WMOD00300 ‎(2)‎

• Contract/Permit #: 2-07-81-V0256
• Title: Cloud Physics Studies in SCPP From 1977-87
• Date: 10/1/1987
• Weather Modification - Doc Type: Report

rlQ~~e 1 O~ log-?r~~abili~y ~a~e~.

Since both the ann~al water year

~re2i?i~3tio~ cn~ Jan + Fe~ + Mar precipita=ion cata fit a s=raight i1ne on

lGg-~r8Da~i:ity ?c?er, the precipi~atio~ is log-~ormal distributed. The 10

scpp =~elc seaS02 years are ~oted ~i~h +'5.
: ~~

Arr obvio~s coaclusion is that

~~e 10 SCPP field secso~s included soree of the wettest and driest years on

r~~r.r? Dl~s a reasohable saEple of the inter~eciate precipitation seasons.

I:: anyt!l:..~g, sepp sc.:Jpled the extrer.1e seaSOGS :no:re than the "normal"

seaso::s.

Five c~ the 10 water year seasons were i:: the tails (~10%

prcja~ility range) ~hile enly two water years were wit~in !25% probability

~-
'-'-

r:or:::a.l.

An in~eresti~g aspec~ of the water year pro~ability is that 82/83,

85/87 a~d 76/77 were each EI Nino years with 82/83 being in the wettest 5%

c: water vears and 86/87 and 76/77 being in the driest 10% of water years. (?

Tne SCPP was operated over the A~erican River Basin :rc~ Sacramento to

La~e Tahoe (Fig~re 2).

T~e University of ~yoDing's instr~~ented King Air

(~2~~~) aircraft was opera~ed from ~cClellar. AFB (near Sacra~ento). The

Ca~ifo~~~a valley is at a height of < C.l kT. and the )arrier rises at a

~ea~_, cc~sta2t 2.5% s:ope to ~2.5 km just west of Lake :a~oe.

The upwind

conto~rs are smooth compared to most mountain ranges ane eXLend N~V/SSE for

~co KIn.

The distance Irom the foothills to the Sierra crest is ~100 km.

~~e~ra t=rrier cah be viewed as a sinple 2-D inclir.ec plar.e.

~ost orographic stor~s over the Sierra barrier can be described in

:ou= co~biaations 0: stable and

te:::-ms of

unstable plus deep

-ha
'-1....-

~ -...
srre.l..iO~' .

ihe~efore, t~e :o~~ s~ages of Sierra storns ere ~. Geep, stable

~
L.

Gee?,

u~stab:e orcg=a?~lC. 3. shallow, stable o~ographic,

crcgrc?:1lC,

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