By now, the global impacts of atmospheric dust have been well-established. Nevertheless, relevant properties such as size distribution, depolarization ratio, and even single-scattering albedo have been shown to vary substantially between dust producing regions and are also strongly dependant on the conditions under which the dust is emitted. Even greater variations have been documented during the process of long-range transport. With continued improvement of detection technologies, research focus is increasingly turning to refinement of our knowledge of these properties of dust in order to better account for the presence of dust in models and data analysis. The purpose of this study is to use a combination of lidar data and models to directly observe the changing properties of dust layers as they are transported from their origin in the Taklamakan Desert of western China. With the co-operation of the Xinjiang Institute of Ecology and Geography, a portable micropulse lidar system was installed at Aksu National Field on the northern edge of the Tarim Basin in late April 2013, during the Spring dust storm season. Over six days, data were collected on the optical properties of dust emissions passing over this location. The measurements of this lidar have shown the dust over Aksu on these days to have a significantly higher depolarization ratio than has been previously reported for the region. Model results show this dust was then transported across the region at least as far as Korea and Japan. Models from the Naval Aerosol Analysis and Prediction System (NAAPS) show that during transport the dust layers became intermixed with sulfate emissions from industrial sources in China as well as smoke from wildfires burning in south-east Asia and Siberia. The multi-wavelength raman-elastic lidar located in Gwangju South Korea was used to observe the vertical structure of the layers as well as optical properties such as colour ratio, depolarization ratio and extinction coeffcient after regional-scale transportation and mixing with other aerosols. By comparing the observations of the Gwangju lidar with those taken near the source at Aksu, we investigate the extent of the change in optical properties of the dust layers over time. There is some evidence that the layers were also transported in some form to North America but these observations are preliminary and will require further investigation.
Generating highly validated and well-resolved vertical profiles of water vapor is crucially important to understand short
and long term global climate changes. Latest results of a newly developed water vapor Raman lidar instrument at the
Environment Canada’s Centre for Atmospheric Research Experiments (CARE) (44°14'02" North, 79°45'40" West) will
be presented. The CARE Raman lidar setup utilizes third harmonic (355 nm) output of employed YAG laser to probe
aerosols, water vapor, and nitrogen profiles. By manipulating inelastic backscattering lidar signals of the Raman nitrogen
channel (386.7 nm) and Raman water vapor channel (407.5 nm), vertical profiles of water vapor mixing ratio (WVMR)
from the near ground up to 9 km geometrical altitude are routinely deduced, calibrated, validated, and compared against
WVMR profiles obtained from simultaneously performed and collocated radiosonde launches. Seasonal effects and
variations of WVMR will be also discussed and related to Raman lidar setup efficiency.
Obtaining high resolution vertical profiles of water vapor is crucially important to understand short and long term global
climate changes. Raman lidar technique is widely recognized as the most effective tool to study water vapor and aerosols
profiles in the lower atmosphere. The Great lakes area is one of the ideal areas to study the environmental impact of
water vapor and aerosols profiles on air quality due to its dynamic ecological system, and proximity to most North
American industrial centers. Latest results of a newly developed water vapor Raman lidar instrument at the Environment
Canada's Centre for Atmospheric Research Experiments (CARE) (44°14'02" North, 79°45'40" West) will be presented.
In this study, the instrument is described and its capabilities are illustrated along with preliminary measurements. The
CARE Raman lidar setup utilizes third harmonic (355 nm) output of employed YAG laser to probe aerosols, water
vapor, and nitrogen profiles. By manipulating inelastic backscattering lidar signals of the Raman nitrogen channel (386.7
nm) and Raman water vapor channel (407.5 nm), a vertical profile of water vapor mixing ratio from the near ground up
to 12 km geometrical altitude is deduced. Vertical profile of the backscattering ratio obtained at 1064 nm using another
elastic lidar will be shown and related to the Raman lidar results.
