NPL - Commercial Fiducial Reference Measurements for validation of Surface Temperature from Satellites (FRM4STS) ESA Contract No. 4000113848_15I-LG D100 - Technical Report 2: Results from the 4 th CEOS TIR FRM Field Radiometer Laboratory Inter-comparison Exercise Part 2 of 4: Laboratory comparison of radiation thermometers JUNE 2017 Approval/Acceptance ESA Craig Donlon Technical Officer NPL Andrew Brown Project Manager Signature Signature
127
Embed
D100 - Technical Report 2: Results from the 4 CEOS TIR FRM ... · CEOS TIR FRM Field Radiometer Laboratory Inter-comparison Exercise Part 2 of 4: Laboratory comparison of radiation
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
NPL - Commercial
Fiducial Reference Measurements for validation of Surface Temperature from Satellites (FRM4STS) ESA Contract No. 4000113848_15I-LG
D100 - Technical Report 2: Results from the 4th CEOS TIR FRM Field Radiometer Laboratory Inter-comparison Exercise Part 2 of 4: Laboratory comparison of radiation thermometers
JUNE 2017
Approval/Acceptance
ESA Craig Donlon Technical Officer
NPL Andrew Brown Project Manager
Signature Signature
NPL REPORT ENV 14
2016 comparison of IR brightness temperature measurements in support of satellite validation. Part 2: Laboratory comparison of radiation thermometers. I. Barker-Snook, E. Theocharous and N. P. Fox
June 2017
NPL Report ENV 14
2016 comparison of IR brightness temperature measurements in support of satellite validation. Part 2: Laboratory comparison of radiation
thermometers.
I. Barker Snook, E. Theocharous and N. P. Fox
Environmental Division
Abstract
Under the auspices of CEOS a comparison of terrestrial based infrared (IR) radiometric instrumentation
used to support calibration and validation of satellite borne sensors with emphasis on sea/water/land
surface temperature was completed at NPL during June and July 2016. The objectives of the 2016
comparison were to establish the “degree of equivalence” between terrestrially based IR Cal/Val
measurements made in support of satellite observations of the Earth’s surface temperature and to
establish their traceability to SI units through the participation of National Metrology Institutes (NMIs).
During the 2016 comparison, NPL acted as the pilot laboratory and provided traceability to SI units
during laboratory comparisons. Stage 1 consisted of Lab comparisons, and took place at NPL during the
week starting on 20th June 2016. This Stage involved laboratory measurements of participants’
blackbodies calibrated using the NPL reference transfer radiometer (AMBER) and the PTB infrared
radiometer, while participants’ radiometers were calibrated using the NPL ammonia heat-pipe reference
blackbody. Stage 2 took place at Wraysbury reservoir during the week starting on 27th June 2016 and
involved field measurements of the temperature of the surface of the water. Stage 2 also included the
testing of the same radiometers alongside each other, completing direct daytime and night-time
measurements of the surface temperature of the water. Stage 3 took place in the gardens of NPL during
the week staring on 4th July 2016 and involved field measurements of the temperature of the surface of
a number of solid targets. Stage 3 included the testing of the same radiometers alongside each other,
completing direct daytime and night-time measurements of the surface temperature of targets, including
short grass, clover, soil, sand, gravel and tarmac/asphalt. This report provides the results of Stage 1,
together with uncertainties as provided by the participants, for the comparison of the participants’
radiometers. During the 2016 comparison, all participants were encouraged to develop uncertainty
budgets for all measurements they reported. All measurements reported by the participants, along with
their associated uncertainties, were analysed by the pilot laboratory and are presented in this report.
NPL Report ENV 14
NPL Report ENV 14
NPL Management Ltd, 2017
ISSN: 2059-6030
National Physical Laboratory Hampton Road, Teddington, Middlesex, TW11 0LW
Extracts from this report may be reproduced provided the source is acknowledged and the extract is not taken out of context.
