en-microwave remote sensing

Kishore Kumar Parida EC200117313 [1]

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4MICROWAVE REMOTE SENSING

Microwave Remote Sensing(MRS)

Presented by

Kishore Kumar Parida EC200117313

Under the guidance ofMr. Rowdra Ghatak


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What is microwave remote sensing?

•A special application of microwave communications technologies for the purpose of collecting geophysical information about targets (objects and media) without making physical contact.

•Microwave reflections or emissions from earth materials bear no direct relationship to their counterparts in the visible portions of the spectrum.


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•There is an interaction between the EM waves and matter.

•The target imposes a modulation on the EM wave which becomes its identifying characteristics.

•Sensors use microwave communications technologies.

•Active (radar) and passive (microwave radiometry) measurements.

How does it work?


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•Passive: uses natural energy, either reflected sunlight or emitted thermal or microwave radiation

•Active: sensor creates its own energy

•Transmitted toward Earth

•Interacts with atmosphere and/or surface

•Reflects back toward sensor (backscatter)

Active and Passive Microwave Sensors


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In the microwave region of the EM spectrum, the power collected by a microwave antenna is:

P blackbody = k Tb * bandwidth

Microwave Brightness Temperature, Tb, of a media is the product of the media emissivity and its physical temperature. For blackbodies, = 1.0Tb = * T phys

Microwave Radiometry


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Microwave Radiometer

KB*(receiver gain)

Tsys = Radiometer Output power

Tsys = T ant + T RecWhere K=Boltzman’s constant

B=bandwidth

TRec = (1-NF)*290 K; NF=Receiver noise figure

Tant= scene brightness temp collected by antenna

Resistor noise

Antenna Receiver

Square Law detector

LPF

Trec

+


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Radiative Transfer Theory

The TB measured by spaceborne radiometer is the linear sum of individual contributions from the atmosphere and surface


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Defense Meteorological Support Program (DMSP)


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Three Day Average of Some MRS Parameters


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What is a Microwave Scatterometer?

•A special purpose radar sensor that measures scattering from the earth’s surface i.e., a scatter-meter

•If the objects are having smaller wavelengths,then scattering occurs


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Satellite Microwave Scatterometer

Pr = Pt * σWhere σ = ocean Scattering coeff. Or Normalized radar Cross-section


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Scatterometer Applications

•Ocean Wind Vector (wind speed & direction)• Hurricanes & Typhoons• Sea Ice Imaging• Land Imaging


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Antarctic Sea Ice Imaging


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Tropical Rainfall Measuring Mission (TRMM)

• Microwave remote sensing of rainfall• TRMM Microwave (Radiometer) Imager• Precipitation Radar


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Greenland Ice Melt - 4 day intervals


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Precipitation Radar - Hurricane Rainfall Image


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Synthetic Aperture Radar

•Generally refers to the case of a moving radar and a stationary target- usually an extended scene, such as the surface of the Earth.

•ISAR refers to the case in which the radar is relatively stationary and a rotating target provides all(or most) of the motion to create the synthetic aperture.


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Comparison Between RAR and SAR


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SAR Modes


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Side-Looking Radar System


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SLR Operation


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Conclusion

•microwave sensors provide valuable geophysical measurements• Remote sensing satellites provide global coverage each day• Day/night all weather• Atmosphere• Water vapor, cloud liquid water, precipitation• Sea Ice and land snow cover• Ocean• Surface winds, sea surface temperature


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REFERENCES

[1] Lillesand Thomas M. and Ralph W. Kiefer,”Remote Sensing and Image Interpretation”, fourth edition, chapter 8,pp. 616-692

[2] Sullivan Roger J., “Radar Foundations for Imaging and Advanced Concepts”, Chapter 7, pp.191-194

[3] http://www.engr.ucf.edu/centers/cfrsl/[4] http://trmm.gsfc.nasa.gov/[5] Ulaby, F.T., R.K.Moore, and A.K.Fung, Microwave Remote

Sensing: Active and Passive, Addison-Welsey, Reading, MA; vol.1: Microwave Remote Sensing Fundamentals and Radiometry, 1981;vol. II: Radar Remote Sensing and Surface Scattering and Emission Theory, 1982;vol. III.


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THANK YOU

en-microwave remote sensing

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