Remote Monitoring of Processes 

That Shape Desert Surfaces: 

The Desert Winds Project 

By j. F. McCAUlEY, C. S. BREED, P. j. HElM, 

G. H. BilliNGSlEY, D. j. MacKINNON, M. j. GROliER, 

and C. K. McCAUlEY 

Acquisition and analysis of geometeorologic data 

from remote satellite-relay stations 

in different desert regions of Arizona 

U.S. GEOLOGICAL SURVEY BULLETIN 1634 
DEPARTMENT OF THE INTERIOR 

WilliAM P. ClARK, Secretary 

U.S. GEOlOGICAl SURVEY 

Dallas l. Peck, Director 

Library of Congress Catalog-Card No. 84-601115 

UNITED STATES GOVERNMENT PRINTING OFFICE : 1984 

For sale by the 

Distribution Branch, Text Products Section 

U.S. Geological Survey 

604 South Pickett St. 

Alexandria, VA 22304 
CONTENTS 

Abstract 1 

Introduction 1 

Previous work 3 

Indirect methods used to reconstruct ancient and present wind 

regimes 3 

Direct methods, using mechanical equipment 3 

Remote monitoring of desert surfaces, using satellite relay systems 6 

The Desert Winds Project 7 

Equipment now being utilized 7 

Special sensors and additional station-related experiments 9 

Site selection and associated geologic studies 9 

Vicksburg site 9 

Subsurface geology 12 

Surficial geology 12 

Surface geologic process 13 

Data analysis and display 13 

Gold Spring, Ariz., event 14 

Vicksburg, Ariz., event 14 

Sumnary 18 

References cited 18 

FIGURES 

1. Schematic diagrrun of the data-acquisition and -tranffinission links for U.S. C~ological Survey's Desert Winds Project 2 

2. Photograph of wind-fluted and corraded "Nubian" orthoquartzite fran top of 

the Gilf Kebir Plateau, southwestern Egypt 4 

3. Photograph of wind-etched and -fluted ventifact of white crystalline 

limestone (Thebes Limestone of Eocene age) fran the Limestone Plateau east 

of the Kharga Oasis, Egypt 5 

4. Sketch of flaw pattern of slightly negatively bouyant helium bubbles 

around fluted ventifact fran the Western Desert of southwestern Egypt 5 

5. Photograph of discarded block of granitic gneiss collected fran Chephren 

quarry in the desert west of Aswan, Egypt 6 

6. Photograph of geameteorologic (Geamet) station of the Desert Winds Project 

undergoing testing and calibration on grounds of U.S. Geological Survey 

Field Center, Flagstaff, Ariz. 7 

7. Photograph of inside of storage compartment for electronic components in 

Geamet station 8 

8. Map showing locations of Geamet stations presently deployed in the deserts 

of Arizona 10 

9. Photographs of Geamet stations on sites near Vicksburg and Gold Spring, 

Ariz. 11 

10. Chart showing operational history of Geomet station network from late 

1979 through late 1983 13 

11. Maps of surface and upper air conditions over the Western United States 

that gave rise to strong wind event of late March 1981 at Gold Spring, 

Ariz. 14 

12. Graphs of condensed display of meteorologic data fran Gold Spring Geamet 

station for March 26, 1981 15 

13. Graphs of condensed display of meteorologic data fran Vicksburg Geamet 

station for August 8, 1981 16 

14. Erosion-potential semilog chart showing daily precipitation and total 

daily theoretical capacity of winds to move sand in August 1981 at 

Vicksburg, Ariz., Geamet site 18 

III 
Any use of trade names and trademarks in this publication is 

for descriptive purposes only and does not constitute endorsement by 

the U.S. Geological Survey. 
Remote Monitoring of Processes That Shape Desert Surfaces: 

The Desert Winds Project 

By j. F. McCauley, C. S. Breed, P. j. Helm, G. H. Billingsley, D. j. MacKinnon, M. j. Grolier, 

and C. K. McCauley1 

Abstract 

Investigations of wind as a geologic agent have 

been hampered by a scarcity of long-term onsite 

measurements of wind velocity (including peak gusts, 

direction, and periodicity), precipitation frequency and 

intensity, relative humidity, and soil and air 

temperatures in key desert localities. This report 

describes a new long-term study, using data obtained 

by meteorologic and geologic sensors coupled to 

nonattended solar-powered data-collection platforms. 

