Analysis of cloud radiative effects and radiative budget in the Central Arctic based on satellite and ship-borne observations

Clouds influence the shortwave (SW) and longwave (LW) radiative fluxes, thereby affecting the radiative budget by enhancing or diminishing the heat budget at the surface (SFC), at the top of the atmosphere (TOA), and through the atmosphere. In the Arctic, their complexity enhances due to their intrinsic interactions with several physical processes and feedback mechanisms.

With the aim to further investigate the Arctic system, the project (AC)³ (Arctic Amplification: Climate Relevant Atmospheric and SurfaCe Processes and Feedback Mechanisms) established two major field campaigns in summer of 2017. Both performed in situ and remote sensing observations over the ocean with PS106 and in the air with ACLOUD (Macke and Flores, 2018, Wendisch et al., 2019). The observations collected during PS106 are considered to investigate the effects and influence of clouds in the radiation budget for the summer central Arctic.

The PS106 expedition took place aboard the German research vessel Polarstern which was equipped with active and passive remote sensing instrumentation (Griesche et al., 2020). The synergistic operation of this instrumentation was used to derive macro and microphysical properties of clouds by applying the Cloudnet algorithm. These retrievals together with vertical profiles of temperature and relative humidity are used as input to the Rapid Radiative Transfer Model for GCM applications (RRTMG). The results of the broadband SW and LW radiative simulations along with hourly satellite products from Clouds and the Earth’s Radiant Energy System (CERES) Synoptic 1-degree Ed.4. are compared to ship-borne observations indicating a better agreement for single-level liquid clouds than for more challenging sky conditions. The results of the comparison bring sufficient information to discuss a radiative closure assessment for selected case studies and for the entire PS106 expedition. Based on these results the cloud radiative effect (CRE) is calculated indicating a net effect of -8.1 W/m².

The study is extended by applying this methodology to the recent Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC). Preliminary results will be presented for the first leg which will allow a direct comparison of the contrasting properties of cloud radiative effects during summer and winter season.

References

Griesche, H. J., and coauthors. (2020): Application of the shipborne remote sensing supersite OCEANET
for profiling of Arctic aerosols and clouds during Polarstern cruise PS106, Atmos. Meas. Tech., 13,
5335–5358, https://doi.org/10.5194/amt-13-5335-2020

Macke, A. and Flores, H. (2018): The Expeditions PS106/1 and 2 of the Research Vessel POLARSTERN
to the Arctic Ocean in 2017 , Berichte zur Polar- und Meeresforschung = Reports on polar and marine
research, Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 719 , 171 p.
http://hdl.handle.net/10013/epic.4ff2b0cd-1b2f-4444-a97f-0cd9f1d917ab

Wendisch, M., and coauthors. (2019): The Arctic Cloud Puzzle: Using ACLOUD/PASCAL Multiplatform
Observations to Unravel the Role of Clouds and Aerosol Particles in Arctic Amplification. Bull. Amer.
Meteor. Soc., 100, 841–871, https://doi.org/10.1175/BAMS-D-18-0072.1