Approved on behalf of NPLML by Teresa Goodman, Earth Observation, Climate and
3 PARTICIPANTS’ RADIOMETERS AND MEASUREMENTS ................................. 4
3.1 MEASUREMENTS MADE BY VALENCIA UNIVERSITY .............................. 4
3.1.1 Description of the Radiometer and Route of Traceability .................................................. 4 3.1.2 Uncertainty Contributions Associated with UoV’s measurements at NPL ........................ 6 3.1.3 Comparison of UoV radiometers to the NPL reference blackbody .................................... 8
3.2 MEASUREMENTS MADE BY BALL AEROSPACE ....................................... 23
3.2.1 Description of radiometer and route of traceability .......................................................... 23 3.2.2 Uncertainty contributions associated with Ball Aerospace’s radiometer ......................... 24 3.2.3 Comparison of BESST radiometer to NPL reference blackbody ..................................... 25
3.3 MEASUREMENTS MADE BY KIT .................................................................... 27
3.3.1 Description of radiometer and route of traceability ............................................................... 27 3.3.2 Uncertainty Contributions associated KIT’s measurements at NPL ...................................... 28 3.3.3 Comparison of KIT Heitronics KT15.85 IIP to the NPL reference blackbody ................ 29
3.4 MEASUREMENTS MADE BY ONERA ............................................................. 33
3.4.1 Description of radiometer and route of tracibility ............................................................ 33 3.4.2 Uncertainty contributions associated with ONERA’s measurements at NPL .................. 33 3.4.3 Comparison of radiometer to the NPL reference blackbody ............................................ 35
3.5 MEASUREMENTS MADE BY CSIRO ............................................................... 52
3.5.1 Description of Radiometer and route of traceability Make and type of Radiometer: ...... 52 3.5.2 Uncertainty contributions associated with CSIRO’s measurements at NPL .................... 53 3.5.3 Comparison of CSIRO ISAR 5D to the NPL reference blackbody .................................. 53
3.6 MEASUREMENTS MADE BY STFC RAL ........................................................ 57
3.6.1 Description of the radiometer and route of tracibility ...................................................... 57 3.6.2 Uncertainty contributions associated with STFC RAL’s measurements at NPL ............. 59 3.6.3 Comparison of RAL’s SISTeR to the NPL reference blackbody ..................................... 59
3.7 MEASUREMENTS MADE BY SOUTHAMPTON UNIVERSITY.................. 64
3.7.1 Description of radiometer and route of traceability .......................................................... 64 3.7.2 Uncertainty contributions associated with UoS’ measurements at NPL .......................... 64 3.7.3 Comparison of UoS’ ISAR to NPL reference blackbody ................................................. 65
3.8 MEASUREMENTS MADE BY DMI ................................................................... 69
3.8.1 Description of radiometers and route of traceability ........................................................ 69 3.8.2 Uncertainty contributions associated with DMI’s measurements at NPL ........................ 70 3.8.3 Comparison of DMI’s radiometers to the NPL reference blackbody. .............................. 71 3.8.4 Additional comments from DMI regarding the radiometer lab comparison .................... 77
3.9 MEASUREMENTS MADE BY OUC, QINGDAO ............................................. 77
3.9.1 Description of radiometers and route of traceability ........................................................ 77 3.9.2 Uncertainty contributions associated with OUC’s measurements at NPL ....................... 79 3.9.3 Comparison of OUC’s radiometers to the NPL reference blackbody .............................. 80
NPL Report ENV 14
8
3.10 MEASUREMENTS MADE BY GOTA .............................................................. 89
3.10.1 Description of radiometer and route of traceability .......................................................... 89 3.10.2 Uncertainty contributions associated with GOTA’s measurements at NPL ..................... 91 3.10.3 Comparison of CE312-2 to NPL reference blackbody ..................................................... 92
3.11 MEASUREMENTS MADE BY RSMAS, UNIVERSITY OF MIAMI ........... 99
3.11.1 Description of radiometer and route of traceability .......................................................... 99 3.11.2 Uncertainty contributions associated with RSMAS’ measurements at NPL .................. 100 3.11.3 Comparison of the RSMAS radiometer to NPL reference blackbody ............................ 102
4 SUMMARY OF THE RESULTS ................... ERROR! BOOKMARK NOT DEFINED. 5 DISCUSSION ................................................... ERROR! BOOKMARK NOT DEFINED.
Establishment or traceability route for primary calibration including date of last
realisation and breakdown of uncertainty. The following error analysis is based on
laboratory measurements with the Landcal blackbody P80P (blackbody combined uncertainty
was 0.34 K; Appendixes B and E) on May 13-18, 2016, and estimates from the above
references. Blackbody measurements were taken at six fixed temperatures (0-50 ºC) in two
different runs with instrument realigning. The values reported below are typical values for all
blackbody temperatures considered for each band of each radiometer (units 1 and 2). The mean
values considering all bands of each radiometer are also given.
Type A
- Repeatability: Typical value of the standard deviation of 15 measurements at fixed blackbody
temperature without re-alignment of radiometer.
Unit 1 B1 B2 B3 B4 B5 B6 mean
K 0.01 0.04 0.04 0.06 0.06 0.08 0.05
%
(at 300 K)
0.002 0.012 0.012 0.019 0.019 0.025 0.015
Unit 2 B1 B2 B3 B4 B5 B6 mean
K 0.01 0.03 0.03 0.04 0.05 0.05 0.03
%
(at 300 K)
0.002 0.009 0.009 0.015 0.017 0.018 0.012
- Reproducibility: Typical value of difference between two runs of radiometer measurements
at the same black body temperature including re-alignment.
