Results of a performance analysis of an airborne Doppler radar wind shear detection system are given in vugraph form. It was concluded that both CO sub 2 and Ho:YAG lasers are feasible for dry microburst applications, but with limited performance in wet microbursts. The Ho:YAG performs better than the CO sub 2 for a set of identical lidar parameters

Huffaker, R. Milton

English

NASA Technical Reports Server

N88_17627
AIRBORNEDOPPLERLIDARDETECTIONOFWINDSHEAR
RESULTSOF PERFORMANCEANALYSIS
NASALaRCILOCKHEEDPO_SEPAK8630A
OCTOBER22-9.3,1087
COHERENTTECHNOLOGIES,INC.
R. MILTONHUFFAKER
253
https://ntrs.nasa.gov/search.jsp?R=19880008243 2020-03-20T08:17:06+00:00Z
0
4muo
q..
amid
(J
0
O
ii........o • • • • • • • • • • • o • • oo • • • • • • • • • • • o • o •• • • • • • • • • • • • • • • oo • • • • • • • • • • • • Q e 00 • • • • • • • • • • • 4 9 4 Q
e • • • • • • • • • • • • 4 • t
4 e • • • • • • • • • • o o _ • %
_|O0 • .o o e e ego O_o _
ooo . ..o.o.ee SS*o_
ill • ettSti||Jtt_#_l
I I I • I • • • _ • • • • • _ i _ _ Id
/
t e I o o o • • • o B P P I 0 F I J _ _ _
! ! e e e e • • . w e e B I _ | | t • • _
! ! e _ e e _ e . e e e e o e e _ _ _ _ • |
t e O O • 0 • • • • • • • • • • • _ _ _ p
e 0 0 • e • • • • • • • • • • • • o o _ •
t 0 0 0 o e • • • • • • • • • • • • o • •
0 0 • e • o • • • • • • • • • • • • • • •
0 O • o o • • • • • • • • • • • • • • • •
0 e o e • • • • • • • • • • • • • • • • •
e 0 • • • e • • • • • • • • • • • • • • •
e • • • • • • • • • • • • • • • • • • • •
e o • • o e • • • • • • • • • • • • • o 4
: : ; " ' "i ...... n ...... ," " "
lull T_OlOH
q_
m
Q
254
AIRBORNEWINDSHEAR
LIDARCOMPUTERSIMULATION
READINPUTPARAMETERS
SET UP MEASUREMENTGEOMETRY
Z,O,q_,AR
REALIZATIONLOOP
SHOTLOOP
RANGEGATELOOP
CALCULATE_ (AFCLHITRAN)
INTERPOLATE_, C_
n
CALCULATEE {RECEIVEDPOWER}
MULTIPLYBY SRF
SPECKLE,REFRACTIVETURBULENCE
MISMATCH
, PHASEFRONT
INCOHERENTSAMPLELOOP
IF C_/2<_R)(USESA_IER FOR ALL)
255
APPLYEXPONENTIALF UCTUATIONTOE {POWER}
X SRF
SPECKLEDOXINATEDP F
N CALCULATE.WIDEAND NARROWBANDSNR
Bw = 4 Vmax/k; Bn = lit
INTERPOLATERUERADIALVELOCITYFROM
MICROBURST,V
r
A
CALCULATEESTIMATEDVELOCITYV
r
CONVOLVE WITHGAUSSIANTEMPORAL
r
PULSE
CALCULATEV LOCITYWIDTH
SECONDMOMENT
CALCULATECRAMER-RAOE {VEL. ERROR}= _v
USESNR ANDVEL. WIDTH
W
CHECKIF _ < V THRESHOLD?
v max
IF NO, THROWESTIMATEAWAY
256
IF YES, GENERATEA CAUSSIANR.V. VE
MEAN= O, STDDEV=
V
¢
, A
CALCULATEVm= Vr + VE
COMPLETEINCOHERENTSAMPLELOOP
CALCULATEMEDIANV and snr
Ill
(IF EVErtNUMBER,AVE.TWOIN MIDDLE)
COMPLETERANGEGATELOOP
COMPLETESHOTLOOP
CALCULATE
COMPLETER ALIZATIONLOOP
