Imaging Science Ph.D. Defense: Jonathan Miller
Low Cost Radiometer Design for Landsat Surface Temperature Validation
Jonathan Miller
Imaging Science Ph.D. Candidate
Chester F. Carlson Center for Imaging Science, RIT
Abstract:
Land Surface Temperature (ST) represents the radiative temperature of the Earth’s surface and is used as an input for hydrological, agricultural, and meteorological science applications. Due to the synoptic nature of satellite imaging systems, ST products derived from spaceborne platforms are invaluable for estimating ST at the local, regional, and global scale. Over the past two decades, an emphasis has been placed on the need to develop algorithms necessary to deliver accurate ST products to support the needs of science users. However, corresponding efforts to validate these products are hindered by the availability of quality ground based reference measurements. NOAA’s Surface Radiation Budget Network (SURFRAD) is commonly used to support ST-validation efforts, but SURFAD’s instrumentation is broadband (4-50 micrometer) and several of their sites lack spatial uniformity, which can lead to large ST calculation errors. To address the apparent deficiencies within existing validation networks, this work discusses a prototype instrument developed to provide ST estimates to support validation efforts for spaceborne thermal sensor products. Specifically, a two band prototype radiometer was designed, built, calibrated, and utilized to acquire ground reference data to validate ST product(s) derived from Landsat 8 imagery. Additionally, the radiometers proposed in this research were designed to calculate the largest unknown variable used to create Landsat 8 derived ST products: the target emissivity. Algorithms have been developed with the purpose of using Landsat 8’s two thermal bands to calculate the ST of a given scene. One popular method is the split window algorithm, which uses at sensor apparent temperatures collected by band 10 and 11 of Landsat, along with atmospheric data to calculate the surface leaving temperatures. A key input into the split window algorithm is the emissivity of the target, which is currently calculated using data from another spaceborne sensor. This emissivity calculation is not ideal because, like the ST calculation, the emissivity is also propagated through the atmosphere before being calculated. An ideal approach is to measure and calculate the emissivity close to the surface, thus eliminating any atmospheric compensation errors. Four additional response bands were added to the radiometer resulting in a six band instrument capable of calculating the ST and emissivity of a ground target, through the use of a temperature emissivity separation (TES) algorithm.
Intended Audience:
Undergraduates and graduates. Those with interest in the topic.
Event Snapshot
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Open to the Public
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No