Unit 1 B1 B2 B3 B4 B5 B6 mean
K 0.08 0.10 0.08 0.06 0.09 0.05 0.08
%
(at 300 K)
0.027 0.033 0.025 0.021 0.029 0.018 0.026
Unit 2 B1 B2 B3 B4 B5 B6 mean
K 0.06 0.06 0.06 0.05 0.05 0.04 0.06
%
(at 300 K)
0.021 0.021 0.019 0.017 0.017 0.015 0.018
Total Type A uncertainty (RSS):
Unit 1 B1 B2 B3 B4 B5 B6 mean
K 0.08 0.11 0.08 0.09 0.10 0.09 0.09
%
(at 300 K)
0.028 0.035 0.028 0.029 0.035 0.031 0.031
Unit 2 B1 B2 B3 B4 B5 B6 mean
K 0.06 0.07 0.06 0.07 0.07 0.07 0.07
%
(at 300 K)
0.022 0.023 0.021 0.023 0.024 0.023 0.022
Type B
- Primary calibration: 0.34 K (estimation of the total uncertainty of the Landcal blackbody
P80P).
NPL Report ENV 14
6
- Linearity of radiometer: 0.06 K (Typical value for all bands in the temperature range 0-
40 ºC according to reference 2).
- Drift since last calibration: It has been corrected using the calibration measurements
performed with the Landcal blackbody P80P mentioned above. A linear correcting equation has
been derived for each band and radiometer, with the radiometer measured temperature and the
detector temperature as inputs. The uncertainty for this correction is the RSS of the typical
estimation uncertainty of the linear regression (0.05 K for unit 1 and 0.04 K for unit 2) and the
uncertainties resulting from the propagation of input temperature errors (standard deviations for
15 measurement at a fixed temperature) in the linear correcting equation. The resulting
uncertainty in the correction of calibration drift is 0.07 K for unit 1 and 0.05 K for unit 2.
- Ambient temperature fluctuations: The effect of ambient temperature fluctuations is
compensated in the CE312 radiometers by measuring the detector cavity temperature by means
of a calibrated PRT. The uncertainty in this process is the uncertainty of the internal PRT, which
is 0.04 K according to reference 2.
- Atmospheric absorption/emission: Negligible due to very short path length and radiometers
working in the atmospheric window.
Total Type B uncertainty (RSS): 0.35 K for both units 1 and 2.
Type A + Type B uncertainty (RSS): 0.37 K for unit 1 and 0.36 K for unit 2.
Operational methodology during measurement campaign. The Landcal Blackbody Source
P80P was set at six fixed temperatures (0-50 ºC) in two different runs. Enough time was allowed
for the blackbody to reach equilibrium at each temperature. Radiometers were aligned with the
blackbody cavity, and placed at a distance so that the field of view was smaller than the cavity
diameter. Standard processing (see references above) was applied to the radiometer readouts to
calculate the equivalent brightness temperature. Due to the radiometer responsivity drift with
time, a correction is applied depending on the difference between the measured brightness
temperature (Tm) and the detector temperature (Td):
Tc = Tm + a(Tm - Td) + b
where Tc is the corrected brightness temperature, and a and b are band-dependent coefficients
derived from linear regression from the calibration measurements at the six temperatures in the
two runs.
Blackbody usage (deployment), previous use of instrument and planned applications. Field measurements of land surface temperature and emissivity for validation of thermal
infrared products from satellite sensors.
3.1.2 Uncertainty Contributions Associated with UoV’s measurements at NPL
The tables below show the uncertainty breakdown for the measurement of the laboratory
radiometer comparison at NPL. The RMS total refers to the square root of the sum of the
squares of all the individual uncertainty terms.
NPL Report ENV 14
7
CE312-2 Unit 1
Uncertainty
Contribution Type A Type B
Uncertainty in
Value / %
Uncertainty in
Value /
(appropriate units)
Uncertainty in
Brightness
temperature/K
Repeatability of
measurement 0.015 0.05
Reproducibility of
measurement 0.026 0.08
Primary calibration 0.34
Linearity of radiometer 0.06
Drift since calibration 0.07
Ambient temperature
fluctuations 0.04
Atmospheric
absorption/emission
RMS total 0.09 K/0.031 % 0.37
CE312-2 Unit 2
Uncertainty
Contribution Type A Type B
Uncertainty in
Value / %
Uncertainty in
Value /
(appropriate units)
Uncertainty in
Brightness
temperature/K
Repeatability of
measurement 0.012 0.03
Reproducibility of
measurement 0.018 0.06
Primary calibration 0.34
Linearity of radiometer 0.06
Drift since calibration 0.05
Ambient temperature
fluctuations 0.04
Atmospheric
absorption/emission
RMS total 0.07 K/0.022 % 0.36
NPL Report ENV 14
8
3.1.3 Comparison of UoV radiometers to the NPL reference blackbody
3.1.3.1 Comparison of CE312-2 Unit 1 to the NPL reference blackbody
The photo below shows the UoV radiometer viewing the NPL reference blackbody.
