Download Report No. R 91-2, Design of Physical Cloud Seeding Experiments for the Arizona Atmospheric PDF

TitleReport No. R 91-2, Design of Physical Cloud Seeding Experiments for the Arizona Atmospheric
LanguageEnglish
File Size6.4 MB
Total Pages105
Document Text Contents
Page 1

DESIGN OF PHYSICAL CLOUD SEEDING
EXPERIMENTS FOR THE ARIZONA ATMOSPHERIC

MODIFICATION RESEARCH PROGRAM

FINAL REPORT

PREPARED FOR

ARIZONA DEPARTMENT OF
WATER RESOURCES

UNDER IGA-89-6189-450-0125

FEBRUARY 1991

U.S. DEPARTMENT OF THE INTERIOR
Bureau of Reclamation

Denver Off ice
Research and Laboratory Services Division

Water Augmentation Group

Page 2

7-2090 (4-81)
Bureau of Reclamation TECHNICAL REPORT STANDARD T I T L E PAGE

DESIGN OF PHYSICAL CLOUD SEEDING
EXPERIMENTS FOR THE ARIZONA ATMOSPHERIC
MODIFICATION RESEARCH PROGRAM

Arlin B. Super, Jon G. Medina,
and Jack T. McPartland

9. P E R F O R M I N G O R G A N I Z A T I O N N A M E A N D ADDRESS

Bureau of Reclamation
Denver Office
Denver CO 80225

12. S P O N S O R I N G A G E N C Y N A M E A N D ADDRESS

Same

February 1991
6. P E R F O R M I N G O R G A N I Z A T I O N C O D E

8. P E R F O R M I N G O R G A N I Z A T I O N
R E P O R T NO.

10. WORK U N I T NO.

11. C O N T R A C T OR G R A N T NO.

13. T Y P E O F R E P O R T A N D P E R I O D
C O V E R E D

( 14. SPONSORING A G E N C Y C O D E

15. S U P P L E M E N T A R Y N O T E S

Microfiche and hard copy available at the Denver Office, Denver, Colorado.

16. A B S T R A C T

Cloud seeding experiments have been designed by the Bureau of Reclamation for winter orographic
cloud systems over the Mogollon Rim of Arizona. The experiments are intended to test whether key
physical processes proceed as hypothesized during both ground-based and aircraft seeding with
silver iodide. The experiments are also intended to document each significant link in the chain of
physical events following release of seeding material up to, and including, snowfall at the ground
at a small research area about 60 km south-southeast of Flagstaff. The physical experimentation
should lead to a substantially improved understanding of winter seeding potential in clouds over
Arizona's higher terrain. Such understanding and documentation are a logical prelude to any future
experimentation intended to determine seeding impacts over a large area during several winters.
Several analysis approaches are suggested to evaluate the physical experiments which range from
detailed case study examination to exploratory statistical analysis of experiments pooled into similar
classes. Experimental coordination and organization are addressed, and budgets are presented for
a 5-year program estimated to have a total cost of $9.5 million.

1 1 7 . K E Y WORDS A N D D O C U M E N T A N A L Y S I S

a . D E S C R I P T O R S - -
weather modification/ cloud seeding/ precipitation augmentation/ precipitation

enhancement/ artificial seeding/ cloud physics/ orographic clouds/ supercooled liquid water/ cloud liquid
water/ liquid water content/ ice crystals/ snow/ precipitation/ plume tracking/ transport and diffusion/ clouds

I I U N C L A S S I F I E D I

b. I D E N T I F I E R S - - Mogollon Rim/ Happy Jack/ Hannagan Meadow/ White Mountains/ Flagstaff/ Alpine/
Payson/ Conconino National Forest/ Prescott National Forest/ Camp Verde/ Winslow/ Arizona

c . C O S A T I F i e l d / G r o u p COWRR: SRIM:

18. D l S T R l B U T l O N S T A T E M E N T

A v a i l a b l e f rom t h e N a t i o n a l T e c h n i c a l In format ion Serv i ce . Opera t ions
D i v i s i o n . 5285 Por t R o y a l Rood. Spr ing f ie ld . V i r g i n i a 22161.

1 9 . S E C U R I T Y C L A S S
( T H I S R E P O R T )

U N C L A S S I F I E D
20. S E C U R I T Y C L A S S

( T H I S PAGE)

2 \ . NO. O F PAGE

90
2 2 . P R I C E

Page 52

Figure 1.2. - Proposed experimental area centered on
Allen Lake Tank and surroundtng reglon.

Page 53

2. DATA ANALYSIS PLAN

2.1 Introduction

Field studies and analyses of winter clouds over the Mogollon Rim during mid-January to mid-
March of 1987and 1988were performed to investigate opportunity and feasibility for precipitation
enhancement by cloud seeding. Results of those analyses are given in a report by Super et al.
(1989), hereafter referred to as SHM in this data analysisplan. Their efforts focused on the study
of (1) availability and distribution in spaceand time of SLW which are crucial for cloud treatment,
(2) occurrence and character of natural ice crystals, (3) T&D of a tracer to simulate seeding, and
(4) evolvement and character of weather and cloud conditions that produce precipitation and
potentially seedable circumstances.

