The Study of Verification and Correction of Cloud Base and Top Height Retrievals from Ka-band Cloud Radar in Boseong, Korea during Fall 2013

Abstract:

In this study, the cloud base and top heights observed by Ka-band (33.44 GHz) cloud radar at the Boseong National Center for Intensive Observation of severe weather (NCIO) in Korea during the fall of 2013 (September to November) were verified and corrected. For comparative verification, the base and top heights data obtained from ceilometer (CL51) and Communication, Ocean and Meteorological Satellite (COMS), respectively were used. During rainfall, the cloud base and top heights observed by the cloud radar were lower than that observed by ceilometer-COMS due to signal attenuation and reflectivity caused by raindrops. The stronger rainfall intensity gets, the more the difference grows. In the case of rainfall, the base and top heights data from cloud radar could be replaced with these obtained data from ceilometer-COMS. In the case of no rainfall, the cloud base and top heights observed by the cloud radar and ceilometer-COMS were relatively similar. The clouds with thin thickness or low density were more effectively observed in cloud radar compared to ceilometer-COMS. Based on these results, in case of rainfall or missing cloud radar data, the ceilometer and COMS data were effectively used to correct the cloud radar data. These corrected cloud data were used to classify the cloud types of low (Cloud base height (CBH) < 2 km), middle (2 km ≤ CBH < 6 km), and high (CBH ≥ 6 km) clouds, and it was shown that the frequency of occurrence for low clouds were highest. When the low clouds were further subdivided, the most common type was shown to be deep precipitable clouds (CBH < 200 m and Cloud top height (CTH) ≥ 2 km), followed by non-precipitable clouds (200 m ≤ CBH < 2 km) and shallow precipitable clouds (CBH < 200 m and CTH < 2 km) in this order.