The UoV radiometer viewing the NPL reference blackbody
Figures 3.1.1 to 3.1.7 show the output of the six channels of the CIMEL CE312-2 unit 1
radiometer when it was viewing the NPL reference blackbody maintained at different
temperatures. The same figures also show the brightness temperature of the NPL reference
blackbody as a function of time. The uncertainty bars in the figures represent the uncertainty
values provided by Valencia University which correspond to the measurements shown in the
Figures, as well as the uncertainty of the NPL reference blackbody. Tables 3.1.1 to 3.1.7 which
are shown below each Figure, list the difference between the average temperature displayed by
each radiometer channel during the monitoring period and the corresponding average brightness
temperature of the NPL reference blackbody.
NPL Report ENV 14
9
Figure 3.1.1: Plot of the measurements of the different channels of the CIMEL CE312-2
Unit 1 radiometer when it was viewing the NPL reference blackbody while it was maintained
at about -30 °C.
Table 3.1.1: The deviation of the different radiometer channels δT of the CIMEL CE312-2
Unit 1 radiometer from the average blackbody temperature, over the measurement interval for
a nominal blackbody temperature of -30 °C.
Channel (μm) δT (mK) 10.54 171
11.30 293
10.57 819
9.14 1398
8.68 583
8.42 1798
NPL Report ENV 14
10
Figure 3.1.2: Plot of the measurements of the different channels of the CIMEL CE312-2
Unit 1 radiometer when it was viewing the NPL reference blackbody while it was maintained
at about -15 °C.
Table 3.1.2: The deviation of the different radiometer channels δT of the CIMEL CE312-2
Unit 1 radiometer from the average blackbody temperature, over the measurement interval for
a nominal blackbody temperature of -15 °C.
Channel (μm) δT (mK) 10.54 65
11.30 68
10.57 293
9.14 469
8.68 209
8.42 611
NPL Report ENV 14
11
Figure 3.1.3: Plot of the measurements of the different channels of the CIMEL CE312-2
Unit 1 radiometer when it was viewing the NPL reference blackbody while it was maintained
at about at 0 °C.
Table 3.1.3: The deviation of the different radiometer channels δT of the CIMEL CE312-2
Unit 1 radiometer from the average blackbody temperature, over the measurement interval for
a nominal blackbody temperature of about 0 °C.
Channel (μm) δT (mK) 10.54 80
11.30 0
10.57 110
9.14 220
8.68 140
8.42 280
NPL Report ENV 14
12
Figure 3.1.4: Plot of the measurements of the different channels of the CIMEL CE312-2
Unit 1 radiometer when it was viewing the NPL reference blackbody while it was maintained
at about 10 °C.
Table 3.1.4: The deviation of the different radiometer channels δT of the CIMEL CE312-2
Unit 1 radiometer from the average blackbody temperature, over the measurement interval for
a nominal blackbody temperature of about 10 °C.
Channel (μm) δT (mK) 10.54 29
11.30 -31
10.57 9
9.14 29
8.68 49
8.42 59
NPL Report ENV 14
13
Figure 3.1.5: Plot of the measurements of the different channels of the CIMEL CE312-2
Unit 1 radiometer when it was viewing the NPL reference blackbody while it was maintained
at about 20 °C.
Table 3.1.5: The deviation of the different radiometer channels δT of the CIMEL CE312-2
Unit 1 radiometer from the average blackbody temperature, over the measurement interval for
a nominal blackbody temperature of about 20 °C.
Channel (μm) δT (mK) 10.54 -9
11.30 -39
10.57 -59
9.14 -59
8.68 -9
8.42 -79
NPL Report ENV 14
14
Figure 3.1.6: Plot of the measurements of the different channels of the CIMEL CE312-2
Unit 1 radiometer when it was viewing the NPL reference blackbody while it was maintained
at about 30 °C.
Table 3.1.6: The deviation of the different radiometer channels δT of the CIMEL CE312-2
Unit 1 radiometer from the average blackbody temperature, over the measurement interval for
a nominal blackbody temperature of about 30 °C.
Channel (μm) δT (mK) 10.54 -51
11.30 -81
10.57 -101
9.14 -161
8.68 -81
8.42 -211
NPL Report ENV 14
15
Figure 3.1.7: Plot of the measurements of the different channels of the CIMEL CE312-2
Unit 1 radiometer when it was viewing the NPL reference blackbody while it was maintained
at about 45 °C.
Table 3.1.7: The deviation of the different radiometer channels δT of the CIMEL CE312-2
Unit 1 radiometer from the average blackbody temperature, over the measurement interval for
a nominal blackbody temperature of about 45 °C.
