Cloud observations at THAAO Observatory during the Arctic YOPP 2020

The radiative effects of clouds and their microphysical structure in Polar regions are still object of large uncertainty, that contribute to determine the large inaccuracies of climate model in the representation of clouds and their effects.

In the frame of the CLouds And Radiation in the Arctic and Antarctica (CLARA2) project, a celiometer has been installed in November 2019 at the Thule High Arctic Atmospheric Observatory, THAAO, an international infrastructure located in proximity of Thule Air Base (76.5°N, 68.8°W), Greenland (http://www.thuleatmos-it.it/) with the aim of strengthening the cloud observational capability at the Observatory already including, among the other instruments, a microwave profiler and upward- and downward-looking pyranometers and pyrgeometers operating since July 2016.

CLARA2 should have contributed to the YOPP 2020 Arctic Special Observing Period (SOP) in February-March with intensive measurements of the atmospheric vertical structure by means of a microwave profiler, a celiometer and daily radiosoundings, but the arrival of the COVID19 prevented the involved researchers to carry out the field campaign at THAAO. Nonetheless the automatic measurements were collected regularly also during the 2020 SOP.

The temporal evolution of the cloud’s presence and characteristics during the two months SOP will be presented and discussed in terms of meteorological conditions, broadband surface radiation fluxes, cloud’s geometrical characteristics, phase and liquid water path.