ã2017CaliforniaInstituteofTechnology.Governmentsponsorshipacknowledged.

NISAR:TheNASA-ISROSARMission

MonitoringForestDisturbanceTomanage our forests optimally to sustain the desiredbenefitsasamulti-facetedresourcerequiresknowledgeof how forests changeover time in response to naturaldisturbances and management activities. Forestdisturbancesincludebothstressesanddestructiveagents;

these include invasive species, diseases aswell as plantand animal pests; fire; changes in climate and seriousweather events such as tornadoes, hurricanes and icestorms; pollution of the air, water, and soil; real estatedevelopmentofforestlands;andtimberharvest.

MonitoringGlobalForestResources

NISARwillprovidenoveldataformappingandmonitoringoftheUnitedStates’ and international forest resources. The timber industry, forestservices,andnaturalresourcemanagersalikewillbenefitfromthe12-day-repeat,all-weathermappingcapabilityofglobalforestcoverchange.

Forests as a Multi-Faceted Resource

Forestshave apivotal role asa renewablenatural resource. Asdemand for forestproducts and thecompetition for forest landare increasing, modern timber management is committed tosustainableforestmanagement.Currently,timberhasmorethan30,000 applications worldwide. Also, non-timber products areharvested in forests, likeotherplants for foodormeatof gameanimals. In addition to the productive function of forests, theyhaveacentralroleintheprotectionandstabilizationofthenaturalenvironmentorrealestate,likewatercirculation,airpurification,or soil erosion protection. Forests are key to sustain crucialbiodiversity and enhance conditions for agricultural production.Forestsalsoserveasocialfunctionasarecreationalresource,animportant labor market, living space, and enhance nationaldefense.

TheNISARMission–PulsedRadarwithPicosecondPrecisionAcriticalpartofanyradarsysteminspace,isthecontrolandmaintenanceof timing of the radar pulses that are sent out and received. Timingaccuraciesontheorderofpicosecondsarenotuncommoninsuchsystems,andisnecessarytomaintainthroughoutthemanysubsystemsthatmakeuptheinstrument.ShownatleftisaprototypeoftheNISARControlandTimingBoard (CTB) that is used by engineers for system testing and in theconstructionofanengineeringmodelthatprecedestheconstructionoftheflightunitthatwillultimatelyoperateinspace.

ã2017CaliforniaInstituteofTechnology.Governmentsponsorshipacknowledged.

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Withtheworld’spopulationcriticallydependentonsustainably managed and utilized forest resources,the need is greater now than ever before for theapplicationofmoderntechnologytoprovidedetailedand timely informational map data to the timberindustry, resource managers and forest policymakers.Amongthetechnicaltoolsthatareusedtoaddress these issues are the satellites that providesynopticviewsof theglobe fromspace. Resourcessuch as this are routinely used to guide policydecision-makersandcommercial interestsalike, forexample, in order to plan forest managementactivities, support preparation of information forforest real estate transactions domestically and inforeigncountries,andtomonitortheeffectsofforestpolicychangeslikeloggingconcessionsortrackillegallogginginadynamicglobalmarketplace.The upcoming NISAR mission will address theseneedsthroughadependableobservingstrategythat

willcollecthighresolution(25m) imageryover90%oftheEarth’slandsurfacesthirtytimesperyear.Theuseofactivelygeneratedmicrowavesignals(L-andS-band, or equivalently, 24 cm and 10 cmwavelength)onboard the satellite,means that theobservations will be able to be reliably planned,collected and distributed at time scales that arecommensurate with the satellite’s 12-repeat cycle.SARimagesfromsatellitessuchasNISARareknownfortheirabilitytopenetratethroughcloudsandtheirday/night imaging capability. Hence even undernear-perpetualdensetropicalorfrequenttemperatecloud cover that are characteristicsof global forestecosystems, SAR imagery will provide bi-weeklyobservations that complement optical data andprovideindependentinformationthatissensitivetothemappingofforestdisturbance,includingbelow-canopy inundation from natural and catastrophicfloodingevents.

NationalAeronauticsandSpaceAdministration Formoreinformation,visithttp://nisar.jpl.nasa.gov/applications

JetPropulsionLaboratory/CaliforniaInstituteofTechnology/Pasadena,California/www.jpl.nasa.gov

ImageData©JAXA/METI2007-2009.ImageProcessing:EarthBigData,LLC.

Observations of the Earth’s land surfaces from space using activemicrowavesensorsallowsforreliableandrepeatedmeasurementstobemadeevenunderdensecloudcover.Whenforestscanopiesaredisturbed,suchthatstandingtreesarepartiallyorwhollyfelledorremoved,orsignificantfractionsoftheuppercanopyarelost,e.g.inaforestfire,arichvarietyofradarsignalsaremeasuredresultingincharacteristicvariationsinpolarizationandfrequencysignatures.Such observations can beused todetermine both the timing andextentofforestcoverchangeinanobservedtimeseries.Shown at right are data collected by the Japanese ALOS satellitemissionoperatingfrom2006to2011.Theimageisathree-datecolorcompositewhereradarsignaturesresultincolorcombinationsthatare directly related to various types of forest disturbance andregrowth.TheNISARmissionwillprovidedataofsimilarquality,yetatgreaterobservationfrequencyandeasydataaccessbyU.S.timberindustry,naturalresourcemanagers,naturaldisasterpreventionandresponseteams, researchers, andpolicy decisionmakers. Thedatawill be acritical complement to the U.S. global land observing system byprovidingroutine,global,cloud-freeforestmonitoringcapacity.

Three-date (2007, 2008, 2009) L-Band radar image of timberproduction land in southern Louisiana, one of themost intensivetimberproductionareasoftheUnitedStates.Redandyellowcolorsreadily show various dates and intensities of forestmanagementactivities (clear-cut and selective logging). Blue and purple colorsshowareasandstageofre-growingforestplantations.

Radar Imaging of Forest Disturbance