Channel (μm) δT (mK) 10.54 -133
11.30 -81
10.57 -120
9.14 -203
8.68 -193
8.42 -293
3.1.3.2 Comparison of CE312-2 Unit 2 to the NPL reference blackbody
Figures 3.1.8 to 3.1.14 show the output of the six channels of the CIMEL CE312-2 radiometer
unit 2 when it was viewing the NPL blackbody maintained at different temperatures. The same
Figures also show the brightness temperature of the NPL blackbody as a function of time. The
uncertainty bars in the figures represent the uncertainty values provided by Valencia University
which correspond to the measurements shown in the Figures, as well as the uncertainty of the
NPL reference blackbody. Tables 3.1.8 to 3.1.14 shown below each Figure list the difference
between the average temperature displayed by each radiometer channel during the monitoring
period and the corresponding average brightness temperature of the NPL reference blackbody.
3.5.1 Description of Radiometer and route of traceability
Make and type of Radiometer:
ISAR 5D
Outline Technical description of instrument:
Full information on this radiometer can be found in: Wimmer, W., and I. Robinson, 2016: The
ISAR instrument uncertainty model. J. Atmos. Oceanic Technol. doi:10.1175/JTECH-D-16-
0096.1, in press.
Establishment or traceability route for primary calibration including date of last
realisation and breakdown of uncertainty:
Pre workshop calibration completed 22/05/2016.
Post workshop calibration completed 05/07/2016.
Operational methodology during measurement campaign:
Alignment was achieved using an alignment piece specifically designed for the dome nuts on
the end to slot into. This is the same way the instrument is aligned during calibration and
deployment.
The ISAR runs continuously and is post processed using calibration scripts which incorporate
the uncertainty model, instrument data and pre and post calibrations to calculate the uncertainty.
Radiometer usage (deployment), previous use of instrument and planned applications. This ISAR is installed on RV Investigator, Australia’s blue water science vessel. It is part of
Establishment or traceability route for primary calibration including date of last
realisation and breakdown of uncertainty:
The IR120 has been calibrated using the CASOTS blackbody.
Operational methodology during measurement campaign:
The operational procedure for the IR120 is to perform a calibration with the CASOTS, before
and after any deployment over ice or water.
Radiometer usage (deployment), previous use of instrument and planned applications. The IR120 has been used for several ice campaigns in Greenland and a similar instrument has
been mounted on an automatic weather stations deployed From January-June 2015 and 2016
3.8.2 Uncertainty contributions associated with DMI’s measurements at NPL
3.8.2.1 Uncertainty contributions ISAR
Table 3.8.1 shows the uncertainty budget associated with measurements made by the DMI
Establishment or traceability route for primary calibration including date of last
realisation and breakdown of uncertainty:
OUCFIRST is calibrated before and after each measurement campaign using the blackbody
manufactured by LR TECH INC. The overall uncertainty of OUCFIRST is about 0.1 K.
Operational methodology during measurement campaign:
OUCFIRST has two measurement modes, one for lab calibration and the other one for outdoor
measurement. For lab calibration, OUCFIRST measures the ambient blackbody 30 times, the
heated blackbody 30 times and target blackbody 40 times. For outdoor mode, OUCFIRST
measures the ambient blackbody 30 times, the heated blackbody 30 times, the sky 10 times and
the sea 40 times. Using the self-calibration system in OUCFIRST, SST is calculated for each
measuring cycle.
NPL Report ENV 14
79
Radiometer usage (deployment), previous use of instrument and planned applications. OUCFIRST is now under testing and has been deployed on the research vessel Dong Fang
Hong II of Ocean University of China and operated for three campaigns in the China Seas in
2015 and 2016.
3.9.2 Uncertainty contributions associated with OUC’s measurements at NPL
3.9.2.1 Uncertainty contributions ISAR
Table 3.9.1 shows the uncertainty budget associated with measurements made by the ISAR
OUC radiometer.
Table 3.9.1: The uncertainty budget associated with measurements made by the OUC
radiometer
Sources of uncertainties arising within the ISAR SST retrieval processor. A more detailed
breakdown is available in the reference paper: Wimmer, W., and I. Robinson, 2016: The ISAR
instrument uncertainty model. J. Atmos. Oceanic Technol. doi:10.1175/JTECH-D-16-0096.1,
in press.
NPL Report ENV 14
80
3.9.2.2 Uncertainty contributions OUCFIRST
Uncertainty Contribution Type A
Uncertainty in
Value / %
Type B
Uncertainty in
Value /
(appropriate
units)
Uncertainty in
Brightness temperature
K
Repeatability of
measurement(1)
Reproducibility of
measurement(2)
Primary calibration(3)
0.023 K
/0.008%
0.009 K
/0.003%
0.12 K
0.023 K
0.009 K
0.12 K
RMS total
0.025 K
/0.008% 4 0.12 K 0.12 K
(1) Typical value of the standard deviation of 143 measurements at fixed black body temperature without
re-alignment of radiometer.