Data obtained from these geometeorologic ("Geomet") 

stations in type desert areas of Arizona are 

automatically relayed by the Geostationary 

Operational Environmental Satellite (GOES) to the 

U.S. Geological Survey in Flagstaff, Ariz., in real 

time, and converted to graphic form. Preliminary 

computer analysis of the data indicates strikingly 

different meteorologic patterns that control, in great 

part, the local surficial geology of different desert 

areas. 

INTRODUCTION 

Studies of the conditions that affect the surficial 

geology of arid and hyperarid parts of the Earth, 

including parts of the Southwestern United States, 

have been hampered by an acute absence of data on 

such key parameters as windspeed and the fraction of 

time needed above the velocity threshold to erode 

local surface materials. The short-term time 

frequency of changes in wind direction near the 

surface, which also is poorly known, is a key factor in 

determining the shape and movement of dunes. Also 

generally unavailable are high-resolution data on the 

periodicity and intensity of precipitation, as well as on 

soil temperature, air temperature, and relative 

humidity. This absence of detailed geometeorologic 

information is largely due to the inhospitality of desert 

regions to human habitation, except where groundwater supplies, irrigation projects, oases, or such 

exotic rivers as the Nile are present. In deserts as a 

whole, a negative correlation exists between 

population concentration and areas of high wind, so 

1

MUseum of NOrthern Arizona, Flagstaff, AZ 86001. 

that even today most measurements of meteorologic 

data in the uninhabited parts of deserts are obtained 

only during field expeditions of relatively short 

times pan. 

Another problem is that the records at existing 

isolated stations in deserts commonly reflect the 

effects of nearby trees and buildings rather than 

ambient conditions of the surrounding barren areas. 

Most of these meteorologic stations are located at or 

near airports for the purpose of supporting local air 

traffic. Worse, the heights and locations of many of 

their instruments have been changed during the 

lifetime of the stations, so that long-term data 

analysis is difficult, at best. Thus, the role of wind as 

an agent of erosion, transportation, and deposition in 

arid regions remains one of the least studied aspects of 

geology. 

The primary source of most present and past 

meteorologic data in the United States is the U.S. 

National Oceanic and Atmospheric Administration 

(NOAA). One of its prime responsibilities is to provide 

data to the aviation industry and, to a lesser extent, to 

agricultural interests and the general public. 

Generalized temperature and precipitation 

measurements, as well as studies of storm movements 

and severe weather disturbances, such as tornadoes 

and hurricanes, are also important interests and 

responsibilities of NOAA. 

The limitations and absence of geologic 

credibility of the wind data acquired by the U.S. 

National Weather Service (NWS), a division of NOAA, 

were summarized by Lyles (1976). Measurements 

commonly are made at varying heights above the 

ground, generally at the local airport, and with a wide 

variety of equipment; thus, the wind data from most 

stations are not strictly comparable~ In addition, most 

measurements are made with mechanical equipment, 

and the strip-chart output is laborious to analyze and 

not readily amenable to computer processing. At most 

stations, windspeed measurements are averaged over 

1-minute intervals once each hour and recorded for 

submission to the U.S. National Climatic Center 

(NCC), Asheville, N.C., where they can be retrieved 

upon request. The NCC can provide yearly summaries 

of the general meteorology of both U.S. and foreign 

regions, daily averages for each month at each station, 

and climatic summaries over the lifetime of a given 

station; peak-gust data, however, are reported only as 

the daily extremes. 

Introduction 1 
As shown by Bagnold (1941), the carrying 

capacity of wind varies with the cube of the excess 

velocity of the speed required to set loose particles in 

motion (threshold velocity), and most of the work of 

wind is probably accomplished during brief high-energy 

episodes represented by the peak gusts. Attempts to 

utilize hourly 1-minute averages for studying wind as a 

geologic agent (for example, to predict wind power and 

possible rates of erosion and transportation of surface 

materials of various grain sizes and cohesiveness) are 

apt, therefore, to be misleading. In addition, the 

properties of the boundary layer (the zone of retarded 

airflow near the ground and below the free-air stream) 

depend strongly on the degree of surface roughness, 

which is a function of the surficial geology, 

topography, and the presence of vegetation of various 

types. Research on this critically important interface 

between the atmosphere and the ground surface has 

been almost entirely neglected except for the 

empirical work of Bagnold (1941) and the work of the 

U.S. Department of Agriculture that was spurred by 

the Dust Bowl catastrophe of the middle 1930's 

(Chepil, 1956). 

