Near real time data from ASIMet loggers (Meteorology)

UOP Buoys are normally equipped with two nearly identical ASIMet systems, which measure redundant sets of meteorological parameters. Both ASIMet loggers are usually equipped with satellite transmitters, either Argos Platform Terminal Transmitters or Iridium modems provisioned for Short Burst Data (SBD) messaging. The SMILE and SOFS buoys use Iridium telemetry only.
Aside from the delivery method, these data streams have a few differences, because of differences in the buoy systems and on-shore processing systems.

Iridium

Hourly averages of ASIMet data are transmitted houry.
Times in Iridium data messages reflect the end of the hour during which averaged data was collected; these times are corrected to the center of the sample in our real-time processing. This correction is being applied beginning on June 12, 2017, to accommodate more buoys using a mix of Argos and Iridium telemetry.
The magnetic rotation correction applied to the wind data is shown in the text files served on our web site.

Argos

Hourly averages of ASIMet data are transmitted approximately every 3 hours, or 8 times daily. Data is sent in 6-hour buffers, however in some locations, satellite passes may be more than 6 hours apart during some parts of the day, resulting in data gaps.
Times in Argos data transmissions reflect the start of the hour during which averaged data was collected; this time is corrected to the center of the sample in the near real time processing. This correction is being applied beginning on June 12, 2017, to accommodate more buoys using a mix of Argos and Iridium telemetry.
A magnetic rotation is performed on wind direction (wind east and north are adjusted) in UOP's near-real-time Argos processing system; correction values are normally taken from the National Center for Environmental Information (NCEI, formerly NGDC) on-line declination calculator, using the International Geomagnetic Reference Field (IGRF) Model. The value of the applied correction is given in the text file served on the project's real time data page.

All real-time meteorology text files begin with comment lines that start with % to make them Matlab-compatible. Header lines include the buoy name and deployment number, ASIMet serial number, the magnetic correction that has been applied (which may be 0), and the processing date in local (Eastern) time. There is also a column header line.
For Iridium files:
%year mo day hr yday BPR ATMP STMP WNDE WNDN WSPD WDIR RH SRAD LRAD PRC PRATE SAL COND
For Argos files:
% year mo day hr yday BPR ATMP STMP WNDE WNDN WSPD WDIR RH SRAD LRAD PRC PRATE SAL COND
Times in Iridium text files reflect the start of the hour during which averaged data was collected, in UTC.

Argos NameIridium NameUnitsNote
yearyear 4-digit year
monmon Month number, starts at 1
dayday Day of month, starts at 1
yeardayyearday Day of year, starts at 1
hourhour UTC; starts at 0
NAmin minute
BPbprdBBarometric pressure
ATatmp°CAir temperature
SSTsst°CSea surface temperature
WNDEwndem/sEastward componenet of wind speed
WNDNwndnm/sNorthward componenet of wind speed
RHhrh%Relative humidity
SWswrW/m2Shortwave radiation
LWlwrW/m2Longwave radiation
RNprecipmmPrecipitation level
COcond1Sea surface conductivity
salsalPSUSea surface salinity
wnd_spdwndsm/sWind speed
wnd_dirwndd°Wind direction (to)
rain_rateNAmm/hrrain rate, simple first difference on hourly levels



Text updated: June 12, 2017