In their report, SHM concluded that essential SLW existed in at least portions of most of the storms
studied. Analysis indicated relatively large amounts of SLW flux at ridge top that were not
consumed due to inefficient precipitation processes. Studies indicated rapid cloud transition
between apparently seedable and nonseedable status.

Transport and diffusion studies, with a tracer to simulate seeding from the ground (hereafter
referred to as ground seeding), indicated that ground-released AgI would generally disperse in the
lower 0.5 to 1.0 Ian above the Mogollon Rim when stratiform clouds prevailed. This layer is
frequently too warm in Arizona for the generation of significant numbers of ice crystals by
conventional ground-released AgI. Consequently, SHM recommended experimentation with newly
developed chemicals that laboratory studies indicate are more efficient at warm temperatures, near
- 6 0 C, that frequently occur in the moist lower layer. T&D studieswere recommendedin cases
of embedded convection which were not researched in the tracer experiments but are common in
Arizona winter clouds. The use of upwind high-elevation sites for ground seeding also needs to be
investigated. Despite improved ground seeding, SHM indicate that many Arizona storms will
require aircraft release of seeding materials (hereafter referred to as aircraft seeding) to achieve
proper targeting and so experiments need to be conducted to develop such treatment strategies.

It was recommended by SHM that a several-year physical experiment and analysis program be
conducted over the Mogollon Rim to establish the feasibility of obtaining additional precipitation
by cloud seeding and to determine and develop proper treatment strategies that could be
implemented in a future randomized seeding program. Experimentation and data analyses
suggestedby SHM would develop preliminary estimates of benefits and costs of cloud seeding. If
warranted, a subsequent randomized cloud seedingprogram could be conducted to demonstrate the
technology on sufficient casesto more precisely establish treatment effects over a larger area and
to determine confidence levels.

This report proposes in part 1 that the next Arizona field experiments concentrate on the study of
physical processesthat result from cloud treatment. Therefore, data analysesshould be tailored to
well describe the evolving processes. Since similar analyseshave been performed in experiments
conducted in California, Colorado, and Montana in recent years, considerable computer software
exists for performing the required analyses. When possible, this software should be used in future
Arizona experiments. Required data analysis software should be developed or existing software
modified to analyze results from physical studies conducted.

39

Page 104

NOAA
Environmental Research Labs
325 Broadway
Boulder CO 80303
(303) 497-3000

Particle Measuring Systems,
Inc. (PMS)

1855 South 57th Court
Boulder CO 80301
(303) 443-7100

Rosemount, Inc.
Box 959
14300 Judicial Road
Burnsville MN 55337
(612) 435-4300

Science Associates
PO Box 230
Princeton NJ 08542
(609) 924-4470

Science Engineering
Associates

PO Box 115
South Willington CT 06265
(203) 487-1869

University of North Dakota
Center for Aerospace Studies
PO Box 8216 University Station
Grand Forks ND 58201
(701) 777-2791

University of Wyoming
Dept. of Atmospheric Science
PO Box 3038 University Station
Laramie WY 82071
(307) 766-4947

Vaisala, Inc.
2 Tower Office Park
Woburn MA 01801
(617) 933-4500

WeatherMeasure
1165 National Drive
Sacramento CA 95834
(916) 928-1000

Weather Modification Inc.
PO Box 198
Bowman ND 58623
(701) 523-5606

*
u.s GPO 1991 573-185/20,018

Microwave radiometers

Aircraft optical array probes,
liquid water content meters,
and data acquisition systems

Aircraft temperature sensors, ice
detector systems.

General meteorological equipment

Aircraft data systems

Aircraft cloud physics services,
meteorological data analysis

Aircraft cloud physics services,
meteorological data analysis.

Upper air sounding systems, laser
ceilometers, temperature/humidity
sensors, general meteorological
equipment

General meteorological equipment

Aircraft data systems, aircraft
contract services

90

Page 105

Mission of the Bureau of Reclamation

The Bureau of Reclamation of the U.S. Department of the Interior
is responsible for the development and conservation of the
Nation's water resources in the Western United States.

The Bureau's original purpose "to provide for the reclamation of
arid and semiarid lands in the West" today covers a wide range of
interrelated functions. These include providing municipal and
industrial water supplies; hydroelectric power generation; irrigation
water for agriculture; water quality improvement; flood control; river
navigation; river regulation and control; fish and wildlife
enhancement; outdoor recreation; and research on water-related
design, construction, materials, atmospheric management, and
wind and solar power.

Bureau programs most frequently are the result of close
cooperation with the U.S. Congress, other Federal agencies,
States, local governments, academic institutions, water-user
organizations, and other concerned groups.

- -- -- -- -p --

A free pamphlet is available from the Bureau entitled
"Publications for Sale." It describes some of the technical
publications currently available, their cost, and how to order
them. The pamphlet can be obtained upon request from the
Bureau of Reclamation, Attn D-7923A, PO Box25007, Denver
Federal Center, Denver CO 80225-0007.

Similer Documents