Retrieve optical depth using microwave vegetation indices from WindSat data

2014 ◽  
Author(s):  
Yunqing Li ◽  
Jiancheng Shi ◽  
Tianjie Zhao ◽  
Tao Zhang
Keyword(s):  
Optical Depth ◽  
Vegetation Indices

scholarly journals THEORETICAL MODELLING STUDY ON THE RELATIONSHIP BETWEEN MULTI-FREQUENCY MICROWAVE VEGETATION INDEX AND VEGETATION PROPERTIES (OPTICAL DEPTH AND SINGLE SCATTERING ALBEDO)

2018 ◽  
Vol XLII-3 ◽  
pp. 1623-1627
Author(s):  
S. Talebi ◽  
J. Shi ◽  
T. Zhao
Keyword(s):  
Optical Depth ◽  
Vegetation Index ◽  
Vegetation Indices ◽  
Soil Surface ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Theoretical Modelling ◽  
Vegetation Monitoring ◽  
Scattering Effects ◽  
The Relationship

This paper presents a theoretical study of derivation Microwave Vegetation Indices (MVIs) in different pairs of frequencies using two methods. In the first method calculating MVI in different frequencies based on Matrix Doubling Model (to take in to account multi scattering effects) has been done and analyzed in various soil properties. The second method was based on MVI theoretical basis and its independency to underlying soil surface signals. Comparing the results from two methods with vegetation properties (single scattering albedo and optical depth) indicated partial correlation between MVI from first method and optical depth, and full correlation between MVI from second method and vegetation properties. The second method to derive MVI can be used widely in global microwave vegetation monitoring.

scholarly journals Using vegetation indices for soil-moisture retrievals from passive microwave radiometry

2001 ◽  
Vol 5 (4) ◽  
pp. 671-678 ◽  
Author(s):  
E.J. Burke ◽  
W.J. Shuttleworth ◽  
A.N. French
Keyword(s):  
Soil Moisture ◽  
Optical Depth ◽  
Vegetation Index ◽  
Empirical Relationship ◽  
Vegetation Indices ◽  
Passive Microwave ◽  
Microwave Emission ◽  
Retrieval Algorithm ◽  
Emission Model ◽  
Normalised Difference Vegetation Index

Abstract. Surface soil moisture and the nature of the overlying vegetation both influence microwave emission from land surfaces significantly. One widely discussed but underused method for allowing for the effect of vegetation on soil-moisture retrievals from microwave observations is to use remotely sensed vegetation indices. This paper explores the potential for using the Normalised Difference Vegetation Index (NDVI) in soil-moisture retrievals from L-band (1.4 GHz) aircraft data gathered during the Southern Great Plains '97 (SGP97) experiment. A simplified version of MICRO-SWEAT, a soil vegetation atmosphere transfer (SVAT) scheme coupled with a microwave emission model, was used as the retrieval algorithm. Estimates of the optical depth of the vegetation, the parameter that describes the effect of the vegetation on microwave emission, were obtained by calibrating this retrieval algorithm against measurements of soil moisture at 15 field sites. A significant relationship was found between the optical depth so obtained and the observed NDVI at these sites, although this relationship changed with the resolution of the microwave brightness temperature observations used. Soil-moisture estimates made with the retrieval algorithm using the empirical relationship between optical depth and NDVI applied at two additional sites not used in the calibration show good agreement with field measurements. Keywords: NDVI, soil moisture, passive microwave, SGP97

scholarly journals Mapping carbon stocks in Central and South America with SMAP vegetation optical depth

2021 ◽  
Author(s):  
David Chaparro ◽  
Grégory Duveiller ◽  
María Piles ◽  
Mercè Vall-llossera ◽  
Alessandro Cescatti ◽  
...  
Keyword(s):  
South America ◽  
Optical Depth ◽  
Vegetation Index ◽  
Vegetation Indices ◽  
Microwave Remote Sensing ◽  
Carbon Stocks ◽  
Airborne Lidar ◽  
Low Frequencies ◽  
L Band ◽  
Airborne Lidar Data

Mapping carbon stocks in the tropics is essential for climate change mitigation. Passive microwave remote sensing allows estimating carbon from deep canopy layers through the Vegetation Optical Depth (VOD) parameter. Although their spatial resolution is coarser than that of optical vegetation indices or airborne Lidar data, microwaves present a higher penetration capacity at low frequencies (Lband) and avoid cloud masking. This work compares the relationships of airborne carbon maps in Central and South America with both (i) SMAP L-band VOD at 9 km gridding and (ii) MODIS Enhanced Vegetation Index (EVI). Models to estimate carbon stocks are built from these two satellite derived variables. Results show that L-band VOD has a greater capacity to model carbon variability than EVI. The resulting VOD-derived carbon estimates are further presented at a detailed (9 km) spatial scale.

Comparison between SMOS Vegetation Optical Depth products and MODIS vegetation indices over crop zones of the USA

2014 ◽  
Vol 140 ◽  
pp. 396-406 ◽  
Author(s):  
Heather Lawrence ◽  
Jean-Pierre Wigneron ◽  
Philippe Richaume ◽  
Nathalie Novello ◽  
Jennifer Grant ◽  
...  
Keyword(s):  
Optical Depth ◽  
Vegetation Indices ◽  
The Usa

Comparison of SMOS and AMSR-E vegetation optical depth to four MODIS-based vegetation indices

2016 ◽  
Vol 172 ◽  
pp. 87-100 ◽  
Author(s):  
J.P. Grant ◽  
J.-P. Wigneron ◽  
R.A.M. De Jeu ◽  
H. Lawrence ◽  
A. Mialon ◽  
...  
Keyword(s):  
Optical Depth ◽  
Vegetation Indices

Voyager UVS observations of stellar occultations by the rings of Saturn

1984 ◽  
Vol 75 ◽  
pp. 265-277
Author(s):  
J.B. Holbelg ◽  
W.T. Forrester
Keyword(s):  
Optical Depth ◽  
Distance Scale ◽  
Density Waves ◽  
Ring Density ◽  
Stellar Occultations ◽  
Saturn’S Rings ◽  
Saturn's Rings

ABSTRACTDuring the Voyager 1 and 2 Saturn encounters the ultraviolet spectrometers observed three separate stellar occultations by Saturn's rings. Together these three observations, which sampled the optical depth of the rings at resolutions from 3 to 6 km. can be used to establish a highly accurate distance scale allowing the identification of numerous ring features associated with resonances due to exterior satellites. Three separate observations of an eccentric ringlet near the location of the Titan apsidal resonance are discussed along with other ringlet-resonance associations occurring in the C ring. Density waves occurring in the A and B rings are reviewed and a detailed discussion of the analysis of one of these features is presented.

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