AN ABSTRACT OF THE THESIS OF
Suryya Kanta Sarmah
for the
(Degree)
(Name)
Date thesis is presented
Title
in
M. S.
ì5
Meteorology
(Major)
:!t
M
A RADAR AND SYNOPTIC STUDY OF RAIN AT A POINT
Abstract approved
A
(Major professor)
radar echo-contour height measurement at different gain
settings of the receiver, from RHI pictures shows that heavy rain
occurs at the points above which steep echo-contour gradients ap-
pear. In this study, radar data came from the AN/CPS9 radar
located at McCulloch peak, about five milesfrom the OregonState Uni-
versity campus. The data for rain intensity and drop-size distribution came from filter paper rain-drop recorders exposed by ob-
servers situated at various positions beneath the radar beam at
ferent azimuth. The occurrence
of heavy
rain intensity at
dif-
a point
with the appearance of steep echo-contour gradient showed more con-
sistency for convective and cold front showers than with warm front
showers. In the case of convective showers it appears that strong
echo-contour gradients lying near the freezing level do not neces-
sarily associate with rain. The study
of
drop-size distribution
shows that steep echo-contour gradients also occur with the expan-
sion of the distribution pattern towards bigger drop sizes, thus indicating the presence of up-draft with steep echo-contour gradient.
A RADAR AND SYNOPTIC STUDY
OF RAIN AT A POINT
by
SURYYA KANTA SARMAH
A THESIS
submitted to
OREGON STATE UNIVERSITY
partial fulfillment of
the requirements for the
in
degree of
MASTER OF SCIENCE
June
1963
In Charge of Major
Chairman of
epartment of Physics
Dean of Graduate School
Date thesis is presented
Typed by Muriel Davis
'Ç
IL
i
ACKNOWLEDGMENT
I
acknowledge the guidance, suggestions and help given by
Dr. F. W. Decker, Chairman, Atmospheric Science Branch of
Oregon State University, in all phases of my work. Also, appreci-
ation is extended to Robert J. Massey, John
D.
Pembrook, Ronald
E. Rinehart, Donald M. Takeuchi, John V. McFadden, and Robert
C. Lamb
for their help in drawings, calculations, photography,
synoptic analysis and operating the radar for this study.
I
also
wish to thank all other workers of Atmospheric Science Branch,
who he'ped in collection of data,
rain-drop counting and numerous
other details connected with the research effort.
TABLE OF CONTENTS
Page
INTRODUCTION
1
THEORETICAL CONSIDERATIONS
3
COLLECTION OF DATA
DATA ANALYSIS
RESULTS
Case of 2 March 1963
Synoptic Conditions
Radar and Surface Observations
8
10
Dropsize Distribution
10
10
10
12
Drop-size Distribution
13
15
16
Case of 27 and 29 March 1963
Synoptic Conditions
Radar and Surface Observations
DISCUSSIONS
18
CONCLUSIONS
25
RECOMMENDATION FOR FURTHER RESEARCH
27
BIBLIOGRAPHY
71
LIST OF FIGURES
Time versus
(1)
(2)
(3)
Height of echo-contour at different gain settings
Rain intensity R
Reflectivity
Z
curves for:
Page
1
2
3
4
5
6
7
8
2 March 1963
Station 1
Station 2
Station 3
Station 4
27 March 1963
Station 1
Station 4
Station 5
29 March 1963
Station 1
49
51
53
55
58
60
62
64
Rain drop-size distribution curve for:
March 1963
Station 1
Station 2
Station 3
Station 4
Station 4
27 March 1963
Station 1
Station 4
Station 5
29 March 1963
Station 1
2
lA
2A
3A
4A1
4A2
SA
6A
7A
8A
50
52
54
56
57
59
61
63
65
LIST OF TABLES
Pa g e
Tables for RHI measurements
2 March 1963
Station I
IA
Station 2
lIA
Station 3
lIlA
Station 4
IVA
27 March 1963
Station 1
VA
Station 4
VIA
Station 5
VIlA
29 March 1963
Station 1
VIllA
Tables for Drop-size Distribution
2 March 1963
Station 1
IB
Station 2
11E
Station 3
IIIB
Station 4
IVE
27 March 1963
Station 1
VB
Station 4
VIE
Station 5
VUB
29 March 1963
Station 1
VIllE
Tables for Rain Intensity and Reflectivity
2 March 1963
Station 1
IC
11G
Station 2
Station 3
111G
Station 4
IVC
27 March 1963
Station 1
VC
Station 4
VIC
VIIC
Station 5
29 March 1963
Station 1
VIIIC
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
45
46
47
47
48
48
LIST OF PLATES
Pa g e
Plate
2
I
II
March 1963. PPI Photographs at 1612 PST
At
O
and -3db receiver gain
at -6 and -9db receiver gain
66
67
March 1963. RHI Photographs at 1618 PST.
Azimuth 255°
2
and -3db receiver gains
III
At
IV
At -6 and -9db
V
O
receiver gains
At -12 and -18db receiver gains
68
69
70
A RADAR AND SYNOPTIC STUDY OF RAIN AT A POINT
INTRODUCTION
Since the second world war, radar has increasingly played a
significant role in meterology. It successfully detects storms and
precipitation, but quantitative measurements still fail to give satisfactory estimates of precipitation amounts. Several workers (7; 14)
studied both point and aerial rainfall by using radar, but a survey of
literature shows very little work done
on point
precipitation by using
stepped-gain control of the radar receiver or other method for obtaming echo-contour gradients on the RHI display at different gain
settings. Few papers report comparison of such indications with
rain intensity, drop-size distribution and reflectivity observed at
a
point at different phases of rain. Fewer papers also explain these
observations and comparisons on the basis of the physical processes
involved.
Atlas
(1)
reported heavy turbulence associated with steep con-
tour gradients. Boucher
1. 25
(
5)
by using a vertically pointing radar of
cm. wavelength found the upper limit of hourly rate of precipi-
tation a function of the depth of the precipitation echo.
A
limited
study undertaken by Illinois State Water Survey (13) sought to esti-
mate rainfall by using echo height as an indication, but results
proved uncertain.
A
correlation
of heavy
turbulence and echo
intensity came indirectly from the ThunderstormProject(2,p.117)
which showed that severe turbulence most often occurred in conjunction
with pilots' reports of heaviest rain with both observations taken at
the same time and place.
With all these
results in mind, the author made
and radar study of convective and frontal rains on
a synoptic
Z, 27
and 29
March 1963, in western Oregon and presents these results of at-
tempts to explain the observed phenomena in terms of known or
suspected physical processes involved.
3
THEORETICAL CONSIDERATIONS
The Radar Equation
(a)
The average power Pr received by the
filling precipitation target is given by
=
72
(_ Pt?9
radar from a beam
(2, p. 30)
hAp2
z
KI2
(1)
J
where
=
power transmitted by the radar
angular widths of the beam
pulse length
h
Ap
=
aperture of the antenna
=
wavelength of the electromagnetic radiation
transmitted
constant for the type of precipitation.
(K(2
Therefore, for observation at a fixed point
r
=
constant and hence
r CZ
The variable
where
constant
N1D6 where
Z
drops having diameters
C
D
and
,
N
equals the nimber of
extends over the whole sam-
Y
pling volume.
Thus, larger drops contribute to the greater reflec-
tivity.
If the
operator reduces the gain of the receiver the weaker
4
echo signals will fail to produce indications in the radar output.
Then, the indicated signal will come only from the regions of strong-
er reflectivity.
(b)
Bergeron (3), after examining the various mechanisms
for release of precipitation, came to the conclusion that to account
for the release of precipitation it suffices to have a few ice crystals
(formed either by freezing of droplets or, less likely, by sublimation of vapor on special nuclei) among a much larger population of
super cooled droplets in those parts of the cloud with a temperature
below -10°C.
a
Findeisen (10), from an independent study, came to
similar conclusion.
(c) Houghton (12), usiñg Langmuir' s (16)
values of collision effi-
ciency, compared the growth rates of drops by coalescence with
those of ice crystals by sublimation. He concluded that the growth
of
precipitation elements by sublimation proceeds initially much
more rapidly than by coalescence, the two processes reaching equal
effectiveness when the particles have masses comparable to drizzle
drops and that for larger particles the accretion process increasingly dominates.
(d) Bowen (6)
of cumulus cloud
and Ludlam(18) using a very simplified model
structure investigated the formation of showers
by droplet coalescence process.
5
Assuming that
"wa,
the liquid water content depends only on
height "z" and fall velocity fl,C.<V, Ludilam deduced that the following equation gives the growth of the droplet from radius R0 to R
between z0 and z:
z
(U-V)
EV
JR0
___ fwdz
dR
=
4A
(2)
z0
Here
E
=
collection efficiency
density of liquid water
V
=
fall velocity of larger drop
U
=
updraft velocity
iY
=
velocity of smaller drops
=
When "V" exceeds "U", the drops descend, and at the cloud
base
z0
z
Hence, the right hand side of the equation (2) is zero.
.
Thus the maximum size with which the drops will fall out of the
cloud base depends solely on the updraft speed "U", and their ra-
dii R0, at the beginning of their growth by accretion.
(e)
Investigations of a large number of investigators (19)
show that for a wide range of rain the following equation applies:
ND
Here
No
D
ND
=
=
N0e
-)D
(3)
8x10 3
m3
drop diameter
number of drops er unit of air volume in the size
range D to D +
The parameter
of
)
depends on rain intensity "R" and has units
mm:
=
4.