(2) Typical value of difference between two runs of radiometer measurements at the same black body
temperature including re-alignment.
(3) Typical value of difference between radiometer brightness temperature and ASSIST II Blackbody
temperature.
3.9.3 Comparison of OUC’s radiometers to the NPL reference blackbody
3.9.3.1 Comparison of ISAR to the NPL reference blackbody
Figures 3.9.1 to 3.9.7 show the measurements completed by the OUC ISAR radiometer when
it was viewing the NPL blackbody maintained at different temperatures. The uncertainty bars
shown in orange in the Figures represent the uncertainty values provided by OUC which
correspond to the measurements shown in the Figures. Also shown in blue in these Figures are
the values of the brightness temperature of the NPL reference blackbody along with their
combined uncertainty values.
NPL Report ENV 14
81
Figure 3.9.1: Measurements of the OUC ISAR radiometer when it was viewing the NPL
blackbody maintained at about -30 °C. The deviation of the ISAR radiometer from the
average blackbody temperature over the measurement interval was 2413 mK
Figure 3.9.2: Measurements of the OUC ISAR radiometer when it was viewing the NPL
blackbody maintained at about -15 °C. The deviation of the ISAR radiometer from the
average blackbody temperature over the measurement interval was 515 mK
NPL Report ENV 14
82
Figure 3.9.3: Measurements of the OUC ISAR radiometer when it was viewing the NPL
blackbody maintained at about 0 °C. The deviation of the ISAR radiometer from the average
blackbody temperature over the measurement interval was 229 mK.
Figure 3.9.4: Measurements of the OUC ISAR radiometer when it was viewing the NPL
blackbody maintained at about 10 °C. The deviation of the ISAR radiometer from the average
blackbody temperature over the measurement interval was 157 mK.
NPL Report ENV 14
83
Figure 3.9.5: Measurements of the OUC ISAR radiometer when it was viewing the NPL
blackbody maintained at about 20 °C. The deviation of the ISAR radiometer from the average
blackbody temperature over the measurement interval was 71 mK
Figure 3.9.6: Measurements of the OUC ISAR radiometer when it was viewing the NPL
blackbody maintained at about 30 °C. The deviation of the ISAR radiometer from the average
blackbody temperature over the measurement interval was 94 mK.
NPL Report ENV 14
84
Figure 3.9.7: Measurements of the OUC ISAR radiometer when it was viewing the NPL
blackbody maintained at about 45 °C. The deviation of the ISAR radiometer from the average
blackbody temperature over the measurement interval was 728 mK.
3.9.3.2 Comparison of OUCFIRST radiometer to the NPL reference blackbody.
The photo below shows the OUCFIRST radiometer viewing the NPL reference blackbody.
NPL Report ENV 14
85
The OUCFIRST radiometer viewing the NPL reference blackbody
Figures 3.9.8 to 3.9.14 show the measurements completed by the OUCFIRST radiometer when
it was viewing the NPL blackbody maintained at different temperatures. The uncertainty bars
shown in orange in the figures represent the uncertainty values provided by OUC which
correspond to the measurements shown in the Figures. Also shown in blue in these Figures are
the values of the brightness temperature of the NPL reference blackbody along with their
combined uncertainty values.
Figure 3.9.8: Measurements of the OUCFIRST radiometer when it was viewing the NPL
blackbody maintained at about -30 °C. The deviation of the OUC radiometer from the average
blackbody temperature over the measurement interval was 538 mK.
NPL Report ENV 14
86
Figure 3.9.9: Measurements of the OUCFIRST radiometer when it was viewing the NPL
blackbody maintained at about -15 °C. The deviation of the OUC radiometer from the average
blackbody temperature over the measurement interval was 102 mK.
Figure 3.9.10: Measurements of the OUCFIRST radiometer when it was viewing the NPL
blackbody maintained at about 0 °C. The deviation of the OUC radiometer from the average
blackbody temperature over the measurement interval was 125 mK.
NPL Report ENV 14
87
Figure 3.9.11: Measurements of the OUCFIRST radiometer when it was viewing the NPL
blackbody maintained at about 10 °C. The deviation of the OUC radiometer from the average
blackbody temperature over the measurement interval was 6 mK.
Figure 3.9.12: Measurements of the OUCFIRST radiometer when it was viewing the NPL
blackbody maintained at about 20 °C. The deviation of the OUC radiometer from the average
blackbody temperature over the measurement interval was 27 mK.
NPL Report ENV 14
88
Figure 3.9.13: Measurements of the OUCFIRST radiometer when it was viewing the NPL
blackbody maintained at about 30 °C. The deviation of the OUC radiometer from the average
blackbody temperature over the measurement interval was 22 mK.
