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World Data Centre for Aerosols
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Submit Data    May 24, 2016
Submitting Data to the World Data Centre for Aerosol (WDCA)

The WDCA data holdings are hosted in the EBAS database, which was originally designed for the European Monitoring and Evaluation Programme (EMEP). WDCA data are identified with the project associations GAW-WDCA for fully quality assured data, and GAW-WDCA_NRT for near-real-time data. Data providers benefit from improved data dissemination through WDCA with an increased number of collaborations. Data submitted to WDCA are protected by a fair-use data policy.

Submission Format

Data submitted to WDCA need to be formatted in the EBAS NASA-Ames format by the data provider. This format is based on the ASCII text NASA-Ames 1001 format (ASCII and UTF-8 charsets allowed), but contains additional metadata specifications ensuring proper documentation, and is designed to be easily understandable (see reasoning behind this setup). In this section, you will find format templates for parameters hosted by WDCA.

Submission Procedure

The normal mode of submitting data to WDCA is the regular, annual data submission. Stations formally associated with GAW make a voluntary commitment to submit their aerosol observations to WDCA. The deadline for data submissions for a given year is the end of the following year, unless a contributing network has a tighter deadline. WDCA also offers advanced data reporting that establishes complete traceability of the measurement and data analysis process. Participation in the advanced data reporting scheme is voluntary unless required by a contributing project or framework. The usual steps for submitting data for the first time include:
  1. Registering your station with GAWSIS:
    If you are submitting data to WDCA for the first time for a given station, you need to check whether the station is already registered with the GAW station information system (GAWSIS). If this isn't the case, you need to find the person responsible for the station as a whole. Either this person or yourself after being authorized by that person may register the station. Please contact WDCA by e-mail to ebas@nilu.no, and indicate who will register the station. This person will then receive login credentials for GAWSIS. After login, the menu item "Register a new station" is available in GAWSIS, where a form needs to be filled in to complete the station registration.
  2. Initial contact with WDCA:
    Please establish the initial contact with WDCA by writing an e-mail to ebas@nilu.no. In your mail, please indicate the station you are intending to report data for, the GAWSIS station ID, and the parameters you intend to report. In return, you will receive three further IDs: 1) the EBAS station code; 2) the EBAS platform code; 3) a code for your lab analysing the data, which you will need for the metadata in your submission. The reason for having several station codes lies in several frameworks collaborating. The three letter GAW IDs and the IDs used in the CLRTAP EMEP database EBAS were introduced independently and are maintained for consistency.
  3. Quality assure your data:
    This step will probably take longest of all steps in this data submission guideline, and is prerequisite for any further use of the data. Please make sure that you followed the respective standard operating procedure (SOP) valid for your instrument, both during data collection and data processing and evaluation. There will likely be periods for which the data is invalid due to calibrations or malfunctions, and there may be additional conditions (activity around the station, etc.) you will want to convey to the data user. WDCA uses a system of flags for this purpose. Each flag is assigned a three digit integer number. The flags commonly used for a data type are listed on the same page as the corresponding data format template. If you don't find what you are looking for there, please consult the complete list of these flags at http://www.nilu.no/projects/ccc/flags/flags.html. The list of flags is comprehensive, but may not be complete. If there is a condition you think is not covered, please send an e-mail to ebas@nilu.no for guidance or an extension of the list of flags.
  4. Assemble / Update Metadata Header:
    1. First-time submitters:
      In assembling the header with metadata for a first-time data submission, it is probably easiest just to copy the respective template valid for the parameter to be reported (see menu on the left), and adapt it to the station and protocols used for data collection and processing. Each line in the online template, or the respective line number, is a link pointing to an explanation of the content. The explanation always begins with a specification of the syntax used. Items enclosed in “<>” mark a place holder to be replaced with content or key words as described. Please follow the syntax exactly since many lines contain a keyword identifying the content, and these keywords are recognised by string comparison. Be reminded to use either the ASCII or UTF-8 character settings in your editor.
    2. Experienced submitters:
      If you have submitted data for a given parameter to WDCA before, you can copy the header from the previous year to start with, and update at least the fields containing a date or time. However, please make sure to check through the metadata items and update them in case any changes occured in your setup. Especially for later trend analysis, it is rather important that any changes that may have caused a rupture in the dataset are documented in the metadata.
  5. Format data, join header and data sections:
    The data section of an EBAS NASA-Ames file consists of a fixed width, fixed number format ASCII table, with the number formats specified in the file header. Please refer to the parameter specific pages for examples (menu on left). Once the data section is constructed, please join header and data section into one file, and name the file using the file name stated in the header.
  6. Submit Data:
    The files containing the data submissions are uploaded to EBAS’s anonymous FTP-site, which is accessible at:
    To prevent abuse of this server, it is configured in "blind-drop" mode. It accepts uploads only and ignores directory requests, i.e. you won't be able to see the files you just uploaded, and you won't be able to delete them once they are uploaded. If you uploaded a file in error, please send an e-mail to ebas@nilu.no and specify the details. Currently, you won’t receive an automated acknowledgement of receipt, but this service is due to be added.

Legacy Data

For assessing trends in load and properties of atmospheric aerosol, long time series are of vital importance. The WDCA therefore welcomes submissions not only of recently collected data, but also of legacy data. This includes data that may not yet have been collected in compliance with any standard operating procedure recognised today.

Further Background Information

  • Why do we ask the data providers to format their data in a specific format?

    1. Avoiding of errors: It has turned out that reformatting the data for the provider increases the number of errors in the data. The reformatting process involves often lengthy correspondence between data provider and centre on how to interpret the data, and is prone to misunderstanding and information loss. A clearly defined format as interface between data provider and centre avoids this information loss.
    2. Scientific standard of data provider: The annual data submission represents the essence of a year’s scientific work at the station. It is part of most data providers’ standard and their own wish to assemble this part of their work themselves.
    3. Work load at data centre: EBAS collects over 6000 datasets per year, including co-operating networks. With reformatting this amount of data, the number of other services EBAS could offer was rather limited. Together with data providers and users, it was decided to free these resources in favour of data interpretation and dissemination.

  • Why do we use data formats based on NASA Ames 1001, a rather old specification?

    1. Simplicity: The format consists of a pure ASCII text that may be assembled and used with numerous, readily available spreadsheet applications, plotting applications, and numerical libraries. It is readable and understandable for a human reader. It is streamlined enough to make the instructions on assembling it fit on a few pages, which is rarely matched by other formats, but still contains the essential information for efficient data archiving, discovery, and documentation.
    2. Reduce format confusion: Some features and specifications of NASA Ames 1001 and EBAS NASA-Ames are certainly outdated and targeted at older IT environments. However, as long as necessary new features can be implemented within the existing format, defining an only slightly optimised new format would only add to the format confusion and prevent the use of existing routines and libraries.
    3. Keep threshold low: Other formats like NetCDF or HDF have come into use in the modelling and satellite communities, respectively. However, these are binary formats, not plainly readable for a human, and special applications or routines and a steep learning curve are required for assembling them. For EBAS, it is the intention to keep the threshold for data providers as low as possible. EBAS NASA-Ames has been in use for well more than a decade, and is used also by countries with less developed atmospheric monitoring infrastructures.
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