CALCULATEcT_
vE
257
:3
E
bO
t_
(9
..C:
bO
(jq/u!)oloJu!o_
C
0
|
258
AIRBORNE WINDSHEAR LIDAR BASE CASE PARAMETERS
(CO_ LASER)
ATMOSPHERIC PARAMETERS
LaRC PROVIDED MICROBURST FIELDS
NO RAINp HAIL, CLOUDS
MID-LATITUDE SUMMER MODEL ATMOSPHERE
AEROSOL BACKSCATTER COEFFICIENT _ = 5 x 10 -8 (m °1
MODIFIED NOAA-WPL-37 C 2 PROFILE
n
.st -1 )
LASER PARAMETERS
WAVELENGTH [CO 2 10P(20)] _ = 10.591 _m
PULSE ENERGY = 5 ma
OVERALL OPTICAL EFFICIENCY = .1
PULSE DURATION = 2 _s
300 m RANGE RESOLUTION
10 PULSES AVERAGED
15 cm TELESCOPE DIAMETER (e -2 INTENSITY)
3 km FOCAL RANGE
AIRCRAFT POSITION AND LIDAR ANGLE PARAMETERS
4 km TO CENTER OF MICROBURST (ON-AXIS)
500 m HEIGHT ABOVE GROUND LEVEL
-30 LIDAR ELEVATION POINTING ANGLE
t
259
AIRBORNE WINDSHEAR LIDAR BASE CASE PARAMETERS
(Ho:YAG LASER)
ATMOSPHERIC PARAMETERS
LaRC PROVIDED MICROBURST WIND FIELD
NO RAIN, HAIL, CLOUDS
MID-LATITUDE SUMMER MODEL ATMOSPHERE
AEROSOL BACKSCATTER COEFFICIENT p =
MODIFIELD NOAA-NPL-37 C 2 PROFILE
n
1.25 x 10 -6 (m -1-st -1)
LASER PARAMETERS
WAVELENGTH [Ho:YAG] _ = 2.0913 _m
PULSE ENERGY = 5 m3
OVERALL OPTICAL EFFICIENCY = .2
PULSE DURATION = .5_s (4 SAMPLES AVERAGED INCOHERENTLY OVER 2 ps)
300 m RANGE RESOLUTION
10 PULSES AVERAGED
15 cm TELESCOPE DIAMETER (e -2 INTENSITY)
3 km FOCAL RANGE
AIRCRAFT POSITION AND LIDAR ANGLE PARAMETERS
4 km TO CENTER OF MICROBURST
500 m HEIGHT ABOVE GROUND LEVEL
-3 ° LIDAR ELEVATION POINTING ANGLE
260
CO_ SYSTEMATIC PARAMETRIC ANALYSIS
Step 1: OPTIMIZE PULSE DURATION/RANGE RESOLUTION:
.5 _sp 1 _sp 2 _s, 3 _s_ 5 _sp & _s
(75m)p (150m), (300m), (450m)_ (750m)_ (?OOm)
Step 2: EXAMINE NUMBER OF SHOTS: lm 2_ 5, 10_ 50p 100
Step 3: EXAMINE FOCUSING: f = 3 km, T = m
Step 4: EXAMINE OPTICAL DIAMETER: D = 7.5 cm, 15 cm_ 20 cm
Step 5: EXAMINE REFRACTIVE TURBULENCE EFFECTS: C 2 C 2 x 10
n' n
Step & : EXAMINE PULSE ENERGIES:
l_J, 50_J, .5mJ9 5mJp lOmJ, 15mJ, 20mJ_ lOOmJ
Step 7: EXAMINE AEROSOL BACKSCATTER EFFECTS:
= 5 x 10 -8 10 -8, 10 -9 10 -10 10 -11 (m-l.sr -1)
Step 8: EXAMINE WET MICROBURST
Step 9 : EXAMINE AIRCRAFT POSITION: 4, 3, 2_ 1 km FROM CENTER
TAKEOFF PROFILES
OFF-AXIS ENCOUNTERS
Step 10:
Step 11:
EXAMINE AZIMUTHAL SCAN: ENCOMPASS ENTIRE WIND FIELD IN
A 2-DIM PLANE AT 5 ° INCREMENTS
MULTIPLE REALIZATIONS
261
EE_
.<t::
:..1
13:::
LLI
:E
Or )
LL!
Z
0
8
t
01- St- I/,,-
E
LLI
rd.9
Z
.,..1::
i1
(8P)NOIIOI",IIIX:I_llVMY3-1:3,kVM-_
262
<(
[Z:
Z
-- <I::
,.,rY
Ld
Z
O_
©
O0
O_
I O
Ol _ 0 _- OL- St- 0_-
(s/w),LI_IgO-13ACINIM-IVlClV_l
263
FF
<
__J
E_
<
LLJ
OO
I,I
Z
O
CO
E_
I I
It
,I ! ! I
\ I' I
\
G- Ol- _L- 0_-
E
V
W
0
Z
