scholarly journals Improved Cloud Detection Utilizing Defense Meteorological Satellite Program near Infrared Measurements

1982 ◽  
Author(s):  
James T. Bunting ◽  
Robert P. d'Entremont
Keyword(s):  
Near Infrared ◽  
Cloud Detection ◽  
Defense Meteorological Satellite Program ◽  
Infrared Measurements ◽  
Meteorological Satellite

scholarly journals Assessment of the relative accuracy of hemispheric-scale snow-cover maps

2002 ◽  
Vol 34 ◽  
pp. 24-30 ◽  
Author(s):  
Dorothy K. Hall ◽  
Richard E. J. Kelly ◽  
George A. Riggs ◽  
Alfred T. C. Chang ◽  
James L. Foster
Keyword(s):  
Snow Cover ◽  
Near Infrared ◽  
Passive Microwave ◽  
Defense Meteorological Satellite Program ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Microwave Imager ◽  
Meteorological Satellite ◽  
Microwave Data

AbstractThere are several hemispheric-scale satellite-derived snow-cover maps available, but none has been fully validated. For the period 23 October–25 December 2000, we compare snow maps of North America derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) and operational snow maps from the U.S. National Oceanic and Atmospheric Administration (NOAA) National Operational Hydrologic Remote Sensing Center (NOHRSC), both of which rely on satellite data from the visible and near-infrared parts of the spectrum; we also compare MODIS maps with Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSM/I) passive-microwave snow maps for the same period. The maps derived from visible and near-infrared data are more accurate for mapping snow cover than are the passive-microwave-derived maps, but discrepancies exist as to the location and extent of the snow cover even between operational snow maps. The MODIS snow-cover maps show more snow in each of the 8 day periods than do the NOHRSC maps, in part because MODIS maps the effects of fleeting snowstorms due to its frequent coverage. The large (~30 km) footprint of the SSM/I pixel, and the difficulty in distinguishing wet and shallow snow from wet or snow-free ground, reveal differences up to 5.33 x 106 km2 in the amount of snow mapped using MODIS vs SSM/I data. Algorithms that utilize both visible and passive-microwave data, which would take advantage of the all-weather mapping capability of the passive-microwave data, will be refined following the launch of the Advanced Microwave Scanning Radiometer (AMSR) in the fall of 2001.

Using near infrared measurements to evaluate NaCl and KCl in water

2019 ◽  
Vol 27 (2) ◽  
pp. 147-155
Author(s):  
Reisha D Peters ◽  
Scott D Noble
Keyword(s):  
Aqueous Solutions ◽  
Near Infrared ◽  
Average Error ◽  
Spectral Measurements ◽  
Salt Solutions ◽  
Saturation Point ◽  
Test Set ◽  
Solution Type ◽  
All Solutions ◽  
Infrared Measurements

Spectral differences between aqueous solutions of NaCl and KCl have received minimal attention in previous research due to strong similarities between the two salts and the lack of motivation to differentiate between them. Correlations between salinity and absorbance have been developed previously with varying degrees of linearity but have not been tested to saturation. This work will demonstrate that correlating spectral measurements and the concentration of NaCl and KCl in water can be extended up to the saturation point of both salts and that solutions of these salts with unknown concentrations can be distinguished. Spectral data for samples of NaCl and KCl in single-salt solutions were collected up to saturation and correlations were developed for differentiating between solutions of the two species. These correlations were able to correctly identify the solution type for all solutions in the test set and estimate their concentrations with an average error of 0.9%.

scholarly journals Influence of Detector Size and Positioning on Near-Infrared Measurements and Iso-pathlength Point of Turbid Materials

2021 ◽  
Vol 9 ◽  
Author(s):  
Hamootal Duadi ◽  
Idit Feder ◽  
Dror Fixler
Keyword(s):  
Critical Parameter ◽  
Near Infrared ◽  
Tissue Oxygenation ◽  
Experimental System ◽  
Optical Path ◽  
Optical Parameters ◽  
Infrared Measurements ◽  
Profile Changes ◽  
Physical Phenomena ◽  
Crossing Point

Measuring physical phenomena in an experimental system is commonly limited by the detector. When dealing with spatially defined behaviors, the critical parameter is the detector size. In this work, we examine near-infrared (NIR) measurements of turbid media using different size detectors at different positions. We examine cylindrical and semi-infinite scattering samples and measure their intensity distribution. An apparent crossing point between samples with different scatterings was previously discovered and named the iso-pathlength point (IPL). Monte Carlo simulations show the expected changes due to an increase in detector size or similarly as the detector’s location is distanced from the turbid element. First, the simulations show that the intensity profile changes, as well as the apparent IPL. Next, we show the average optical pathlength, and as a result, the differential pathlength factor, are mostly influenced by the detector size in the range close to the source. Experimental measurements using different size detectors at different locations validate the influence of these parameters on the intensity profiles and apparent IPL point. These findings must be considered when assessing optical parameters based on multiple scattering models. In cases such as NIR assessment of tissue oxygenation, size and location may cause false results for absorption or optical path.

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