1
R°
21
where R is in
mm
hour
The relation between reflectivity and rain intensity depends on
constants "a" and "b", when given by (19)
Z =
aRb
Thus the average power received by the radar is given by
-Pr=
cl
Rb
(4)
r
where "r" is the distance of the point of observation from the radar
and C1 is a constant.
Therefore, variation of rain
intensity
should appear as the
variation in the strength of the sina1 received by the radar, and
RHI
pictures taken at different gain settings of the receiver should
indicate stronger echo gradient for greater rain intensity.
7
COLLECTION OF DATA
The data used here came from the observations made in con-
nection with Project 491 of Agricultural Engineering Department of
Oregon State University, Corvallis, and the Signal Corps study un-
der contract DA-36-039 SC-89186, on
2, 27
and 29 March 1963.
Each observer had an instrument kit for measuring meteorological
elements such as pressure, temperature, and humidity.
I-le
also
had filter papers impregnated with methylene blue dry dust for
cording drops
(4) by
re-
exposing them for a few seconds in the rain at
the positions mentioned on page 28.
The general instruction called
for observations at intervals of ten minutes, and more frequently
when some changes occurred.
The author, who also served as an
observer, found rain intensity so variable that he took filter paper
observations very frequently. The discussion of this appears later.
At the same time
radar AN/CPS-9 at McCulloch Peak
(2, 200 feet)
five miles from Oregon State University campus took RHI pictures
along the azimuths of the observing stations at intervals of about ten
minutes and also took PPI pictures at different steps of the receiver
gain control.
E1
DATA ANALYSIS
From the projection of the processed RHI pictures on a screen,
I
drew the echo-contours very carefully as the outer margin of the
echo at each different gain settings of the receiver.
The position of
the observing station is determined by reference to the range marks
in RHI
pictures at different azimuths. The heights of the contours
over the station appear
By using a
VillA.
groups of 0.
of the
2
irz
Tables lA, lIA, lilA, IVA, VA, VIA, VIlA,
calibrated overlay which divides drops into sized
mm diameter difference, we measured the diameter
drops. From these we calculated instantaneous rain intensity
(4), the
number of drops per cubic meter of air and radar reflecti-
vity.
If N1 is the number of drops having diameter D and
velocity V, A
=
area of the filter paper, then the number of drops
"N" per cubic meter of
N/rn3
air is given by
N1
where t
A V1t
We have
terminal
=
time for which the filter
paper was exposed.
used the terminal velocities ofraindrops as givenbyLaws(17)
Tables IB, IIB,IIIB, IVB, VB, VIB, VIIB,andVilIBshow these meas-
urernents. Rain intensity and reflectivity data appear in Tables IC,
11G, 111G,
IVC, VC, VIC, VIIC, VIIIC.
These tables provide values
for drawing the graphs shown here.
In
eachofthe Figures
1, 2, 3, 4,
5,6,
7
and 8,time is plotted
along the x-axis and radar echo heights at different gain settings of
the receiver, rain intensity and calculated reflectivity are plotted
along the y-axis. In Figures lA, ZA, 3A, 4A, 5A, 6A, 7A, 8A, the
number of drops per cubic meter of air and diameter at the intervals of 0.
In
2
mm are plotted along the y-axis and x-axis respectively.
all the figures the lines joining different points are used for
visual aids only.
10
RESU LTS
Case of
2
March
1963.
Synoptic conditions:
A.
On 28
February 1963, a cold front had moved over Oregon
coming from the northwest.
This brought a maritime polar air
mass to rest over Oregon at least until Monday of the next week.
An anticyclone off the coast of Oregon and California acted with a
low
pressure center
on the southern Alaskan coast to produce upper
air winds from 290° to 280° with speeds of
20 to 70
knots at 850 mb
and 300 mb,respectively.
The winds blew more westerly and s orne-
what slower than those of
12
2300Z,
2
hours earlier. The Salem sounding at
March 1963, showed a moist air mass with nearly neutral
stability. The
+5
stability index for Salem at 0800 PST on the same
day (2 March 1963) decreased to +2 at 2000 PST.
Likewise, the
freezing level dropped from 3600 feet to 2800 feet in the same time
period. At the surface air had 43° F temperature with a relative
humidity of 84%. The wind continued high and northerly with cloudy
sky over most of Oregon and rain showers west of the Cascades.
B.
Radar and surface observations:
in all but one station, the storm passed over during the period
11
of observation.
Hence Figures 2, 3, 4 represent plotting of data for
continuous surface observations from the beginning to the end of the
storm. These figures,including number
1, show
some interesting
characteristics, which include the following:
1.
Heavy rain intensity observed at the surface invariably
associates with steep echo-contour gradients at different step gains
at higher elevations whereas the same at lower elevation does not.
The weak rain intensity exhibited at 1440 PST and 1610 PST in
Stations
# i
and
respectively, is due to exposure of filter pa-
# Z
pers at the intervals of ten minutes. Considering the highly variable
nature of shower intensity, quite possibly at those times filter paper
missed the heavy intensity part of the shower. This appears more
evident from flgures
3
and 4, where observers exposed filter paper
at shorter intervals of time. The only exception to this occurred in
the rain intensity at
17 10
no convergence of echo
Z.
PST at Station #4 (Figure 4),which shows
contours.
The peak rain intensities do not seem to occur at the same
time as that of the occurrence of steep contour gradients. This may
result from the fact that the drops arrive at a later time than their
observation by the radar while still aloft and also because of taking
radar pictures at intervals of several minutes.
3.
Although heavy rain is in all cases associated with the low-.
est gain setting of -18 db all -18 dbechoes are not associated with
12
heavy rain intensity as are evident from FIgures
PST) and
4.
2
1
(at 1537 and 1608
(1527 and 1537 PST).
Convergence or compactness of lower gain settings seem to
coñtribute more for heavier ráin inténsity compared to that at higher
gain settings.
C.
Drop-size distribution:
The drop-size spectra in all phases of rain deviates greatly
from the Marshall and Palmer distribution (19).
A
frequent samp-
ling of the drop-size distribution made at the Station #4 from the beginning of the shower from 1600 to 1606 PST(Figure 4A1) clearly in-
dicates how the drop-size spectra broadened with an increase of rain
intensity. The initiation of rain in all cases associates with increase
in the number of small drops, indicating rain from the leading edge.
Figure.4A
at 1720, 1725 and 1731 PST shows how the patterns of
distributions change towards the end of rain showers. These two
figures indicate that shift in the drop-sizes toward lower diameter
range goes on more rapidly at the end of the shower than does the
rise at the beginning
cated by the curves
of the shower.
1, 2
and
3
For heavy part of the rain indi-
inFigure 4A21drop-size distribution
show similar pattern exceptfor the one atthe heaviestpart ofthe rain
(1710 PST), which shows a deficit of drops from 0.
3
to 0.
7
mm
13
diameter interval.
In all the
stations, the drop-size spectrum shifts to greater
diameter region withthe increase in the height of echo-contour
packing.
Some of the general characteristics of drop-size distribution
in all the four stations considered include the following:
1.
Bimodal type which agrees with that found by using rain-
drop size camera (20).
2.
0. 9
Tendency for increase in number in the diameter range of
mm to
1. 3
mm instead of gradual diminution with increase in
diameter, except in the case of Station
much irregularity.
#2
where the curves show
Also towards the end,there appears a tendency
for increased population in the diameter range of 2.
1
mm to 2.
5
mm.
Case of
A.
27
and 29 March 1963
Synoptic conditions:
On Tuesday, 26
March 1963, a maritime polar air mass coy-
ered Oregon and the Pacific Northwest. On Wednesday morning,
27
March 1963, a low pressure area off the southwestern coast of Oregon began to intensify and move towards Oregon, reaching the coast
at about 1300 PST.
This low and an occluded front dominated the
14
synoptic situation during the period of field observations on Wednesday.
Because the low continued to intensify during the period of its
passage over the observing network, pressure continued to drop untu
1800 PST, when it
reached a minimum of 972.
8
mb on the baro-
graph at the Iysics-Ghemistry Building at Oregon State University.
The upper air, flow moved generally from 2200 to 2400 with speeds
of 25 to 65 knots
March.
The stability index decreased from +7 at 0400 PST to
1500 PST,
of
at 850 to 300mb respectively, at 1000 PST on
27
+1
at
indicating a marked decrease in stability about the time
frontal passage. Cloudiness predominated over the Pacific North-
west with rain over western Oregon during the afternoon and evening.
Light -to -moderate northerly
surface winds predominated
during the afternoon observations.
About 2300 PST another occluded front passed over Oregon,
while still another passed at 1100 PST on 28 March 1963.
The pas-
sage of many lines of precipitation during 28 March, provided one
of the significant
differences in weather from the previous day. Sur-
face winds increased during the afternoon and early evening to gusts
of over 70
miles per hour at places. These winds caused minor
damage over much of western Oregon, making it the worst wind
storm since the record breaking storm of
12
October 1962.
The weather of 29 March 1963,remained under the influence of
15
incoming maritime polar air.
decreased somewhat from
Upper air winds from the southwest
1000 PST to
speeds of
36 to 79
tween 850 to 300mb at 2200 PST on 29 March 1963.
knots be-
During the
12
hour period ending at 1600 PST, the freezing level over Salem
dropped from 4400 feet to 3700 feet.
This same time periodbrought
a slight increase in stability index from +3 to +5.
area in the Gulf
of Alaska on 26 March,
The low
pressure
increased to the extent that
evidence of it appeared even on the 1500 PST, 29 March synoptic
weather map. This low is partly responsible for the pressure field
during the period of observation.
B.
