ARM Thumbnail Browser Glossary


Table of Contents

  • ARM
  • ARM Archive
  • ARM Thumbnail Browser
  • ARM Program Acronyms/Glossary
  • Cloud and Radiation Testbed (CART)
  • Data Level
  • Data Quality Color Calendar
  • Data Quality Report (DQR)
  • Data Stream
  • External Data
  • Facility
  • File
  • Geophysical Focus Area (GFA)
  • Global Earth Coverage
  • Instrument
  • Instrument Category
  • Measurement
  • NetCDF
  • North Slop of Alaska/Adjacent Arctic Ocean(NSA/AAO)
  • Novice Interface
  • Power Interface
  • Catalog Interface
  • Quick Looks
  • Site
  • Southern Great Plains (SGP)
  • Tropical Wetsern Pacific (TWP)
  • Value Added Product (VAP)
  • ARM

    Atmospheric Radiation Measurement (ARM) Program

    Link to more ARM documentation

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    ARM Archive


    The ARM Archive supports the scientific field experiments of the Atmospheric Radiation Measurement (ARM) Program by storing and distributing the large quantities of data collected from these experiments

    Link to more ARM documentation

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    ARM Thumbnail Browser


    The ARM Thumbnail Browser allows the user to view thumbnail images of ARM data files, select files, view data quality information, and order files based on a search criteria

    Link to more ARM documentation

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    ARM program Acronyms/Glossary

    ARM program related terms and definitions

    Link to more ARM documentation

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    Cloud and Radiation Testbed (CART)

    ARM’s field sites, instruments, and data system are considered the integrated system known as the Cloud and Radiation Testbed (CART). The field research sites, also known as CART sites, are used to study the effects of clouds on global climate change. The three primary locations, Southern Great Plains (SGP), Tropical Western Pacific (TWP), and North Slope of Alaska/Adjacent Arctic Ocean (NSA/AAO), are heavily instrumented to gather massive amounts of climate data

    Link to more ARM documentation

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    Data Level

    The data level is an indication of the extent of formatting, processing, or reviewing that has been completed on a data file. The data level is a two-character code (e.g.,a0,c1) that follows the first period in a data stream name or file name.

    ARM data are classified into several data levels. The levels represent the amount of processing the data have gone through.

    Data Level*
    Processing Status
    00 data Raw data
    a0 data Data that have been converted to netCDF
    a1 data Data that meet a0 requirements, are usually expressed in scientific units, and have had calibrations applied
    a2, a3, a4, . . ., a9 a1 data that have been further processed
    b1 Data that meet a1 requirements and have had quality control (min/max/delta) checks applied
    b2, b3, b4, . . ., b9 b1 data that have had additional quality control checks applied
    c1 Derived data products
    c2, c3, c4, . . ., c9 c1 data that have been further processed
    *Note: some data have not been processed through all phases (e.g., data level goes from being level 00, then a0, a1, and then c1).

    The amount of processing to which data have been subjected can be determined  for most data streams by the data level extension of the data stream name. Raw data, collected directly from the instrument or external source, are designated with a .00 extension. Data designated as a0 have minimally undergone a format change from the raw (binary, ascii, other) format to netcdf. If the data are also expressed in scientific units and calibration factors have been applied (as needed), the data are assigned an a1 data stream name extension. Data that have been further processed but do not meet the minimal requirements of b1 level data are assigned data levels of a2, a3, etc. The latter are considered intermediate products and are not usually intended for use by the scientific community.

    To be designated as b1 data, the data must meet the minimal requirements of a1 level data plus have had basic quality measures applied. These QC measures usually take the form of minimum/maximum/delta (change from previous sample) checks. If further processing is conducted on b1 data, the data are assigned data levels of. b2, b3, etc.

    Data designated by a c1 extension are derived data. These data are the output of an algorithm applied to ARM and/or external data to calculate values that might not be directly measurable. These algorithms are called Value-added Procedures and the output is called a Value-added Product.

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    Data Quality Color Calendar

    This color calendar displays daily color for a data stream and its measurements.

    The color calendar will display quality information in terms of 24 hour aggregated colors for each measurements.

    The color that one sees on the Quick Looks page of the Thumbnail Browser is derived from the following rules:

    Daily Color Rules (Auto QC)
    Color Rule
      (BLACK):  >50% of data elements are missing (e.g., data gap, temporary malfunction)
      (WHITE):  0% of the data elements have been assessed
      (GREEN):  >=80% of existing data elements are good
      (RED):  >20% of existing data elements are bad
      (YELLOW):  data exists but does not meet criteria for any other color
      (GRAY):  Undetermined (e.g., file not yet received)
    DQR colors in the Quick Looks page represents DQR-based (manually evaluated) quality information with definitions corresponding to those above for the automated GREEN, YELLOW, and RED colors, respectively.
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    Data Quality Report (DQR)

    A description of an event or observation that is believed to alter data quality from its normal patterns of measurement error. The scope of a DQR is usually limited to a specific time interval and class of data files

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    Data Stream

    Collections of data files that have a common source and structure are called data streams

    A data stream  name consists of a first part with abbreviations for the site, data source, and facility, a period, and a second part indicating the data level. A data stream describes a type of file from a particular location. A data stream is actually broken up into daily pieces (or rarely, longer-period pieces). The pieces are files with the same basic name structure but differing in time.

