MADIS ACARS Variables - Numeric

-------------------------------------------------------------------------------------------
Code       Name                                Units      Max          Notes      Database  
                                                       QC Level*                 FSL  AWIPS
-------------------------------------------------------------------------------------------
DD        wind direction                       deg          1            1        X     X
FF        wind speed                           m/s          1            1        X     X
U         u wind component                     m/s          1            1        X     X
V         v wind component                     m/s          1            1        X     X
T         air temperature                      K            2            2        X     X
TV        virtual temperature                  kg/kg        2            2        X     X
TD        dewpoint temperature                 K            2            3        X     X
RH        relative humidity                    %            2            3        X     X
Q         specific humidity                    kg/kg        2            3        X     X
DPD       dewpoint depression                  K            2            3        X     X
AH        absolute humidity                    g/(m**3)     2            3        X     X
WVMR      water vapor mixing ratio             g/kg         2            3        X     X
REPWVQC   reported water vapor QC              code         0            4        X     X
RHPROBE   rh in probe                                       0            4        X     
RH1       rh sensor 1                          %            0           19,20     X
RH2       rh sensor 2                          %            0           19,20     X
RHUNCER   rh uncertainty                       %            0           19,20     X
TDUNCER   dewpoint uncertainty                 K            0           19,20     X
MACH      mach number                                       0            4        X     
TASPEED   true air speed                       m/s          1           19        X
MEDEDR    median eddy dissipation rate         m**(2/3)/s   1            5,21,22  X     
MAXEDR    maximum eddy dissipation rate        m**(2/3)/s   1            5,21,22  X     
VACC      vertical acceleration                m/s/s        0                     X     
PEAKVG    peak vertical gust                   m/s          0                     X      
TURBIDX   turbulence index                     code         1           17,21,22  X     X
HT        pressure altitude                    m            2            6        X     X
GPSHT     geometric height determined by GPS   m            0           19        X
BAROHT    barometric-corrected height          m            0            6        X
P         pressure                             Pa           2            6        X     X
LAT       latitude                             deg N        1                     X     X
LON       longitude                            deg E        1                     X     X
HEAD      heading                              deg          0                     X     
FLPHASE   phase of flight                      code         0           16        X     X
ICECOND   icing condition                      code         1           12,21     X
ROLL      aircraft roll angle flag             code         0            7        X     X
TINT      time interpolation indicator         code         0            8        X      
LINT      location interpolation indicator     code         0            8        X      
DINT      decoding-correction indicator        code         0            9        X      
LTINT     loc./time interpolation indicator    code         0            8              X
RMEDEDR   reported median EDR                  m**(2/3)/s   0            5        X      
RMAXEDR   reported maximum EDR                 m**(2/3)/s   0            5        X      
REPRH     reported rh                                       0            4        X      
TPREC     temperature precision                K            0                           X
LLSPEC    original specification of lat/lon    code         0           15              X
PLATTYP   data platform type                   code         0           13        X     X
DATASRC   source that provided the data        code         0           14        X     X

MADIS ACARS Variables - Character

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Code       Name                                Character               Notes      Database
                                               Size                              FSL  AWIPS
-------------------------------------------------------------------------------------------
REPGSTA   reporting ground station             4                        10        X     X
ORIGAPT   originating airport                  6                        10        X
DESTAPT   destination airport                  6                        10        X
RCPTIME   receipt time                         9                        11        X     X
TRBTIME   time of maximum turbulence           9                        19        X
FLNUM     flight number                       13                                        X

Notes

Wind speed and direction are reported and stored in the database. The user can optionally select u & v wind components and those will be calculated and returned. The QC results from speed and direction will be used In either case, and if one of the map projections has been selected via the MSETDOM call, the winds will be rotated to match the projection.
Air temperature is the temperature variable stored in the database. For aircraft that are also reporting dewpoint temperature (a minority) the user can optionally select virtual temperature, which will then be calculated by the MADIS API. The QC results from air temperature will apply in either case. Also note that if virtual temperature cannot be calculated (missing or bad dewpoint or pressure), and the air temperature passed all QC checks, the air temperature will be returned instead, and a QC data descriptor value of "T" will be assigned.
In the FSL database relative humidity is the moisture variable stored for TAMDAR data, and water vapor mixing ratio is used for non-TAMDAR data. Relative humidity is the form of moisture in the AWIPS database. The user can optionally select any of these variables, specific humidity, dewpoint depression, or absolute humidity and these values will be calculated by the MADIS API. In all cases, the QC results from the dewpoint temperature will be used (with the FSL database, there's currently no QC in the AWIPS database).

