Cloud Base Height at the Thule High Arctic Atmospheric Observatory (THAAO_CBH)

Measurements of Cloud Base Height (CBH) at the Thule High Arctic Atmospheric Observatory (THAAO) are carried out by means of a LUFFT Nimbus CHM15k ceilometer. The ceilometer is a laser remote sensing device with embedded algorithm for determining layers of particles and droplets in the atmosphere. The CHM15k Algorithm provides the Cloud Base Height (CBH) together with the Cloud Penetration Depth (CPD), and it is able to discriminate up to 3 different layers of clouds in the same profile. In addition, the CHM15k algorithm provides the degree of cloud coverage, the Total Cloud Cover (TCC), in terms of eighths (octas) of the sky, and provides a flag for the presence of fog , snow or rain precipitation during the measurement. All the above parameters are obtained by means of the CHM15k algorithm every 15 seconds and then the median values over 10-minute averages are calculated. Measurements start in December 2019 and are carried out all year round.