Characteristics of cirrus clouds and its radiative properties based on lidar observation over Chung-Li, Taiwan

Das, Subrata Kumar; Chiang, Chih-Wei; Nee, J. B.

doi:10.1016/j.atmosres.2009.02.008

Cited by 32 publications

(33 citation statements)

References 58 publications

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“…To clearly differentiate a cirrus cloud from a water cloud we considered two conditions, a limit for the cloud base height and its correspondent temperature. For example, Das et al (2009) considered lidar signals only above 8 km. In our case those signals displaying a cloud base below 7.5 km were discarded.…”

Section: Signal Analysis Selection Of the Cirrus Clouds And Determinmentioning

confidence: 99%

Towards an automatic lidar cirrus cloud retrieval for climate studies

et al. 2013

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Abstract. This paper presents a methodology to calculate lidar ratios for distinct cirrus clouds that has been developed and implemented for a site located in the Southern Hemisphere. The cirrus cloud lidar data processing aims to consider a large cloud variability and cirrus cloud monitoring through a robust retrieval process. Among cirrus features estimates for complex scenes that lidar systems can provide, we highlight cloud geometrical information and extinctionto-backscatter ratio (known as lidar ratio or LR). In general, direct information on cirrus cloud microphysics is difficult to derive because LR depends on the presence of ice crystals and their properties such as shape, size, composition and orientation of particles. An iterative process to derive a stable LR value has been proposed. One of the keys is to restrict the analysis to conditions allowing accurate multilayer events. This method uses nonparametric statistical approaches to identify stationary periods according to cloud features and variability. Measurements performed in the region of the metropolitan city of São Paulo (MSP) have been used to implement and test the methodology developed for cirrus cloud characterization. Good results are represented by examining specific cases with multilayer cirrus cloud occurrence. In addition to the geometrical parameters obtained, cirrus LR values were calculated for a single day ranging from 19 ± 01 sr to 74 ± 13 sr for 2 observed layers. This large difference in LR can indicate a mixture of ice crystal particles with different sizes and shapes in both layers of the cirrus clouds. Trajectory analyses indicate that both of these cloud layers can be associated with different air mass and should be considered as 2 distinct clouds in climatology.

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Section: Signal Analysis Selection Of the Cirrus Clouds And Determinmentioning

confidence: 99%

Towards an automatic lidar cirrus cloud retrieval for climate studies

et al. 2013

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“…This algorithm was proven its robustness to inverse the lidar equation such as demonstrated in previous studies with applications on cloud characteristics (Das et al, 2009;Di Donfrancesco et al, 2006;, desert dust layer (Mona et al, 2012), volcano ash plume (Marenco et al, 2011) or smoke plume Vadrevu et al, 2012).…”

Section: Lidar Inversion Methodologymentioning

confidence: 98%

Evaluation of wildland fire smoke plume dynamics and aerosol load using UV scanning lidar and fire–atmosphere modelling during the Mediterranean Letia 2010 experiment

Leroy-Cancellieri

Augustin

Filippi

et al. 2014

Nat. Hazards Earth Syst. Sci.

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Abstract. Vegetation fires emit large amount of gases and aerosols which are detrimental to human health. Smoke exposure near and downwind of fires depends on the fire propagation, the atmospheric circulations and the burnt vegetation. A better knowledge of the interaction between wildfire and atmosphere is a primary requirement to investigate fire smoke and particle transport. The purpose of this paper is to highlight the usefulness of an UV scanning lidar to characterise the fire smoke plume and consequently validate fireatmosphere model simulations.An instrumented burn was conducted in a Mediterranean area typical of ones frequently subject to wildfire with low dense shrubs. Using lidar measurements positioned near the experimental site, fire smoke plume was thoroughly characterised by its optical properties, edge and dynamics. These parameters were obtained by combining methods based on lidar inversion technique, wavelet edge detection and a backscatter barycentre technique. The smoke plume displacement was determined using a digital video camera coupled with the lidar.The simulation was performed using a mesoscale atmospheric model in a large eddy simulation configuration (Meso-NH) coupled to a fire propagation physical model (ForeFire), taking into account the effect of wind, slope and fuel properties. A passive numerical scalar tracer was injected in the model at fire location to mimic the smoke plume. The simulated fire smoke plume width remained within the edge smoke plume obtained from lidar measurements. The maximum smoke injection derived from lidar backscatter coefficients and the simulated passive tracer was around 200 m. The vertical position of the simulated plume barycentre was systematically below the barycentre derived from the lidar backscatter coefficients due to the oversimplified properties of the passive tracer compared to real aerosol particles. Simulated speed and horizontal location of the plume compared well with the observations derived from the videography and lidar method, suggesting that fire convection and advection were correctly taken into account.

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“…As previously reported, cirrus clouds in the UT are often observed [1]. For stable clouds, the terminal velocities can be measured and used for deriving the ice crystal properties [1][2].…”

Section: Introductionmentioning

confidence: 90%

“…The lidar facility used to detect the cirrus cloud has been reported before [1][2]. Briefly, a laser at 532 nm operated at 30 Hz frequency is sent into the atmosphere in the zenith direction.…”

Section: Instrument and Methodology: Lidar System For Cirrus Researchmentioning

confidence: 99%

Measurements of Terminal Velocities of Cirrus Clouds in the Upper Trosphere

Nee

Chen

Chiang

et al. 2016

EPJ Web of Conferences

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Cirrus clouds are composed of ice crystals condensed from humidity due to low temperature condition in the upper atmosphere. The microphysics of cirrus clouds including sizes and shapes of ice particles are not well understood but are important in climate modeling. Ice crystal will fall under gravitational sedimentation to reach terminal velocities which depend on the size, mass, and ice habit. We studied here the terminal velocity of cirrus clouds by using lidar observations at Chungli (25N, 121E). The terminal velocities for a few cases of stable cirrus clouds are measured to determine the ice particle sizes and processes in the upper atmosphere.

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Characteristics of cirrus clouds and its radiative properties based on lidar observation over Chung-Li, Taiwan

Cited by 32 publications

References 58 publications

Towards an automatic lidar cirrus cloud retrieval for climate studies

Towards an automatic lidar cirrus cloud retrieval for climate studies

Evaluation of wildland fire smoke plume dynamics and aerosol load using UV scanning lidar and fire–atmosphere modelling during the Mediterranean Letia 2010 experiment

Measurements of Terminal Velocities of Cirrus Clouds in the Upper Trosphere

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