<
6
(S/W)AZI007-4AGNIM7VICIV_I
264
40£
<
_J
0£
Or}
Z
W
Z
0
rn
n-i_
I I I, I I I
(s/m)_0_3 _LlOO33ACINIM03HFISW_I_
W
" C9
Z
o
265
9I I §I I I I /_ ® ..
(BP)3SION-OI-qVN91S
266
E_
Or)
Z
LLJ
Z
C__
©
FTn
n<_
O_
I I I I I
_I Ol _ 0 S- 01- _I-
(s/w)kLiOOq3AGNIMqVIGV_
267
<
r-q
__J
<
W
EE
O0
D
Z
W
Z
C_
0
CO
nI
I I I
I I I I I
o
E
W
Z
<
nI
(s/w) A.LIOO-BACINIM-iVlCIVN
268
E_
<C
J
__J
<C
Iii
(7}
Z
Ii1
Z
n/
0
r-lq
OC
B_
I I I ! I, I I
+I Ol l_ 0 +- Of- 91- 0_
(s//m) ,kJ.130-13ACINIMqVICIV !
269
0:2
<
dE)
O_
<
LO
EE
O0
Ld
Z
0
0]
O_
m
(s/w) ,kllOOq3ACINIt_9VlCNN
270
<
D
l.l....-=l
_._I
CK
<
b2
I
O0
Z
1 I I
%
LLJ
2:_
0 /
(SP)3SION-OI-]VN91S
271
fl Ol I_ II f- I1- fl-
(s/w) _lOOl3AONIM7VIGV_
-s
4II
E
1
(SP)3SION-O±-7VNOIS
273
[_ILL
<C
E3
___1
<C
bJ
I
(./3
1,1
Z
0
133
_t Ot _ 0 _- Of- m
(s/w)LLIOO-I-qAGNIM-lVLGVa
274
EK
<_
n
rt"
<E
L_LJ
ZE
O0
Z
I!!
Z
EE
0
m
rid_
i I I
o
M
8
O_
I I I ! I I i
fl Ol _ 0 S- 01- _1-
1
E
LLJ
(9
Z
,<
n-"
(s/w) _IDOTqAC]NIMqVIC]V_]
275
<__J
W
Z
0
Ol
' i I i I I I I
0
o
m
w
II
m
! I, I !. I I I i_ i
6 9 L 9 _ f l: _ 1
--U
Z
I
,q
(s/w)._o_3 ,U_lOO13A
276
E_
<_
_J
OF)
I,I
Z
0
m
Otr
I i i 1
o
-- II
_ f_i
1 ! !
E
LLI
0
Z
<
02
(EIP)3SION-OI-7VNOIS
277
E_
<_
r-_
w
ZE
or)
n
Z
w
Z
O
m
[z:
I
E
W
Z
<_
E_
(SP)3Sl0N-01-qVNOlS
278
.<
_J
.<
W
(/)
W
Z
O
I-D
I i i
i i I I I I
Ol _ O _- Ol- _;l-
u
E
W
Z
<
n_
(s/uJ)LU0073AONIMqvlav'a
279
0£
E_
LO
I
Z
W
Z
0
03
Ot _ 0 _- 01- Si- Or-
E
V
m
Z
nl
(s/w) £1_IDO73ACINIM7VICIV_I
280
SUPI'IARYOF PERFORMANCE
(I_ARCMICROBURSTMODEL,11:00MIN,)
1 20 MJ C02_LIDAR LINE-OF-SIGHT WIND VELOCITY ERROR <I M/S TO 8 KM IN
THE DRY MICROBURST TEST CASE,
, 5 rIJ Ho:YAG LIDAR LINE-OF-SIGHT WIND VELOCITY ERROR < ,5 M/S TO 8 KM
IN THE DRY MICROBURST TEST CASE,
3, 5 MJ C0,2 I_IDAR PENETRATES TO WITHIN I KM OF WET MICROBURST CENTER,
4, 5MJHo:YAGPENETRATES TO WITHIN ,5 KM OF WET MICROBURST CENTER,
11 P_OTH C02 (100 MJ) AND Ho:YAG (10 MJ) PERFORM WELL TO 3 KM OPERATING
OUTSIDE THE BOUNDARY LAYER WHERE:
PETA (C02) = S x 10-11 M-1 ' SR-1
BETA (!Io:Y,_G)= 1,25 x I0-9 M-I ' SR-1
ii
,5, LIDAR PERFORmaNCE IN WET MICROBURST r4ODEL DOES NOT IMPROVE SIGNIFICANTLY
WITH REASONABLE INCREASES IN LIDAR PARAMETERS,
281
CONCLUSIONS
1 BOTHCO2 ArIDHo:YAG,_ESHO_ FEASIBLEFORAIRBORNE!'_INDSHEARDETECTION
FORDRYMICROBURSTS!'IITHLIMITEDPERFORMANCEINI'IETMICROBIJRSTS.
2. Ho:YAGPERFORMSBEITERTHANCO2 FORA SETOF IDENTICALLIDARP_S.
3. THESERESULTSAREQU#LIFIEDBYTHELIMITEDNUMBEROF TESTCASES.
282'


Airborne Doppler lidar detection of wind shear. Results of performance analysis

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server