A new lidar instrument, dubbed AeRO (Aerosol Raman Ozone) Lidar, is being developed at Environment Canada's
Centre For Atmospheric Research Experiments (CARE). The new system will use three lasers to simultaneously
measure ozone, water vapour and aerosol profiles (including extinction) from near ground to the tropopause. The main
thrust will focus on understanding Air Quality within the airshed with the capability of looking at Stratospheric
Tropospheric Exchange (STE) processes to determine the magnitude and frequency of such events leading to elevated
levels of tropospheric ozone. In addition a wind profiler through a partnership with University of Western Ontario will
soon be deployed to CARE to provide complementary observations of the tropopause. The lidar participated in the
ARC-IONS field campaign during April and July of 2008. During the field campaign, daily ozonesondes were released
to further compliment the lidar measurements. Details of the system design and preliminary results from the lidar
measurements will be presented.
The remote sensing techniques of Lidar and Sunphotometry are well suited for understanding the optical characteristics
of aerosol layers aloft. Lidar has the ability to detect the complex vertical structure of the atmosphere and can therefore
identify the existence and extent of aerosols that have undergone long-range transport. Inversion techniques applied to
Sunphotometry data can extract information about the aerosol fine and coarse modes. As part of the REALM network
(Regional East Atmospheric Lidar Mesonet), routine measurements are made with a vertically-pointing lidar at the
Centre For Atmospheric Research Experiments (CARE). In addition, a CIMEL sunphotometer resides at CARE (part of
AERONET) yielding an opportunity to achieve an optical climatology of aerosol activity over the site. Environment
Canada's mobile lidar facility called RASCAL (Rapid Acqusition SCanning Aerosol Lidar), operating in zenith mode
only, was also deployed to Western Canada during the months of March and April, 2005 to provide an opportunity to
measure the long-range transport of trans-Pacific pollutants that impact the coastal areas of British Columbia frequently.
During that time a long-range transport event was observed on 13-14 of March 2005. Further analysis has shown the
event originated from North African dust storms during the period 28 February to 3 March. The optical coherency of
these active and passive remote sensors will be presented, along with other supporting observations, for forest fire smoke
plumes transported over CARE (in 2003) and the first documented case of Saharan dust to impact Western North
America.
A mobile scanning lidar facility called RASCAL (Rapid Acquisition SCanning Aerosol Lidar) was involved in a measurement campaign in the interior British Columbia and coastal areas, including the Gulf Islands. RASCAL was part of a tandem of highly specialized vehicles providing mobile measurements using dual-wavelength scanning lidar technology and a sophisticated high temporal resolution chemistry package providing real-time in-situ measurements. The synergistic approach allowed detailed measurements of the complex three-dimensional structure of the atmosphere and coincident detailed chemistry observations of the constituents near the ground. One of the measurement sites, included the town of Golden, B.C., a small town nestled between the Purcell Mountains on the west and the Rocky Mountains on the east. The poor air quality in Golden is attributed to local industrial, residential (wood smoke) and vehicular sources as well as the steep mountains rising on both sides, and the absence of wind. These factors provide a unique airshed for air quality observations which include the complex re-circulation of pollutants due to upslope and downslope flows. In addition the springtime months of March and April provide an opportunity to measure the long-range transport of trans-Pacific pollutants that impact the coastal areas of British Columbia frequently and sometimes even penetrate to the borders of Ontario and Quebec. Lidar measurements near Vancouver, Whistler and Saturna Island show the extent and nature of these trans-Pacific plumes.
Two different lidar platforms were employed in the Pacific 2001 field study. A simultaneous upward/downward airborne lidar system called AERIAL (AERosol Imaging Airborne Lidar) was flown aboard the National Research Council of Canada Convair 580(CV580). The primary task of this platform was to establish a regional picture of particulate matter (PM) concentrations in the Lower Fraser Valley (LFV). The high temporal and spatial resolution of the lidar provided images of PM stratification and boundary layer structure along predetermined flight lines. The flight lines were divided into a series of north-south and east-west lines to provide a snapshot of the LFV as well as provide aerial support for four ground sites. The airborne lidar system also including a cross-polarization channel that is sensitive to particle shape (non-sphericity), for example smoke plumes from forest fires. There were 9 flights flown over a 3 week period including 2 night flights. The primary purpose of the night flights was to map PM transport in the lake valleys along the north range of the LFV. A scanning lidar facility called RASCAL (Rapid Acquisition SCanning Aerosol Lidar) was part of a suite of instruments making longer term measurements at the Langley Lochiel ground site. The lidar system was programmed to take three elevation scans (west, north and east) of the troposphere from the horizon to near zenith. Measurements were conducting for approximately 16 hours per day except longer during aircraft night flights. Results from both the airborne and scanning lidar facilities will be presented.
