Horizontal profiles of longwave and shortwave radiation components over sea ice near Barrow, Alaska during the 2011 melt

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.

Land cover layer, digitized from the PEF Survey of Western Palestine (1880)

Geographic information systems allow the extraction and quantitative analysis of information from historical maps. The aims of this research were to examine the completeness of information represented on the 1881 Palestine Exploration Fund (PEF) map, to quantitatively reconstruct the landscape of nineteenth century Palestine and to explore whether spatial patterns in land cover/land use can be partially explained statistically by physical and human factors. Using historical aerial photos, we concluded that most of the major past landscape features were indeed shown on the PEF map, with an average overall correspondence of 53%. Forests and Mediterranean maquis were more abundant at distances greater than 2 km from towns and villages. Specific land cover/land-use types were associated with certain soil types, topographic regions and rainfall thresholds. In conclusion, the 1881 PEF map can serve as a reliable reference for understanding the land cover/land-use patterns of nineteenth century Palestine.

Survey of Western Palestine 1880, Palestine Exploration Fund 1:63,360 mosaicked map

The Palestine Exploration Fund (PEF) Survey of Western Palestine (1871-1877) is highly praised for its accuracy and completeness; the first systematic analysis of its planimetric accuracy was published by Levin (2006). To study the potential of these 1:63,360 maps for a quantitative analysis of land cover changes over a period of time, Levin has compared them to 20th century topographic maps. The map registration error of the PEF maps was 74.4 m using 123 control points of trigonometrical stations and a 1st order polynomial. The median RMSE of all control and test points (n = 1104) was 153.6 m. Following the georeferencing of each of the 26 sheets of the PEF maps of the Survey of Western Palestine, a mosaicked file has been created. Care should be taken when analysing historical maps, as it cannot be assumed that their accuracy is consistent at different parts or for different features depicted on them.