Input File Formats

Aspen can ingest sounding data that is provided in the following file formats.

Note that the file formats are not complete; i.e one format will contain information that another format does not support. Metadata in particular is not consistent between file formats.

Warning: Aspen automatically detects the format of the file that it opens, and assumes that the sounding contained is from the associated instrument. This can lead to ambiguities, if Aspen is used to process a file that it has written. For instance, if dropsonde data are saved by Aspen in “CLASS” format, and then this file is used as input to Aspen, the program will assume that the data are from an upsonde sounding, rather than a dropsonde. This can lead to erroneous results within Aspen, since the characteristics of the sounding system affect the processing procedures. In addition, care should be taken not to process data twice when using formats Aspen can both read and write.

NCAR AVAPS GPS Dropsonde “D” files

The AVAPS D file includes metadata in header and footer lines, with a variable number of data lines in between. Line contents are determined from an identifier at the beginning of the line: “S” lines for sounding data, “P” for pre-launch data, “A” for launch observation, and “COM” and other identifiers for metadata. Data lines are arranged in fixed width columns, with a standard set of data parameters reported. Header lines above the data lines give the column contents and units, and footer lines below the data lines give additional metadata about the sounding.

The data is reported in time order for both upsondes and dropsondes.

NCAR GAUS Upsonde files

The GAUS file includes metadata in header and footer lines, with a variable number of data lines in between. Line contents are determined from an identifier at the beginning of the line: “S” lines for sounding data, “P” for pre-launch data, “A” for launch observation, and “COM” and other identifiers for metadata. Data lines are arranged in fixed width columns, with a standard set of data parameters reported. Header lines above the data lines give the column contents and units, and footer lines below the data lines give additional metadata about the sounding.

The data is reported in time order for both upsondes and dropsondes.

NCAR MCASS Upsonde files

The MCASS file includes metadata in header and footer lines, with a variable number of data lines in between. Line contents are determined from an identifier at the beginning of the line: “S” lines for sounding data, “P” for pre-launch data, “A” for launch observation, and “COM” and other identifiers for metadata. Data lines are arranged in fixed width columns, with a standard set of data parameters reported. Header lines above the data lines give the column contents and units, and footer lines below the data lines give additional metadata about the sounding.

The data is reported in time order for both upsondes and dropsondes.

NCAR CLASS Upsonde files

The CLASS file starts with a 15 line header section, followed by a variable number of data lines. The data lines are arranged in fixed width columns. A mandatory set of 21 data parameters is reported, even though a number of these (specifically the “quality” values) are always marked with a missing value indicator.

The data is reported in the sequence of decreasing pressure, i.e. from the surface upward, regardless of the direction of the sounding.

NCAR GLASS Upsonde files

The GLASS file starts with a 15 line header section, followed by a variable number of data lines. The data lines are arranged in fixed width columns. A mandatory set of 10 data parameters is reported.

The data is reported in the sequence of decreasing pressure, i.e. from the surface upward, regardless of the direction of the sounding.

Comma Separated Values (CSV)

The “Comma Separated Value” file format is used for data interchange between Aspen and other software. This is the recommended file format for users who are importing data from an instrument that doesn’t produce other specific input file types. It is a free form structure, with one data record per line, and the fields in a record separated by commas. A CSV file can be read directly into Microsoft Excel, and the data will be correctly organized in the spreadsheet.

For input to Aspen, certain conventions must be followed within the CSV file. Each line begins with an identifier, followed by one or more fields. The order of the lines is generally not important, within the following guidelines:

• The first line must be:

  FileFormat,CSV
  

• After the first line, the launch time must be provided on lines as follows:

