Ceilometers have a wide range of uses beyond their most common application in cloud detection. This article looks at the use of ceilometers in a number of different disciplines, outlining their advantages and applications in each of these fields.
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A ceilometer is a device that uses a laser or other type of light source to determine the height of a cloud ceiling or a cloud base. They can also be used to measure aerosol concentration or precipitation.
A ceilometer is basically an Atmospheric LIDAR device (Light Detection and Ranging). These highly cost-effective devices send short laser pulses into the atmosphere and then measure the light that is scattered back.
From that backscatter signal, it is possible to determine how high the cloud base is, where there is aerosol in the atmosphere, or what type of precipitation is occurring.
These are versatile, multi-use devices employed in various meteorology applications, including air quality and aviation – the latter being key to monitoring visibility and other weather conditions that could affect a flight.
Ceilometers in Wildfire Prevention and Monitoring
Ceilometers as the Lufft CHM 15k and CHM 8k played an essential role in relation to the unprecedented wildfires taking place across almost every continent over the past two years. One of the many scientists investigating the impact of wildfires on air quality is Aaron Kennedy from the University of North Dakota.
Aaron’s team, working with atmospheric scientists, was able to monitor wildfire signals that originated from fires that had originated hundreds of miles away.
North Dakota is in the center of the United States and is home to prairies, agriculture and oil fields. The region suffers from grass fires that typically come from other locations.
Smoke is visible in North Dakota for two to three weeks a year due to summer wildfires as far away as California, British Columbia and areas of Western Canada such as Ontario and Manitoba.
The University of North Dakota uses a ceilometer to investigate aerosols and other pollution formed by wildfires and other sources. A smoke plume can be detected moving towards North Dakota using satellite imagery, and this can be checked using ceilometer data.
The ability to accurately measure and monitor wildfire smoke is essential in instances where atmospheric conditions cause the smoke mix downward and reach the lowest level of the atmosphere - the boundary layer.
Once wildfire smoke reaches the boundary layer, it begins to have public health impacts, including damage to the respiratory system, exacerbating preexisting conditions or putting vulnerable populations at risk.
A ceilometer can help verify how much smoke is present and predict whether this will reach the boundary layer and pose a risk. This was historically reliant on satellite meteorology or even radar in cases where the fire was close by.
Ceilometers are vital to improving future forecasting. For example, many weather models now include ‘smoke parameterizations,’ which simulate an emission source such as a fire or dust and predict where this would go in the atmosphere and what impact this would have on air quality, based on specific meteorological conditions.
The potential to set up a network of ceilometers across the country could enable these evaluations and parameterizations in any region at risk of future wildfires.
Outside of the United States, ceilometers set up on the West Coast of Wales in the United Kingdom and even in the Mediterranean to observe smoke plumes making their way across the Atlantic. The more data that is collected, the better models can be made.
Air Quality Applications
There is scope to employ ceilometers in local air quality studies to evaluate the presence of aerosols from the industry.
One of the critical benefits of ceilometers is their ability to resolve the properties of the boundary layer – the lowest kilometer of the atmosphere. Ceilometers can be used to investigate air quality up to around 15 kilometers above the ground, affording researchers insight into the low- and mid-levels of the atmosphere.
Work has been undertaken to determine the height of the boundary layer over time, using this as a ramp for forecasting and air quality.
The Atmospheric Radiation Measurement (ARM) program uses ceilometers to provide valuable details on cloud bases for use in aviation and climate modeling applications.
In terms of modeling the climate, one of the most significant sources of uncertainty is aerosols, pollution from wildfire smoke and clouds.
Developing a robust understanding of these factors is key to developing reliable and accurate climate simulations. The ceilometer is one of the most important instruments in estimating the height of cloud layers.
Predicting Snow Behavior
Another application under development at the University of North Dakota is looking at the wintertime use of the ceilometer to anticipate ground blizzards - situations where snow that has previously fallen is lifted back off the surface by the wind, causing similar issues to more conventional blizzards.
This phenomenon is common in high latitude parts of the globe, including Antarctica and the Arctic circle. These areas do not get much snow, but the snow they get is very dry and blows around easily. Ground blizzards can be extremely debilitating to travel due to their impact on visibility and can cause significant issues around public safety.
While it is possible to detect this phenomenon using satellites, there may be certain situations where a storm system has passed through an area, where a sinking motion in the atmosphere inhibits cloud cover, and there may still be strong winds.
There is a lot of spatial variability in this phenomenon, and while it may be visible via satellite imagery, this may not be evident to communities in the area affected, particularly at night.
It is often challenging to measure and differentiate falling snow and snow lifted from the ground. It is necessary to use a variety of different instruments to ascertain this.
The ceilometer provides backscatter measurements, so this alone cannot differentiate between blowing snow, falling snow or a combination of the two. Operators must interpret the data and collate this with data from other instrumentation, for example laser disdrometers as the OTT Parsivel².
The HydroMet OTT Parsivel² Laser Weather Sensor
The OTT Parsivel² from HydroMet is a laser disdrometer. This instrument features two sensor heads. As precipitation (hydrometeors) falls between these two sensor heads, the OTT Parsivel² will detect the size distribution of the precipitation to identify what type of precipitation is falling, for example, rain, snow, freezing, sleet, etc.
This instrument can be used to collect particle size data and correlate this with data from a ceilometer, providing exciting research opportunities and enhancing data from other devices.
The ability to acquire a complete picture of the weather and atmospheric phenomena from multiple instruments is a promising and powerful approach. Data from ceilometers provides a robust foundation for these investigations.
This information has been sourced, reviewed and adapted from materials provided by OTT HydroMet. Lufft is one of OTT HydroMet's strong brands for professional environmental monitoring solutions.
For more information on this source, please visit OTT HydroMet.