The instruments on envisat

Gardini, B.; Graf, Gerhard; Ratier, G.

doi:10.1016/0094-5765(95)00050-a

Cited by 17 publications

(11 citation statements)

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“…The radar used in the study is a C band polarimetric scatterometer, which measures all linear polarizations including vertical (VV) and horizontal (HH), so that the work is applicable to the C band SARs flown on the following satellites: ERS 1 and ERS 2 (VV) and RADARSAT (HH). The work will also be applicable to the planned ENVI-SAT satellite, which will carry a polarimetric C band SAR designed to monitor the polar ice caps and the sea ice extent [Gardini et al, 1995]. This SAR will have the polarimetric diversity to measure VV and HH simultaneously or cross polarization with different transmitted and received polarizations in quasi-simultaneous operation with VV or HH [Gardini et al, 1995].…”

Section: Introductionmentioning

confidence: 99%

“…The work will also be applicable to the planned ENVI-SAT satellite, which will carry a polarimetric C band SAR designed to monitor the polar ice caps and the sea ice extent [Gardini et al, 1995]. This SAR will have the polarimetric diversity to measure VV and HH simultaneously or cross polarization with different transmitted and received polarizations in quasi-simultaneous operation with VV or HH [Gardini et al, 1995]. Such varieties in SAR polarizations necessitate the poladmetric aspect of this frost flower signature study.…”

Section: Introductionmentioning

confidence: 99%

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A laboratory study of the effect of frost flowers on C band radar backscatter from sea ice

et al. 1997

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A laboratory study of the effect of frost flowers on C band radar backscatter from sea ice

et al. 1997

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“…Reservoir surface areas were extracted from twelve Envisat advanced synthetic aperture radar (ASAR) images from 21 May 2005 to 15 August 2005, and from 13 June 2006 to 15 August 2006, covering the end of the dry season, the onset of the rainy season, and the early rainy season. Envisat ASAR is a C band radar, which provides images at a spatial resolution of 30 m [ Gardini et al , 1995]. The images used in this study were acquired in dual polarization mode (HV/HH), which also has been found useful in flood studies by Henry et al [2006].…”

Section: Methodsmentioning

confidence: 99%

Determining watershed response in data poor environments with remotely sensed small reservoirs as runoff gauges

Liebe

Giesen

Andreini³

et al. 2009

Water Resources Research

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[1] In the semiarid regions of Africa, there are many small reservoirs used for irrigation. This study explores the practicality of using small reservoirs as runoff gauges by estimating their water storage changes using remote sensing imagery. A simple rainfall-runoff model is developed by observing the surface area and estimating the volume of eight small reservoirs in the Upper East Region of Ghana and in Togo using Envisat advanced synthetic aperture radar satellite images. The model is based on the Thornthwaite-Mather procedure and the assumption that with increasing precipitation, the contributing watershed area increases exponentially. The model parameters were estimated using the 2005 data and were validated using 2006 data. Although the total rainfall amounts were comparable in these 2 years, the rainfall and reservoir filling patterns were quite different. The model results indicate that the overall impact of the reservoirs largely depends on the ratios of reservoir to watershed areas. For this 2 year study, the reservoirs captured on average 34% of quick flow and 15% of overall runoff.

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“…), and subtracting it from the satellite's altitude, a precise estimate (in the order of centimetres) of the surface elevation (water, ice or land) can be obtained (Gardini et al, 1995). Figure 1 illustrate this principle and shows the Saral satellite.…”

Section: Background On Satellite Altimetry In Low Resolution Mode (Lrm)mentioning

confidence: 99%

An Original Processing Method of Satellite Altimetry for Estimating Water Levels and Volume Fluctuations in a Series of Small Lakes of the Pantanal Wetland Complex in Brazil

Costa

Pereira

Maillard

2016

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Satellite altimetry is becoming a major tool for measuring water levels in rivers and lakes offering accuracies compatible with many hydrological applications, especially in uninhabited regions of difficult access. The Pantanal is considered the largest tropical wetland in the world and the sparsity of in situ gauging station make remote methods of water level measurements an attractive alternative. This article describes how satellites altimetry data from Envisat and Saral was used to determine water level in two small lakes in the Pantanal. By combining the water level with the water surface area extracted from satellite imagery, water volume fluctuations were also estimated for a few periods. The available algorithms (retrackers) that compute a range solution from the raw waveforms do not always produce reliable measurements in small lakes. This is because the return signal gets often "contaminated" by the surrounding land. To try to solve this, we created a "lake" retracker that rejects waveforms that cannot be attributed to "calm water" and convert them to altitude. Elevation data are stored in a database along with the water surface area to compute the volume fluctuations. Satellite water level time series were also produced and compared with the only nearby in situ gauging station. Although the "lake" retracker worked well with calm water, the presence of waves and other factors was such that the standard "ice1" retracker performed better on the overall. We estimate our water level accuracy to be around 75 cm. Although the return time of both satellites is only 35 days, the next few years promise to bring new altimetry satellite missions that will significantly increase this frequency.

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The instruments on envisat

Cited by 17 publications

References 0 publications

A laboratory study of the effect of frost flowers on C band radar backscatter from sea ice

A laboratory study of the effect of frost flowers on C band radar backscatter from sea ice

Determining watershed response in data poor environments with remotely sensed small reservoirs as runoff gauges

An Original Processing Method of Satellite Altimetry for Estimating Water Levels and Volume Fluctuations in a Series of Small Lakes of the Pantanal Wetland Complex in Brazil

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