Radar and surface observations:
On 27 March 1963,
rain fell more or less continuously,and ob-
servers recorded data for about five hours. Here
we shall include a
part of the whole body of observations. Consider Stations
and #5. The curves shown inFigures 5,
6
and
7
#1, #4
indicate the associa-
tion of contour packing with heavy rain intensity but not as distinct
packing as in the case of
may result from
(1)
2
March 1963, at least at Station #1.
This
synoptic conditions quite different from the pre-
vious case, (2) observations made a few hours before the occluded
front passed over the observing network and
(db) of the
(3)
step-gain values
radar receiver not uniformly separated from each other.
16
However, the tendency for compactness of the echo-contours with
rain intensity at the surfact exists. This appears more evident
when we consider the
earlier part
of the
observation.
On 29 March 1963, synoptic conditions
those of
27
March. Figure
8
differed markedly from
shows increase of rain intensity with
echo-contour packing and also dependence of intensity of rain on
the height of the echo contour compact region.
The rain intensity
observed at the surfaces does not depend on echo height alone here,
especially at the time of
C.
1417 PST.
Drop-size distribution:
Drop-size distribution pattern deviates greatly from the usual
Marshall and Palmer distribution law (19). The other characteris-
tics such as
mm to 0.
9
(1)
Bimodal type and (2) tendency for increase from 0.
5
mm diameter range appear here. So far as Station #4 is
concerned, maximum rain intensities occur with greater number of
drops from 0. 7 mm up to about 2.
of
larger drops.
On the
3
mm diameter with a clear lack
contrary, the largest drops of the whole
observation network came at about 1405 PST at Station #5.
The drop-size spectra show great diversity from station to
station, as shown inFigures 5A, 6A, 7A and 8A. In Station
drop-size distribution denoted by curve
4
#1
the
shows lack of larger drops
17
beyond
1. 7
mm.
Increased rain intensity is associated with broad-
ening of the spectra towards larger drop-size.
In Station #4 Figure
6A),the distribution pattern differs greatly from that f Sth.tion
#1
(Figure 5A). Here increased rain intensity is associated with in-
crease in number of drops from
#5
0. 5
mm in all the curves. Station
(Figure 7A) shows some diameter preferred for drops at differ-
ent rain intensities. These are 0.
7
mm and
1. 9
mm diameters.
Curve #2, at high rain intensity, shows great fluctuations at different
diameters and are associated with drops, the diameter of which
ranges up to
3.
9,mm but otherwise the same general pattern for all
the curves.
The drop-size distribution for the 29 March 1963 case shown
in Figure 8A,has usual bimodal type with dip in diameter range of
0. 5 to 1.
3
mm.,predomiaant in the case of
cm/hr rain intensity. There is
0. 205
a tendency
cm/hr and
0. 2246
for increase in 0.
7
mm
diameter. With an increase of rain intensity, the dip is made up
and an exponential patte rn prevails.
18
DISCUSSIONS
The observations made under three different synoptic condi-
tions, though exhibiting much difference in both radar and surface
observations from one synoptic condition to another, still show
vividly some of the common features associated with all of them.
Without surface observations or radar pictures taken at short inter-
vals of time, we must find a comparison criterion for surface rain
intensity and radar echo-contour packing at different gain settings.
I
adopted the comparison criterion that gradually increasing rain in-
tensity should associate with gradually converging echo-contours
and gradually decreasing rain intensity should associate with gradu-
ally diverging echo-contours. Visualize the whole situation by con-
sidering a cell having iso-echo contours at different heights. As the
cell moved over the station, these contours converged and diverged
overhead pouring down rains of different intensity according to the
degree of convergence and divergence.
By applying this
criterion to theFigures
1, 2, 3
and 4, we find
that above a certain height, rain intensity increase occurs with con-
vergence of echo-contours at differentdb values except in the case
ofFigure 4. In that exception, the second cell did not show any convergence within a period from 1702 to 1720 PST, though associated
with heavy rain intensity.
19
The occurrence of strong echo gradient aloft (generally much
above the freezing level) can result fromthe presence of strong up-
draft in the convective cell (14). At high accretion rates, particles with
wet surfaces form and these give intense echo. A strong updraft
may carry such particles high into the cloud, and an intense echo
pattern results. Assuming Ludlam's model of convective cloud and
that the rain-drop size distribution spectra does not differ appreciably from the base of the cloud, we should expect expansion of the
spectrum towards bigger drops with increase of updraft and hence the
increase of height
Z
of the echo-contour compact region. Again since
NDI6 and ZOC Rb, increased number of bigger drops as soci-
OC
ated with increase height of the echo compact region, should lead to
greater reflectivity and hence increase in rain intensity and viceversa.
A
careful study of the drop-size distribution curves in Fig-
ure 4A, (curve corresponding to the times 1550, 1600, 1604, 1605,
1720, l7Z5and 1731 PST) supports this argument.
Absence of rain even with contour packing at lower heights
such as in Figure
2
(from 1520 to 1550 and 1627 PST), Figure 4(from
1540 to 1550, 1640, 1650 PST) and to some extent in
Figure
1
(from
1458 to 1600) may come about as follows:
Because of the location of these regions near the freezing
level for that day, Bergeron-Findeisen mechanism of shower
20
release does not occur since this requires rain clouds extending
well above the 0°
C
isotherm
(3).
Sufficiently low heights indicate
absence of strong updraft for formation of raindrops by coalescence,
and hence no rain fall from t1ose regions of strong echo-contour
gradient.
Figure
3
shows precipitation streaks observed at the surface
associated with echo-contour packing and height.
Heavy rain intensity and absence of contour packing as indi-
cated by Figure 4, between the times 1650 and 1720 PST may possibly be explained by assuming it to be a dissipating convective cell.
The absence of strong updraft and the predominance of strong down -
draft may show lack of convergence of echo-contours.
rop-size
distribution curves durin these periods (Figure 4A2) show that the
curves beyond
0. 9
mm diameter maintain their shape with small
variations even though rain intensity decreases) To some extent
the echo-contour spacings resemble that of warm front rain as
shown
inïigures
5, 6 and 7.
The reports of the surface observer
reveal clearly that over the station pressure fell slightly
(0. 01 inch)
at 1530 PST and continued falling until 1625 PST,when the observeras
record showed an increase
til the end of observation at
(0. 01 inch) and
1730 PST.
then remained steady un-
This may possibly show the
most prominent downdraft during the observation of the second cell.
21
In reality, the convective cloud has not the simple
as assumed here.
Probert-Jones and Harper
structure
(21) showed by using
Doppler Radar that both updraft and downdraft of different magnitudes occur in a vertical column of convective cloud at different
heights.
Relations similar to those of
2
March l963,may explain the
association of heavy rain intensity with echo-contour packing in
case of 29 March 1963, shown in Figure
On 27 March 1963, in absence of
8.
strong updraft, the occur-
rence of heavy rain intensity does not occur only with the echocontour packing. However, all echo-contour packings do occur
with heavy rain intensity. Absence of bright band indicates turbu-
lence. Besides that the step-gain values of the gain settings did not
function properly. Though bigger drops contribute, in general, less
for heavy rain intensity, the biggest drops of the whole observation
period did come with initiation of rain at 1405 PST in Station
Figure
7
shows at this time a rain intensity of
O.
7766
particularly strong echo-contour packing at about
Figure7A shows large deficit of smaller drops in
cm/hr with
12, 000
O.
#5.
feet. Also
7mm-i. 7mm
diameter range. Hence, both updraft and coalescence probably
contribute for heavy rain and large drops.
Heavy rain intensity does not always associate with the height
22
of the highest gain settings (0db) as
1410 to 1430 PST).
demonstrated in Figure
5
(from
However, increase or decrease of rain intensity
follows the general criterion, without dependence on height.
A
general deviation of drop-size distribution from Marshall
and Palmer law appeared in all the cases studied.
The drop-size
spectra broadens much more in the case of convective and cold
front shower with increased rain intensity ,but not necessarily in the
case of warm front rain. Thus the larger contribution to rain in-
tensity by larger drops in case of convective shower, compares to
the smaller drops which contribute more in case of warm front pre-
cipi.tation except at 1405 PST in Station #5.
We
may attribute this
fact to the lack of smaller drops, especially from 0.
7
mm to
1. 7
mm diameter range, showing coalescence effect also predominant,
resulting in the formation of bigger drops. For almost the same
intensity of rain in the case of Station
#1
(Figure 1),on
2
March 1963,
at 1650 and 1710 PST, the distribution curves show alternate in-
crease and decrease in number at several diameter points. Close
observation of the radar echo gradients at these points show much
different contour.gradients in both the cases indicating difference in
their updraft velocities. Drop-size distribution curves for Station
#2
(Figure2A,2March),artdthat for Station
27
March,looks similar especially at times
and 1425 PST,
respectively,
#4
(Figure
6A) on
1650 PST, and at 1356
though the latter falls off more
23
rapidly and except that peak in one case is at
it is at
1.
1
mm and in others
0. 7
mm. No direct comparison can be made with radar due
However, all of
to the lack of radar observations at these times.
these fall just in the converging zone of the echo-contours at various db settings, but at different height.
A
comparison of drop distribution spectra with compactness
of iso-echo-contours shows that spectra corresponding to the time
of maximum convergence of echo-contours show more or
lar irregularity in the size range from
ures
ZA
(curve 2), 3A (curves
inFigure 6A (curve
2
and 3).
2
and
3)
0. 3
mm to
and from
.
1. 5
5
less simi-
mm inFig-
mm to
1. 9
mm
Lack of smaller number of drops
indicate that strong updraft associated with compactness of echo-
contours produces bigger drops which subsequently break up after
reaching the critical size due to coalescence in their downward motion and subsequent growth.
