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Microwave Emission Signature of Snow-Covered Lake Ice

Microwave Emission Signature of Snow-Covered Lake Ice. Martti Hallikainen (1) , Pauli Sievinen (1) , Jaakko Seppänen (1 ) , Matti Vaaja (1) , Annakaisa von Lerber (1) , Erkka Rouhe (1) , Juha Lemmetyinen (2) (1) Aalto University School of Electrical Engineering

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Microwave Emission Signature of Snow-Covered Lake Ice

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  1. Microwave Emission Signature of Snow-Covered Lake Ice Martti Hallikainen(1), Pauli Sievinen(1), Jaakko Seppänen(1), Matti Vaaja(1), Annakaisa von Lerber(1), Erkka Rouhe(1), Juha Lemmetyinen(2) (1)Aalto University School of Electrical Engineering (2)Finnish Meteorological Institute International Geoscience and Remote Sensing Symposium 2011 IGARSS 2011

  2. Contents Testsite and data collection Experimental data: - Brightnesstemperature (TB) values - TB differencesbetweenselectedfrequencies - TB differencesbetweenvertical and horizontalpolarization Conclusions IGARSS 2011

  3. TestSite Located in the Greater Helsinki areanotfarfromAirport Lake Bodom (larger) and Matalajärvi (smaller and shallow; freezesearlier) Data overlandcollected in order to compareresults for snow-covered ice vs. snow-covered terrain Scale: lowerleft

  4. AirborneRadiometers HUTRAD Non-ScanningRadiometer HUT-2D Interferometer 6.8, 10.65, 18.7, 23.8, 36.5 and 94 GHz 1.4 GHzdual-pol 50 degoffnadir, V and H polarization Data averagedover the Antennabeam 3.2 to 5 deg 0 to 5 degrange kkkkkkkkkkkkkkkkkkkkkkkkkkkk

  5. Airborne Data Collection Flightaltitude: 300 m and 150 m 5 overpasses at eachaltitude Accurate localization of footprint using aircraft attitude and position Averagedbrightnesstemperaturesused in thispresentation Data collection

  6. OffTrackError: MostlyBelow 20 m

  7. Airborne Data 2004: April 7 2007: January 30, March 20, March 26, April 2 2011: January 27, February 28, March 31 (am/pm), April 14 Data includedrysnowconditions and snow/icemeltingperiod Data collectedwith HUTRAD radiometer (6.8 to 36.5 / 94 GHz) April 14, 2011 data collectedwith HUTRAD and HUT-2D (1.4 GHz) Resultsfrom 2011 flightsdiscussed in thispresentation

  8. In Situ Data Snowtemperatureprofile Snowdensityprofile Snowwetnessprofile Snowdepth Ice thickness Presence of water on ice These data collectedevery 100 m (exceptApril 14, 2011) Additionally, snowgrainsize in selectedlocations

  9. Example of In Situ Data: Temperature

  10. In Situ Data: Snow-Ice Structure

  11. ResultsfromRadiometerMeasurements Brightnesstemperatures at 6.8, 10.65, 18.7 and 36.5 GHz (April 14: also 1.4 GHz) (18.7 GHz: occasionalinterference) Horizontalpolarization (V-polnotshown) TB differencesbetween 18.7 / 36.5 GHz, and 6.8 / 36.5 GHz TB differencesbetweenvertical and horizontalpolarization at eachfrequency (except 1.4 GHz)

  12. Jan 27, 2011, H-Pol, Alt 300 m Lake Bodom: Someslushbelowsnowlayer =>TB36 higher than on Lake Matalajärvi

  13. Feb 28, 2011, H-Pol, Alt 300 m Mostlydrysnow / ice Occasionalwater => TB6 is low

  14. March 31 AM, 2011, H-Pol, Alt 300 m Dryrefrozensnow on top of ice => TB36 is low

  15. March 31 PM, 2011, H-Pol, Alt 300 m Snow top layergettingmoist => TB36 higher, but TB6 ~same as AM

  16. April 14, 2011, H-Pol, Alt 300 m Practically no snow on top of wetslushy ice layer 1.4 GHz: TB higher for Lake Matalajärvi (no in situ data available)

  17. HUT-2D Image on April 14, 2011 Brightnesstemperature for Lake Matalajärvi is higherthanthat for Lake Bodom

  18. Jan 27, 2011, TBH:18-36 and 6-36, Alt 300 m

  19. Feb 28, 2011, TBH: 18-36 and 6-36, Alt 300 m m

  20. March 31, 2011 AM, TBH: 18-36 and 6-36, Alt 300 m Dryrefrozensnow on top of ice => low TB36 valuesmake TB18–TB36 high

  21. March 31, 2011 PM, TBH: 18-36 and 6-36, Alt 300 m Kkkk

  22. Jan 27, 2011, V-H, Alt 300 m

  23. Feb 28, 2011, V-H, Alt 300 m Kkkk Kkkkk

  24. March 31 AM, 2011, V-H, Alt 300 m Kkkk

  25. March 31 PM, 2011, V-H, Alt 300 m

  26. April 14, 2011, V-H, Alt 300 m

  27. Conclusions An extensiverange of frequencieswasused for lake ice observations 36.5 GHzprovidesinformation on drysnow, whereaslowfrequencypenetrationprovidesinformation on water at snow/iceinterface Observedbrightnesstemperaturevariation is substantialwithin Lake Bodomdue to occasionalpresence of water on top of ice Brightnesstemperature for adjacent Lake Matalajärvi is differentfromthat for Lake Bodom, obviouslydue to beingshallow IGARSS 2011

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