[ ] Number of minutes relative to nominal time at which to start window
[ ] Number of minutes relative to nominal time at which to end windowChoose one of the following:
Return one record per fixed station within window, closest to end of window
Return one record per fixed station within window, closest to nominal time
Return one record per fixed station within window, closest to start of window
Return all records within window
No window - return all records in the file containing nominal time
The user selects the "nominal time" of the data to be returned in the Time Selection text entry box. Time "windowing" is used so that the Viewer will know how close in time each station's observation time needs to be to the nominal time in order to be included, and whether or not duplicate records from the same station that are within the time window should be included. The time window is specified by selecting the number of minutes before and after the nominal time to be used for the window, and how duplicates should be handled. Surface stations report observation times around the hour, and many stations report multiple times per hour, so different time window specifications can produce very different sets of data.
The default time window selection will return the most current record for each station within one hour of the nominal time, whose default is the current time.
The maximum window is 180 minutes. Also note that the window is inclusive, that is, using start and end minutes -30,30 with a nominal time of 12:00 will return observations with times ranging from 11:30 through 12:30.
If "No window" is selected, then all records (including multiple reports from the same station) will be returned from the file containing the nominal time. For non-mesonet stations, this will return observation times between 15 minutes before the hour and 44 minutes after the hour. For mesonet stations, data will cover from the hour until 59 minutes after the hour. [This option is really only meant to be used by MADIS developers during testing.]
Filter time by Observation Time or Receipt Time. Observation Time filter is the
default behavior. The Receipt Time is only for real-time data (when the Nominal Time is "0").
For Receipt Time set nominal time is "0". Set start time to "-40" to "-65" minutes.
Set end time to "0". Set return records to "Return all records within window" or
"No window - return all records in the file containing nominal time".
Required settings for Receipt Time
- nominal time is "0"
- return records is all records in window or all records
- end time is "0"
- start time is -30 to -179.
- output format is csv
You can limit the stations returned by their geographic location, or pick a single station (by entering its ID). The default is to pick a single U.S. state from a dropdown menu.
You can also enter the latitude/longitude corners that define a rectangle that contains the desired area. Latitude is positive North, so use positive numbers in the Northern hemisphere and negative numbers in the Southern hemisphere. Longitude is positive East, so use negative numbers in the Western hemisphere and positive numbers in the Eastern hemisphere.
If you select "Get all stations", you'll get data from all over the planet.
Surface datasets include many different networks run by different "providers". If desired, the user can select only a subset of the total by specifying which providers are to be included or excluded. The default is to enable data from all surface providers. Most national-scale networks in North America that report surface conditions are included. Over land, this includes all stations that report standard METARs (ASOS, AWOS, non-automated stations) or SAOs (Canadian stations), as well as modernized (i.e., automated) National Weather Service Cooperative Observer reports. Maritime reports are also available, including the Coastal Marine Automated Network (C-MAN), fixed and drifting buoys, and ship reports. The MADIS meteorological surface dataset also contains a unique collection of thousands of mesonet stations from local, state, and federal agencies, and private firms. One of these mesonets, GPSMET, includes water vapor observations from geo-positioning satellites (GPS) in addition to surface observations.
Some of the mesonets are restricted. Click here for details.
Click here to see the list of mesonet providers, their geographic coverage, and their number of stations.
The user can select which meteorological variables will be returned. The default is to return a standard set of surface variables, namely dewpoint temperature, relative humidity, temperature, wind direction, wind speed, wind gust, and altimeter setting (the form of pressure normally used for sea level pressure across the country). The user can also pull up a window to select from the full list of variables, or can specify returning all variables (watch out, there's a lot of them).
In general, standard scientific units will be returned, e.g., Kelvin for temperatures, meter/second for wind speed. Here are links to the definition of all of the variables, along with their units, for each dataset:
Return observations passing all quality control checks (default)
Return observations passing levels 1,2,3
Return observations passing levels 1,2
Return observations passing level 1
Return all observations regardless of quality control results
The primary variables in all MADIS datasets have been screened by automated quality control (QC) checks. Different variables have different levels of QC, or "stages", applied to them. For example, temperature may have level 1 checks (validity), level 2 checks (internal consistency, temporal consistency), and level 3 checks (spatial consistency). Note that each level of QC incorporates the previous levels, i.e., an observation that has passed level 3 has also passed any applicable level 1 and 2 checks.
Each variable that gets returned will also have its associated QC information returned. This includes a QC data descriptor (a single character summarizing the info), and bitmasks showing which QC checks were applied and the results of the checks. These are labeled "QCD", "QCA", and "QCR" in the output. For details on how to interpret these items, and full details on the QC, click here.
If the user doesn't want to interpret the QC info, he or she can limit the returned obs to selectable levels of quality. In that case, obs that don't meet the selected QC level will be omitted.
User's of MADIS data who want the data filtered by QC results, but don't want to interpret the QC information themselves, should use the default setting.
You can select either text (default) or XML as the output format.
In general, standard scientific units will be returned for the data values, e.g., Kelvin for temperatures, meter/second for wind speed. Here are links to the list of variable names and their definitions, along with their units, as well as other information can be found for each dataset:
For details on how to interpret the QC data descriptor and bitmasks, as well as full details on the QC, click here.
V-variable name
Station ID
Elevation (meters)
Latitude (decimal degrees North)
Longitude (decimal degrees East)
Grid I (has no meaning in this Viewer)
Grid J (has no meaning in this Viewer)
Observation time (GMT)
Provider
Data value
QC data descriptor
QC applied bitmask
QC results bitmask
The CSV text format can be used to put up to 14 variables (and optionally, their QC information) on one line for a single station and time. From left to right, here are the fields in the output:
Station ID
Observation date - mm/dd/yyyy (GMT)
Observation time - hh:mm (GMT)
Provider
Subprovider (if applicable)
Variable #1 value
Variable #1 QC data descriptor (if this option is selected)
Variable #1 QC applied bitmask (if this option is selected)
...
Variable #n value
Variable #n QC data descriptor (if this option is selected)
Variable #n QC applied bitmask (if this option is selected)
You can select how to handle missing data values. If you are planning to write software to read in the numeric values, you should select "-99999.00000" as the missing data flag. If you are planning on using the CSV output as a spreadsheet, you should select "blanks" as the missing data flag.