The terrestrial low latitude boundary layer

Imperial Users onl

Arctic climate change: observed and modelled temperature and sea-ice variability

Changes apparent in the arctic climate system in recent years require evaluation in a century-scale perspective in order to assess the Arctic's response to increasing anthropogenic greenhouse-gas forcing. Here, a new set of century- and multidecadal-scale observational data of surface air temperature (SAT) and sea ice is used in combination with ECHAM4 and HadCM3 coupled atmosphere-ice-ocean global model simulations in order to better determine and understand arctic climate variability. We show that two pronounced twentieth-century warming events, both amplified in the Arctic, were linked to sea-ice variability. SAT observations and model simulations indicate that the nature of the arctic warming in the last two decades is distinct from the early twentieth-century warm period. It is suggested strongly that the earlier warming was natural internal climate-system variability, whereas the recent SAT changes are a response to anthropogenic forcing. The area of arctic sea ice is furthermore observed to have decreased similar to8 x 10(5) km(2) (7.4%) in the past quarter century, with record-low summer ice coverage in September 2002. A set of model predictions is used to quantify changes in the ice cover through the twenty-first century, with greater reductions expected in summer than winter. In summer, a predominantly sea-ice-free Arctic is predicted for the end of this century

Industrial mining heritage and the legacy of environmental pollution in the Derbyshire Derwent catchment: quantifying contamination at a regional scale and developing integrated strategies for management of the wider historic environment

The Derwent Valley Mills World Heritage Site (DVMWHS) exemplifies and records the 18th century birth of the factory or mill technology, and for the industrial spinning of cotton. The site is therefore a key global heritage asset. The Derbyshire Derwent catchment also contains another significant cultural asset with a long history – that of mining and, in particular, lead (Pb) mining. In this paper research on mining- and non-mining related Pb contamination of the Derwent catchment is reviewed and used to identify the risks it poses to the DVMWHS. The upper Derwent soils, though not impacted by mining, have high sediment-borne Pb concentrations, and the Pb is sourced from local conurbations (principally Manchester) and carried to the upper Derwent on the wind. River sediments in the middle and lower parts of the Derwent catchment are contaminated with Pb mined mainly between the 18th and 19th centuries and before, possibly as far back to the Bronze Age. The potential for large-scale, acidity-related chemical remobilization of this Pb is low in the Derwent catchment due to the largely alkaline nature of the underlying soils, but the potential for oxidation-reduction-related, and physical (flood-related), remobilization, is higher. Management guidelines for mining heritage assets and the DVMWHS are developed from the reviewed information, with the view that these will provide a framework for future work in, and management of, the DVMWHS that will be applicable to other World Heritage Sites affected by ongoing and past metal-mining. Focused collaborative work between archaeologists, geochemists, geomorphologists and mineralogistsis vital if the risks to the DVMWHS and other similarly-affected World Heritage Sites are to be quantified and, if necessary, mitigated

The Antarctic climate of the UKMO Unified Model

We examine some aspects of the performance of the United Kingdom Meteorological Office's new climate model over Antarctica. Pressure and temperature fields are presented as a basic check on the model climate. The gradient of pressure between mid-latitudes and high southern latitudes is too great, resulting in an Antarctic trough that is too deep by 4–6 hPa. Temperature is well modelled though the interior is slightly too cold in winter. Precipitation is interesting because of its relevance to mass balance and therefore changes in sea level. The simulation of the pattern of accumulation is good despite somewhat high values at places in the coastal areas, with an areally-averaged value of 182 mm y−1. We also look at the phenomena of the coreless winter and the katabatic winds which are a consequence of the intense radiative cooling. These two effects may provide a useful diagnostic of the model performance