Infrared Albedo and Reflectance/Analysis of the Infrared Data Taken During the Remote Sensing of Oil in Sea Ice Experiment
Infrared Albedo and Reflectance/Analysis of the Infrared Data Taken During the Remote Sensing of Oil in Sea Ice ExperimentDon Perovich, ERDC-CRREL
Scope of Work:
This contract was awarded to two different project proposals combined. The goal of one project is to measure the albedo and reflectance of a layer of oil with ice or water as the underlying substrate:
"We will measure the spectral albedo and reflectance of an oil layer on top of sea ice or water over the wavelength range of 400 to 2500 nm. This encompasses most of the solar spectrum. The optical data will be reduced and examined to see if the presence of a surface oil layer results in a characteristic spectral signature in either albedo or reflectance. Special attention will be paid to near-infrared wavelengths. The optical measurements will be made using an Analytical Spectral Devices FieldSpec Pro.
The measurements will be made outdoors at the CRREL Geophysical Research Facility. The GRF contains a concrete basin, 18. 25 m long x 6. 7 m wide x 2 m deep (60 x 22 x 7 ft), with a removable refrigerated roof that maintains an ice cover and protects the underlying ice surface from snow (if desired). The basin is filled with saltwater. The facility is equipped with an instrument gantry mounted on rails that extend the full length of the basin. Using the outdoor sea ice pond allows us to use sunlight as the illumination source. We will attempt to make measurements under both clear and cloudy conditions. ”
The other is a proposal for the Analysis of the infrared data taken during the JIP Remote Sensing of Oil in Sea Ice experiment.
During the warm-up phase of the JIP Remote Sensing of Oil in Sea Ice experiment, we took data with two infrared (IR ) cameras and generated two IR datasets. This proposal is to analyze all of the IR data (images) collected during the “Oil-Ice Test”.
Set #1 “Overview” IR camera. The overview camera was placed in such a way that it had a view of hoops 4, 5, and part of hoop 3. The camera was adjusted on 1/29/2015 to give a complete view of Hoops 3, 4, and 5 and a partial view of hoops 2 and 3. The camera was set up to take images at one-minute intervals. The Image record begins on 1/9/2015 and goes through 2/20/2015. There are a few gaps in the data record, and there are some periods where the camera took images that were not set to the proper temperature scales.
Set #2 –Data was also taken with a “Roving” IR Camera. This camera, mounted on a tall tripod, was placed to give a close-up view of one or two hoops at a time. We looked closely at Hoops 1, 2B, 4, 5A, 4B, and 6. There are 9 periods of time, with durations of between half of a day to 3 days, during which IR images were collected on the different Hoops.
For the “Overview Camera” data set, we will analyze the time series of images. Since the IR images of the ice sheet cover a wide view, we will be able to analyze and compare the radiative temperature measurements inside the hoops (where oil is present underneath the ice) and outside the hoops. With the “Overview Camera,” we should be able to see differences between how the “Roving Sun” (the artificial sun used during the experiment) affects the change in radiative temperatures inside and outside the hoops.
For the Image analysis of the “Roving” IR Camera, we would perform a separate analysis for each of the 9 positions that the camera was placed in during the test. Analysis of the individual hoop images provided by the “Roving” camera gives us an idea if there are any radiative temperature differences within individual hoops occurring during the warm-up of the ice sheet. Individual hoop IR images can be analyzed for radiative temperature differences (hot and cool spots), and a time series of the IR images of the hoops can also be analyzed. for future experiments.