Fryberger and Dean (1979) devised a method for 

converting the windspeed and wind-direction data from 

World Meteorological Organization (WMO) stations in 

desert regions into "sand roses," which indicate 

potential rates of eolian sand transport. Sand roses 

based on WMO data provide useful syntheses of 

regional sand-moving wind patterns. They have been 

used to interpret dune forms, to show directions of 

Gold Spring station 

Geostationary Operational 

Environmental Satellite (GOES) 

STATES 

Figure 1. Schematic diagram of data-acquisition and 

-transmission links for U.S. Geological Survey's Desert 

Winds Project. GOES, Geostationary Operational 

sand movement, and to characterize present-day windenergy levels in the world's major deserts (Breed and 

others, 1979; Fryberger and Dean, 1979). However, 

the use of sand roses based on WMO wind data as 

predictors of the actual rates of eolian activity is 

severely limited by the absence of corollary data on 

such parameters as actual (as opposed to theoretical) 

surface roughness, and by the very coarse resolution of 

the wind data, as described above. 

The utility of more frequent and more 

systematic measurements than those currently 

available was shown in a study (McCauley and others, 

1981) of the 1977 duststorm in the High Plains of the 

southern United States. This study led to the U.S. 

Geological Survey's Desert Winds Project to measure 

key meteorologic parameters by means of remotesensing geometeorological ("Geomet") stations. These 

measurements, averaged over 6-minute intervals, are 

transmitted every half-hour to the appropriate 

Geostationary Operational Environmental Satellite 

(currently, GOES-6) and back to a receiving station in 

real time, using a combination of ground and space 

telemetry, landline transmission, and computer 

processing (fig. 1). The high-resolution, self-powered 

Geomet stations are not intended to compete with the 

various NOAA observation systems; instead, they 

provide a new data base to study the various 

meteorologic parameters, particularly those related to 

wind, that are geologically important in the shaping of 

various desert environments. 

Wind-direction sensor 

Air-temperature sensor 

Humidity sensor 

Geomet station (DCP) 

Environmental Satellite; SCU, signal-conditioning unit; 

CDCP, convertible data-collection platform. See 

figures 6 and 7 for details of Geomet station. 

2 Remote Monitoring of Processes That Shape Desert Surfaces: 'lbe Desert Winds Project 
Previous work 

Indirect methods used to reconstruct ancient and 

present wind regimes 

One of the first systematic attempts to 

reconstruct wind directions from the geologic record 

was by Reiche (1938) in the Coconino Sandstone 

(Permian) of northern Arizona; this and later work 

were summarized by McKee (1979a, b). In these 

reconstructions, directions of effective (sand-moving) 

winds in present and ancient sandy deserts were 

inferred from the directions of dip of slip-face 

deposits (foreset beds) in sand dunes; these beds form 

on the lee slopes of active dunes. Changes in wind 

direction and velocity were inferred from variations in 

grain size, composition, and sorting, and from 

crossbeds (sets of steeply dipping laminae truncated 

and overlain by other sets with a different dip). 

Techniques for measuring the dip angles and 

azimuths of bedding in dune sands require threedimensional cuts to reveal the true dips of the bedding 

planes. Dip azimuths are then determined in 

directions normal to leveling lines projected onto the 

bedding planes of those beds with the steepest dip 

angles. Azimuths and angles of dip of at least 30 

separate bedding sets should be taken in each active or 

ancient dune area to determine wind-transport 

directions (Reiche, 1938). Goldsmith (1973) noted that 

the modal patterns of azimuth distributions are 

significant, especially where distinct modes correspond 

to sand-carrying winds from different directions. 

