Data files shall be in plain ASCII text format:
The data files consists of a header section and a
data section. The header section contains global information for
the entire file and is placed at the beginning of the file. The
header section contains header labels for each line contained
in the header. The labels are mandatory and shall appear exactly
as given in the descriptions and examples.
Archive files shall be in zipped format and will
contain archives of the following types
Data files shall have an ending of '.DAT'. Zipped archive files shall have an ending of '.ZIP'.
All files will be prefixed with 'CLIMAP_' plus an indicator of the product type. The indicator shall be one of 'RO_' (radio occultation) or 'GB_' (ground based) or 'TO_' (ATOVS).
There will be an indicator of the date of the data. It will have the format yyyymmdd where yyyy is the year, mm is the month and dd is the day of the month.
Finally, in data filenames there will be an indicator,
nnnn, of either an occultation event number (0001-9999) in the
day, or the ground station ID in alpha code ('HERS' for the station
Herstmonceaux) or the ATOVS sounding event/collocation number
of the day (0001-9999).
The format is
CLIMAP_tt_yyyymmdd_nnnn.DAT for data files and
CLIMAP_tt_yyyymmdd.ZIP for zipped archive files.
The following examples should clarify this.
CLIMAP_RO_19970210_0005.DAT - a single day occultation, event 5 on 10 of February 1997.
CLIMAP_GB_19980701_HERS.DAT - 1 day's time series from Herstmonceaux on 1 of July 1998.
CLIMAP_TO_20001231.ZIP - zip archive file containing all ATOVS collocations (with RO and GB) for 31 of December 2000.
The type specifications are given in fortran format:
X is blank space, I is integer, F is float and D is double. The number before the type is the number of spaces occupied by the value, e.g. I4 is a four spaced integer.
The following formatting rules apply to all definitions given below:
The value e.g. ONS of type A4 will occupy the three
leftmost places in a 4 place field. The value 222.22 of type F7.2
will occupy the 6 rightmost places in a 7 place field. The value
0.8888888D+02 of type D14.2 will occupy the 13 rightmost places
in the field.
The file has 80 columns
HEADER DESCRIPTION - Table 1
| HEADER LABEL
Columns 61-80 | DESCRIPTION AND PRECISION | FORMAT |
| Occultation Id | Occultation Id. Same as in filename | I4 |
| Time of Processing | yyyy mm dd hh mm ssv | 6I6 |
| Date of Occultation | yyyy mm dd | 3I6 |
| Time of Occultation | UT of starting point. Hh mm ss | 3I4 |
| Stations | TBD | TBD |
| IPW | 0.1mm | F4.1 |
| No of Data Points 1 | No of data points of type in file | 2I5 |
| Cent of Curv Origin | X Y Z coordinates. 0.001m | 3D10.3 |
| Time since start | Delta t time of radius of curvature. 0.01s | F10.2 |
| Curvature | 0.001 km | F8.3 |
| TaNG PT Lat AND Long | Latititude and longitude of tangent point closest to surface. 0.001deg | 2F8.3 |
| GNSS ID | The PRN of the LEO satellite. Either GPS or GLONASS. | A1,I2 |
| Processing Method | A TBD code identifying the processing method and possibly version no. | A10 |
| Quality Index | A TBD code defining the quality level of the data. | TBD |
| END OF HEADER | 60X |
DATA RECORD DESCRIPTION - Table 2
| Time since start | 0.01 s | 2X,F12.2 |
| Phase shift L1 | Atmospheric phase shift, 10-5 m | D11.5 |
| Phase shift L2 | Atmospheric phase shift, 10-5 m | D11.5 |
| Phase smoothing interval | Time interval over which phase is smoothed, 0.01 s | F6.2 |
| Doppler shift L1 | Uncorrected atmospheric Doppler shift, 10-6 m | D15.6 |
| Doppler shift L2 | Uncorrected atmospheric Doppler shift, 10-6 m | D15.6 |
| Voltage L1 | Reference voltage of receiver 0.01V/V | F6.2 |
| Voltage L2 | Reference voltage of receiver 0.01V/V | F6.2 |
| Transmitter position vector | Geocentric, Earth-fixed x, y, z coordinates, 0.001m | 3D13.3 |
| Transmitter velocity vector | Geocentric, Earth-fixed x, y, z velocities , 10-6 m/s | 3D12.6 |
| Receiver position vector | Geocentric, Earth-fixed x, y, z coordinates, 0.001 m | 3D13.3 |
| Receiver velocity vector | Geocentric, Earth-fixed x, y, z velocities, 10-6 m/s | 3D12.6 |
| Impact parameter I | Impact parameter for L1 0.001km | F8.3 |