The dewpoint temperatures are calculated from data reported by aircraft equipped with the Water Vapor Sensing System (WVSS). For detailed information on the WVSS observations and their processing see the documentation available at http://www.joss.ucar.edu/wvss.

While the dewpoint temperatures are correct, the user should be aware that there are inconsistencies related to the decoding at FSL of the other water-vapor-related variables (rh probe, reported rh, water vapor mixing ratios, reported water vapor QC, and mach number). Therefore, the QC'ed moisture information returned from the MADIS API (dewpoint, rh, ah, dewpoint depression) are all calculated from the dewpoint temperatures.

Reported water vapor QC codes -- FSL database:

       Value      Meaning
       -----      -------
        45        Missing data
        48        Normal operations, ground speed > 60 knots
        49        Normal operations, nonmeasurement mode,
                  ground speed < 60 knots
        50        Small RH, RH measured is < 1.5%; RH set to 1.5%
        51        Humidity element is wet. RH at 5.0 volts for < 120 seconds
        52        Humidity element contaminated.
                  RH at 5.0 volts for > 120 seconds
        53        Heater fail
        54        Heater fail and wet/contaminated humidity element
        55        Single validity bad.  One or more of the input parameters
                  for the mixing ratio calculation are invalid: TOT_PRESS,
                  MACH TAT_WVSS, or RH.  If RH is full scale, RH is
                  considered valid to allow wet/contaminated status to be
                  posted.
        56        Numeric error. Calculated mixing ratio at or above 100,
                  below 0.1-9, or negative, or absolute value of
                  denominator of calculations is less than 10-15.
        57        Dew point is greater than temperature

Reported water vapor QC codes -- AWIPS database:

       Value      Meaning
       -----      -------
         0        Normal operations, measurement mode
         1        Normal operations, nonmeasurement mode
         2        Small RH
         3        Humidity element is wet
         4        Humidity element contaminated
         5        Heater fail
         6        Heater fail and wet/contaminated humidity element
         7        At least one of the input parameters used in the calculation
                  of mixing ratio is invalid
         8        Numeric error
         9        Sensor not installed
        63        Missing data

The reported eddy dissipation rate (EDR) variables contain both data values and embedded code values that are used to indicate reasons why no data values are available. Therefore, a user only interested in the data values themselves should request the median and maximum EDR variables. For more information on the EDR observations see http://www.rap.ucar.edu/research/turbulence/insitu.html.
Reported EDR "no data" codes:
```
       Value      Meaning
       -----      -------
        2.54      Bad CGA  - Insufficient vertical acceleration data
        2.53      Bad ALT  - Altitude out of range
        2.52      Bad MACH - Speed out of range
        2.51      Bad MASS - Aircraft mass out of range
        2.50      Bad FLAP - Flap angle out of range
        2.49      Bad AUTO - Autopilot off
```
The altitude-determining physical variable is pressure. This is converted to altitude by using the U.S. Standard Atmosphere calculation. The standard atmosphere is used at all altitudes and under all pressure conditions. Thus, for instance, it is possible to have ACARS altitudes below ground level on days with high atmospheric pressure. (This is in contrast to other aviation reports such as voice pireps that use a standard atmosphere to compute altitude above 18,000 ft (MSL), but use the current altimeter setting for lower altitudes). The barometric-corrected height is used instead of a pressure altitude below approximately 18,000 ft in AMDAR reports from Japanese airlines.
The user can request either altitude or pressure, and the MADIS API will do the conversion and return the requested variable. In either case, the QC results from the altitude variable will be applied.