The interpretation of wind regimes from dunebedding structures, though widely used in desert 

studies, has several limitations. First, only winds of 

sufficient strength to move sand are recorded by the 

dune beds. Second, winds leave a coherent record only 

during times when surface moisture, soil temperature, 

and vegetation density are such that winds can move 

dune sands in a sustained, orderly way. Third, the 

times of formation of dune structures cannot be 

established, and so the intervals between depositional 

and erosional episodes are unknown. Finally, except 

for one detailed study (McKee and Douglass, 1971) of 

the rates of growth and movement of gypsum sand 

dunes during several intense windstorms at White 

Sands, N. Mex., the method has not been empirically 

field tested over extensive periods under varying 

environmental conditions. 

Another method of reconstructing the groundair-interface situation from the geologic record 

involves analysis of the shapes of ventifacts collected 

from undisturbed wind-produced surfaces. Ventifacts 

are found on "pavements" in both desert and nondesert 

environments in a wide variety of shapes and sizes 

(figs. 2, 3) that commonly differ from the better 

known dreikanter (McCauley and others, 1979a). 

Directions and relative intensities of erosive winds can 

be ascertained from the patterns of flutes, pits, keels, 

and undercut surfaces on ventifacts, according to the 

methods of Whitney (1978), whose earlier work 

included exhaustive laboratory and field studies of the 

rates of wind erosion on rocks and minerals of varying 

hardness and shape. 

Wind-tunnel tests (McCauley and others, 1979b) 

have helped to confirm the reliability of Whitney's 

methods. Various field-oriented ventifacts were 

placed in a windblown stream of negatively buoyant 

helium bubbles, inside the wind tunnel at the Geology 

Department of the Arizona State University, Tempe. 

Preferred orientations were determined when the 

bubbles flowed over, around, and behind the specimens 

in a manner that conformed to the pattern of flutes 

and pits on each ventifact (fig. 4). These directions 

were interpreted to be those of the dominant erosive 

winds in the areas from which the ventifacts were 

collected; other orientations for the ventifacts 

generally gave no correlation between the airflow 

pattern and the shape or texture of the ventifact. 

Ventifact-analysis can yield even more useful 

wind information where the approximate time of 

exposure of the rock to shaping by the wind can be 

established. Examples include wind-eroded 

implements left by Acheulean and Mousterian 

occupants of the Western Desert of Egypt during late 

Pleistocene time (Haynes, 1980), the Libyan Desert 

glass described by Olsen (1979), and broken blocks of 

gneiss abandoned at the Chephren quarry of the Fourth 

Dynasty, dated at about 4,500 yr B.P. (fig. 5), that 

were observed during our 1979 expedition to the 

Egyptian Desert. Even when the age of exposure is 

unknown, analysis of wind-eroded bedrock-surface 

textures gives useful information about the long-term 

intensity and direction of erosive winds (McCauley and 

others, 1977). 

Direct methods, using mechanical equipment 

The elegant experimental and empirical work of 

Bagnold (1941), coupled with his extensive field 

observations, still provides the fundamental basis for 

much of our current understanding of the work of wind 

as a geologic agent. By asking such fundamental 

questions as why sand has the power of selfaccumulation and forms into dunes, whereas dust 

becomes dispersed, Bagnold was directed toward 

extensive wind-tunnel work in 1935-36 that led to an 

improved understanding of the eolian saltation 

process. He showed convincingly that saltation is 

essentially a surface process that occurs mostly within 

a meter or so of the ground and that, except in broken 

country, sand acts like a "moving carpet," in which the 

individual grains bounce over the ground. This 

bouncing motion kicks up more grains and helps to 

sustain the sandflow downwind from its starting 

point. The velocity below that necessary to initiate 

grain movement but sufficient to sustain sandflow for 

a particular grain size, once flow has begun, was 

defined by Bagnold as the impact threshold. He also 

pointed out the relation between surface roughness and 

the upward-velocity gradient in blowing wind above 

the surface in determining th; sand flow. He defined 

the fluid threshold velocity .Y.t' which is the windspeed 

necessary to initiate grain movement and saltation. 

Another important contribution was his discovery that 

the rate of mass sandflow varies as the cube of the 

excess velocity above the threshold velocity at which 

dry sand begins to move. 

