Overview
There are two types of layer data files that contain labels or tracking information for radar echogram layers. The layerData files contain layer information for each frame. The season layerdata files, which are described on this page, are read only and are used by imb.picker and other tools for plotting whole segments at a time (e.g. imb.picker uses these files to plot the flightlines on the map when the layerdata source is selected). In addition to layer information, there is GPS time and location as well as version and metadata information.
The standard file path for season layer data files is:
fullfile(gRadar.support_path,'layer','layer_LOCATION_SYSTEM_SEASON_NAME')where: LOCATION: string containing 'arctic' or 'antarctic' SYSTEM: 'accum', 'kaband', 'kuband', 'rds' SEASON_NAME: follows the YYYY_LOCATION_PLATFORM format
Season layerdata File Fields
Nx is the number of records in the season layerdata file. Season layerdata files contain all the layer information for an entire segment (i.e. contain all frames) and the entries are chronologically ordered. Note that the use of the word "records" here refers to a generic record and is not the same as the raw data file records. Usually the time sampling of a season layerdata file is much lower than the raw data files. The default sampling rates in along-track are dependent on the radar_type as returned from ct_output_dir.m:
|System or radar_type| Default sampling rate (m)| |accum| 5| |kaband |5| |kuband| 5| |snow| 5| |rds| 15|
The fields in the season layerdata file are:
| Command | Description |
|---|---|
| bottom | 1 by Nx double vector containing two way travel time to the bottom. The particular layer that is chosen (default "bottom") can be overridden during season layerdata file creation. |
| elev | 1 by Nx double vector containing the elevation of each record in meters relative to the WGS-84 ellipsoid |
| file_type | String containing 'layer_season'. |
| file_version | String. Current version is '1'. If it contains 'D' anywhere in the string, then this file has been marked for deletion. If it contains 'L' anywhere in the string, then this file has been locked and should not be written to. |
| frm_id | 1 by Nx double vector containing the frame ID of each record (YYYYMMDDSSFFF as a number). Frame numbering starts at 1 and increases monotonically with time. This field is included to provide quick lookup of the frame ID for a particular data point. |
| frm_info | Structure with frame information. |
| frm_info.frm_id | 1 by Nfrms double vector with each frame ID (YYYYMMDDSSFFF). |
| frm_info.start_gps_time | 1 by Nfrms double vector containing the start_gps_time of each frame (seconds since Jan 1, 1970, ANSI C standard). |
| frm_info.stop_gps_time | 1 by Nfrms double vector containing the stop_gps_time of each frame (seconds since Jan 1, 1970, ANSI C standard). |
| gps_source | String containing gps_source field from the csarp_support gps file when this file was created or had its GPS updated. |
| lat | 1 by Nx double vector containing the latitude of each record in degrees |
| lon | 1 by Nx double vector containing the longitude of each record in degrees |
| param | Minimal param structure. |
| param.day_seg | Day segment string YYYYMMDD_SS |
| param.season_name | Season name string in YYYY_LOCATION_PLATFORM format |
| param.radar_name | String containing one of the following strings: 'accum', 'kuband', 'rds', or 'snow' |
| param.sw_version | Software version structure returned from current_software_version.m when this file was created. |
| quality | 1 by Nx double vector containing quality of the bottom label in "bottom". |
| surf | 1 by Nx double vector containing two way travel time to the surface. The particular layer that is chosen (default "surface") can be overridden during season layerdata file creation. |
Functions that use the season layerdata files
- imb.picker
- imb.create_season_layerdata_files