Sea level probability forecasts

Data format

Data for the tidal extremes from the water level ensemble forecast module are distributed in ASCII format. This page defines the format, contains an example, the list of locations and gives the location where data from the experimental version can still be downloaded for a limited period.

Definition

The format has been derived from other formats which are in use for ensemble forecasts, but had to be extended to accommodate the irregularly spaced astronomical tidal extremes and their variable number.
The format is meant to be compatible with the WMO FM 94 BUFR format.

Forecast data

  IIiii YYYYMMDDHH LAT LON N M
  004025 N x { HHHH:MI }
  054003 N x { AAAA }
  M x
  { 0010YY XX
    054004 N x { WWWW } }

Explanation

Descriptor	Description
IIiii	Location identification (see below)
YYYYMMDDHH	Model base time (year/month/day/hour)
LAT	Latitude location model grid point
LON	Longitude location model grid point
N	Number of extremes
M	Number of ensemble members
004025	Time of the astronomical extreme, hours/minutes after YYYYMMDDHH. N signed values after the id 004025
054003	Astronomical tide [cm] wrt NAP according to the harmonic analysis by Rijkswaterstaat, N signed values after the id 054003
001091 P	Ensemble member P
001092 0	Deterministic forecast
001092 1	Ensemble control run
054004	Skew surge [cm], N values after the id 054004

Example

This annotated example is to clarify the formal definition above. It is taken from the 2008102300 run for location Hoek van Holland (06514, see below). For clarity, parts of the data have been replaced by ⋅⋅⋅

Header

06514 2008102300   52.00    4.12 52 38

Astronomical tide

004025  +003:45 +009:06 +014:15 ⋅⋅⋅ +224:35 +231:35
054003   -36     +75     -53    ⋅⋅⋅  -50    +136

Deterministic forecast

001092  0
054004    -9  -19  -19  ⋅⋅⋅  -22  -18

Control forecast

001092  1
054004   -10  -18  -20  ⋅⋅⋅   +6   +5

50 perturbed forecasts

001091  1
054004    -9  -18  -20  ⋅⋅⋅  +11   +6
001091  2
054004   -10  -18  -22  ⋅⋅⋅  -29  -32
⋅⋅⋅
001091 49
054004   -10  -17  -17  ⋅⋅⋅  -15  -16
001091 50
054004    -9  -18  -22  ⋅⋅⋅  +66  +63

Locations

The locations which are currently available are listed in the table below, together with the code which is used for identification and their model coordinates.

Name	IIiii	LAT		LON
Vlissingen	06520	51.42	51°25'00"	3.50	3°30'00"
Roompot Buiten	06516	51.67	51°40'00"	3.62	3°37'30"
Hoek van Holland	06514	52.00	52°00'00"	4.12	4°07'30"
IJmuiden	06522	52.42	52°25'00"	4.50	4°30'00"
Den Helder	06512	53.00	53°00'00"	4.62	4°37'30"
Harlingen	06513	53.25	53°15'00"	5.38	5°22'30"
Huibertgat	06515	53.58	53°35'00"	6.38	6°22'30"
Delfzijl	06511	53.33	53°20'00"	7.00	7°00'00"

Data availability

The data are available on request from KNMI's Licensing Office.