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Desert Landscape

Makhtesh Ramon Cal/ Val Site

Daniela Heller Pearlshtein & Eyal Ben-Dor 

The study proposed two test sites in southern Israel: Amiaz Plain (AP) and Makhtesh Ramon (MR), to be CAL/VAL test sites for HRS sensors. The sites are situated in southern Israel’s arid environment and have the same overpass coverage. Based on the surface characteristics of the areas, the AP site is used for radiometric calibration and the MR site for spectral and thematic validation. We executed several comprehensive fields, airborne and satellite campaigns. The study was conducted in cooperation with NASA, DLR, and ASI, respectively, and carried out during the first validation stage of the sen- sors after they had become operational (EMIT, EnMAP, and PRISMA). We generated a detailed protocol for executing the CAL/VAL mission, from planning the field campaign to field spectral measurements, data quality assurance, and a radiometric reflectance corrected procedure if needed. The suggested methodology integrates both sites into one operational protocol, including the sensors’ radiometric, spectral, and thematic quality. 

HRS Campaign on Makhtesh Ramon

A flight campaign was carried out using the AisaFENIX 1K airborne sensor ( Specim, Spectral Imaging Ltd.) over MR on April 5, 2017, covering 200 km² in 25 flight lines. The AisaFENIX images were atmospherically corrected. Thematic maps of the following minerals were created after validating the quality of the reflectance values obtained: iron oxides (hematite and goethite), clay minerals (kaolinite, Bentonite [ mostly montmorillonite]), sulfate minerals (gypsum), and carbonates (calcite). The analyses were performed separately on every strip and then mosaicked to provide full mineral maps. Extensive quality assessment (QA) processes were applied to the thematic results, including field measurements (by spectral and geology experts), geological maps, and external spectral libraries (e.g., from the US Geological Survey [USGS]) to validate the mapping precision as it reflects the real geological coverage in MR. 

Field Test Sites

Field test sites in MR for the post-launch characterization and calibration of space-based optical imaging sensors. These test sites have unique and homogenous spectral signals for a specific range of passive sensor VNIR ( 400-1000 nm), SWIR 1 ( 1000-1900 nm) SWIR 2  (1900-2500). The test sites are routinely measured with an ASD field spectrometer in a 30X30 meter grid to simulated 1 pixel of 30 m resolution from space.

Acknowledgments

This work was part of Daniela Heller Pearlshtien's PhD research in the RSL,  and was supported by Elbit Systems Electro-Optics (ELOP) and Israel Space Agency (ISA). 

Satellite
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