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The Lower Fuselage (LF) radar animations are produced by HRD/AOML/NOAA.  The data is collected aboard NOAA's WP-3D turboprops.  The animations consist of a series of LF sweeps.  The LF sweeps have the descriptor .swp and follow the internal HRD composite format convention.  There is one .swp file per LF sweep. The sweeps are stored as 2 dimensional binary files.  The files are written with Fortran90 software. Click here for Fortran90 software to read the data. Click here for MatLab function to read the data.  LF sweeps are either plane relative, with the plane position in the  middle of the Cartesian map; or storm relative, with the storm position in the middle of the Cartesian map.   The first record on the files is the radar header containing 128 bytes of general information.  Followed by16 bit packed words containing dbz values:

record diagram

The dbzs are packed 2 per word.  The overall range of the data is from -31.5 dbz to +95.5 dbz in half db steps.  The no data flag is -999.0.  Note that these bytes are packed into words with the first byte going into the high byte of the first word:


dbz diagram

What follows is a description of the information on the Radar Header.  The column on the left contains variable types and sizes, the column in the middle describes the variable contents, and the right column shows sample values from the Frances N43RF flight on August 30, 2004.


-30 WORDS CHARACTER-
Size Content Example
character*4
identifies the file type swp
character*8
flight identification:  yrmodyID
42 plane ID is the "h"
43 plane ID is the "i"
040830I1
character*12
storm or project name Frances
character*4
radar identifier:
"LF"lower fuselage
"TAIL"tail&doppler
"LB"land based
LF
character*32
comment, the track file name if one was used none
character*32
time file was created Mon, Dec  6, 2004,  02:06:01 PM
character*28
the flight level file name if one was used none

-10 WORDS INTEGER-
Size Content Example
1:integer*4 x horizontal dimension on the 3d Cartesian Plane  in bins  240
2:integer*4 y vertical dimension on the 3d Cartesian Plane in bins 240
3: integer*4 z height or level on the 3 dimensional Cartesian Plane 1
4: integer*4 number of sweeps on the composite display 1
5: integer*4 flag:
-1 center plane relative
 0 center earth relative
 1 center storm relative 
-1
6: integer*4 flag:
0 for folded Doppler radar values
1 for unfolded Doppler radar values 
0
7: integer*4 flag: 
0 intervening attenuation is off
1 intervening attenuation is on 
0
8: integer*4
flag:
Bit 0 = 0 unedited Doppler file,  1 edited Doppler file
Bit 1 = 0 vt not added to file,     1 vt added to file
Bit 2 = 0 Joss &Waldvogel vt,    1 Willis vt
0
9: integer*4
spare 0
10:integer*4
spare 0

-24 WORDS REAL-
Type Content Units Example
1:  real
start time of the Cartesian plane (seconds) 65450.81
2:  real
end time of the Cartesian plane   (seconds) 65482.76
3:  real
reference for latitude position   (degrees) 19.40
4:  real
reference for longitude position (degrees) -59.46
5:  real
x scale resolution (kilometer/bin) 1.50
6:  real
y scale resolution (kilometer/bin) 1.50
7:  real
z scale resolution (kilometer/level) 0.50
8:  real
x or horizontal distance with respect to the origin (kilometer) 180.00
9:  real
y or vertical distance with respect to the origin (kilometer) 180.00
10:real
z distance of first level or standard dev. of track for cross section (km) 0.00
11:real
rotation angle or average track for cross section (degrees) 0.00
12:real
radar altitude (meters)  2773.00
13:real
calibration coefficient 1 (1/16 dbZ) -27.13
14:real
calibration coefficient 2  (1/4096 of dbZ) 0.33
15:real
azimuth correction (degrees) 0.00
16:real
elevation correction (degrees) 0.00
17:real
dbz noise threshold (dbz) -99.00
(no threshold used)
18:real
peak power or dbz range for thresholding (kw) or (km) -99.00
(not used)
19:real
pitch correction (degrees) 0.00
20:real
drift correction   (degrees) 0.00
21:real
roll correction (degrees) 0.00
22:real
maximum range of the radar (kilometer) 384.00
23:real
spare for LF,  height of the bright band for TAIL; (km) 0.00
24:real
spare  for LF, depth of the bright band (km) 0.00

FILE TYPE DESCRIPTORS
"CMP "
LF composite
"TA3D"
TAIL 3 dimensional
"DOP3
Doppler 3 dimensional
"WIND"
Wind 3 dimensional
"XSEC"
TAIL cross section
"SWP  "
LF single sweep

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