Measurements of cirrus cloud backscatter color ratio with a two-wavelength lidar

Tao, Zhi‐Yong; McCormick, M. P.; Wu, Deliang; Liu, Zhaoyan; Vaughan, Mark

doi:10.1364/ao.47.001478

Cited by 46 publications

(32 citation statements)

References 15 publications

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“…Still, the value 0.9 of β c,1 064 nm /β c,532 nm is similar to the statistical peak value 0.88 in Ref. [12]. The statistical relationship among lidar ratios, backscatter color ratios, and size distributions of cirrus cloud will be studied in detail in the future.…”

supporting

confidence: 79%

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Measurements of cirrus clouds with a three-wavelength lidar

Liu¹,

Zhong²,

Shi³

et al. 2012

中国光学快报

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A three-wavelength lidar system is set up. The backscatter signals of 355, 532, and 1 064 nm are measured simultaneously to derive the optical depth, lidar ratio, and backscatter color ratio of cirrus clouds, respectively. The lidar configuration and the data processing are described. The case study shows that the optical depths of cirrus clouds are not dependent on wavelength while the backscatter color ratios are.

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supporting

confidence: 79%

“…In this case, by calibrating the lidar signal, we use the attenuated backscatter color ratio to approximate the backscatter color ratio [12] . In conclusion, our lidar system can measure cirrus cloud backscatter signals at 355-, 532-, and 1 064-nm wavelengths simultaneously.…”

mentioning

confidence: 99%

Measurements of cirrus clouds with a three-wavelength lidar

Liu¹,

Zhong²,

Shi³

et al. 2012

中国光学快报

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“…Across the entire cloud, the integrated attenuated backscatter is nearly identical at both wavelengths of the CALIOP LIDAR. This results in a color ratio of close to unity, which is expected for cirrus clouds composed of ice crystals much larger than the CALIOP observation wavelengths (Tao et al, 2008). Similarly, the depolarization ratio is almost constant at 0.4, indicating that the cloud is comprised of ice-particles (Hu, 2007).…”

Section: Resultsmentioning

confidence: 61%

Cirrus cloud-temperature interactions in the tropical tropopause layer: a case study

2011

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Abstract. Thin cirrus clouds in the Tropical Tropopause Layer (TTL) have important ramifications for radiative transfer, stratospheric humidity, and vertical transport. A horizontally extensive and vertically thin cirrus cloud in the TTL was detected by the Cloud Aerosol LIDAR and Infrared Pathfinder Satellite Observations (CALIPSO) on 27-29 January 2009 in the Tropical Eastern Pacific region, distant from any regions of deep convection. These observations indicate that the cloud is close to 3000 km in length along the CALIPSO orbit track. Measurements over this three day period indicate that the cloud event extended over a region from approximately 15 • S to 10 • N and 90 • W to 150 • W and may be one of the most extensive cirrus events ever observed. Coincident temperature observations from the Constellation of Observing Satellites for Meteorology, Ionosphere, and Climate (COSMIC) suggest that the cloud formed in-situ as a result of a cold anomaly arising from a midlatitude intrusion. The event appears to last for up to 2 days and the temperature observations do not show any indication of the expected infrared heating. It is hypothesized that the cloud could be maintained by either nucleation of numerous small ice crystals that don't sediment or by multiple localized ice nucleation events driven by temperature variability at scales smaller than the overall cloud field, producing small icecrystal sizes which have sufficiently long residence times (≈53 h) to maintain the cloud. It is possible that the residence times are augmented by vertical motion which could also act to offset the expected infrared heating. Further observations of similar events will be required in order to conclusively explain this curious cloud.

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“…The "clear air region" is chosen from a day where there are very few aerosols present in the boundary layer, usually from an Arctic intrusion over the measurement site. The values of the calibration constants are further tested by determining the colour ratio (β 1064 / β 532 ) of cirrus clouds (Tao et al, 2008;Bi et al, 2009). This methodology was performed on each lidar system in the network.…”

Section: Calibration Of the Lidar Systemmentioning

confidence: 99%

Developing a portable, autonomous aerosol backscatter lidar for network or remote operations

Strawbridge

2013

Atmos. Meas. Tech.

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Lidar has the ability to detect the complex vertical structure of the atmosphere and can therefore identify the existence and extent of aerosols with high spatial and temporal resolution, making it well suited for understanding atmospheric dynamics and transport processes. Environment Canada has developed a portable, autonomous lidar system that can be monitored remotely and operated continuously except during precipitation events. The lidar, housed in a small trailer, simultaneously emits two wavelengths of laser light (1064 nm and 532 nm) at energies of approximately 150 mJ/pulse/wavelength and detects the backscatter signal at 1064 nm and both polarizations at 532 nm. For laser energies of this magnitude, the challenge resides in designing a system that meets the airspace safety requirements for autonomous operations. Through the combination of radar technology, beam divergence, laser cavity interlocks and using computer log files, this risk was mitigated. A Continuum Inlite small footprint laser is the backbone of the system because of three design criteria: requiring infrequent flash lamp changes compared to previous Nd : YAG Q-switch lasers, complete software control capability and a built-in laser energy monitoring system. A computer-controlled interface was designed to monitor the health of the system, adjust operational parameters and maintain a climate-controlled environment. Through an Internet connection, it also transmitted the vital performance indicators and data stream to allow the lidar profile data for multiple instruments from near ground to 15 km, every 10 s, to be viewed, in near real-time via a website. The details of the system design and calibration will be discussed and the success of the instrument as tested within the framework of a national lidar network dubbed CORALNet (Canadian Operational Research Aerosol Lidar Network). In addition, the transport of a forest fire plume across the country will be shown as evidenced by the lidar network, HYSPLIT back trajectories, MODIS imagery and CALIPSO overpasses

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Measurements of cirrus cloud backscatter color ratio with a two-wavelength lidar

Cited by 46 publications

References 15 publications

Measurements of cirrus clouds with a three-wavelength lidar

Measurements of cirrus clouds with a three-wavelength lidar

Cirrus cloud-temperature interactions in the tropical tropopause layer: a case study

Developing a portable, autonomous aerosol backscatter lidar for network or remote operations

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