Abstracts

Surface Radiation Balance at Summit, Greenland

Konrad Steffen^1
1Cooperative Institute for Research in Environmental Sciences, University of Colorado, CB 216, Boulder, CO, 80309, USA, konrad.steffen@colorado.edu

The determination of a global climatology of the radiation budget at the surface of the Earth is fundamental to understanding the Earth's climate system, climate variability and climate change resulting from human influence. Global estimates of the surface radiation budget cannot be inferred reliably from satellite observations without high accuracy surface-based measurements at various sites in contrasting climatic regions for calibration and validation. Long-term observations of the same accuracy are also required to assess trends within climatic regions. Such measurements are essential in assessing theoretical treatments of radiative transfer in the atmosphere, verifying climate model computations, and for studying trends in surface radiation at scales smaller than normally associated with climatic regions.

The Baseline Surface Radiation Network (BSRN) was installed at Summit, Greenland in summer 2000; this BSRN is the only high-latitude, high-elevation site in the world and hence instrumental in assessing the short- and long-wave radiative fluxes with great precision and high temporal resolution. The BSRN requires that all radiation variables be sampled at 1 HZ with an averaging time of one minute. The final output for each variable should consist of the one-minute mean, minimum, maximum and standard deviation. The radiation parameters measured are: direct solar irradiance, diffuse radiation, global radiation, reflected shortwave radiation, down-welling long-wave radiation and upwelling long-wave radiation.

The radiation climatology will be presented for all radiation parameters; the sum of all radiative fluxes (net radiation) is positive during the April–August time period with a value around 140 MJ m-2 whereas global radiation values are exceeding 900 W m-2 in June at solar noon during clear sky conditions. Long-wave sky radiation varies between 100–240 W m-2 throughout the year and depends strongly at cloud amount and height. The seasonal as well as interannual variability of radiative fluxes will be discussed and compared to the nearby automatic weather station data.

Abstract Categories: 3.2 Low-latitude Forcing of Arctic Change