WMOD00303

• Title: Observational and Numerical Studies of Cloud and Precipitation Development with a View to Rainfall Enhancement
• Date: 4/1/1992
• Weather Modification - Doc Type: Report

v . iN = o.

(3)

.

r .

The microphysics in the model uses bulk parameterizations for both the water and the
ice phase. The water phase is parameterized according to a moclliied form of the Kessler
(1969) scheme. This parameterization is described in detail in Clark (1979). In this scheme,
condensed ~ater exists in two forms, as cloud- and rainwater, with mixing ratios qc and
ca. The ice phase parameterization closely lollows the work ol Koenig and Murray (1976),
herea.:Cter ret'erred to as K-M (The ice phase parameterization will be discussed in more
detail in the next section). The K-M parameterization allows lor two types of particles,
ice crystals initially lormed by heterogeneous ice nucleation or ice splinter processes due to
riming (type A) and ice particles (graupel) initially formed by freezing of raindrops (type
B). Consequently nve categories, denoted by subscript j, lor the water substance have to be
taken into account in the equations for the conservation of heat, water and ice substance.
The categories are:
1. Water vapor

f"

r "

;
,-

,"..

\. .:

2. Suspended drops
3. Rain drops
4. Type A ice

.

\
i ..

S. Type B ice

i
i
l,:

The equations governing heat and moisture conservation are

ro'
( .
f
i......

-DS- pLt. (0 ) pLt. (0 ) pLi. (0 0 0)
P-D =---= 2d1 + ---= 3dJ + -= ;d1 + ;dJ + ". ;-4 5
t OpT OpT OpT '
+ ~~f (Od. - C;dl);.4,5 + ~f (0;dl)1-4.5 + V. (pKHVS-)

(4)

p~~. = -P(Oid1);.2.4., + 1 (0;dJ);aa.4., - pC". + v. (pKHVq.) (5)

.

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