Results from scanning lidar measurements obtained during a large field study entitled Physical and Chemical Evolution of Aerosols in Smelter and Power Plant Plumes will be presented. The Meteorological Service of Canada has recently developed a mobile scanning lidar facility capable of fast azimuth and elevation scanning profiles of the lower troposphere. The lidar was located downwind of the stack source and the scanning speeds were adjusted to allow a complete scanning profile to be collected within 30-60 seconds. The lidar portion of the study was divided into four three- week parts. Ontario Power Generation-Nanticoke is a coal- fired generating station on the shores of Lake Erie. The lidar ground location selected for both the summer and winter study was approximately 8.5 km east of the stacks. The other location was the Noranda-Horne Smelter in Northern Quebec. The lidar was located approximately 4.6 km SE of the smelter during the winter and approximately 2.5 km NNE during the summer study. Preliminary lidar results will be shown for both Nanticoke and Noranda with a focus on the differences between winter and summer periods when the humidity and boundary layer dynamics were very different. New algorithms are being developed to extract boundary layer heights and plume heights for comparison with model predictions.
Simultaneous upward/downward airborne lidar profiles were recently obtained in the Canadian Arctic during the First ISCCP Regional Experiment III. The lidar was mounted on board the National Research Council Canada Convair 580. Additional instrumentation aboard the CV580 included several particle sizing and imaging proves, liquid water content probes, a sensitive meteorological package and a chemistry package to measure particle speciation and bulk aerosol and gas phase properties. Within the four week period 18 flights were accomplished including 4 flights over the surface heat budget of the arctic ice camp. A depolarization channel was added to both the upward and downward lidar to help distinguish particle phase and sphericity. Preliminary lidar results from various ice crystal years, arctic haze layers, and boundary layer growth over open water will illustrate the uniqueness of this dataset. The lidar was also able to detect open leads and refrozen leads by examining the 'ground return' of both the polarized and depolarized channels.
Two aircraft, the National Research Council of Canada (NRCC) Convair 580 (CV580) and NRCC DHC-6 Twin Otter, along with the Yarmouth and Digby Ferries, a ground site near Yarmouth and coordination with satellite overpasses (AVHRR and LANDSAT) provided an exceptionally well rounded compliment of observing platforms to meet the project objectives for the radiation, aerosols and cloud experiment (RACE) (refer to http://www.on.doe.ca/armp/RACE/RACE.html for a complete list of instrumentation and investigators involved). The general flight plans involved upwind measurements of a selected target by the CV580 lidar, followed by coincident flights allowing the Twin Otter to perform in-situ measurements while the Convair used a variety of remote sensors from above. The CV580 then descended to perform in-situ measurements including size segregated samples through the use of a micro-orifice uniform deposit impactor (MOUDI). This paper focuses on the airborne lidar results during RACE and in particular introduces two case studies comparing the lidar with a MOUDI impactor and ASASP particle probe using Mie theory.
Observations of low level stratiform clouds made over the Bay of Fundy from 15 August to 26 September 1995, as part of the Radiation, Aerosol, and Cloud Experiment (RACE) are used in this study. Aircraft, LAND Resources SATellite System (LANDSAT), and the Center for Atmospheric Research Experiment (CARE) lidar observations were used to obtain effective radius (rett), droplet number concentration (Nd). and cloud optical thickness (t). Radiation observations with a 28.5 m resolution at six solar reflectance channels from 0.45 μm up to 2.35 μm of the Thematic Mapper (TM) on LANDSAT were used. The 10.4-12.5 μm infrared channel has a field of view of 114 m. The visible extinction coefficient ( crex1) obtained from an aircraft mounted extinction meter was related to both liquid water content (L WC) and Nd. Optical thickness (t) were obtained from LANDSAT observations. Then, Nd, LWC, and reffalong lines of longitude are averaged at about 10 km intervals. The results showed that the relationships obtained between reff and t for stratiform clouds can be used to estimate reff values from satellite derived 't. Key words: Optical thickness, effective radius, extinction coefficient, aircraft and LANDSAT observations
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