Figure 3.9.14: Measurements of the OUCFIRST radiometer when it was viewing the NPL
blackbody maintained at about 45 °C. The deviation of the OUC radiometer from the average
blackbody temperature over the measurement interval was 18 mK.
NPL Report ENV 14
89
3.10 MEASUREMENTS MADE BY GOTA
Grupo de Observacion de la Tierra y la Atmosfera (GOTA)
Departamento de Física Fundamental Experimental, Electrónica Sistemas Universidad de La Laguna Avda. Astrofísico Fco. Sanchez s/n 38200 La Laguna Tenerife,
- Reproducibility: typical value of difference between two runs of radiometer measurements at
the same black body temperature including re-alignment.
B1 B2 B3 B4 B5 B6 Mean
K 0.05 0.02 0.03 0.03 0.04 0.03 0.03
% 0.01 0.01 0.01 0.01 0.01 0.01 0.01
Total Type A uncertainty (RSS):
B1 B2 B3 B4 B5 B6 Mean
K 0.06 0.10 0.09 0.09 0.12 0.10 0.09
% 0.01 0.03 0.04 0.03 0.04 0.04 0.03
Type B
- Linearity of radiometer: within temperature range of 278-303 K.
B1 B2 B3 B4 B5 B6 Mean
K 0.09 0.11 0.10 0.10 0.11 0.10 0.10
- Primary calibration: typical value of difference between radiometer brightness temperature
and Landcal Blackbody Source P80P temperature.
B1 B2 B3 B4 B5 B6 Mean
K 0.9 0.4 0.3 0.4 0.3 0.2 0.4
- Drift since calibration: 0.0 K (as expected since very recent calibration measurements).
- Ambient temperature fluctuations: 0.3 K
- Size-of-Source Effect: not considered
- Atmospheric absorption/emission: not considered
Total Type B uncertainty (RSS):
B1 B2 B3 B4 B5 B6 Mean
K 0.9 0.5 0.4 0.5 0.4 0.4 0.5
Type A + Type B uncertainty (RSS): 0.5 K
NPL Report ENV 14
91
Operational methodology during measurement campaign: Calibration measurements were
performed in the laboratory following, as close as possible, the procedures described in the
Draft Protocol. The Landcal Blackbody Source P80P was set at four temperatures (278 K,
283 K, 293 K and 303 K) in two different runs. Enough time was allowed for the black body to
reach equilibrium at each temperature. Radiometer was aligned with the black body cavity, and
placed at a distance so that the field of view was smaller than the cavity diameter. Standard
processing (see references above) was applied to the radiometer readouts to calculate the
equivalent brightness temperature. The six bands of the CE312-2 instrument were used.
Radiometer usage (deployment), previous use of instrument and planned applications. Field measurements (hand held and tripod mounted) of land and sea surface
temperature/emissivity. Validation of thermal infrared images from satellite sensors in Canary
Islands as well as laboratory measurements of soil and vegetation emissivity. Planned validation
of thermal infrared images from cameras on board UAVs in forest and crops in Macaronesian
region.
3.10.2 Uncertainty contributions associated with GOTA’s measurements at NPL
Uncertainty Contribution Type A
Uncertainty in
Value / %
Type B
Uncertainty
in Value /
(appropriate
units)
Uncertainty in
Brightness
temperature
K
Repeatability of
measurement
Reproducibility of
measurement
Primary calibration
Linearity of radiometer
Drift since calibration
Ambient temperature
fluctuations
Size-of-Source Effect
Atmospheric
absorption/emission
0.03%
0.01%
0.4 K
0.10 K
-
0.3 K
-
-
0.09 K
0.03 K
0.4 K
0.1 K
-
0.3 K
-
-
RMS total 0.03% / 0.09 K 0.5 K 0.5 K
Mean values for six bands (B1 - B6) are shown. Values for each band are in section 3.10.1.
NPL Report ENV 14
92
3.10.3 Comparison of CE312-2 to NPL reference blackbody
Figures 3.10.1 to 3.10.7 show the measurements completed by the GOTA radiometer CIMEL
Electronique CE312-2 when it was viewing the NPL blackbody maintained at different
temperatures. The uncertainty bars, shown in orange, in the figures represent the uncertainty
values provided by GOTA which correspond to the measurements shown in the Figures. Also
shown in blue in these Figures are the values of the brightness temperature of the NPL reference
blackbody along with their combined uncertainty values.
Figure 3.10.1: Measurements of the GOTA CIMEL CE312-2 radiometer viewing the NPL
blackbody maintained at about -30 °C.
Table 3.10.1 shown below, indicates the deviation δT of the different radiometer channels from
the average blackbody temperature, over the measurement interval for a nominal blackbody
temperature of -30 °C.
