WMOD00417

• Title: Computer Processing of Digital Radar Data Gathered During HIPLEX
• Date: 4/4/1978
• Weather Modification - Doc Type: Report

~''>i''~(~~~~~~'''''''''''''''-''''.~
. .

..

500

TIACI H..
(UlIlCIL _

PRF All RHl SIl
~
~

=..- !: ~ go
~ ~ -= f
~ ~ ~ 5
t'! i:
~ :.
~ --.-
..
j

'"

o~i
~Q"'4
~z'"
-"''''
~~'"
.n>
~>~
....,,'"

~'"
'"

m

o
-

.~--1IIfIlIlIl!WI. ~ 4...r ~r:- ~-.-...---

~- . ;--. .-.--

Q.

~

4

0'

100

2 "
"

RI S4 EI
" .$
I.
2.00 '21 $.0
~ K' i
~ I.
" ~ g'
s t i
!
! !

JOURNAL OF APPLIED METEOROLOGY

11:11314 51f171. ,
) DATE (10'5 I DATE (100'5 I
ZEROS DATE (1'51
nlolE (HIlS-I'Sl TIIoIE (HIIS-IO'Sl
nlolE (1111. "5) nlolE (IlIIl-OO'S)
nlolE (sa: -,'5) T1Io1E csa:.IO'S)
~~ ~~
RtK~~Y R~~~l'Y
'15111 E1 ZEROS
TRANS. ,POWER TRA'mio ~~ER
1105 I
ZEROS T~'$"f"ER 1
R/KIlI I SA PRFIAl11llH' "I
10'\1 'i~DE I.D'(I~~E I
RECt)';'g 0100NT ZEROS 1
RECORD, COUNT RECORO COUNT J
('DOS) \101
RECORD COUNT RECORll COUNT 1
(,'5 I PO 51
FNIDI~ II~COOO 1
S PAlE I I
SPARE :I 1
SPAtE 3 I
SPAIE 4
SPAIE 5
SPARE.
AZIIoIUTH 4ZIIoIUTH
10EG-10'S) {DEG-'OO'SI
AZIMUTH ~~~~~I
(O(G-O.l1
l~~~~~'~r folh~~~:)
~~g~~~)N ~~~~~~,~~
AVERAGED RETU""
.. A'ReRAFT POS'TlONS ..
(CAL'B~ATlON OAU) (
AZ'MUTH AZIMUTH
IOFG-'O'51 10EG-'OO'S I
I~~~w.g.~r AZ'MUTH
10EG-"S I
~~~~~~.~~ (~l~~~Jc\O~\
tLEVAilON ~kg~,~~N
IUEG- 011
AVERAGED RETU""
.. AIRCRAFT POSITIONS ..
(eAL 'BRUION DATA I (
AZIMUTH AZIMUT/l
10EG-,O'SI (DEG-'OO 51
AZIMUTH M~"!~'\~
(OEG-O.'I
ELEVATION f~E:~~~1
(O[G-'O 5 I
H (VATlON 1~~~~llg~
OEG-O'I
.. :~R~~m':sEJ:: to
(CAL'UATlON OAU I (
AZIMUTH UIMUTH
(DEG'IO'SI {DEG-'OO'SI
t~~_~TI~ W~~~~l 8
HJG~~~'~~ to'€~~~~1
EUVUION ElEV4ll0ll
{DEG-o.1l iDEG- "51
AVERAGED RElURIl
... AlIICRAFT POSITIONS"
(CAL'IRATlON D4TA l (
~ ;~ -E NQ. of RECOID;~
~ " // "GAP'//'/',
+ ",... ..,./,.... .... /-....

9
20
21
22
23
24
25
26
21-216
"211-219to
280-2821

283

284

285

286
281-536
.. 531-539"
540-542)

543

544

545

546
541-196
"'191-199"
IlOO-8021

803
04

805

806
801-1056
'''1051-(l59''
,*'10621

....

FIG. 1. Record format of SWR-75 digital radar data.

antenna is sweeping in a constant elevation mode (A
mode) or a volume scan (A+B mode); range interval
indicates the length (kIn) of each data bin, while the
azimuth increment indicates its width (deg). Table 2
shows the settings used during HIPLEX.

VOLUME 17

Each range bin value contains the binary equivalent
of a number up to 255 which is directly related to the
average power received for the corresponding range and
azimuth intervals. The standard deviiations of intensity
estimates are 1.05 and 1.48 dB for the base tilt and
higher elevation sweeps, respectively. Odd numbers
(one-bit on) only occur in those bins where project
aircraft are located as detected by a separate IFF
antenna. Bin positions 251-253 contain a number 0-250
which indicates the bin positions of project aircraft one
through three, respectively. For instance, if bin posi-
tion 252 contains the number 37, this means the proj-
ject aircraft designated as number two has been de-
tected by the IFF antenna to be located at bin position
37, This technique of recording aircra.ft positions allows
the retention of reflectivity values also.
About 13000 records can be recorded on a single tape
which may cover a period of 1-12 h depending on the
number of radials containing echo da.ta.

5. Computer processing software

There are four clearly defined steps involved in the
processing of the radar data. These are outlined in Fig.
:2 and described separately later in this section. Most
of the computer routines comprising these steps are
written in FORTRAN IV. Briefly, the processing pro-
cedure consists of mailing the radar tapes containing
radar data to the processing computer, deleting non-
echo and clearly erroneous information, producing hard-
copy printout and microfiche containing data and
housekeeping information, and optimally compressing
the raw data files. The analyst at this point notes the
problems and generates corrections for input to an
error-correction program, which produces composite
maximum reflectivity and echo top B-scans (a range
and azimuth display of all data contained in a 5 min
volume scan), composite maximum reflectivity and
echo top PPI's, and an optimally compressed, edited
raw data file which is archived on 1.600 cpi magnetic
tape. The analyst inspects the composite B-scan for
the desired contours and defines the area(s) for further
analysis. Specification cards containing area location
information are input to the final processing program
which converts raw digital data to meteorological radar
units (dBZ) and rallfall rates and amounts. Several
distinct reports and data files are produced in the final
processing steps. No adjustments are made to correct

TABLE 2. SWR-75 Radar settings during HIPLEX.

Range delay
Antenna scan mode
Elevation increment
Range interval for data bins
Samples/averaged return

25 km
A+B (volume)
10
0.5 km
32 (lo el)
16 (> 10 el)
414
10

PRF
Azimuth increment for data bins