A Polarimetric Scattering Database for Non-spherical Ice...
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A Polarimetric Scattering Database for Non-spherical Ice Particles at Microwave Wavelengths Zhiyuan Jiang 1 , Yinghui Lu 1,2 , Kültegin Aydin 1 , Johannes Verlinde 1 , Eugene E. Clothiaux 1 , and Giovanni Botta 1,3 1 The Pennsylvania State University, 2 Now at Lawrence Berkeley National Lab, 3 Now at Google Introduction & Motivation Description of Database Results from the Database Summary Single scattering albedo Asymmetry parameter Backscattering cross section Extinction cross section Absorption cross section Scattering cross section Amplitude scattering matrices References: Liu, G., 2008: A database of microwave single-scattering properties for nonspherical ice particles. Bull. Amer. Meteor. Soc., 89, 1563–1570, doi:10.1175/2008BAMS2486.1. Acknowledgements: We would like to thank Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program for hosting the database. Development of the database was supported primarily by NSF Grant AGS-128180. Eugene E. Clothiaux’s contributions to the database were supported by DOE Grant DE-FG02-05ER64058. The authors would like to acknowledge high- performance computing support from Yellowstone provided by NCAR’s Computational and Information Systems Laboratory. Portions of this research were conducted with Advanced CyberInfrastructure computational resources provided by the Institute for CyberScience at The Pennsylvania State University. Scattering properties of ice particles at microwave frequencies are necessary to • retrieve ice-particle physical properties from radar and radiometer observations, • evaluate model microphysics by application of forward operators to their outputs and comparison to observations, and • assimilate active and passive microwave observations in numerical models. Motivated by and complementing previous databases of ice-particle scattering properties, we developed a database containing polarimetric single-scattering properties of aggregates, branched planar crystals, plates, columns, and conical graupel at X- (9.4GHz), Ku- (13.4GHz), Ka- (35.6GHz), W- (94.0GHz) band wavelengths. Units Range agg. den. plate column graupel Incident polar angles degrees min 0 0 0 0 0 max 180 90 90 90 180 inc. 10 10 10 10 10 Incident azimuth angles min 0 0 0 0 0 max 340 30 30 90 0 inc. 20 30 30 10 0 Scattering polar angles min 0 max 180 inc. 1 Scattering azimuth angles min 0 max 355 inc. 5 Database is available at: http://dx.doi.org/10.5439/1258029 Figure 1. Examples of a) an aggregate composed of stellar monomers, b) an aggregate composed of column monomers, c) a branched planar crystal, d) a plate, e) a column and f) a conical graupel particle. Table 2. Matrix of incident and scattered radiation directions for scattering property calculations of different types of ice particles. Table 1. Scattering properties stored in the database. A function of incident direction A function of incident & scattered direction Polarization dependent Figure 2. Database branched planar crystal (a 1 ,b 1 ) scattering cross sections, (a 2 ,b 2 ) backscattering cross sections and (a 3 ,b 3 ) asymmetry parameters for incident h-polarized radiation versus size parameter 2πr e /λ, where λ is the wavelength of the incident radiation and r e is the radius of a solid (0.917 g/cm 3 ) ice sphere with mass equal to that of the crystal. The solid lines represent the results for (blue) sector snowflakes and (red) dendrite snowflakes from Liu (2008). Figure 3. a) Morphology of a branched planar example crystal in the database. b) The phase function p (grey dots) of the example crystal as a function of scattering polar angle θ sca for incident radiation with θ p inc =60º and ϕ p inc =0º; for each scattering polar angle θ sca there are 72 grey dots, representing values for each of the 72 different scattering azimuth angles ϕ sca . The phase function averaged over the 72 values of ϕ sca is represented by the solid red line. The dashed red and blue lines represent the phase functions of the sector snowflake and dendrite snowflake from Liu (2008) with a similar maximum dimension. c) The phase function p of the example crystal for (blue) θ sca =60º and (red) θ sca =120º as a function of scattering azimuth angle ϕ sca for incident radiation with θ p inc =60º and ϕ p inc =0º. d) The phase functions p (averaged over scattering azimuth angle ϕ sca ) of the example crystal as a function of scattering polar angle θ sca for radiation with incident polar angles θ p inc =0º, 30º, 60º, and 90º and with incident azimuth angle ϕ p inc =0º. The scattering results were obtained at the W-band wavelength. A database of single-scattering properties of ice particles at millimeter to centimeter wavelengths is presented. Branched planar crystals, plates, columns, aggregates, and conical graupel are generated and their single-scattering properties calculated. In addition to the scattering properties of each ice particle, including their amplitude scattering matrices as a function of incident and scattered directions that provide full polarization information, the database also contains the physical properties of each ice particle, including the location of each ice particle component, together with imagery of it. Total number Aggregates: 660 Branched planars: 405 Plates: 44 Columns: 30 Graupel: 640 Detailed physical properties of each ice particle are stored in the database. Incident and Scattered Directions x x z z y y x x x x y y y y z z z z a) b) c) f) e) d) Manuscript is available at: http ://www.atmos-meas-tech-discuss.net/amt-2016-228/#discussion
Transcript of A Polarimetric Scattering Database for Non-spherical Ice...