Aircraft roll angle flag -- FSL database:

       Value      Meaning
       -----      -------
        66        roll > 5 degrees
        71        roll ≤ 5 degrees
        78        not reported

Aircraft roll angle flag -- AWIPS database:

       Value      Meaning
       -----      -------
         0        good             
         1        bad

Some high-resolution ascent/descent observations are reported without times, and/or location information. In these cases the FSL decoder interpolates the values and indicates that in the LINT and TINT interpolation indicator codes. The decoder used to create the data in the AWIPS database combines these into one indicator, LTINT. Here are the possible values for these variables:
LINT, TINT -- FSL database:
```
       Value      Meaning
       -----      -------
        105       interpolated
        114       reported
```
LTINT -- AWIPS database:
```
       Value      Meaning
       -----      -------
         0        time interpolated, latitude and longitude reported
         1        time reported, latitude and longitude interpolated
         2        time, latitude, and longitude interpolated
         3        time, latitude, and longitude reported
         7        missing value
```
For more information on the FSL decoder and its processing, see http://acweb.fsl.noaa.gov.

Decoding-correction indicator:

       Value      Meaning
       -----      -------
         84       temperature correction
        102       longitude and wind direction flipped and observation
                  time set to the report receipt time
        108       lat/lon correction (other than interpolation)
        114       no correction applied
        116       observation time set to the report receipt time

For more information on the FSL decoder and its processing, see http://acweb.fsl.noaa.gov.

Not all ACARS reports (North America) include the originating and destination airport variables, and none of the AMDAR (most European and Asian reports) have them. When the ACARS reports are downlinked they are picked up by a reporting ground station which exist at various airports around the U.S.
The observation time returned by the MACARSSTA subroutine is generally used as the nominal time of the data for most applications, however, for interested users, the time of actual ground data receipt are available in the receipt time variable for ACARS reports.
For AMDAR reports in the FSL database, and for all reports in the AWIPS database, this is not the time of receipt, but a time reported in the header of the raw data.
All times reported in the MADIS API are in Universal Coordinated Time, with the format of "YYJJJHHMM", where:
```
    YY  = 2-digit year (good from 1980 - 2179)
    JJJ = Julian date of the year (1-366)
    HH  = Hour (0-23)

    MM  = Minute (0-59)
```
If the receipt time is missing, the 9-character field will be set to all blanks, e.g., " ".

Icing condition:

       Value      Meaning
       -----      -------
         0        no ice is present
         1        ice is present

Data platform type -- FSL database:

       Value      Meaning
       -----      -------
         1        vertical-acceleration measuring aircraft
         2        eddy dissipation rate measuring aircraft
         3        vapor measuring aircraft
         4        vertical gust measuring aircraft
         5        ice measuring aircraft
         6        eddy dissipation rate, RH, ice measuring aircraft

Data platform type -- AWIPS database:

       Value      Meaning
       -----      -------
         0        automatic                                
         1        manned
         2        hybrid, both manned and automatic

Source that provided the data -- FSL database:

       Value      Meaning
       -----      -------
         0        ACARS (direct to FSL from airlines)
         1        MDCRS (from TG's BUFR file from ARINC)
         2        appeared in both ACARS and MDCRS data streams
         3        AMDAR data, including LH BUFR data
         4        TAMDAR data from AirDat, LLC
         5        Canadian AMDAR data from CMC
         6        European AMDAR data

Source that provided the data -- AWIPS database:

       Value      Meaning
       -----      -------
         0        ASDAR
         1        ASDAR (ACARS also available but not operative)
         2        ASDAR (ACARS also available and operative)
         3        ACARS
         4        ACARS (ASDAR also available but not operative)
         5        ACARS (ASDAR also available and operative)

Original specification of latitude and longitude:

       Value      Meaning
       -----      -------
         0        Actual location in seconds
         1        Actual location in minutes
         2        Actual location in degrees
         3        Actual location in decidegrees
         4        Actual location in centidegrees
         5        Referenced to checkpoint in seconds
         6        Referenced to checkpoint in minutes
         7        Referenced to checkpoint in degrees
         8        Referenced to checkpoint in decidegrees
         9        Referenced to checkpoint in centidegrees
        10        Actual location in tenths of a minute
        11        Referenced to checkpoint in tenths of a minute

Phase of flight:

       Value      Meaning
       -----      -------
         3        Level flight, routine observation (LVR)
         4        Level flight, highest wind encountered (LVW)
         5        Ascending (ASC)
         6        Descending (DES)

