Geography
Climate Processes and Change
Research into climate processes and change is an important part of the environmental research group. This includes:
Analysis of global and regional temperature change
Analysis over the 20th century, through comparison of high quality homogenised climate datasets. Of particular concern are contrasts between free-atmospheric changes (as measured by radiosonde and satellite data and assimilated dataset such as reanalyses) and surface temperature changes as measured by conventional instrumentation.
This work has been undertaken in collaboration with the Climate Variability and Trends Group at the Air Resources Laboratory in Silver Spring, Maryland, and the Scripps Institution of Oceanography, San Diego, USA.
Indicative Publications
Pepin , N.C. & Duane, B. (2007) A comparison of surface and free-air temperature variability and trends at radiosonde sites and nearby high elevation surface stations, submitted and accepted, Int. Jnl Climatology
Pepin , N.C. & Norris, J. (2005) An examination of the differences between surface and free air temperature measurements at high elevation sites: relationships with cloud cover, snow cover and wind, J. Geophys. Res., 110, D24112, doi:10.1029/2005JD006150.
Pepin, N. C., and D. J. Seidel (2005): A global comparison of surface and free-air temperatures at high elevations , J. Geophys. Res. , 110 , D03104, doi:10.1029/ 2004JD005047.
Pepin , N.C., Losleben, M. Hartman, M, Chowanski, K. (2005): A Comparison of Snotel and GHCN/CRU surface temperatures with free-air temperatures at high elevations in the western U.S. : Data compatability and trends, Jnl Climate, 18(12), 1967-1985.
Pepin , N.C. & Losleben, M. (2002), Climate change in the Colorado Rocky Mountains: free-air versus surface temperature trends, International Journal of Climatology 22, 311-329.
Climate changes in mountainous regions
Linked to the local outcomes of global warming is a particular concern with climate changes in mountainous regions of the globe.
Mountains have complex climates, but are expected to show rapid environmental responses to climate change because of the strong environmental gradients over short distances, and the snow-ice feedback mechanism. Mountain sites show characteristics of both the free-atmosphere and the surface, so can also be used to cast light on the differences between free-air and surface temperature changes mentioned above.
The staff at Portsmouth has been part of climate monitoring campaigns in mountains around the world, including the Rocky Mountains of the USA, The Pyrenees, The uplands of England and Scotland, and Mt Kilimanjaro in Africa.
Work has been performed in collaboration with the following institutions:
- University of Brunei Darussalam
- University of Colorado Mountain Research Station
- University of Turku Sub-Arctic Research Station
- University of Massachussetts
- University of St Andrews
- Centre for Ecology and Hydrology
Indicative publications
Pepin, N.C. & Kidd, D. (2006) Spatial temperature variation in the Eastern Pyrenees, Weather 61, 300-310
Pepin, N.C. (2001), Lapse rate changes in northern England , Theoretical and Applied Climatology 68 (1/2) 1-16
Pepin, N.C. (2000), Twentieth century change in the climate record for the Front Range, Colorado, U.S.A., Arctic, Antarctic and Alpine Research 32 (2):, 135-146
Responses of the cryosphere to climate change
Another emergent research strand is the response of the cryosphere (snow and ice) in mountain regions to contemporary climate change.
This work involves a wide range of foci ranging from global analyses examining long term changes in snow cover in mountains and its influence on surface energy balance and mountain temperatures, to regional influences of atmospheric circulation on snow cover, and local field investigation into factors influencing snow distribution at the altitudinal and latitudinal forest-tundra ecotones (areas which are expected to show rapid environmental response to climate change).
The latter work is based on field-sites in the Front Range of the Colorado Rockies and Finnish Lapland respectively. In addition the university is involved in a climate monitoring project on Mt Kilimanjaro which is examining the role of the mountain thermal circulation in transporting moisture to the summit region. This is shown to be a strong control over the mass balance of the summit glaciers which are currently in rapid retreat.