Evaporation may also play a great role
('5).
Deficit of middle-sized drops as indicated inFigures 4A, 5A
and curves
1
and
2
in Figure 8A and corresponding increase in big-
ger sized drops may result from the aerodynamic break up proc-
ess ( 9).
General nature of the curves inFigure 4A, especially all but
1,
and curves
1
and
2
inFigure 8A,resemble those given by
24
Blanchard (4, Figure
3)
for thunderstorm in Hawaii.
Lack of reliable wind data and other pa r am e t e r
s did not
allow detailed calculations of trajectories etc.
Calculation of radar reflectivity from the drop-size distribution at the surface when plotted against time shows peaks at times
where there is contour packing, indicating good correlation between
echo-contour packing height and reflectivity observed at the surface.
25
CONCLUSIONS
The limited number of cases studied so far prevent drawing
statistical conclusions. However, the cases studied here show the
following:
1.
In the case of instability showers of 2 March 1963, the
greater rain intensity almost invariably coincided with steep echocontour gradient on RHI display, at different gain settings of the
radar receiver, over the point of observation. Observed rain intensity depends on the degree of steepness and also on the height of
the steep region over the point of observation.
packing near the freezing level did not
Steep echo-contour
coincide with heavy
rain.
2.
In the case of warm front rain of 27 March 1963, echo-
This contrasts
contour compactness shows heavy rain intensity.
with the dependence of rain intensity on the height of the echo-con-
tour compact region in the instability shower of
3.
2
March 1963.
In the case of cold front rain of 29 March 1963,the single
case studied shows similarity to the instability shower.
4.
For the same order of rain intensity, in general, the
greater number
of
larger drops occurred in the case of instability and
cold front shower than in the warm front shower and vice versa.
26
5.
Height of echo at maximum gain setting
(O
db) does not in-
dicate heavy rain intensity. Rain intensity does not show preference for a particular gain settings used, although compactness of
lower gain settings indicate heavier rain intensity compared to that
of higher gain settings.
6.
Drop-size distribution patterns greatly deviate from Mar-
27
RECOMMENDATION FOR FURTHER RESEARCH
This author considers that a main result of this study associ-
ating heavy rain intensity with steep echo-contour packing deserves fur-
ther study for different kinds of rains and at different times of the
year by adopting similar procedures for statistical comparisons.
Further study should include at least the following:
1.
Reiterated calibration of the radar step-gains before and
after observations.
2.
RHI
pictures taken at shortest possible intervals in one
particular azimuth inthe direction of motion of the echo with surface observers located beneath the radar beam along the line of echo
movement at suitable spacings.
3.
Surface observations including filter paper exposure
made as frequently as possible.
4.
Improvement on the rain gauge which gives only an inte-
grated value over a period. To find correct instantaneous intensity
of rain would need accurate calibration.
If the
results of this study get confirmation in new evidence,
quantitative innovations might make a new approach to the "charac-
terization of precipitation by radar" and in addition, enable one to
study orographic effect on precipitation.
28
STATION IDENTIFICATION
Station Number
i
Location
Range
Azimuth
Physics -Chemistry
Building, Oregon
State University
5 7
mi
137°
2
Wren
4. 8
mi
232°
3
Newport Rd.
6 0
mi
255°
4
Blodgett
8 7
mi
255°
5
4. 4
11 2
mi
240°
miles from
Blodgett School
29
Height of radar echo contours at different
gain settings of the receiver from RHI tracings
Table IA
Station
Date:-2 March 1963.
L
Time Hei2ht of echo contours over the stationx2000E Remarks
0db -3db -6db -9db -12db l8db
number PST
Serial
1
2
3
4
s
6
7
8
9
10
11
12
13
14
15
16
17
18
1428
1437
144?
1458
1507
1519
1527
1537
1548
1559
1608
1617
1626
1638
1648
1658
1708
1717
7.70 7.50
7.40
6.30 0.00
0.00
7. 70
5. 00
7. ¿0 7. 20
4. 70 4. 7Q
3. 00 2. 90
2. 40 2. 40
0. 00
3. 60
3. 20
7. 70
4. 80
3. 40
2. 50
3.00 3.00
2.80
2.00 1.40
2. 80 2. 60
2. 50
2. 90
2. 85
2.
90
1. 80
1. 40
0. 00
2.90 2,60
2.40
2.30 1.80
0.00
4. ¿0
4. 60
3. 10
3. 10
1.20
7.90 7.40
7.00
6.90 6.60
0.00
7. 40 7. 20
6. 90 6. 30
9. 90 9. 50
6. 95
6. 30
6. 30
3. 90
9. lO
30
60
2. 20
10
1. 30
8.70
8. 50
9. 15
8. 50
9. 00
8.40
35
1.40
6.50 6.30
6.00
5.80 5.7
8. 50
5. 60
3. 70
3. 20
3. 15
3. 10
8. 30
9. 90
3. 00
2. 85
9.40
lO
2. 50
1. 80
8. 80
I.
6.
3.
9.
8.
8.
5
1. jO
1. 30
0.00
0.00
1.20
O.
00
1. 30
1. 90
0.00 holes from
2.
4to4.9and
from 2.4 to
5. 2 at -9db
-12 db.
30
Table lIA
Station
Date:-Z March 1963.
Z
Serial Time
number PST
i
Z
3
4
5
1517
1520
1527
1537
1549
Heightofecho contours over the station
at different gain setting x 2000'
0db
-3db
-6db
-9db -12db -18db
*
2. 10
2. 00
1. 80
70
1. 50
*
2.45
1.95
1.65 1.55
1.20
*
3. 50
*
2. 80
2. 35
2. 00
1. 90
1. 80
1. 90
1. 60
1. 20
1. 10
*
2.70
2.00
1.70 1.70
0.00 overhanging
portion of the
echo not
measured
6. 50
8. 30
6. 60
2. 20
6. 50
8. 30
30
0. 00
4. 10
1. 60
6. 30 6.
8 00 8.
3. 00 2.
1. 60 1.
00
00
50
1. 00
1. 20
6. 25
4. 50
4. 30 4. 30
1.
7.50
8.00
7.00
7.50
7.50 7.50
6.80 6. 60
1.20
7. 50
7. 50
1.
.
6
7
8
9
Remarks
1600
1609
1618
1627
*
*
0.00 weak region
aloft excluded
10
11
12
13
14
1640
1650
1701
1710
1720
7. 10
6.40
6. 1
5. 90
5. 90 0. 00
20
0.00
0.00
0. 00
The echo contour at 0db was not distinct enough for accurate
mea sure ment.
31
Table niA
Station
Date:- 2 March 1963.
3
Serial Time
Number PST
Height of echo contours overthe station Remarks
at different gain settings x 2000'
9db -12db -18db
0db 3db -6db
1
1550
6. 90 6. 60
6. 60
6. 40 6. 40
0. 00
2
1601
8.00 8.00
7.90
7.90 7.80
1.60
3
1610
6. 90
6. 70
6. 70
6. 50 6. 50
0. 00
4
1618
7. 20 6. 80
6. 80
6. 50 6. 50
0. 00
5
1628
6.60 6.50
6.30
6.30 6.20
1.40
6
1640
7.70 6.40
4.20
4.20 4.20
0.00 Thebulging
portion
excluded
7
1650
4. 00 4. 00
3. 80
3. 80
3. 80
1. 50
8
1702
6. 80 6. 40
6. 10
5. 80 4. 80
0. 00
9
1712
6. 55
6.00
6.00
5.50 4.60
0.00
10
1721
6. 10 6. 10
5. 90
5. 10 4. 60
0. 00
11
1731
5.50 5.20
5.00
4.90 4.70
0.00
32
Table IVA
Station
Date:-
4
Serial
Time
Number PST
Z
March 1963
Height of echo contours,
over the station x 2000
-6db
-9db -12db -18db
0db -3db
i
1540
1.50 1.40
1.20
1.20 1.20
0.00
2
1550
1.40 1.30
1.30
1.20 0.00
0.00
3
1601 6. 40 6. 20
6. 20
5. 50 0. 00
0. 00
4
1610 6. 20 6. 10
6.00
5.80 5.80
0.00
5
1618 8.00 7.60
7.20
7.00 7.00
1.40
6
1628 3. 60 3. 10
3. 00
2. 70
2. 40
0. 00
7
1640
1. 30
1. 30
1. 30
1. 30
0.00
0.00
8
1650
1.40 1.40
1.40
1.40 1.40
0.00
9
1702
4.60 4.30
4.30
4.00 4.00
0.00
4.60
4.50
4.00
2. 50
0.00
10
1711 6. 10
11
1721
3.50 1.50
1.40
1. 30
1. 30
0.00
12
1731 3.50 3.30
3.00
1.20 0.90
0.00
Remarks
hole in
9 db
oi the echo
border
holeat-lZdb
0
db is not
distinct
33
Table
Station
Date:-
1
Serial Time
number PST
*
VA
27
March 1963
Remarks
Height of echo contours
over the station x 2000
0db -3db
-9db -12db-18db
--J
-3. 28 -13.02 -14.86-19.48
1
1313
3.90 3.70
0.00
0.00 0.00
2
1323
2.80 ¿.00
1.75
1.40 0.00
3
1333
2. 95
0. 00
0. 00
0. 00 0. 00
4
1343
4.80 4.80
0.00
0.00 0.00
5
1353
2.00 0.00
0.00
00
6
1411
9.40
8. 10
4. 60
2.75 0.00
7
1422
8. 80
8. 40
3. 20
2. 90
8
1432
6. 40
5. 90
4. 50
2. 90 0. 00
9
1442
7. 10 6. 50
6. 12
3.00 0.00
10
1453
7.00 7.00
4.70
2.70 2.40
11
1613
3.50 3.00
3.00
0.00 0.00
When calibrated after
3
0.00
0. 00
weeks, the step-gains showed these values.