The turbulence index is calculated from the median and maximum eddy dissipation rates, as follows:

       Value      Meaning
       -----      -------
         0        median < 0.1 | maximum < 0.1
         1        median < 0.1 | 0.1 <= maximum < 0.2
         2        0.1 <= median < 0.2 | 0.1 <= maximum < 0.2
         3        median < 0.1 | 0.2 <= maximum < 0.3
         4        0.1 <= median < 0.2 | 0.2 <= maximum < 0.3
         5        0.2 <= median < 0.3 | 0.2 <= maximum < 0.3
         6        median < 0.1 | 0.3 <= maximum < 0.4
         7        0.1 <= median < 0.2 | 0.3 <= maximum < 0.4
         8        0.2 <= median < 0.3 | 0.3 <= maximum < 0.4
         9        0.3 <= median < 0.4 | 0.3 <= maximum < 0.4
        10        median < 0.1 | 0.4 <= maximum < 0.5
        11        0.1 <= median < 0.2 | 0.4 <= maximum < 0.5
        12        0.2 <= median < 0.3 | 0.4 <= maximum < 0.5
        13        0.3 <= median < 0.4 | 0.4 <= maximum < 0.5
        14        0.4 <= median < 0.5 | 0.4 <= maximum < 0.5
        15        median < 0.1 | 0.5 <= maximum
        16        0.1 <= median < 0.2 | 0.5 <= maximum
        17        0.2 <= median < 0.3 | 0.5 <= maximum
        18        0.3 <= median < 0.4 | 0.5 <= maximum
        19        0.4 <= median < 0.5 | 0.5 <= maximum
        20        0.5 <= median | 0.5 <= maximum
        63        Missing value

The platform with station name 00001152 is not actually a single aircraft. This is a catch-all station name for reports that don't indicate the actual aircraft. Therefore, the position consistency and temporal consistency checks aren't applied.
The RH1, RH2, RHUNCER, TDUNCER, TASPEED, GPSHT and TRBTIME variables are only available for TAMDAR reports. See note 11 for a description of how TRBTIME will be formatted by the MADIS API. For more information on TAMDAR see http://www.crh.noaa.gov/tamdar.
The TAMDAR reports include two sensors used for relative humidity. A "consensus RH" is also reported as the primary moisture variable, and this is what's used for RH, TD, etc. Users interested in seeing the values from both sensors can select the RH1 and RH2 variables.
The RH uncertainty variable is the theoretical RSS (root-summed-squared) uncertainty of the consensus RH value in percent. Two error source components are used in the RSS calculation: temperature uncertainty (assumed to be +/- 0.4C) and the RH sensor uncertainty (assumed to be +/- 2% absolute error [not RH times 2%]). Other inputs to the calculation are air temperature, pressure altitude and indicated air speed. The uncertainty is additive with the reported humidity, so if RH is 30% and RHUNCER is 20%, the estimated range of the RH is 30% +-20%, i.e., 10-50%.
Dewpoint uncertainty is derived from the RH uncertanty variable in the following way. If the RH uncertainty is ≥ 0.49, the dewpoint uncertainty is set to 999. Otherwise, two subsidiary dewpoints are calculated by assuming the RH is 1) RH + RHUNCER, and, 2) RH - RHUNCER. The dewpoint uncertainty is one-half the difference between 1) and 2).
The MEDEDR, MAXEDR, TURBIDX and ICECOND variables for TAMDAR reports are accompanied by level 1 QC results from the TAMDAR provider. These variables can also be reported by the other providers, but these do not have any QC. Therefore, API users interested in seeing the data from these providers should request all data, not just data passing any QC level.
The eddy dissipation rates available in the ACARS and TAMDAR reports are calculated using different algorithms. The NCAR algorithm used for ACARS calculates EDR from fluctuations in the vertical motion of the aircraft (current algorithm), or fluctuations in the vertical wind (proposed new algorithm). The TAMDAR algorithm calculates EDR from fluctuations in the horizontal wind, as revealed by fluctuations in the indicated airspeed. When the turbulence is isotropic, the NCAR and TAMDAR algorithms should agree.

^*The QC information is only available with the FSL database.