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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