Table VIA
Station
Date:-
4
27
March 1963.
* 0
Remarks
Height of echo contours
over the station x 2000'
-12db-18db
-3db
-9db
-3.28 -13.02 -14.86-19.48
Time
number PST
Serial
0
1
1339
6.2
5.0
4.2
0.0
0.0
2
1349
9. 6
9.
4.
3
0. 0
0. 0
3
1359
6.9
5.6
5.2
4.9
4.5
4
1408
9. 6
6. 9
5.
5
2. 8
0. 0
5
l418.. 6.2
4.8
4.6
3.2
0.0
6
1429
5.
7
4. 6
3. 2
2. 0
0. 0
7
1438
8.
3
7.
2.
7
1. 0
0. 0
8
1448
4.2
3.8
1.2
1.0
0.0
9
1500
6. 3
5. 9
4.
0. 0
0. 0
1
7
7
no
surface data
9db contour aloft
When calibrated after 3 weeks, the step-gains showed these values.
35
Table VilA
Station
Serial
number
Date:-
5
Time
PST
O
*
*
0
27
Height of echo contours
over the station x 2OOO
-12db -18db
-3d.b
-9db
-3.28 -13.02 -14.86 -19.48
1
1358
9. 30
8. 32
6. 90
4. 30
2. 80
2
1407
7. 00
6. 55
6. 20
5. 90
2. 65
3
1416
6.45
5.65
4.70
4.55
0.00
4
1427
8. 15
6. 00
3. 60
3. 00
2. 80
5
1437
8. 10
7. 80
3. 60
2. 90
2. 70
6
1447
4. 80
4. 65
4. 20
0. 00
0. 00
7
1459
4. 85
4. 00
0. 00
0. 00
0. 00
When calibrated after
3
March 1963.
Remarks
weeks,the step-gains showed these values.
36
Table VillA
Station
Date:- 29 March l963
1
Serial
Time
number PST
0
*
Remarks
Height of echo contours
from the base lin x 2000
-18db
-12db
-3db
-9db
-19.48
-3.28 -13.02 -14.86
1
1333
2. 75
2.75
2.05
2. 05
0. 00
2
1342
3.25
2.85
2.05
1.90
0.00
3
1347
4.20
4. 10
1.95
1.25
0.00
4
1404
3. 13
2. 10
1. 70
0. 00
0. 00
5
1413
2.70
2.50
1.92
1.60
0.00
6
1417
6.60
4.85
2.70
2.20
0.00
7
1428
6. 40
5. 42
4. 30
3. 05
0. 90
8
1436
3. 55
3. 47
2. 82
2. 65
2. 15
9
1449
4. 60
3. 58
2. 35
2. 25
1. 90
10
1456
5. 15
4. 60
3. 50
3. 20
0. 90
11
1505
4.90
4.50
4.40
4.30
2.00
12
1516
5.70
5.50
4.50
2.50
0.00
13
1524
2.37
2. 30
2. 10
2.05
1.90
When calibrated after
3
weeks, the step-gains showedthese values.
Table
Station l
Serial
Time
number PST
-
-
-
.3
i
1420
584.0
198.0
2
1430
No
Rain
3
1440 3468.0
4
1450
1960.0
S-
1500-
.5
.9
16.0
1.82 00.8
266.0
87.0
70.18 68.0
544.0
163.5
IB
Number of drops/rn3
2 March 1963
Mean diameters of 0. 2 mm intervals
-________________________________
1.1
1.3
175
1.7 17
2.1
2.3
2.7
2.5
2.9
31
00.76
00.36
65.00
15.62
16.73
79.27 27.2
15.45
6.48
4.91
1.13
0.57
0.91
0.48
10.00
0.94
12
1610
No
Rain
13.
1620
892.0
3420
125.0
8.00
8,8
1.82
14
1630
1060.0
88.0
9.5
1.45
0.53
0.45
15
1640
408.0
408.0
132.5
55.64
5.33
11.59
40.80
22.36 8.23
3.23
16
1650
192.0
176.0
71.5
69.45 25.33
20.00
12.95
8.73 1.13
1.08
17
1656
420.5
261.2
116.3
37.11 27.21
16.70
16.30
18
1700
598.6
217.7
105.4
39.58 14,51
9.28
19
1710
164.0
98.0
43.0
22.18 17.33
22.73
20
1720
60.0
30.0
8.5
1.87
0.45
2.91
1.34
0.36
1.09 5.77
2.82
0.91
0.88
4.45 3.29
1.21
0.55
0.53
051
16.85
7.42 5.49 11.51
2.02 9.56
3.65
17.14
6.73 9.84
2.96 1.13
1.07
5.08
0.86
0.85
2.08
0.98
0.18
(J
-J
Table lIB Number
Station 2
Serial Time
number PST
i
.3
_:1
.5
.7
.9
1516
i
drops/rn3
2
__________
_____
o
Mean diameters of O. 2 mm intervals
1.5
1.7
1.9
1.3
1.1
0.68
0.76
0.36
2.1
2.3
2.5
1.55
0.94
March1963
__3J_9
3.1_
0.15
520-
2-5
1550
No Rain
6
1600
1088
74
1.5
0.73
0.26
7
1606
28
30
8.0
7.27
1.87
0.68
0.76
1.09
0.65
0.46
0.15
8
1610
60
32
23.0
21.82
5.87
6.82
3.05
2. 18
5.65
2.46
1.04
9
1620
328
90
130.5
53.45 11.47
12.05
7.43
2.91
6.94
3.85
10
1640
12
6
11. 0
0. 53
0. 23
0. 76
0. 18
0. 48
0. 15
0. 15
0. 14
11
1650
84
42
79.5
10.76 71.20
59.77
47.81
33.09
13.87
6.31
4.00
3.52
12
1710
424
148
24.5
35.64 13.07
5.68
3.05
13
1720
296
138
38.0
13.45
7.73
1.36
1.14
5. 09
0.73
0.52
0.37
2.60
0.25
0.27
0.81
1.48
Table IIIB Number of drops/rn3
2
Station 3
Serial Time
Number
i
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
PST.
.1
.3
1543
72
2256
1545
58
1028
1550
4
332
142
1555
580
1600 18448
550
1605 17508
876
7304 1800
1610
4
1615
856
1620
2748
232
1625
3004
180
1630
46
800
1635
96
776
1640
284
24
224
1645
2408
1650
310
3756
1655
Rain
No
244
1700
3120
1705
2284
212
1710
172
1556
1715
1224
302
212
1720
2792
.5
l2O
18.5
0.5
2.0
.7
.9
5,82 1.07
17.45 12.00
1.09
4.27
2.18-
0.53
32.53
86.93
106.70
0.27
21.87
17.33
8.27
2. 18
6. 55
2. 13
164.0
137.5
285.5
66.55
163.60
296.70
0.5
64.5
39.0
46.91
19.27
12.0
7.5
10.0
36.5
16.73 31.20
22.18 9.87
30.5
49.0
34.5
46.5
39.0
16.36 7.73
32.73 10.93
14.91 3.20
37.09 14.13
39.86 15.20
e2diames. of
1.5
1.3
Li
0.91
9.09
1.14
30.23
57.95
74.09
18.64
9.32
7.05
2.27
30.00
8.41
0.91
8.41
2.27
6.59
1.7
1.29
1.9
0.62
0.73
16.73
33.27
7.45
0.32
8.22
9.84
1.61
0.62
4.62
4.62
3.08
15.62
8.57
3.05
0.38
1.52
13.64
8.18
1.09
5.48
2.58
2.15
0.62
1.45
0.65
0. 31
13. 52
8. 36
2.29
1.52
4.36
1.52
25.33
54.29
29.14
2.29
2.91
1.52
2.18
0.38
9.33
7.45
2.1
2.3
2.96
10.52
1.48
5.77
1.41
1.04
1.78
1.97
1.13
1.78
0.56
1.85
7.90
1.85
2.5
2.7
2.9
3.1
1.34
5.50
2.73
1.25
2.63
1.23
0.99
1.07
0.52
0.67
0. 77
1.29
1.13
March 1963
Table
Station 4
Time
Serial
number PST
i
2
3
4
5
6
7
8
9
10
11
12
13
14-16
17
18
19
20
21
22
23
24
1550
1600
1604
1605
1606
1610
1615
1616
1620
1625
1630
1635
1640
IVB
Number of drops/rn3
2
1
292
408
816
488
3292
1340
456
1060
488
472
40
40
400
March 1963
Mean_diarneteofO.2 mm intervals
.3
244
240
180
174
584
506
24
326
392
130
24
50
66
.
