Environ Remote Sensing
Environ Remote Sensing ERS 186
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Dan Skiles IV
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Dan Skiles IV
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This 12 page Class Notes was uploaded by Dan Skiles IV on Tuesday September 8, 2015. The Class Notes belongs to ERS 186 at University of California - Davis taught by Staff in Fall. Since its upload, it has received 62 views. For similar materials see /class/187674/ers-186-university-of-california-davis in Environmental Resource Science at University of California - Davis.
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Date Created: 09/08/15
Russ an Santa Ana Merms and quick in review Water quality Turbid water red Vegetation green clear to turbid r150 mgL clear water blue blue green yellow red Water Quality organic constituents Plankton is the generic term used to describe all the living organisms plant and animal present in a waterbody that cannot resist the current unlike fish Plankton may be subdivided further into algal plant organisms phytoplankton animal organisms zoolankton bacteria bacteriaplankton and lower plant forms such as algal fungi Phytoplankton are small singlecelled plants smaller than the size of a pinhead Phytoplankton sink to the ocean or waterbody oor when they die All phytoplankton in water bodies contain the photosynthetically active pigment chlorpohyll a algaeladen K Water Percent Re ectance Percent Re ectance a 400 500 600 700 800 900 Wavelength mn AlgaeLaden Water with Various Suspended Sediment Concentrations Percent Re ectanc e Percent Re ectance b 400 500 600 700 800 900 Wavelength mn Percent re ectance of clear and algaeladen water based on in situ spectroradiometer measurement Note the strong chlorophyll a absorption of blue light between 400 and 500 nm and strong chlorophyll a absorption of red light at approximately 675 nm Percent re ectance of algae laden water with various concentrations of suspended sediment ranging from 0 500 mgl Chlorophyll in Ocean Water I A remote estimate of nearsurface chlorophyll concentration generally constitutes an estimate of nearsurface biomass or primary productivity for deep ocean water Where there is little danger of suspended mineral sediment contamination Numerous studies have documented a relationship between selected spectral bands and ocean chlorophyll Chl concentration using the equation Chl x Ll1LAyy Where L011 and L012 are the upwelling radiances at selected wavelengths recorded by the remote sensing system and x and y are empirically derived constants The most important SeaWiFS algorithms involve the use of band ratios of 443355 nm and 490555 nm Global Chlorophyll a gm3 Derived from SeaWiFS Imagery Obtained from September 3 1997 through December 31 1997 Truec olor SeaWjF S image of the Chlorophyll a distribution Eastern US on September 30 1997 on September 30 1997 derived from SeaWjF S data Dissolved Organic Matter I Sunlight penetrates into the water column a certain photic depth the vertical distance from the Water surface to the 1 percent subsurface irradiance level Phytoplankton Within the photic depth of the water column consume nutrients and convert them into organic matter via photosynthesis Zooplankton eat the phytoplankton and create organic matter Bacterioplankton decompose this organic matter All this conversion introduces dissolved organic matter DOM into oceanic nearshore and inland water bodies These include Humic substances and tannins In many instances there may be su icient dissolved organic matter in the water to reduce the penetration of light in the water column Stuff at the Bottom The ability to see the bottom of the water column depends on its depth and the wavelength used for sensing This is a complex problem due to atmospheric attenuation airwater boundary interface refraction and water column attenuation Water Vapor Water vapor Makes our planet unique in solar system is up to 004 of atmosphere by volume Is the key molecule in radiation transfer Is changing on small temporal and spatial scales Is needed to correct remote sensing views of earth surface Will be a measure of climate change in next century Climate System Energy Balance Re ected salar r i Outgoing longwava radiation radiatinn 1 7w 2 235w mZ Raiiectad by Eminad by the clouds aamsnl atmaspnare d atmosphere H 17 Latent 73 heat 324 Back radiation unanimousm 3 2 an In Ian was lane uaa Iloo man no 200 2400 m M Figure 3 Mommodeled decrease in radium with increase of water vapor over the mg of abimdancas encouan in the teamum atmosphere p muu myquot quot quot 39 m m m mu um um um um run mm W Figure l mu vnpux Variation of direct beam sunlight in and near an absorption band of a trace gas 0 11 przss 12 M 1000 Aquot o 1 Intensity of 1 sunligmt Water Vapor The basics behind sounding 7V1 Height or 22 atmospheric pressure p M 818p sensitivity Water Vapor The basics behind Sounding Basically absorption increases with concentration of water vapor and the thickness of the gas layer These variables determine the transmittance of thermal IR through the atmospheric pro le The atmosphere is not necessarily homogenous in its pro le and differences in the concentration and thickness of water vapor layers occur thus the transmittance will decrease more steeply in some regions of the pro le as compared to others This can be quanti ed by taking the derivative of transmittance with respect to atmospheric pressure height for different wavelengths Thus for each wavelength the radiation received back at the sensor is predominantly coming from a different altitude Moreover if the temperature at each level is known and the pressure is known than it is possible to estimate the concentration of the water vapor or other gas for that matter In fact if the bands are placed with respect to other gasses such as C02 than their concentrations can be estimated as well although one must be careful to avoid interference from other absorption features 1m mmr m m 7 m 1 w a H mm mm mm w c m lean y pm w 1 mm i quot EFINEIll 701 my 7 3 27 17 7 7 S I I eoEsra SOUNDER WATER VAPOR BANDS 11 AEVUTC 7rocT794 uwclMss Radiative Transfer through die Aimospliere Riuiiisal A vilgwiimnn bz Blah e quot is Mm Water Vapor Radiative tmnsfer equation basics Radiance leaving earihratmosphere systan is Sum Ofradlatlon emissions from earthrsurface and each atmospheric level that are anmlttedto Lop ofaimosphere Upwellmg radiance mtmslty R for cloudless atrnosphae is given by R1 Bulk BATik HG gtl p E 1quot BTkv H033 lup any surface mieainn uf szuspheric dnwnwelling where first term comes from earthrsurface second Lam om Lhe aimosphere a Weighted sum oflayaradiances and third Lam is i ored Clouds Clouds come in lots of different shapes and sizes vary over small spatial and temporal scales both high altitude and low altitude comprised of liquid water and ice mallte it dif cult to retrieve land surface features complex from a remote sensing perspective may play a critical feedback role in climate processes and global warming Clouds Remote sensing of clouds is heavily reliant on the physics of scattering In 1908 Gustav Mie showed that for a spherical scatterer the scattered radiation is a function of viewing angle index of refraction and the size parameter X 23 ZDrO Where r is the radius of the spherical scatterer Clouds consist of water drops or ice crystals with radii on the order of 10 um Drizzle is approx 100 um Raindrops are on the order of 1000 um
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