Parametrization schemes of incident radiation in the North Water Polynya

Surface incident radiation is a critical component of the Arctic surface en ergy balance making it important for sea-ice model parametrizations to prop erly account for these fluxes. In this article, we test the performance of various incident short-wave (K down arrow) and long-wave (L down arrow) flu x parametrizations using unique observations from the 1998 International No rth Water (NOW) Polynya Project between March and July. The dataset include s hourly observations over terrestrial, fast-ice and full marine polynya en vironments allowing for parametrization comparisons between each environmen t and determination of any seasonal biases. Performance testing is highly d ependent on observed input parameters that contain relative errors, however , significant differences between the marine and fast-ice fluxes are eviden t. Results are very similar between the terrestrial and fast-ice sites. The best K down arrow clear-sky schemes underestimate fluxes in the colder sea son and overestimate them in the warm season, with greater biases in the ma rine setting. The K down arrow cloudy-sky results suggest a similar cold an d warm season bias but with greater magnitudes, especially in the marine en vironment. The K down arrow cloudy-sky schemes require seasonal improvement s, especially in the marine atmosphere. The L down arrow clear-sky fluxes w ere generally overestimated during the colder season. Accounting for a less emissive atmosphere resulted in better flux approximations in all environm ents. L down arrow cloudy-sky fluxes were generally underestimated. Adjusti ng the cloudy-sky emissivity improved the estimated fluxes, however, result s were very different in the marine setting. The L down arrow cloudy-sky pa rametrizations may require re-evaluation due to a consistent negative bias as the observed flux increases.