KNMI purchased 50 units of CHM15k "NIMBUS"
Long before automated weather stations were available, weather and clouds were already observed visually by officially trained and certified meteorological observers. Today, there are still human observers active in many weather services around the globe. Observers look at the sky and estimate cloud fraction in octa and the height of the cloud base. This provides essential information for (aviation) meteorology and, on longer time scales, for climate research and monitoring.
In the nineties, the Royal Netherlands Meteorological Institute( KNMI) started automating the visual observations of present weather, visibility and clouds using automatic weather stations with dedicated optical sensors. For cloud observations, ceilometers were purchased and deployed in the measurement network on a 24/7 operational basis.
After 15 years of use, the old ceilometer had reached the end of their service lives and technical support is no longer available, as the product was phased out by the manufacturer. The time had come to look for a new cloud height sensor replacing the old ones. The requirements included, that the new ones need to be more sensitive for high cirrus clouds and should have limited capabilities for aerosol layer detection. Moreover, the sensors should be accessible remotely.
Ceilometer CHM 15k „NIMBUS“
The LIDAR-based cloud height sensor / ceilometer CHM 15k is prepared to work throughout the year and in any climate
Exact results due to high sensitivity of the used lidar sensor technology! Reliable and accurate results at any time of the day or night are ensured by long-life laser sources, filters with narrow bandwidth and high-sensitivity photodetectors.
- Aerosol backscatter profile, cloud base height, cloud penetration depth, aerosol layer height, cloud cover, vertical visibility, Sky Condition Index
- Optical (LIDAR)
- Measuring range up to 15 km (50,000 ft), optimized detection of several cloud layers, simple eye-safe operation, service-friendly modular device design, various data telegrams including raw data
- RS485, LAN, RS232 oder Modem V.21, V22