.080 0.075 1230-1250 74 24 4.433-4.498 0.256 1628-1652 275

AtmosphericTemperature 25 4.482-4.549 0.25

Land/CloudProperties

7 2105-2155 110 26 1.360-1.390 150 (SNR)8 405-420 880 27 6.535-6.895 0.259 438-448 838 28 7.175-7.475 0.2510 483-493 802

Cirrus CloudsWater Vapor

29 8.400-8.700 0.2511 526-536 754 Ozone 30 9.580-9.880 0.25

12 546-556 750 31 10.780-11.280 0.2513 662-672 910

Surface/CloudTemperature 32 11.770-12.270 0.25

14 673-683 1087 33 13.185-13.785 0.2515 743-753 586 34 13.485-13.785 0.25

Ocean Color/Phytoplankton/Biogeochemistry

16 862-877 516 35 13.785-14.085 0.2517 890-920 167

Cloud TopAltitude

36 14.085-14.385 0.3518 931-941 57

AtmosphericWater Vapor

19 915-965 250

37

Cross Comparison of Radiometers at Miami

26.00

26.50

27.00

27.50

28.00

28.50

29.00

29.50

30.00

05/30/01 05/30/01 05/31/01 05/31/01 05/31/01 05/31/01 06/01/01

Date and Time (GMT)

JPL - kinetic

salinograph (D)

Hard Hat (E)

DAR011 (F)

MAERI (H)

SISTer (I)

38

Means and standard deviations of the estimated skin SST differences between pairs of radiometers for the

entire cruise period, and for each half of the cruise Time 150.50 to 152.00 150.50 to 151.25 151.25 to 152.00

Radiometer Pair

Mean (K)

Std.Dev (K)

N Mean (K)

Std.Dev (K)

N Mean (K)

Std.Dev (K)

N

MAE-ISA 0.002 0.135 80 0.005 0.135 69 –0.015 0.135 11 MAE-SIS 0.046 0.066 144 0.046 0.066 74 0.045 0.068 70 MAE-JPL 0.007 0.114 148 0.052 0.111 77 -0.042 0.096 71

MAE-DAR -0.008 0.076 149 0.022 0.071 78 -0.041 0.067 71 ISA-SIS 0.038 0.101 79 0.030 0.101 67 0.085 0.093 12 ISA-JPL 0.026 0.142 81 0.027 0.141 70 0.018 0.150 11

ISA-DAR 0.007 0.114 80 0.019 0.112 69 -0.064 0.107 11 SIS-JPL -0.048 0.099 144 -0.009 0.103 74 -0.088 0.078 70

SIS-DAR -0.053 0.074 144 -0.019 0.054 74 -0.088 0.076 70 JPL-DAR -0.014 0.103 148 -0.028 0.102 77 0.000 0.102 71

The Third International Infrared Radiometer Workshop to be held in Miami in the late spring of 2009

39

Variations in the bulk-, skin-, air-temperatures

and wind speed on June 7, 2001 at L. Tahoe

8

10

12

14

16

18

20

0000 0400 0800 1200 1600 2000 0000

Time (UTC)

0

5

10

15

20

25

30

35

40

45

50

Wind Speed

Air Temperature

Bulk TemperatureSkin Temperature

Net Radiation (rescaled)

40

Land Surface Temperature Results

MODIS, ASTER, AATSR

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Documents

Cross Validation of Thermal Infrared Remotely Sensed Data In-Flight Using Automated Validation Sites © 2010 California Institute of Technology. Government