During the 1970's, several attempts were made 

to quantitatively measure wind velocities and 

directions, precipitation, and other meteorologic data 

Introduction 3 
Figure 2. Wind-fluted and corraded "Nubian" 

orthoquartzite from top of the Gil£ Kebir Plateau, 

southwestern Egypt. Long projections point in 

direction of strong northerly winds (north arrow on 

that may relate to geologic studies of Mars. These 

efforts were based on machines that produce analog 

strip-chart output. Late in 1975, we became 

informally involved in one such study of climbing sand 

dunes in the western part of the Navajo Indian 

Reservation, in cooperation with Northern Arizona 

University, Flagstaff (Cotera and McCauley, 1977). 

Three portable mechanical weather stations of two 

types were eventually deployed by C. K. McCauley in 

various places at the base and top of the climbing-dune 

field at Paiute Trail Point, about 65 km northeast of 

Flagstaff (McCauley and Breed, 1980). 

The first machine installed was a five-parameter 

weather station that records wind velocity and 

direction, air temperature, relative humidity, and 

precipitation. These parameters are recorded 

continuously on the same chart at a speed of 1 em/h. 

The chart motor is powered by a 12-V lantern battery, 

and the timer uses three 1.5-V D batteries. Each 

parameter is recorded by a stylus that traces the 

measurements on pressure-sensitive paper. Although 

the machine is capable of recording for a total of 90 

days, the field records contained numerous gaps due to 

unpredictable jamming of the chart paper, a failure 

mode that could not be corrected. Much of this 

jamming occurred during periods of high windspeed, 

specimen). Precipitation is nearly nonexistent in this 

desert, which is one of the two most arid regions on 

the Earth. 

and thus valuable data on the potential carrying 

capacity of the wind have been lost. 

Later, two other similar machines were installed 

that record only wind direction and velocity at 2-

second intervals, and thus allow the recording of shortterm gusts. Two strip charts, one for velocity and the 

other for direction, are housed in the same case and 

run by separate motors powered by a 12-V car 

battery. At a chart speed of 2.5 cm/h, the machines 

are capable of recording for a total of 756 hours (31.5 

days). A pressure bar produces a trace of dots on the 

pressure-sensitive chart at 2-second intervals. Wind 

velocity ranging from 0 to 160 km/h is recorded at 

intervals of 3.2 km/h. (Input at our stations is 

currently in customary units but will be converted 

later to SI.) The windspeed and wind-direction sensor 

consists of a three-cup anemometer and vane that can 

be placed at variable heights above the surface. 

These instruments required periodic adjustment 

and repair owing to various component failures in the 

field. Recorder diodes as well as the brush assembly 

of the anemometer and vane sensors required 

occasional replacement. In addition, the anemometer 

cups broke away from the main assembly several 

times, and windblown sand occasionally impaired free 

movement of the sensors or jammed the recording 

4 Remote Monitoring of Processes 'lbat Shape Desert Surfaces: The Desert Winds Project 
Figure 3. Wind-etched and -fluted ventifact of white 

crystalline limestone (Thebes Limestone of Eocene 

age) from the Limestone Plateau east of the Kharga 

Oasis, Egypt. Windward projections are anchored by 

small siliceous fossils. Flutes on top surface are 

eroded by negative flow, which results from boundarylayer separation of airflow, as shown by experimental 

results (see fig. 4). 

c. c G 

Figure 4. Flow pattern (arrows) of slightly negatively 

buoyant helium bubbles around fluted ventifact from 

the Western Desert of southwestern Egypt. Specimen 

is oriented into simulated dominant wind of that 

region. Experiment was conducted in wind tunnel at 

stylus, although the machines were enclosed in 

louvered instrument shelters and protected by filters. 

Frequent failure of the car batteries used as power 

supplies led to their replacement by larger, longer 

lived bus batteries. In addition to these repair and 

maintenance problems, nonsynchronization of the 

speed and direction sensors made pairing of the data 

from these machines extremely tedious. 

These types of battery-powered strip-chart 

instruments provide a method of acquiring geologically 

useful meteorologic data in areas that are reasonably 

accessible. Because they are subject to various types 

of mechanical failure, however, they need to be 

serviced far more frequently than satellite-relay 

systems. The chief deficiency of these batterypowered instruments is that there is no way to 

determine when failure occurs. In many cases, failures 

in the Paiute Trail Point array happened a few days 

after laborious and expensive servicing, and caused 

long gaps in the records. In summary, drawbacks to 

this type of instrumentation for remote 

geometeorologic monitoring are: (1) the unreliability 

of many mechanical recording components in a desert 

environment, (2) the relatively low resolution of the 

tediously reduced strip-chart data, (3) the need for 

frequent calibration of the machines-a difficult 

procedure once they are emplaced in the field-and (4) 

necessary periodic visits to the machines for 

replacement of batteries and chart paper. 

