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Remote sensing

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Articles 91 - 97 of 97

Full-Text Articles in Environmental Monitoring

Relating Surface Backscatter Response From Trmm Precipitation Radar To Soil Moisture: Results Over A Semi-Arid Region, Haroon Stephen, Sajjad Ahmad, Thomas C. Piechota, Chunling Tang Jan 2010

Relating Surface Backscatter Response From Trmm Precipitation Radar To Soil Moisture: Results Over A Semi-Arid Region, Haroon Stephen, Sajjad Ahmad, Thomas C. Piechota, Chunling Tang

Public Policy and Leadership Faculty Research

The Tropical Rainfall Measuring Mission (TRMM) carries aboard the Precipitation Radar (TRMMPR) that measures the backscatter (σº) of the surface. σº is sensitive to surface soil moisture and vegetation conditions. Due to sparse vegetation in arid and semi-arid regions, TRMMPR σº primarily depends on the soil water content. In this study we relate TRMMPR σº measurements to soil water content (m(s)) in the Lower Colorado River Basin (LCRB). σº dependence on ms is studied for different vegetation greenness values determined through Normalized Difference Vegetation Index (NDVI). A new model of σº that couples incidence angle, m(s), and NDVI is used …

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Land Surface Brightness Temperature Modeling Using Solar Insolation, Haroon Stephen, Sajjad Ahmad, Thomas C. Piechota Jan 2010

Land Surface Brightness Temperature Modeling Using Solar Insolation, Haroon Stephen, Sajjad Ahmad, Thomas C. Piechota

Public Policy and Leadership Faculty Research

Retrieval of land surface emissivity and temperature from microwave brightness temperature data is a complex problem. The diurnal variation of temperature due to the diurnal cycle of solar radiation and weather conditions makes this problem even more challenging. In this paper, we use solar radiation in modeling the temporal variation of the brightness temperature state of the surface. Solar insolation modeling is used to estimate the diurnal variation of land surface brightness temperature. Solar radiation and brightness temperature are linked through temperature of the surface which is derived based on the radiation balance equation. The temperature state model behaves consistent …

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Satellite-Based Estimation Of Chlorophyll-Α Concentration In Turbid Productive Waters, Wesley Moses Dec 2009

Satellite-Based Estimation Of Chlorophyll-Α Concentration In Turbid Productive Waters, Wesley Moses

School of Natural Resources: Dissertations, Theses, and Student Research

Inland, coastal, and estuarine waters, which are often turbid and biologically productive, play a crucial role in maintaining global bio-diversity and are of immense value to aquatic life as well as human-beings. Concentration of chlorophyll-a (chl-a) is a key indicator of the trophic status of these waters, which should be regularly monitored to ensure that their ecological balance is not disturbed. Remote sensing is a powerful tool for this.

Due to the optical complexity of turbid productive waters, standard algorithms that use blue and green reflectances are unreliable for estimating chl-a concentration. Algorithms based on red and near-infrared (NIR) reflectances …

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Impacts Of Meteorological Factors On Modis-Observed Fire Activity In The North American Boreal Forest: The Role Of Lightning, David A. Peterson Oct 2009

Impacts Of Meteorological Factors On Modis-Observed Fire Activity In The North American Boreal Forest: The Role Of Lightning, David A. Peterson

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The meteorological impact on wildfire activity in the North American boreal forest during the fire seasons of 2000 – 2006 is statistically analyzed through an integration of the following data sets: the MODerate Resolution Imaging Spectroradiometer (MODIS) level 2 fire products, the 3-hourly 32-km gridded meteorological data from North American Regional Reanalysis (NARR), the instantaneous lightning data collected by the Canadian Lightning Detection Network (CLDN), and the Alaska Lightning Detection Network (ALDN). Positive anomalies of the 500 hpa geopotential height field, convective available potential energy (CAPE), number of cloud-to-ground lightning strikes, and the number of consecutive dry days are found …

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Soil Moisture And Water Stage Estimation Using Precipitation Radar, Sumit Puri Jan 2009

Soil Moisture And Water Stage Estimation Using Precipitation Radar, Sumit Puri

UNLV Theses, Dissertations, Professional Papers, and Capstones

In south-western United States, soil moisture data is important for drought studies in the region which is experiencing a drought for many years, whereas in South Florida, water stage data is required by hydrologists to monitor the hydrological flow in wetlands. Soil moisture data and water stage data are not sufficiently available due to sparse monitoring stations. Installation of dense measuring stations over an extended area is costly and labor intensive. Therefore, there is a need to develop an alternative method of measuring soil moisture and water stage. Microwave remote sensing has proven to be a useful tool in the …

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Microwave Backscatter Modeling Of Erg Surfaces In The Sahara Desert, Haroon Stephen, David G. Long Jan 2005

Microwave Backscatter Modeling Of Erg Surfaces In The Sahara Desert, Haroon Stephen, David G. Long

Public Policy and Leadership Faculty Research

The Sahara Desert includes large expanses of sand dunes called ergs. These dunes are formed and constantly reshaped by prevailing winds. Previous study shows that Saharan ergs exhibit significant radar backscatter (σ°) modulation with azimuth angle (f). We use σ° measurements observed at various incidence angles and f from the NASA Scatterometer (NSCAT), the SeaWinds scatterometer, the ERS scatterometer (ESCAT), and the Tropical Rainfall Measuring Mission's Precipitation Radar to model the σ° response from sand dunes. Observations reveal a characteristic relationship between the backscatter modulation and the dune type, i.e., the number and orientation of the dune slopes. Sand dunes …

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Modeling Microwave Emissions Of Erg Surfaces In The Sahara Desert, Haroon Stephen, David G. Long Jan 2005

Modeling Microwave Emissions Of Erg Surfaces In The Sahara Desert, Haroon Stephen, David G. Long

Public Policy and Leadership Faculty Research

Sand seas (ergs) of the Sahara are the most dynamic parts of the desert. Aeolian erosion, transportation, and deposition continue to reshape the surface of the ergs. The large-scale features (dunes) of these bedforms reflect the characteristics of the sand and the long-term wind. Radiometric emissions from the ergs have strong dependence on the surface geometry. We model the erg surface as composed of tilted rough facets. Each facet is characterized by a tilt distribution dependent upon the surface roughness of the facet. The radiometric temperature (T(b)) of ergs is then the weighted sum of the T(b) from all the …

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