Surface Radiation Measurements at the Koldewey Ground Station (Arctica)

Daily averaged radiation data are available from 31 July 1992.

Since 1992 surface radiation measurements have been carried out by the
Alfred Wegener Institute for Polar and Marine Research (AWI) at
Koldewey Station in the framework of the Baseline Surface Radiation
Network (BSRN) in cooperation with the Norsk Polarinstitutt. The
radiation signals are taken in one minute intervals and stored as
averages over 5 minutes. They include:

- global radiation (pyranometer CM11, Kipp+Zonen),
- reflected solar radiation (pyranometer CM11, Kipp+Zonen),
- diffuse sky radiation (pyranometer CM11, Kipp+Zonen),
- direct solar radiation (NIP, Eppley mounted on a sun tracker),
- OG1 (global>530nm, pyranometer CM11, Kipp+Zonen),
- RG8 (global>695nm, pyranometer CM11, Kipp+Zonen),
- UV (300-370nm, TUVR, Eppley),
- sunshine duration (Solar 111, Haenni),
- downward long-wave radiation (pyrgeometer Eppley),
- upward long-wave radiation (pyrgeometer Eppley).

The pyranometers and pyrgeometers are ventilated with slightly
preheated air to minimize hoar frost problems and zero offsets during
cloudless and windless conditions. The instruments were maintained
continuously several times per day throughout the year. After one year
of operation they are re-calibrated at the German Weather Bureau
according the World Radiometric Reference (WRR).

At AWI, the radiation measurements - averaged over 5 minutes - are
archived together with the data from the mast measurements, daily
upper air soundings and routine synoptic surface observations in a
relational database (SYBASE). Additionally some derived quantities
(Iqbal 1983) such as the solar elevation, extraterrestrial solar
insolation, astronomical sunshine duration are available.

In order to obtain daily averaged radiation data, each day was
subdivided into eight 3-hourly intervals (0-3, 3-6, ..., 21-24
UTC). For each 3-hourly interval an average was derived irrespective
of the number of measurements. This procedure was chosen in order to
minimize problems resulting from missing values. If one or more
3-hourly averages were missing, no daily average was calculated.

Data are accessible via Web network by means of the AWI-Home-Page,
'http://www.awi-bremerhaven.de', and can be obtained from AWI after
prior consultation.