Radar Remote Sensing

M.Safdar

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1- Introduction1.1- Main Parameter1.2- Processing Scheme

2- System Description2.1 Mission Description 2.2 Satellite Description 2.3 Data Structure

3- Principle of Operations4- Wind Speed and Wind Direction

5.1 Observing Geometry 5.2 Wind Retrieval

5- Rayleigh Roughness Criteria6- Fan Beam

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Launched in 1999 and out off work in 2009The Sea Winds scatterometer on the QuikSCAT satellite 25-km measurements across a 1600-km swath, samples more than 90% of the global ocean every 24 hours

Introduction

Main Parameters

QuikSCAT satellite Components

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Mission Description

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Required period 4 days(57 orbits)

Orbital period 101 minutes(14.25 orbits/days)

Local Sun time at Ascending 6:00 AM ± 30 minutes

Altitude above equator 803 km

Inclination 98.616

Table 1 - Nominal Orbital Parameters

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Alternate view of the SeaWinds dual-beam scanning concept (image credit: University of Central Florida)

Detailed view of SeaWinds scanning geometry (image credit: Brigham Young University)

Satellite Description

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Principle of Operation

Satellite Description

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The diagram bellow shows the QuikSCAT satellite in position over the ocean

Rotating pencil-beam scatterometer

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QSCAT viewing geometry (Spencer et al., 2000).

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Response of radar backscatter to different surface roughness criteria: (a) smooth, (b) intermediate, and (c) rough (Sabins, 1997)

Angular variation of backscatter for different roughness conditions (Ulaby et al., 1982b).

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Sequence of pulses returned to the receiver showing the fading (variability of signal levels) on a pulse-to-pulse basis (Moore, 1983).

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Example of a fan-beam scatterometer (Ulaby et al., 1982).

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QSCAT scanning pattern showing helixes traced by the inner beam (light shade) and outer beam (dark shade) as spacecraft orbits (Spencer et al., 1997).

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Swath coverage spanning several days showing the crossing patterns of ascending (top) and descending (middle) orbit passes over northern South America, along with the combination of both (bottom) (Long et al., 1993).

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Thanks