Sensor information
The following *.cgn file was used to retrieve the data for PoldatDB:(TSB = ThermoSalinograph Bow, TSK = ThermoSalinograph Keel) POLDAT Configuration File: PDDB4.MIW 26-JAN-1995 14:31 Start of Computation ............: 01-JUN-1994 00:00 End of Computation ..............: 04-JUN-1994 00:00 Length of Statistic Interval ....: 10 min 0 sec Output File Format ..............: VMS Output-Format of Time ...........: YY MM DD hh mm Output-Format of Position .......: degree(decimal) sign Output-Format ID (internal)......: 1211 SNo Format v m - + s n d.d<< Value Sensor Error >>v m - + s n d.d 3 num * 3.2 TSB temperature 2 3.2 4 num * 2.2 TSB conductivity 2.2 5 num * 2.2 TSB salinity 2.2 7 num * 3.1 air temperature luv 3.1 8 num * 4.0 rel. humidity 4.0 9 num * 3.1 dewpoint 3.1 10 num * 4.1 air pressure 4.1 11 num * 4.1 rel. wind velocity luv 4.1 12 num * 4.0 rel. wind direction luv 4.0 14 num * 4.0 global radiation 4.0 15 num * 5.0 visibility 5.0 16 num * 5.0 ceiling 5.0 17 num * 4.0 true wind direction 4.0 18 num * 4.1 true wind velocity 4.1 45 num * 4.1 gyro heading 4.1 60 pos * 1.4 system position lat 4.1 61 pos * 1.4 system position lon 4.1 68 num * 5.1 system depth 5.1 80 num * 3.1 filter course made good 3.1 81 num * 3.1 filter speed made good 3.1 108 num * 3.2 TSK temperature 2 3.2 109 num * 2.2 TSK conductivity 2.2 110 num * 2.2 TSK salinity 2.2 112 num * 3.2 ozone concentration 3.2 119 num * 4.1 max rel. wind veloc. last min 4.1 120 num * * 3.4 precipitation 3.4Frequently, averaged values (m), as offered by Poldat, were taken. The visibilities and cloud ceilings base on minimum values (-), the max rel. wind veloc. last min on maximum values (+), while all navigation data are taken from the last valid (v) instantaneous data within the statistic intervals. To calculate the precipitation the averages (m) and numbers of events (n) were retrieved.
Timing
The time information, offered in PoldatDB, represents the center of the 10-minute statistic interval. Please keep in mind, that all instantaneous values are normally taken about 5 minutes later.
Wind
Wind direction and wind speed are measured at a height of 37m above sea level at the port and starboard side of the ship. Only the windward sensor gets registered. Data for Max. Relative Wind Velocity exist after 10-18-94. The U_Wind and V_Wind components are calculated using the true wind direction and true wind velocity. A positive (negative) U_Wind denotes a wind component from west (east), while a positive (negative) V_Wind denotes a wind component from south (north).
Temperature
The air temperature is measured at a height of 27m above sea level at the port and starboard side of the ship. Only the windward sensor gets registered.
Humidity
On board of POLARSTERN air humidity informations are available from a hair hygrometer (rel. humidity) and a dewpoint sensor (dewpoint) at a height of 27m above sea level. Both informations are used to calculate one validated relative humidity, which is the basis for all other humidity information offered in PoldatDB.
Surface air pressure
The air pressure taken at POLARSTERN is reduced to sea level. From 5-18-93 to 10-6-94 the surface pressure was sampled in hPa once a minute and stored only as integer. Thus the 10-minute averages - taken during this time - have a rather low resolution.
Precipitation
Precipitation measurements on board of Polarstern started at 10-18-94. Only rain events are normally quantified. Due to several problems with the sensor, the data should be taken with care. Data which are obviously wrong are already excluded from the database. Nevertheless, it is still possible that some rain events are missing, that extreme sea spray affects the measurements and that accumulated snow melts within the sensor and gets measured as liquid precipitation hours or days after the snowfall.
Radiation
Global ratiation is measured by using an artificially ventilated pyanometer. A description of the instrument can be found at http://www.kippzonen.com/product/cm11.html. The instrument is placed at the level of the craw`s nest, a position, not totally free of cast shadow problems.Nighttime values are normally not set to zero. They vary +/-0 and can be used to quantify offsets of the instruments which also occur during daytime. Especially the older data are subject of rather huge offset problems and have to be taken with care. The given extraterrestrial insolation and sun elevation data are calculated after Iqbal, M. 1983: An Introduction to Solar Radiation.
Water temperature und salinity
Only some validated data are available interactively yet. The validation work is ongoing. More data will be available in future. For information about the validation status please contact Gerd Rohardt
Cloud height
Till 2011-10-25 the colud height was measured using the cloud ceilometer LD-WHX05 (Impulsphysik, Germany) with a maximum range of 12,000 feet. The value 20,000 denotes clear sky above the vertically pointing instrument. After 2011-10-25 the ceilometer CL51 (Vaisala, Finland) with a range up to 43,000 feet was used and the clear sky value was changed to 50,000.
Other data
The data from the bathymetry and chemie are not available via the WEB at this time, but archived in unvalidated form in PoldatDB.