Airborne doppler radars dynamical fields: data set description page


Data set source
Information on available Data
Quality Control Processing
Data format
References
Data selection page

3D mesoscale fields retrieval within the FASTEX frontal cyclones from airborne Doppler radar data

Data set source

  • NCAR ELECTRA
  • NOAA P3
  • This data set is computed by scientists working on data retrieval from Airborne Doppler Radar. Data are included in the FASTEX Central Archive at the date of the first international publication using these data.

    Information on available data in the FASTEX Central Archive

    The following files are available at this time:

    aircraftdatefile name begin dateend dateref. lat.ref. lon.
    NCAR ELECTRA970112 elec_ucla_970112_1558.tar.gz (postscript files) 19970112 15:580019970112 16:1930
    NCAR ELECTRA970112 elec_ucla_970112_1625.tar.gz (postscript files) 19970112 16:250019970112 16:4700
    NCAR ELECTRA970112 elec_ucla_970112_1650.tar.gz (postscript files) 19970112 16:503019970112 17:1740
    NCAR ELECTRA970112 elec_ucla_970112_1720.tar.gz (postscript files) 19970112 17:203019970112 17:3430
    NCAR ELECTRA970112 elec_ucla_970112_1742.tar.gz (postscript files) 19970112 17:414519970112 17:5820
    NCAR ELECTRA970112 elec_ucla_970112_1801.tar.gz (postscript files) 19970112 18:010019970112 18:2200
    NOAA P3970205MANDOP_19970205_IOP11.dat 19970205 23:000019970206 05:450056.770-25.056
    NOAA P3970209MANDOP_19970209_IOP12.dat 19970209 14:550019970209 19:500057.308-30.215
    NOAA P3970217MANDOP_19970217_IOP16.dat 19970217 05:083019970217 12:233049.877-15.693
    NOAA P3970219MANDOP_19970219_IOP17.dat 19970219 04:100019970219 10:100057.573-22.728


    Quality Control Processing

  • MANDOP analysis

    The 3-D wind fields are obtained using the NOAA-P3 airborne Doppler radar measurements dataset for IOP11 (970205), IOP12 (970209), IOP16 (970217) IOP17 (970219). The MANDOP analysis is described in Scialom G. and Y. Lemaitre(1990). The IOP12 fields are analysed in Lemaitre Y., et al. (1999); the IOP16 fields in Bouniol, D. et al.(1999).

    All these files are provided by Alain Protat (CETP/CNRS/UVSQ, France).

  • Data Edition
    The following data contaminations are corrected during the pre-processing step:
    1. the echo returned from the Earth or sea surface is eliminated by removing the radar gates that contain the non-meteorological reflectivity of the ground/sea in their sampling volumes.
    2. the projection of the ground-relative velocity of the aircraft onto each radar beam is subtracted from the measured radial velocity along this beam
    3. Doppler velocities need to be "unfolded". The unfolding process of these velocities is a continuity test, in which the current radar gate is compared with an average of the ten previous gates along the same beam, and also with the same gate from the previous beam. The radar gate is eliminated if the difference is greater than a fixed threshold (6 ms-1). This process is initialized with the in-situ measurement of the wind components projected onto the beam axis.
    4. the apparent antenna motion effect, due to the fact that the Inertial Navigation System is located some distance away from the antenna (Lee et al. 1993), is removed. This effect is only significant when the pitch and heading angles of the aircraft are changing rapidly with time (like during purls).

  • Overview of the MANDOP method
    The method consists in expanding the three wind components in terms of orthonormal functions. Two non-colinear radial wind measurements and two physical constraints (namely the boundary condition w=0 at ground level and the airmass continuity equation) are included in the analysis as variational constraints in order to retrieve the three wind components".

  • UCLA analysis

    The 3-D fields are obtained using the ELECTRA airborne Doppler radar measurements dataset for IOP2 (970112) All these files are provided by Brian Bosart (UCLA).

    After editing the sweep files and determining the appropriate navigation corrections, one runs the 'Reorder' software,which interpolates each antenna of ELDORA onto a 3D grid. Then, the dual-Doppler synthesis is made using the 'cedric' sofware. Information on reorder and cedric softwares can be found at NCAR/ATD. Information on ELDORA Data Processing can be found ATD ELDORA Data Processing Overview page .

    Please note that only plots (postscript files) are available in the FASTEX Cenral Archive.

  • Data providers validation

    Each set of data is validated by the data providers before sending it to the FASTEX Central Archive

  • Data format

  • MANDOP analysis

    ASCII files including the following parameters:
    altitude,latitude,longitude, 3 wind components and reflectivity

    Coverage and resolution:

    Spatial coverage: between 400 km x 400 km and 800 km x 800 km horizontally, 6 km vertically;
    Resolution 5 km horizontally, 0.3 km vertically
    Temporal coverage: 1 field per flight

  • UCLA analysis

    Postscript files contain reflectivity for each radar antenna (DBZF and DBZA) Radial Velocities for each antenna (VGA and VGF), vorticity (VORT), divergence (DIV), vertical motion (WUP and WVAR) all superimposed on the wind field vectors (WF). There are horizontal plots of each of these at levels between 0.4 km and 5.2 km at an interval of 0.4 km.

  • References

  • MANDOP analysis

    Bouniol, D., A. Protat, and Y. Lemaître, 1998: Mesoscale dynamics of a deepening secondary cyclone (FASTEX IOP16) : Three-dimensional structure retrieved from dropsonde data. Quart. J. Roy. Meteor. Soc., 125, 3535-3562.

    Lee, W. -C., P. Dodge, F. D. Marks, and P. H. Hildebrand, 1993: Mapping of airborne Doppler radar data. J. Atmos. Oceanic Technol., 11, 572-578.

    Lemaitre, Y., A. Protat, and D. Bouniol, 1999: Pacific and Atlantic "bomb-like" deepenings in mature phase : a comparative study. Quart. J. Roy. Met. Soc., 125, 3513-3534.

    Scialom, G., and Y. Lemaitre, 1990: A new analysis for the retrieval of the three-dimensional wind field from multiple Doppler radars. J. Atmos. Oceanic Technol., 7, 640-665.

    Scialom, G., A. Protat, and Y. Lemaitre, 1999: Vertical structure of a FASTEX secondary cyclone derived from dual-beam airborne radar data. Quart. J. Roy. Met. Soc., submitted.

  • UCLA analysis


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    Updated: 26 October 2000