.5
30. 5
36.5
57.0
61.0
207.5
69.5
30.5
71.5
122.5
49.0
7.0
45.0
12.5
1.1
1.3
1.5
2. 67
2. 27
0. 38
0.73
9.82 12.53
14.91
6.67
50.18 27.20
9.32
11.14
3.43
10.86
15.62
24.57
.7
.9
7. 27
123.60
44.36
31.27
74.18
121.80
130.55
12.00
32.73
8.00
38.13
28.27
18.40
36.27
78.40
82.67
9.33
20.27
4.80
31.36
23.18
7.50
15.68
29.32
63.18
54.77
7.05
8.86
1.36
552
1.09
7.45
14.91
21.09
1.7
0.65
5.32
5.00
6.61
1.94
9.33
32.38
38.86
20.93
7.81
1.90
5.27
5.27 5.97
22.18 17.58
14.91 6.61
11.09 6.61
6.00 2.9
.36
1.02
6.29
14.86
4.76
19.43
18.67
6.29
3.82 2.90
17.09 7.90
17.09 9.84
22.18 10.48
15.64 5.97
12.91 6.61
1.9
2.1
0.31
6.31
2.37
1.54 2.22
5.23 2.07
3.85
1.77
4.46 1.77
10.46 12.15
3.85
2.37
3.85
1.19
1.54 1.19
2.3
0.70
3.80
5.77
2.5
0.54
0.67
2.7
2.9
31
0.64
0.91
0.875 0.86
2.68
3.51
0.880 0.86
.54
.52
1.000
0.27
1.07
2.68
2.68
3.89
5.40
0.26
0.25
0.50
0.25
0.99
1.50
1.50
1.98
1.48
.28
16451655
1700
1701
1705
1710
1715
1720
1725
1731
No
328
100
244
276
48
108
80
280
Rain
24
14.5
82
43.0
32
14.5
66
70
66
6
2.0
65.5
14.5
34.0
5.0
9.09
41.45
94.91
2.91
13.45
30.55
10.55
15.73
19.73
21.87
12.00
10.93
12.00
5.07
1.87
7.95
15.68
13.86
8.41
22.27
7.95
1.14
2.50
0.38
0.38
0.36
0.32
0.32
2.46
1.85
5.69
5.69
8.77
2.46
0. 31
2.37
0.59
1.77
8.44
6.67
1.48
0.56
1.13
3.52
5.21
2.25
0.85
0.27
1.56
3.25
3.77
0.52
Table
Station
2
3
4
5
6
7
8
9
10
11
12
13
14
Number of drops/rn3
27 March 1963
Time
Serial
number PST
1
VB
i
1230
1240
1317
1332
1340
1348
1355
1410
1420
1430
1440
1453
1502
1510
.1
5687.0
3238.0
2139.0
1102.0
857.2
1184.0
847.9
669.4
1192.0
669.4
1927.0
3853.0
3984.0
4555.0
.3
.5
7
.9
557.80 173.5 94.00 38.10
421.76
78.23 89.05 39.91
51.02
10.21
5.57 6.88
998.90
43.36 24.2 25.85
265.30 71.43 21.03 6.35
190.50
37.42 37.11 11.79
318.40 46.94 51.95 20.68
65.30
7.15
4.45 1.63
114.30
81.64 35.62 21.77
228.60
77.18 39.18
334.70 89.79 97.96 29.39
416.30 40.82 38.59 47.89
228.60 63.27 68.28 57.25
302.00 59.19 23.74 14.15
Mean diameters of O. 2mm intervals
1.3
Li
1.5
1.7
30.92
34.01
6.96
10.44
0.77
6.18
10.37
19.44
7.78
5.83
3.25
15.77
13.00
34.32
12.99
25.05
12.06
0.78
6.99
19.79
16.08
9.88
5.44
4.64
1.65
-
7.33
1.05
0.78
2.1
2.3
2.5
3.02
4.79
5.48
2.30
0.57
2.30
1.64
2.7
29
3.1
0.84
1.01
3.02
0.55
1.30
19.44
6.99
10.11
18.65
0.66
0.63
6.68
3.95
8.16
7.42
6.68
6.58
5.92
3.29
0.66
10.39
0.60
3.14
3.14
0.63
0.63
3.02
3.02
3.02
4.84
0.55
1.06
0.50
0.50
Tabi VIB Number of drops/rn3
1
2
3
4
s
6
7
8
9
10
11
12
13
14
1342
1353
1356
1359
1407
1410
1415
1417
1425
1433
1443
1445
1455
1501
27 March 1963
_______________________--
Station 4
Serial
Time
number PST
Mer diameters of
.3
702.00 32.65
3551.00 24.48
277. 60
57. 14
.s
2073.00
1143.00
32.64
310.20
228.60
81.64
367.40
310.20
146.90
138.80
48.98
400.00
55.10
75.51
22.45
57.15
40.81
14.29
37.76
78.57
1.5
1.7
1.9
2.1
0.50
2.65
1.06
1.53
2. 19
2. 12
1. 02
0.50
3.53
0.55
0.55
0.55
1.10
0.82
1.06
1.06
1.01
0.51
1.10
1.10
0.60
40. 27
23. 19
23. 32
17. 81
10. 53
6. 28
10. 28
14.84 22.78
2.967 35.92
IO. 39
9. 79
68.28 65.30
65.31 50.07
48.98 48.98
108.30 79.46
65.30 67.48
21.52 13.06
38.59 28.30
48.80 24.49
14.84
15.77
23.32
15.55
10.39
17.07
9.87
2.64
8.79
3.77
7.86
4.84
0.29
3.45
1.72
1.15
24. 12
13. 22
51 95
3. 95
4. 40
3. 63
1. 72
49.17
24.12
74.21
64.93
29.68
8.81
23.30
21.77
33.43
38.10
10.53
10.53
15.80
13.17
10.53
8.16
5.65
8.79
8.79
7.53
1.57
1.81
1.15
13.91
10.20
5.44
2.33
0.74
0.74
2.42
7.86
5.89
2.42
2.12
0.30
2.30
2.88
15.55
18.55
20.78
23.75
24.49
4.45
2.60
4.28
0.33
0.26
0.27
3.77
1.57
24.88
3.1
2.5
3.95
3.29
.
2.9
2.3
7.42
6.30
43. 04
IO. 20
1.3
3.89
2.72
34. 70
57. 14
i.i
mm intervals
9.28
6.49
43.04 44.63
19.30 21.22
244. 90
175.50
163.30
.9
4.08
12.25
261.20 57.14 24.49
359.20 8.16 8.16
81.64
48.98
.7
O. 2
2.7
1.21
1.72
1.01
0.53
0.26
0.25
Table VIIB Number of drops/rn3
27 March 1963
Seriàl
number
i
2
3
4*
5
6
7
8
9
10
11
12
13
14
15
*
Time
_________
F'ST
. i
. 3______
. 5
1350
1910.0
65.3
16.33
1355
1260.0 587.0
57.00
1400
3951.0 122.4 32.66
1405 11379.0 1314.0 184.40
1410
5257.0 326.6
73.47
1415 34013,0 5061.0 224.50
1420
7183.0 435.4
44.22
1425 17088.0 244.9
51.02
1430
1208.0 1012.0
36.73
1435
2677.0 130.6
57.14
1440
1926.0 228.60 71.43
1445
1240.0 146.9
31.63
1450
3053.0 449.0
1455
2433.0 473.5
77.55
1500
530.6 167.3
39.79
At diameters 3. 4 mm, 3.
6
.
7
37.11
11.87
27.74
25.23
50.47
113.80
24.74
32.16
22.26
117.30
31.17
31.17
.9
23.95
14.15
18.15
16.33
28.30
40.13
41.73
32.65
28.30
27.21
21.77
17.42
69.76 16.33
53.43 15.78
Mean diameters of 0. Z mm intervals
1.1
1.3
1.5
1.7
1.9
12. 99
10. 88
10. 39
7.43
11.66
10.11
5.94
7.42
18. 66
24. 88
13. 36
25.97
23. 75
19. 75
9.28
24.74
14.25
28.51
14.84
21.03
9.87 6.28
31.82 7.33
30. 84
16. 44
16, 08
10. 97
26.90
21.33
13.91
5.57
34.98
14.77
12.44
5.44
19.29
12.62
18.43 8.79
8.35
10.20
15.55
3.89
10.39
12.99
12. 98
8.91
4.82
5.94
5. 92
2.63 3.77
2.63 7.54
3. 95 7.54
8. 79
5. 23
5.93 3.77
1.32 1.26
2.30 2.83
0.66 0.63
1.32 0.63
mm and at 4 mm,, the number of drops per cubic meter of air
2.
1
2. 3
2. 5
2.7
2.9
3.1
0.58
6.32
0.55
0.00
2.19
0.53
3.18
1.02
1.53
0.51
3.02
1.51
LOi
3.52
1.83
2.19
1.10
0.88
1.70
0. 82
O.
53
O.
53
0. 63
3.63
3.02
7.86
12.09
6.05
5.04
8.06
3.63
1.81
3.02
2. 12
1.15
1.92
1.92
6.90
1.15
2.30
1. 72
0.60
0.30
is O. 48, O. 47,
and
O.
1.68
0. 26
0.26
93 respectively.