Table 3.10.1: The deviation of the different radiometer channels δT from the average
blackbody temperature, over the measurement interval for a nominal blackbody temperature
of -30 °C.
Channel (μm) δT (mK) 11.0-11.7 2632
10.3-11.0 2182
8.9-9.3 2645
8.5-8.9 2248
8.1-8.5 2670
NPL Report ENV 14
93
Figure 3.10.2: Measurements of the GOTA CIMEL CE312-2 radiometer viewing the NPL
blackbody maintained at about -15 °C.
Table 3.10.2, shown below, indicates the deviation of the different radiometer channels δT from
the average blackbody temperature, over the measurement interval for a nominal blackbody
temperature of -15 °C.
Table 3.10.2: The deviation of the different radiometer channels δT from the average
blackbody temperature, over the measurement interval for a nominal blackbody temperature
of -15 °C.
Channel (μm) δT (mK) 11.0-11.7 966
10.3-11.0 791
8.9-9.3 1055
8.5-8.9 996
8.1-8.5 998
NPL Report ENV 14
94
Figure 3.10.3: Measurements of the GOTA CIMEL CE312-2 radiometer viewing the NPL
blackbody maintained at about 0 °C.
Table 3.10.3, shown below, indicates the deviation of the different radiometer channels δT from
the average blackbody temperature, over the measurement interval for a nominal blackbody
temperature of 0 °C.
Table 3.10.3: The deviation of the different radiometer channels δT from the average
blackbody temperature, over the measurement interval for a nominal blackbody temperature
of 0 °C.
Channel (μm) δT (mK) 11.0-11.7 589
10.3-11.0 593
8.9-9.3 552
8.5-8.9 207
8.1-8.5 596
NPL Report ENV 14
95
Figure 3.10.4: Measurements of the GOTA CIMEL CE312-2 radiometer viewing the NPL
blackbody maintained at about 10°C.
Table 3.10.4, shown below, indicates the deviation of the different radiometer channels δT from
the average blackbody temperature, over the measurement interval for a nominal blackbody
temperature of 10 °C.
Table 3.10.4: The deviation of the different radiometer channels δT from the average
blackbody temperature, over the measurement interval for a nominal blackbody temperature
of 10 °C.
Channel (μm) δT (mK) 11.0-11.7 599
10.3-11.0 432
8.9-9.3 572
8.5-8.9 255
8.1-8.5 184
NPL Report ENV 14
96
Figure 3.10.5: Measurements of the GOTA CIMEL CE312-2 radiometer viewing the NPL
blackbody maintained at about 20°C.
Table 3.10.5, shown below, indicates the deviation of the different radiometer channels δT from
the average blackbody temperature, over the measurement interval for a nominal blackbody
temperature of 20 °C.
Table 3.10.5: The deviation of the different radiometer channels δT from the average
blackbody temperature, over the measurement interval for a nominal blackbody temperature
of 20 °C.
Channel (μm) δT (mK) 11.0-11.7 255
10.3-11.0 257
8.9-9.3 276
8.5-8.9 297
8.1-8.5 287
NPL Report ENV 14
97
Figure 3.10.6: Measurements of the GOTA CIMEL CE312-2 radiometer viewing the NPL
blackbody maintained at about 30 °C.
Table 3.10.6, shown below, indicates the deviation of the different radiometer channels δT from
the average blackbody temperature, over the measurement interval for a nominal blackbody
temperature of 30 °C.
Table 3.10.6: The deviation of the different radiometer channels δT from the average
blackbody temperature, over the measurement interval for a nominal blackbody temperature
of 30 °C.
Channel (μm) δT (mK) 11.0-11.7 88
10.3-11.0 114
8.9-9.3 95
8.5-8.9 75
8.1-8.5 151
NPL Report ENV 14
98
Figure 3.10.7: Measurements of the GOTA CIMEL CE312-2 radiometer viewing the NPL
blackbody maintained at about 45 °C.
Table 3.10.7, shown below, indicates the deviation of the different radiometer channels δT from
the average blackbody temperature, over the measurement interval for a nominal blackbody
temperature of 45 °C.
Table 3.10.7: The deviation of the different radiometer channels δT from the average
blackbody temperature, over the measurement interval for a nominal blackbody temperature
of 45 °C.
Channel (μm) δT (mK) 11.0-11.7 48
10.3-11.0 43
8.9-9.3 31
8.5-8.9 178
8.1-8.5 206
NPL Report ENV 14
99
3.11 MEASUREMENTS MADE BY RSMAS, UNIVERSITY OF MIAMI
Institute/organisation: Rosenstiel School of Marine and Atmospheric Science
University of Miami, 4600 Rickenbacker Causeway,
Miami, FL 33149, USA Contact Name: Prof. Peter Minnett