An integrated instrument package for measuring and understanding the surface radiation budget of sea ice is presented, along with results from its first deployment. The setup simultaneously measures broadband fluxes of upwelling and downwelling terrestrial and solar radiation (four components separately), spectral fluxes of incident and reflected solar radiation, and supporting data such as air temperature and humidity, surface temperature, and location (GPS), in addition to photographing the sky and observed surface during each measurement. The instruments are mounted on a small sled, allowing measurements of the radiation budget to be made at many locations in the study area to see the effect of small-scale surface processes on the large-scale radiation budget. Such observations have many applications, from calibration and validation of remote sensing products to improving our understanding of surface processes that affect atmosphere-snow-ice interactions and drive feedbacks, ultimately leading to the potential to improve climate modelling of ice-covered regions of the ocean. The photographs, spectral data, and other observations allow for improved analysis of the broadband data. An example of this is shown by using the observations made during a partly cloudy day, which show erratic variations due to passing clouds, and creating a careful estimate of what the radiation budget along the observed line would have been under uniform sky conditions, clear or overcast. Other data from the setup's first deployment, in June 2011 on fast ice near Point Barrow, Alaska, are also shown; these illustrate the rapid changes of the radiation budget during a cold period that led to refreezing and new snow well into the melt season.

Daily measurements of incoming and outgoing broadband fluxes of longwave and shortwave radiation, incoming and outgoing spectral fluxes of shortwave radiation, and air temperature and humidity, along with sky and surface photographs, all measured simultaneously every 5 m along a 200-m transect on landfast sea ice near Barrow, Alaska from 5 to 13 June 2011. The transect included a mix of bare ice (scattering layer), shallow melt ponds, and deep melt ponds. During the measurement period some refreezing took place, along with some light snowfall on the later days. Measurements were made around local noon each day (local noon in Barrow in summer is around 14:30 Alaska Summer Time (UTC-8). Times in the data files are given in UTC, but files are named with the local date, even if the observations occasionally occurred early on the following day UTC. In addition to latitude and longitude, distance along the profile is given in meters from an average starting point at 71.366563°N, 156.544292°W.There are nine datasets associated with each day's transect: one contains the broadband radiation data, the air temperature and humidity, and the surface and sky photographs, four contain the incoming (downward) spectral irradiance broken into four wavelength regions, and four contain the reflected (upward) spectral irradiance broken into four wavelength regions.Projects: Norwegian Research Council FRINAT (197236/V30) and POLRES (196143/S30).

Supplement to: Hudson, Stephen R; Granskog, Mats A; Karlsen, Tor Ivan; Fossan, Kristen (2012): An integrated platform for observing the radiation budget of sea ice at different spatial scales. Cold Regions Science and Technology, 82, 14-20