LJ
Table VIIIB Number of drops/rn3
Station i
Time
Serial
number PST
i
2
3
4
s
6
7
8
9
10
11
12
13
14
15
16
1333
1340
1350
1400
1410
1420
1430
1440
1450
1500
1510
1520
1530
1540
1550
1600
-
Mean diameters of
.3
.5
326.50 79.08
220.40 61.22
163.30 61.23
69.38 56.12
134.70 18.37
122.40 10.21
52.48 13.12
114.30 17.35
186.90 28.57
269.40 104.10
326.50 173.50
866.0 268.10 54.13
2057.0 318.40 40.82
473.5
1105.0
65.30
8.85
24.48 4.08
332.0
1122.0
244.9
555.1
244.9
995.9
726.5
408.2
489.8
571.4
5502.0
4735.0
.7
81.63
29.68
37.11
23.01
17.07
11.13
11.66
14,84
22.26
105.40
127.60
56.23
32.65
0.37
5.94
2.47
29 March 1963
------------- ------________j__j
35.37
12.75
7.62
15.24
5.44
0.93
18.55
0.93
13.91
2.32
8.43
8.35
12.99
28.76
38.00
4.69
6.96
2.32
0.62
0.93
0.54
4.90
14.77
9.79
11.95
58.78
65.30
17.87
15.24
0.73
1.45
1.3
5.83
0.78
10.88
0.39
1.94
6.66
5.05
23.32
0.11
13.20
0.98
3.11
0.26
O. 2
mm intervals
1.5
1.7
4.64 0.82
5.94 3.29
6.68
Lii
1.11
1.9
1.57
2.51
1.88
0.31
14.84 5.92
7.40 7.20
2.81
7.42
2.42
2.3
0.72
1.15
2.5
0.68
0.55
2.7
2.9
3.1
0.82
1.44
0.39
1,37
0.55
0.38
0.53
0.51
0.76
0.60
1.97
4.77 2.82
5.94 2.30
2.1
0.45
0.31
2.51
1.73
1.51
2.42
1.25
0.60
Station
Serial
number
1
Table IC
Time
PST
2
Zmm
m3
6
4
1420
1430
1440
1450
6. 930
No
890. 670
381. 110
5-12
1500-1610
No
35. 410
3. 950
1
2
3
13
14
15
16
17
18
19
20
1620
1630
1640
1650
1656
1700
1710
1720
726.
3467.
1500.
1907.
3098.
-
March 1963
100
070
000
139
000
2. 890
R.E-1
hr
.
00425
Rain
.
.
26460
11210
Station
Serial
number
1
10
.
17540
.51257
.
.
9
11
12
13
March 1963
6
Zmm
m3
RS
1516
12.59
No
.00410
Rain
0.56
194.53
.01832
1600
1606
1610
1620
1640
1650
1710
1720
7
2
Time
PST
1520-1550
00234
23420
38540
.
11G
6
8
.
Table
2-5
Rain
.02100
.
2
2599. 99
516. 26
31. 17
3610. 80
36.49
22.86
hr
.
.
23580
13890
.00850
.
.
68320
02750
.01510
38400
00260
u,
Table
Station
Serial
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Table IVG
111G
March 1963
mni°
cm
Z_
m3
126.16
.03650
32.73
.02380
4.51
.00369
53.87
.01368
2165.98
.38220
8032.44
1.03100
.37310
983.66
0. 15
.00002
1105. 1
.23610
1052.93
.17190
.02350
44.84
2.32
.00120
61.54
.01990
424.70
13410
427.78
.08900
No Rain
8.27
.01000
.03467
93.81
4. 15
.00640
18.82
.02020
2
3
Time
PST
1543
1545
1550
1555
1600
1605
1610
1615
1620
1625
1630
1635
1640
1645
1650
1655
1700
1705
1710
1715
1720
.
604. 14
.
16985
Station 4
Serial
Number
Time
PST
12
13
1550
1600
1604
1605
1606
1610
1615
1616
1620
1625
1630
1635
1640
14-16
1645-1655
I
2
3
4
5
6
7
8
9
10
11
17
18
19
20
21
22
¿3
24
March 1963
Zm
Rcm
m3
39.94
.02190
2
1700
1701
1705
1710
1715
1720
1725
1731
85. 20
927. 02
1218. 56
2976.43
500.
649.
5654.
1080.
82
55
99
18
1771.04
415.56
44.49
14.72
.
.
.
03866
19410
24360
.46930
.
.
.
.
12974
16490
87240
37310
.37330
.
10178
.03250
.00890
No Rain
1975. 04
2276. 10
2720.86
1989.70
6406.73
1075. 64
41.70
25.69
.
.
15610
30474
.40144
.73240
.67025
.
19810
.01250
.00833
Table VC
Station
Serial
number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Table VIC
27
1
Time
PST
1230
1240
1317
1332
1340
1348
1355
1410
1420
1430
1440
1453
1502
1510
March 1963
mm6
3652. 090
638. 700
208.700
64.200
21. 768
28. 500
63.498
11. 050
303. 889
694. 420
842. 300
2281. 870
873.400
1174.52
R
.
hr
56250
22990
.09750
.04500
.01500
.02240
.03190
.00750
.
.
10760
18470
.02465
.
31290
.20780
.22100
Station
Serial
number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
4
27
Time
PST
1342
1353
1356
1359
1407
1410
1415
1417
1425
1433
1443
1445
1455
1501
March 1963
cm
Ri-
z _mm6
m3
524. 91
1023. 81
4566.46
.
.
.
1440
1325
6258
3147. 33
3385. 38
.4700
6134.91
.5183
1418. 77
2639.49
3338. 15
1965. 93
2245.78
1149.95
113.54
57.91
.
.
3867
3880
.4419
.
6380
.5350
.3730
.2090
.0589
.0444
-J
Station
Serial
number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Table VIIC
27
5
Time
PST
1350
1355
1400
1405
1410
1415
1420
1425
1430
1435
1440
1445
1450
1455
1500
March 1963
cm
R-
Zmm6
m3
184. 910
4153. 330
3389. 490
20292.800
2556.700
1982.780
4521. 170
3485.750
3181. 240
1195.610
893. 231
1511.650
795. 768
524. 600
207. 140
Station 1
Serial
number
13360
1
.03480
2
.
19960
3
.77645
.54250
.37105
.64429
.43740
.57900
.24800
4
.
.
17190
.18100
.
.
19840
13650
.07120
5
6
7
8
9
10
11
12
13
14
15
16
Table VIIIC
29 March 1963
Time
PST
1333
1340
1350
1400
1410
1420
1430
1440
1450
1500
1510
1520
1530
1540
1550
1600
mm 6
m3
475. 740
800. 707
263. 646
35. 618
7.024
129.
926.
2007.
916.
752.
554.
864
840
165
570
840
111
61.583
48. 598
455
.
2. 366
4. 038
cm
nr
.
.
.
12490
13550
10120
.01720
.02080
.
.
.
.
.
.
03635
11900
20500
22460
24270
31660
.03949
.03348
.
.
.
00036
00273
00280
OD
2 MARCH 1963
1-0-1
FIGURE
0db
STATION
o
1
M:
Precipitation and radar-echo characteristics
S-0_S -12db
6-0-6 -18db
G)
X
-
7-0-7
R
8-0-B
Z---
L14
10-
9.
8
7a
F_12
/
k10
b8
\
1
10-
2-0-2 - 3db
3-0-3 - 6db
4-0-4 - 9db
8
Rain Intensity, R x 10_1 Cm
mm6 hr
Reflectivity, Z x io3
\\\\
\\\
I
U
II
\\
/1111
II
\/
//TI
\\\\
I
\
Ill/I
I
',/'\
/,,A\
:
y//,7(
V,
/
I
I
1430
1440
'%.4li
1500
1520
Time-
16d0
___
i 20
140
-
100
4-t
2
MARCH 1963
FIGURE lA
STATION
1-0-1-
1640 R= .2340
2-e-2-
1650 R=
4-0-4-
i
cm
.3854hr
1710 R= .384
2
50
hr
Marshall-Palmer Distribution
for R = 3. 85
hr
10
m
3
o
io2
\
1
.3
.5
.7
.9
1.1
1.5
1.9
Diameter, mm
Rain drop-size dstribution
2.3
2.7
-
3.1
41
20
FIGURE2
STATION
2
18
1-0-1
2-0-2
3-0-3
= - 3db
= - 6db
4-0-4
=
9db
= -
-12db
5-O-5 = -18db
6-O-6 = Z ----7-O-7 = R
16
- io
io
9
.
-
8
.1,2
.
14
.
-I
.
E
e
12
:
:f
10
o
.
..0
be
X
-4
-4
-3
-3
?\
6
.
I
II
4
\
-2
I
\
I
.
I
.
2
\
'3
1520
1530
1540
1550
;.
1600
1610
-1
\
I
I
1620
1
30
1640
1650
iJoo
Time
Precipitation and radar-echo characterit1cs
iio
1720
'
1730
\6
\
-
\
5.
MARCH 1963
FIGURE 2A
STATION
\\
3
-
\\
2
'!
-
\\
1-o-1 1640 R=
.0085-
2-e-2 1650 R=
.6832i.
hr
3_e_3 1710 R=
.O27S..
1720 R=
\Tl
'\_o_s averageR=
-
.O151183ZE..
.
6-O-6 Marshall and Palmer distribution
mm
',
-
5
2
for R
6.83--
3
E
io2
\
4
.
.
.
.
:
2
\
lo
I
.1
i
I
.5
I
I
.9
I
I
1.3
I
I
i
1.7
Diameter, mm
Rain drop-size distribution
I
2.1
I
i
2.5
I
2.9
6
1
20
18
2
MARCH
1963
FIGURE
I
1-0-1 =
3
STATION
3
0db
2-0-2 =
-
3db
3-0-3 =
-
6db
4-0-4= - 9db
5-0-5= -12db
6-0-6= -18db
.
ii=
16
1.
2-3.
4-5.
14
---
:
9
9
8
8
-7
.
.
I
12-
10
-
:
:
10
.
I
-6
'
.
Io
I
d
'
I
_10-
I
'*
-o
<
.
.
-5
.
.-
.
.
i
.-
+
-05
.
f-
4-
m
.7
J
o
N.
O)
Q)
I
8
.1
Q)
X
I
6-
I
.
*
4
-
.
-3
I
I
4-
-2
II.
.7
2_
-1
c
I
II
.
\
:'
\.
./
.,.JD_c
:
;3
I
1550
1600
1620
1640
Time
Prec ipitation and radar-echo ch ir
-1
1
00
.
