| DATA_SET_DESCRIPTION |
Data Set Overview
=================
As part of GRSFE the directional variations in thermal emission
of different surfaces were investigated. Results were obtained
using hand-held thermistor probes (to determine local kinetic
temperature) and a ground-based, hand-held infrared radiometer
(to determine scene-averaged infrared brightness temperature
from multiple view angles).
Field work took place in the Lunar Crater Volcanic Field.
Three natural sites were selected, and four artificial sites
were constructed. The natural sites included: (1) Dry playa.
The selected site was relatively smooth and flat, with a very
small number of interbedded rocks less than 0.5 cm in size.
Although a number of desiccation cracks were present, they
occupied a small fraction of the radiometer field of view;
observations at multiple viewing angles and directions suggests
they are not important in the thermal emission from the
ensemble surface. (2) Rocky playa. This surface consisted of
dry playa material, with approximately 10 % of the surface
covered by rocks with size 1-10 cm. (3) A'a lava flow. A 3-m
square, vegetation-free surface was selected within the Black
Rock Lava Flow; the surface was extremely rough, with 1-m
variations in heights occurring.
Four artificial sites were constructed on the Lunar Lake playa.
The artificial sites consisted of a 1 meter square patch of
material overlying undisturbed playa material. The sites were:
(1) Smooth sand. Overturned playa material was covered to a
uniform depth of about 10 cm with sand. (2) Smooth sand plus a
single rock. A similar sand surface was constructed, and a
single 13-cm cubical rock was placed on top. (3) Pebble
surface. Smooth playa material was covered to a depth of about
10 cm with 1- to 3-cm rounded pebbles. (4) Rocky surface.
Playa material was covered with a close-packed single layer of
15- to 30-cm slightly weathered and rounded rocks. After
construction, each site was allowed to partially equilibrate
with sunlight and ambient temperatures for 36 hours prior to
beginning measurements.
Infrared brightness temperature measurements for each surface
were obtained with a hand-held 8- to 14-micron broadband
infrared radiometer obtained from the Cole-Parmer Instrument
Co. Manufacturer's specifications indicate an absolute
calibration to about 3 K, with relative uncertainties between
measurements of better than 2 K; field investigation suggests a
relative calibration that was usually better than this over
short time spans. Although the field of view of the radiometer
is small, an internal averaging function allowed the instrument
to be swept over the entire site in a boustrophedonic pattern
in order to obtain a reading of the brightness temperature of
the ensemble surface. Measurements were made of each site at
emission angles of 0, 30 and 60 deg, and, for the latter two
emission angles, every 45 deg of azimuth; measurements of the
sand and playa sites were obtained at additional emission
angles. Experiments were performed to determine the radiometer
field of view using adjacent surfaces which had differing
temperatures; the field of view was sufficiently well defined
that no significant emission was thought to come from regions
outside of the specific sites.
Measurements of the actual surface kinetic temperature were
made with a hand-held thermistor probe. The probe was
thermally connected to the surface only at the time of the
measurement and insulated from the atmosphere by a molded piece
of styrofoam. The probe itself had a time constant of 10 s in
air, and was held in contact with each surface for up to 30 s
to obtain a stable temperature. For the rocky and rough
surfaces, temperatures were obtained for a representative
sampling of surface orientations (typically about 30), and the
strike and dip of each local surface was recorded. In order to
obtain measurements of all surfaces at the same local times,
data were acquired over a span of three days, partially
overlapping with other GRSFE field and aircraft investigations.
Logistical and weather problems prevented obtaining complete
diurnal coverage of each site.
Processing Level Id : 3
Software Flag : N
Processing Start Time : 1989-07-21T00:00:00.000
Processing Stop Time : 1990-01-11T00:00:00.000
Parameters
==========
Data Set Parameter 'RADIANCE'
-----------------------------
Radiance is the amount of energy per time per projected area
per steradian.
Data Set Parameter Name : RADIANCE
Data Set Parameter Unit : WATT/(METER*METER)/STERADIAN
Sampling Parameter Name : TIME
Sampling Parameter Unit : HOUR
Minimum Sampling Parameter : N/A
Maximum Sampling Parameter : N/A
Sampling Parameter Resolution : N/A
Sampling Parameter Interval : 2
Minimum Available Sampling Int : N/A
Noise Level : UNK
Data Set Parameter 'TEMPERATURE'
--------------------------------
The temperature of a system is a measure of the heat content
of the system, and determines if a system is in thermal
equilibrium with other systems.
Data Set Parameter Name : TEMPERATURE
Data Set Parameter Unit : DEGREES
Sampling Parameter Name : TIME
Sampling Parameter Unit : HOUR
Minimum Sampling Parameter : N/A
Maximum Sampling Parameter : N/A
Sampling Parameter Resolution : N/A
Sampling Parameter Interval : 2
Minimum Available Sampling Int : N/A
Noise Level : UNK
Source Instrument Parameters
============================
Instrument Host ID : FEXP
Data Set Parameter Name : RADIANCE
Instrument Parameter Name : RADIANCE
Important Instrument Parameters : 1
Instrument Host ID : FEXP
Data Set Parameter Name : TEMPERATURE
Instrument Parameter Name : TEMPERATURE
Important Instrument Parameters : 1
Measurement Information
=======================
Not Applicable
Processing
==========
Processing History
------------------
Source Data Set ID : N/A
Software : UNK
Product Data Set ID : FEXP-E-RMTR/THRM-3-RDR-TEMPERATURE-V1.0
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