  Year,2001
  Month,08
  Day,01
  Hour,17
  Minute,58
  Second,34
  

• The launch observation data or other metadata may be optionally provided in lines labeled with the parameter name (case-insensitive) from the list of examples below:

  latitude,17.42451,"units=deg"
  longitude,126.50004,"units=deg"
  pressure,1002.6,"units=hPa"
  temperature,28.6,"units=deg C"
  rh,82.7,"units=%"
  speed,7.5,"units=m/s"
  direction,261.4,"units=deg"
  altitude,15.5,"units=m"
  gpsaltitude,15.5,"units=m"
  comments,"180 sec,  4-8 sat, eye drop,"
  datatype,"AVAPS SOUNDING DATA, Channel 2"
  equipmenttype,"8"
  platformtype,"WC 130"
  platformid,"65-0963"
  project,"RAINEX"
  flight,"RF04"
  agency,"NCAR"
  ptuwindtimediff,"-0.06"
  radiationcorr,"0"
  trackingtype,"08"
  sondeid,"980730027"
  sondetype,""
  operator,"Nick"
  soundingdescription,"D20000609_220604.1 345327 STEPS 2000 june 9 flt1"
  launchobssource,"IWGADTS Format (IWG1)"
  launchobstime,"07:11:24"
  sondemodel,"RS904"
  launchsite,"R/V Tommy Thompson"
  thermosensor,"Vaisala RSS904"
  

• To designate a dropsonde sounding, include a line:

  Ascending,"false"
  

• A “Fields” line defines the data fields and their order, for the succeeding “Data” lines. For an input CSV file to be read properly by Aspen, the following data field names (case-insensitive) must be used:

  Fields	Aspen utilization
  time pressure	Required input data fields
  temp rh rh1 rh2 speed direction latitude longitude altitude ascent sats gpsalt	These data fields will be utilized if provided
  others	Other data fields in input will be ignored

• The “Units” lines documents the units of each data field. Note that the units shown here must be adhered to; Aspen will not make units conversions. At least the time and pressure fields must be provided:

  Units,sec,mb,deg C,%,m/s,deg,deg,deg,m,deg C,m/s,m/s,m/s
  

• The “Data” lines follow after all of the preceding records.

Some other rules apply:

• Long strings should be enclosed in quotes.
• Don’t include commas in strings
• Capitalization is not important.
• The data series must be ordered in time
• Time tags less than zero will be ignored
• Don’t use reserved strings in the first field of a line.
• “Fields” must come before “Data”
• Missing data are simply represented by empty fields, i.e. two commas in succession, or a trailing comma on the end of a line, indicating that the last field is missing.

The following demonstrates a small CSV file:

FileFormat,CSV
Year,2001
Month,08
Day,01
Hour,17
Minute,58
Second,34
Pressure,57.6,"units=mb"
Temperature,-59.9,"units=deg C"
RH,,"units=%"
Speed,7.9,"units=m/s"
Direction,92.0,"units=deg"
Latitude,30.9909,"units=deg"
Longitude,-119.5005,"units=deg"
Altitude,19610.0,"units=m"
Ascending,"false"
Fields,Time,Pressure,Temperature,RH,Speed,Direction,Latitude,Longitude,Altitude,Dewpoint,Uwnd,Vwnd,Ascent
Units,sec,mb,deg C,%,m/s,deg,deg,deg,m,deg C,m/s,m/s,m/s
Data,0.3,,,,,,,,,,,,
Data,0.8,,,,,,,,,,,,
Data,11.8,,,,11.52,69.53,,,,,-10.79,-4.03,
Data,38.8,71.06,-60.33,,8.23,104.25,30.99129,-119.50375,18295.7,,-7.98,2.03,-39.94
Data,51.8,77.01,-63.75,,8.67,160.11,30.99174,-119.50441,17799.7,,-2.95,8.15,-36.35
Data,66.3,83.86,-62.29,,,,30.99267,-119.50520,17276.1,,,,-35.06
Data,75.8,88.52,-64.99,,8.95,119.15,30.99295,-119.50592,16944.3,,-7.82,4.36,-34.01

Vaisala MW41 Upsonde files

Aspen can read in ASCII text files from the MW41 radiosonde system, but will not apply quality control procedures as this is done by the MW41 software and should not be duplicated. The use case for this is using Aspen to convert from MW41 format to other more widely used formats for sounding data.

WMO TEMP messages

Aspen can extract levels information from a WMO TEMP message. Aspen will not attempt to apply QC to a WMO message, but the data it contains can be examined in the Levels tab or plotted in the XY Graph or Skew-T tabs. In this case Aspen is used for data visualization rather than data processing.