I
1720
cJ)
.
cter stic
2
MARCH 1963
FIGURE 3A
STATION
l-O-1 1600R=
.3822e-
2-0-2 1605
R
1.03 cm
3-e-3 1610
R =
.37
4-O-4
54
3
cm
-j-
Marshall and Palmer
R = 10.3 mm
stribution for
i06-
3
3
2
2'
sio4L.
3
i
cn
o
z
12 \4
3
Rain drop-size distribution
lu
.1
.5
.9
I
1.3
1.7
Diameter, mm
2.1
2.5
r
1-o1
2 MARCH 1963
2-0-2
3-0-3
FIGURE 4
STATION 4
-18
-
1.6
-
14
o
-
3db
6db
9-
4-O-4 - 9db
5-O-5 -12db
6-O-6 -18db
7-O-7 Z--8-O-8 R
8-
8-
7-
7a1
.
I.
.
.
12
4-
6-
6-
o-4
)
4
I
I
-10
-
-8
X
I
4.
.
I.
-6
'-4
N
-
I
r
G)
t
.
I
E-
5-
I
I
.
-
o
m
4-
.
i
'.
-
I
4
-ei
t.
8I
I
3-
3_
2-
2
1
1
4
4
\
-4
n
is
4,'
2
.3
i
4/'
4
.
4
4
4
5
\
8
-4.
i-
i540
1600
I
6
1620
_________:
.
I
8
:7
I
I
I
1640
1700
1720
1740
Time
Precipitation and radar-echo characteristics
(Ji
),o
5
\
/\/-\/-\
\
)
lo
5
l-o-1 1550 R=
i\ \
\
\\\
\
\\
2-8-2 1600
R=
3-e-3 1604
R=
.O2l9i.
.
L5
_\ \
\
.
O387i.
1947i!i.
hr
4-h-4 1605 R= .243621.
\
\
56
STATION 4
6()
I
FIGURE 4A
MARCH 1963
2
\\
hr
\\
5-e-5 16O6R=.4693-hr
,
6-0-6 1616 R= .8724wt
\\
\
\\\\
\
7-0-7 Marshall and Palmer distribution
\\
\
for R
\
= 8.
72-hr
io2
3
Rain drop-size distribution
lOi
I
.1
I
I
.5
I
t
.9
I
I
I
I
Diameter, mm
i
I
2.1
J
i
2.5
2.9
MARCH 1963
2
FIGURE
2
57
STATION 4
1-o-1 1710 R
cm
=
.7324j
.
2-B-2 1715 R= .67
-
'1,5
3-e-3 1720 R= .1981
-hr
-
4-s--4 1725 R= .0125
a
hr
5-s-S
i
lo-
R= .0083
1731
-,
.
_4
2
3
S
lo
c)
ri--
-
S
o
X
S
z
S
2
io2
S
-
le
3
S
[1
:i
5
j
.5
J
.9
i
I
1.3
1.
2.1
Diameter, mm
Rain drop-size distribution
2.5
2.9
27
20
18
16
MARCH 1963
FIGURE 5
STATION
-
1-0-1=
.-
i
lo
.
io
0db
2-0-2
-
3db
3-O-3 =
-.
9db
9
9
-
4-O-4= -12db
-
5-0-5=
6-0-6=
8
-18db
R
7-0-7= Z---
14
.
1,2
-
-
8
7
LO
.
1n
12:
-6
-
m-
r.-
-5
-3
8-
_5
-4
!;
.
6
.
.
.
-3
3
.
-5
4-
2.
3.
/
.
/
'
6
/
2-
.
7
_®--___
.
2
\
\
\
___,'
0
_---/1
-
i
I
13
'
1400
'
1420
1440
isoo
.
Time
Pre cipitation and
radar-echo characteristics
u-1
OD
20
27 MARCH 1963
1-0-1
FIGURE 6
=
Ocb
.
STATION
2-0-2
4
10
31-
-
io
3-0-3=-9db
.
.
:=_
4-0-4= -12db
18
-
.
S-0-5
=
6-O-6
.r
707=
.
-
-18db
R
Z---.
l6
-
14
1.
4-
-
.
.
-
(
.2
'T
10
Io
rn
-
6
.
N
.
!
i
;
6
2
<
.
.
2
7
EI
.
.
-
7C(
1
.
12-
8
-
5
i
5
.-
:
\1
2
:
-
1
4:7O
I
1340
1400
i
Time
I
1420
I
1440
Precipitation and radar-echo characteristics
1500
-1
>
:;io
61
i
3xlOt
27
MARCH
1963
flGURE 6A
STATION
4
1
b
1325-
1-0,-1
1353
R
2-9-2
1356
R= .6258v
3-e-3
1425 R =
=
4-A-4 1301 R
=
.
.
.
638
Cm
0444
2
5-0-5
i
Marshall and Palmer distributio
mm
for
R=6.3---
o
co
rJ
o
X
z
102
4
5I
3
ii
Rain drop-size distribution
I
5
.9
1.3
1.7
Diameter, mm
2.1
2.5
'
2.9
3.3
27 MARCH 1963
-20
FIGURE
7
1
.
/'s/NT\
2
t
y
-
.
I
c)
2
1
i
t
I
I
15
6
b
.2
S
-
N
i
:
:
-5
.;
-
-
4
-
I)
-
-3
I
I
t
-3
"d
I
.
!hE
\
.
,
.'
-
;t
"
C!)
r-'
I
.
I\
I
I
-8
.
I
r\
R
L--01
i
ej
-8
lo
Z----
/\
i
4/II
-
)
:
.
i::
-lo
6-O-67-O-7-
_____
,
16
C
-ho
2-O-23-O-3- 4-O-4- -12db
5-O-5--18db
t
'-
0db
3db
9db
-
,
.18
j
STATION 5
1
X
\\
\ \
2
7.
-
2
\
/
2
,
6
l5O
\
\._
-
.4,5
'
1460
'
l42O
Time
1I4O
Precipitation and radar-echo characteristics
i
.7
.6
i
-
-
ico
t")
29 MARCH 1963
FIGURE 8
STATION
-
i
i-o-1- 0db
2-0-2- - 3db
3-0-3- - 9db
4-0-4- -12db
5-0-5- -18db
6-0-6- R
7-0-7- Z----
16
-14
-
8
8
7
- 7
o
L
Pr
6
12
+.
EI
_°
rn
o
t
1
-
10
-5
,
X
N
-
.
.,
.
.
-4
.
8
-
b
.
.6
.
I
i
.
:4
,'í
:
:
-
Cd
-3
'
a.
-4
_4
2
.
6
2
:
i
i
®_
7
_-o__
:
I
i40
I
I
1400
1420
I
I
1440
Time
Precipitation and radar-echo characteristics
I
1500
I
::?-1520
6
i540
-
65'
5
29
MARCH
FIGURE 8A
1963
STATION
5
1
lo
l-o-1
1440
R=
2-0-2
1450
R= 2246?-
3-e-3
1500
R
.2427
R=
.3l66
4-A-4 1510
.2O5-
hr
Marshall and Palmer distributionfor Rr3.l7!
5-O-5
IL
3
106
5
4
10
sL
3t
\\
"v'VNt\J\/\/\
\
r;3
z
io2
4
,
5
1OL
I
.1
I
I
.5
9
1.3
1.7
2.1
Diameter, mm
Rain drop-size distribution
2.5
2.9
3.3
APR
2
2
March 1963.
1612 PST.
March 1963. 1612 PST;
63
+1° tilt;
APR
63
+
1°tilt; -3
PLATE I
O
db gain
db gain
setting
setting
67
APP
2
March
1963.
1612 PST.
63
+1° tilt;
APR
2
March
1963.
gain setting
-9 db
gain setting
63
1612 PST. +10
PLATE
-6 db
tilt;
II
pî
O
2
.8
e
Io
!TAT.
.0
J
lM7.TMCANO$OFFCtT
OCGON STAtE UNWIRSITY
ATIIPHEftjc
I%J
t
SCIPJCE EPANCH
M.CUU.00H PEAK CaEcal
A'SÇfl.tSflNØ.
MIR
I
ANTENNA
AZIMUTH
U*ASKDI.
,
.O
,.9
8c,y
________________________
HEI
T-TNØuCAJjQ8QFt(T
OREGON STAT L
t
I$N10tP41tt
ATMORPNSPJCSCILMC&PRANCN
.&CULLOCH PEAK OREGON
ORI
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I.
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8
3
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t
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__________________
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2
71
BIBLIOGRAPHY
1.
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analysis of rain storms. (All Weather Flying Division
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2.
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3.
Bergeron, T. On the physics of clouds and precipitation. In:
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4.
Blanchard, D. C. Rain drop size distribution in Hawaii rains.
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Boucher, R. J. Synoptic-dynamic implications of 1. 25 cm vertical beam radar echoes. In: Proceedings of the txth
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Bowen, E. G.
7.
Byers,
8.
Couch, Richard W.
9.
Dingle, A. N. and K. R. Hardy.
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Use of radar in determining the amount
, etal.
over
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Geophysical Union 29:187-96. 1948.
H. R.
Surface observations of the electrical
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11.
Findeisen, W. Die Kolloid-meteorologischen vorgauge bei
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12.
Houghton, H. G., A preliminary quantitative estimate of precipitation mechanisms. Journal of Meteorology 7:363.
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13.
illinois. State Water Survey. Study on intensity of surface
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Johnson, R. M., E. A. Mueller and G. E. Stout. Investigation
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15.
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Laws, J. O. Measurements of fall velocities of water drops
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Ludlam, F. H. Production of showers by coalescence of
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Marshall, J. S. and W. M. Palmer. The distribution of rain
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Mueller, E. A. and G. E. Stout. Drop-size distribution in
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