| Impact parameter II | Impact parameter for interpolated L2 to L1 sampling rate Hocke et al. 1997 0.001 km | F8.3 |
| Bending angle L1 | Angle of refraction of L1, not corrected for ionospheric effects. 10-8rad | D14.8 |
| Bending angle L2 | Angle of refraction of L2, not corrected for ionospheric effects. 10-8rad | D14.8 |
| Bending angle | Corrected for ionospheric effects. Hocke et al. 1997. 10-8rad | D14.8 |
| Latitude of tangent point | Geodetic latitude is the angle betweenthe equatorial plane and the local normal to the surface of the Earth (in this case an ellipsoid). Geodetic coordinates 0.001deg | F8.3 |
| Long. of tangent point | Latitude and longitude represents the position of the tangent point of the raypath, projected to the surface of the Earth. That this position shifts with time does not indicate that the retrieved profiles are non-vertical because the integrations are performed vertical, but merely that the profiles are representing an average. 0.001 deg | F8.3 |
| Altitude | The altitude above the surface of the Earth at the position in listed in the header. 0.001 km | F8.3 |
| Refractivity | Derived using the Abel transform. The dry density is linear in the refractivty. 10-4 | D15.9 |
| Retrieved dry Pressure | The dry pressure is derived integrating the hydrostatic equation, neglecting that water vapour could be responsible for some of the refractivity. Derived given humidity profile. 0.01hPa | F7.2 |
| Retrieved dry temperature | The dry temperature is calculated from the derived pressure and density via an equation of state (the ideal gas equation). 0.01K | F7.2 |
| External temperature | A temperature profile taken from an NWP model or independent measurements. This temperature is assumed true below 15km. Above 15km the derived dry temperature is used and a smooth transition is made. Hence no water vapour is derived above 15km 0.01 K | F7.2 |
| Retrieved total pressure | The total pressure is the sum of the partial pressure of dry air and water vapour, and is derived in an iterative algorithm Høegh et al. 1998. Derived given temperature profile, 0.01hPa | F7.2 |
| Retrieved water vapour pressure | The derived water vapour pressure might at some altititudes become negative, but this is a result of noise. The water vapour pressure and the total pressure are calculated in an iterative algorithm which stops when tthte water vapour pressure changes less than 0.01mb between two iterations. 0.01hPa | F5.2 |
| Integrated volume | This is meant as a quality measure. It is the distance between two adjacent layers times the area covered by rays having altitudes in this interval. A high integrated volume indicates that many irregularities may have been averaged and the assumption of spherical symmetry might be slightly violated and hence the derived parameters might be less reliable. 0.1 km3 | F8.1 |
HEADER DESCRIPTION - Table 3
| HEADER LABEL
Columns 61-80 | DESCRIPTION | FORMAT |
| Station Id | 4 letter station code | A4 |
| Station Position | lat/long to 0.001deg, height above MSL to 0.001km (Dave), or lat/long/height wrt the ellipsoid. The MSL deeds a geoid. Precision of positions depend on the solution procedure for each day. TBD | TBD |
| Day of measurement | Day of measurement. Yyyy mm dd | 4I4 |
| No of Data Points | Number of data points in this measurement | I3 |
| Processing Method | A TBD code identifying the processing method and possibly version no. | A10 |
| Quality Index | A TBD code defining the quality level of the data | TBD |
| END OF HEADER | Last record in the header section | 60X |
DATA RECORD DESCRIPTION - Table 4
| Time | 1s, sampling of 15min. hhmmss | 4I2 |
| Total Zenith Delay | Dealy in mm with precision of 0.1mm | F7.1 |
| Zenith Wet Delay | Only when pressure is available (maybe an estimate). 0.1mm | F7.1 |
| Integrated Water Vapour | In mm with precision of 0.1mm | F7.1 |
| Surface Pressure | The surface pressure value used in the dry delay modelling. Only used if available. 1Pa. TBC | I4 |
| Surface Temperature | The surface temperature used in dry delay modelling. Only used if available. 0.01K. TBC | F7.2 |
TBD. Awaits input from KNMI.
HEADER DESCRIPTION - Table 5
TBD
DATA RECORD DESCRIPTION Table 6
TBD
TOVS Data Format
TBD Awaits input from KNMI
View PDF format data file example