Study of Planar Ice Crystal Orientations in Ice Clouds from Scanning Polarization Lidar Observations Export

@article{NOEL:2005:HAL-00147433:1, abstract = {{T}his paper presents a study of the orientation of ice crystals in cirrus and midlevel clouds, based on the analysis of several cases of scanning polarization lidar observations. {T}he maximum angle that crystals deviate from the horizontal plane is inferred at consecutive altitude levels by fitting angle-dependent measurements of the linear depolarization ratio and backscattered intensities to a theoretical model with a {G}aussian distribution of tilt angles. {T}he average deviation angle is linked to the angular variation of backscatter. {A} rare observation of so-called {P}arry-oriented columns is also given to highlight the different backscattering behavior with lidar angle. {F}or planar crystals, two orientation modes are found that depend on cloud temperature. {H}igh-level cold (< \~{}-30°{C}) clouds show a maximum deviation angle of \~{}1.0°, while for warmer (>\~{}-20°{C}) mi-dlevel clouds this angle averages \~{}2.0°. {T}his difference is caused by variations in particle shape and fall attitude that depend on temperature, likely involving a transition from simple plates to more widely fluttering dendrites at the warmer temperatures. {P}olarization lidar scans are clearly uniquely suited for the study of ice crystal orientations in clouds.}, author = {{n}oel, {v}incent and {s}assen, {k}enneth}, citeulike-article-id = {4828539}, citeulike-linkout-0 = {http://hal.archives-ouvertes.fr/hal-00147433/en/}, journal = {{J}ournal of {A}pplied {M}eteorology}, keywords = {cirrus, crystals, ice, lidar, microphysics, orientation}, pages = {653--664}, posted-at = {2009-06-12 18:43:44}, priority = {2}, title = {{S}tudy of {P}lanar {I}ce {C}rystal {O}rientations in {I}ce {C}louds from {S}canning {P}olarization {L}idar {O}bservations}, url = {http://hal.archives-ouvertes.fr/hal-00147433/en/}, volume = {44}, year = {2005} }

TY - JOUR ID - NOEL:2005:HAL-00147433:1 L3 - citeulike-article-id:4828539 N2 - {T}his paper presents a study of the orientation of ice crystals in cirrus and midlevel clouds, based on the analysis of several cases of scanning polarization lidar observations. {T}he maximum angle that crystals deviate from the horizontal plane is inferred at consecutive altitude levels by fitting angle-dependent measurements of the linear depolarization ratio and backscattered intensities to a theoretical model with a {G}aussian distribution of tilt angles. {T}he average deviation angle is linked to the angular variation of backscatter. {A} rare observation of so-called {P}arry-oriented columns is also given to highlight the different backscattering behavior with lidar angle. {F}or planar crystals, two orientation modes are found that depend on cloud temperature. {H}igh-level cold (< ~-30°{C}) clouds show a maximum deviation angle of ~1.0°, while for warmer (>~-20°{C}) mi-dlevel clouds this angle averages ~2.0°. {T}his difference is caused by variations in particle shape and fall attitude that depend on temperature, likely involving a transition from simple plates to more widely fluttering dendrites at the warmer temperatures. {P}olarization lidar scans are clearly uniquely suited for the study of ice crystal orientations in clouds. JF - {J}ournal of {A}pplied {M}eteorology EP - 664 TI - {S}tudy of {P}lanar {I}ce {C}rystal {O}rientations in {I}ce {C}louds from {S}canning {P}olarization {L}idar {O}bservations VL - 44 SP - 653 KW - cirrus KW - crystals KW - ice KW - lidar KW - microphysics KW - orientation AU - {n}oel, {v}incent AU - {s}assen, {k}enneth PY - 2005/// UR - http://hal.archives-ouvertes.fr/hal-00147433/en/ ER -