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A Polarimetric Scattering Database for Non-spherical Ice Particles at Microwave Wavelengths
Zhiyuan Jiang1, Yinghui Lu1,2, Kültegin Aydin1, Johannes Verlinde1, Eugene E. Clothiaux1, and Giovanni Botta1,31The Pennsylvania State University, 2Now at Lawrence Berkeley National Lab, 3Now at Google
Introduction & Motivation
Description of Database
Results from the Database
Summary
Single scattering albedo
Asymmetry parameter
Backscattering cross section
Extinctioncross section
Absorption cross section
Scattering cross section
Amplitudescattering matrices
References:Liu, G., 2008: A database of microwave single-scattering properties for nonspherical ice particles.Bull. Amer. Meteor. Soc., 89, 1563–1570, doi:10.1175/2008BAMS2486.1.
Acknowledgements: We would like to thank Department of Energy (DOE) Atmospheric RadiationMeasurement (ARM) Program for hosting the database. Development of the database wassupported primarily by NSF Grant AGS-128180. Eugene E. Clothiaux’s contributions to the databasewere supported by DOE Grant DE-FG02-05ER64058. The authors would like to acknowledge high-performance computing support from Yellowstone provided by NCAR’s Computational andInformation Systems Laboratory. Portions of this research were conducted with AdvancedCyberInfrastructure computational resources provided by the Institute for CyberScience at ThePennsylvania State University.
Scattering properties of ice particles at microwave frequencies are necessary to• retrieve ice-particle physical properties from radar and radiometer
observations,• evaluate model microphysics by application of forward operators to their
outputs and comparison to observations, and• assimilate active and passive microwave observations in numerical models.Motivated by and complementing previous databases of ice-particle scatteringproperties, we developed a database containing polarimetric single-scatteringproperties of aggregates, branched planar crystals, plates, columns, and conicalgraupel at X- (9.4GHz), Ku- (13.4GHz), Ka- (35.6GHz), W- (94.0GHz) bandwavelengths.
UnitsRange
agg. den. plate column graupel
Incident polar angles
degrees
min 0 0 0 0 0max 180 90 90 90 180inc. 10 10 10 10 10
Incident azimuth anglesmin 0 0 0 0 0max 340 30 30 90 0inc. 20 30 30 10 0
Scattering polar anglesmin 0max 180inc. 1
Scattering azimuth anglesmin 0max 355inc. 5
Database is available at: http://dx.doi.org/10.5439/1258029
Figure 1. Examples of a) an aggregate composed of stellar monomers, b) anaggregate composed of column monomers, c) a branched planar crystal, d) aplate, e) a column and f) a conical graupel particle.
Table 2. Matrix of incident and scattered radiation directions for scattering property calculations of different types of ice particles.
Table 1. Scattering properties stored in the database.
A function of incident directionA function of incident & scattered direction
Polarization dependent
Figure 2. Database branched planar crystal (a1,b1) scattering cross sections, (a2,b2)backscattering cross sections and (a3,b3) asymmetry parameters for incident h-polarizedradiation versus size parameter 2πre/λ, where λ is the wavelength of the incidentradiation and re is the radius of a solid (0.917 g/cm
3) ice sphere with mass equal to that ofthe crystal. The solid lines represent the results for (blue) sector snowflakes and (red)dendrite snowflakes from Liu (2008).
Figure 3.a) Morphology of a branched planar example crystal in the database.b) The phase function p (grey dots) of the example crystal as a function of scattering polarangle θsca for incident radiation with θp
inc=60º and ϕpinc=0º; for each scattering polar angle
θsca there are 72 grey dots, representing values for each of the 72 different scatteringazimuth angles ϕsca. The phase function averaged over the 72 values of ϕsca isrepresented by the solid red line. The dashed red and blue lines represent the phasefunctions of the sector snowflake and dendrite snowflake from Liu (2008) with a similarmaximum dimension.c) The phase function p of the example crystal for (blue) θsca=60º and (red) θsca=120º as afunction of scattering azimuth angle ϕsca for incident radiation with θp
inc=60º and ϕpinc=0º.
d) The phase functions p (averaged over scattering azimuth angle ϕsca) of the examplecrystal as a function of scattering polar angle θsca for radiation with incident polar anglesθp
inc=0º, 30º, 60º, and 90º and with incident azimuth angle ϕpinc=0º. The scattering results
were obtained at the W-band wavelength.
A database of single-scattering properties of ice particles at millimeter tocentimeter wavelengths is presented. Branched planar crystals, plates, columns,aggregates, and conical graupel are generated and their single-scattering propertiescalculated. In addition to the scattering properties of each ice particle, includingtheir amplitude scattering matrices as a function of incident and scattereddirections that provide full polarization information, the database also contains thephysical properties of each ice particle, including the location of each ice particlecomponent, together with imagery of it.
Total number
Aggregates: 660
Branched planars: 405
Plates: 44
Columns: 30
Graupel: 640
Detailed physical properties of each ice particle are stored in the database.
Incident and Scattered Directions
x x
z z
y y
x x x xy y y y
z z z z
a) b)
c) f)e)d)
Manuscript is available at: http://www.atmos-meas-tech-discuss.net/amt-2016-228/#discussion