    Example of Data Stream:

    -**-*-***-** -*
    |  | |   |   `---->data level - the level of data processing
    |  | |   `-------->facility name (e.g., E12 - extended facility No.12)
    |  | `------------>abbreviation for instrument name (e.g., ebbr - Energy Balance Bowen Ratio(EBBR) station: surf. met&soil data for heat flux)
    |  `-------------->## - time integration instrument parameter
    `----------------->site (e.g., sgp - Southern Great Plains)
    Click here to view ARM Archive's Catalog of Data Streams (The information in this catalog is current as of March 11, 2003 )
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    External Data

    The ARM data structure also includes similar data collected by other programs. These data frequently represent spatial areas such as satellite scenes and interpolated mesonet data. More information about the spatial extent of the external data can be obtained from the following link.

    Link to more ARM documentation

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    A small physical location within an ARM site, where one or more instruments make measurements.

    The SGP site has central (C..), extended (E..), boundary (B..), and intermediate (I..) facilities. The TWP site has installations on Manus Island (C1), Nauru Island (C2) and Darwin(C3), Australia. The NSA site includes installations at Barrow (C1) and Atqasuk (C2).  Apart from this there are also some external (X..) facilities available for ARM program.


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    A single data file contains a limited time period of measurements from a data stream. Data files allow the information to be segmented into manageable increments for processing, storage and retrieval; usually ARM data files are in cdf format with one file per day

    ARM netCDF files are named according to the following naming convention


    sss                    is the site identifier (e.g. sgp, twp, nsa)

    nn                     is optionally the data integration period in minutes (e.g. 1, 5, 15, 30, 1440)

    inst                   is the instrument basename (e.g. mwr, wsi, mpl)

    qqq                  is an optional qualifier that distinguishes these data from other data sets produced by the same instrument

    Fn                    is the facility designation (e.g. C1, E13, B4)

    ln                      is the data level (e.g. a0, a1, b1, c1)


     An example netCDF data file name is

             This file contains 5-minute averaged microwave radiometer data from the Southern Great Plains Vici site for January 15, 1999.  The data level is ‘c1’ indicating the data were derived or calculated via Value-Added Processing (see Data Levels).

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    Geophysical Focus Area (GFA)
    These are high-level topics defined within the ARM Program that represent physical themes measured by the Program.
    Link to more ARM documentation
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    Global Earth Coverage
    Data from external sites (other than SGP, TWP, NSA) with global spatial coverage. These are typically satellite data that have not been "trimmed" to cover only an ARM site.
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    A field device which measures one or more physical attributes. Some instruments may be complex collections of multiple 'sensors' or instrument groups. For simplicity, each physically integrated device will be called 'an instrument'

    Link to more ARM documentation

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    Instrument Category


    Categories for data sources (including Value Added Products and Quality Measurement Experiments), keyed to the type(s) of instrument(s) involved in the measurements.

    Link to more ARM documentation

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    ARM Program Measurements [within Geophysical Focus Areas (GFA)]

    A value which represents a physical attribute of the environment. Examples include wind speed, air temperature, total direct radiation, etc.

    Note: The classification of ARM measurements into geophysical focus areas is currently incomplete. If you do not find the results you expect, you should use the instruments "search path" instead.


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    A binary, self-documenting file format used to store ARM data files. NetCDF was developed by UCAR and public domain software libraries for working with NetCDF files can be found at

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    North Slop of Alaska/Adjacent Arctic Ocean(NSA/AAO)

    The third Cloud and Radiation Testbed (CART) site, the NSA/AAO site is located in Barrow, Alaska. Its polar regions are predicted to undergo the largest warming in response to the increasing carbon dioxide in the atmosphere

    Link to more ARM documentation

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    Novice Interface

    The user answers a sequence of questions that allow the application to display thumbnail images and finally a list of files that may be ordered.

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    Power Interface

    The user is asked to select the site, date range and data stream names. These selections allow the application to display thumbnail images and finally a list of files that may be ordered.

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    Catalog Interface

    The user is asked to select the site and year, instrument category and facility type, instrument and data level, facility and month from the catalog of available Quick Looks. These selections allow the application to display thumbnail images and finally a list of files that may be ordered.

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    Quick Looks


    Graphs, usually  provided daily, showing the pattern of a measurement. Quick Looks are

    currently available for only a few of the thousands of ARM measurements, but

    more measurements will be included in future.

    Link to more ARM documentation

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    A large geographic region (e.g., 55,000 square miles for the SGP site) where ARM instruments are installed.

    There are three ARM sites  Southern Great Plains(SGP), Tropical Western Pacific(TWP), and North Slope of Alaska(NSA). There are also external data available for ARM.

    Link to more ARM documentation

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    Southern Great Plains(SGP)

    The first of the Cloud and Radiation Testbed (CART) sites, the SGP site is located in south Kansas and north Oklahoma. It is host to virtually every type of cloud system through out the year.

    Link to more ARM documentation

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    Tropical Western Pacific(TWP)

    The second Cloud and Radiation Testbed (CART) site, it is located in the south Pacific Ocean, occupying Manus Island, Nauru Island, and Darwin, Australia. The site features the warmest ocean water, highest atmospheric water vapor contents, and the most covective cloud regimes in the world. It also plays a key role in the El Niño phenomenon.

    Link to more ARM documentation

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    Value Added Product (VAP)

    ARM data files and data streams that are derived from advanced algorithms or include the merging of data from more than one input data source are called value added products (VAPs). The value added products have a data level of c1 or higher and have a data flow pattern that is different from the directly processed data streams. The scope of active VAPs is continually evolving.

    Link to more ARM documentation

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    This page last modified on Wednesday, 06-October-2004 17:00:00 GMT