WMOD00584

• Title: Use of Nested Models to Simulate Regional Orographic Precipitation
• Date: 11/1/1992
• Weather Modification - Doc Type: Report

Oct. 82 . May 83 (gauges> 2700 m msl)

May 15 . Sept. 30. 1983 (gauges> 2700 m msl)

a

b

600

2100

, .
-
17'"

~"'-O,I.'x+~
R"2 . 0.990

E500
oS
ci
'g 400
Q:
~3OO
o
2-
~2oo
GO'
0>
a 100
Cl

fIx) ~ 0.987' x.. 19.1
R^2 ~ 0.992

E 1900
E
-: 1700

f1500
ll.
~13QO
o
~11oo
o
&900
::>
..
Cl 700

o
o 100 200 300 400. 500 600
MM4 Oaifv CumlJl:lfivA PrMnit:ttinn lmml

500
500 1000 1500 2000
MM4 Daily Cumulative Precipitation (mm)

c

January. December 1988 (<2100 m msl)

d January - December 1988 (>2700 m msl)
800 800

~
- ;
I..-"

1(.) . 0,288'. + 15,9
R"2 - 0,93

E'7oo
E
"':' 800
Q,
'0
.1:500

~4oo
o
~'3OO
..
o
&200
::>
..
Cl 100

i
l)--
./ f;1
/f _f"
~ ~
t:- '7

.q'I-O,61'.. 66,6
R"2 _ 0,95

E700
E
-: 600
a
'g
~5OO
ll.
~4OO
o
~3OO
o
&200
"
..
Cl 100

o
o 100 200 300 400 500 600 700 800
MM4 Daily Cumulative Precipitation (mm)

o
o 100 200 300 400 500 600 700 800
MM4 Daily Cumulative Precip<<ation (mm)

Figure 4. Scattergram comparisons of paired observed and MM4 predicted cumulative
daily precipitation in, the Gunnison Basin. Lines fitted to the data show a
correlation coefficient and slope for winter season precipitation in 1982-83 (a).
Summer precipitation was less linear in 1983 (b). Predictions in 1988 (c,d) were
more nonlinear with large overpredictions by MM4 for gauges located at elevations
below -2100 m (c) and above -2700 msl (d). Results indicate a seasonal and
regional predictive capability for cumulative precipitation that is useful for
climate studies"

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Figure 5. Vertical cross section (a) of ice particle concentrations (number per
liter) through the cloud, and corresponding horizontal pattern (b) of cloud water
mixing ratio (g kg-l) contours and ice crystal concentration > 2 1-1 (stippled) in
the surface layer. The cross section passes along line AB shown on Figure 5b.
Bold lines indicate elevation contours (kIn msl) Grand Mesa is marked by the bold
M. Note the cloud development along the major ridges an~ its propagation into the
wind shown by bold vectors.