An Assessment of Polar WRF Microphysics and Boundary Layer Schemes using Data from the Norwegian Young Sea Ice Experiment
Abstract
Observations over the Arctic ocean are limited in both space and time due to difficulty in maintaining ground-based instruments, particularly during the winter. Past have shown that clouds are particularly difficult to simulate over the Arctic ocean. To evaluate how well the Polar Research and Forecasting model (Polar WRF) performs over newly formed sea ice, radiative fluxes and surface temperature data from the model were compared to data from the Norwegian Young Sea Ice Experiment (N-ICE2015). N-ICE2015 was a 6-month field campaign from January through June 2015 during which a research vessel was frozen into the Arctic ocean north of Svalbard. During the winter, a number of large storms passed over the N-ICE domain, changing the temperature from -40 to 0 °C over several hours. These storms also modified the near-surface temperature and humidity inversions, radiative and turbulent heat fluxes, and the impact of clouds on the surface. Storms of this magnitude have not been documented before as thoroughly as during the N-ICE campaign. Previous studies have compared polar WRF simulations with data for the SHEBA field campaign, showing that the Polar WRF underrepresents temperature during times of short-term temperature increases. These storm periods seen during SHEBA were of smaller magnitude than those seen during N-ICE. Preliminary examination of boundary layer and microphysics schemes for the N-ICE domain over the entire experiment show an overestimation of the net radiative flux due to an overestimation in the net shortwave flux. A compensating low bias in the net longwave flux counteracts some of the overestimation of the shortwave flux, but not enough to simulate the correct net radiative flux. Latent and sensible heat fluxes both have a larger range of values in the model simulations than in the observations, and are generally underestimated, particularly during storm periods. All model simulations in the spring have a warm bias, causing the melting point of sea ice to be reached earlier than in the observations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A52B..06M
- Keywords:
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- 0321 Cloud/radiation interaction;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3359 Radiative processes;
- ATMOSPHERIC PROCESSESDE: 0764 Energy balance;
- CRYOSPHEREDE: 1621 Cryospheric change;
- GLOBAL CHANGE