Despite their drawbacks, these instruments do 

fill a need and have yielded much valuable information 

on the complexities of the local wind regime at Paiute 

Trail Point, particularly on the effects of local 

topography on the regional windflow pattern 

(McCauley and Breed, 1980). Machines of this type, 

however, are only marginally useful for long-term 

monitoring of conditions in desert regions because 

technical personnel, vehicles, and time are required to 

tend the machines properly. 

NEGATIVE 

FLOW . 0 

~c. 

GC.•o•'1 e,.. 

c 

Cl " 

. .. 

the Arizona State University, Tempe. Note reversal of 

direction of flow behind ventifact; erosion by this 

"negative flow" results in carving of pits and flutes on 

downwind side of specimen. 

Introduction 5 
0 lOcm 

................ 

Figure 5. Discarded block of granitic gneiss collected 

from Chephren quarry in the desert west of Aswan, 

Egypt. This block, which was probably slabsided when 

quarried (about 4,500 yr B.P.), now shows extensive 

wind grooving and raised ribs where resistant quartz 

veinlets crosscut the gneiss. 

Remote monitoring of desert surfaces, using satellite 

relay systems 

During the 1980's, satellite telemetry provided a 

major technological breakthrough in the remote 

monitoring of such meteorologic, hydrologic, and 

geophysical parameters as wind, temperature, 

barometric pressure, precipitation, snowpack depth, 

stream runoff, and seismicity. Remotely located selfpowered stations that can acquire, store, process, and 

replay at regular intervals both digital and analog data 

from a wide variety of field sensors are becoming 

commonplace in the geosciences. These small, 

portable stations are currently available from several 

manufacturers and can be tailored to the user's 

needs. Almost 1,600 such stations are currently in use 

in the United States, and about 250 are deployed 

overseas. The largest single user is the U.S. 

Geological Survey, which has pioneered in their 

deployment to replace previous labor-intensive 

methods of monitoring streamflow and other groundand surface-water-related parameters. The work 

began with a random-access system to the Landsat 

satellite and was followed by more sophisticated selftimed access systems to geostationary satellites. The 

U.S. Army Corps of Engineers also has a large array of 

similar stations for flood-control applications. 

The need for better monitoring of climatic 

conditions in the American West, with emphasis on the 

role of wind erosion, can be seen dramatically in the 

recent summary by Sheridan (1981). Accdrding to him, 

10 percent of U.S. land is undergoing severe 

desertification, and about twice that area is 

threatened in those parts of the country that receive 

less than 20 in. (50 em) of annual precipitation. The 

causes are complex, and the long-term effects 

difficult to predict, but there is no doubt that each 

year tens of thousands of acres of cropland and 

rangeland are being permanently damaged or totally 

abandoned and left to the ravages of the wind and the 

growth of undesirable "invader" weeds (Pimentel and 

others, 1976). Two recent events illustrate the 

extensive local and regional geologic effects of wind 

processes on surficial sediments exposed to adverse 

sets of meteorological conditions. 

A significant wind event that caused an 

enormous amount of erosion within a few hours 

occurred in the San Joaquin Valley, Calif., during 

December 1977. The intensity and severity of this 

storm and its geologic effects were reported by 

Wilshire and others (1981). Damage included fallen 

powerlines, blown-out windows and automobile 

windshields, toppled buildings, extensive sandblasting, 

defoliation of trees, scouring of bedrock, and 

deposition of sand in agricultural fields. Telephone 

poles were sandblasted to their very tops. Particles 

averaging 2.5 mm in triaxial dimension were imbedded 

in poles to heights of 240 em above the ground; at 

160 em above the ground the average size of embedded 

particles was 3.2 mm, and at 80-cm height the average 

size was 4.9 em. Gravel ripples formed in a matter of 

hours on formerly smooth surfaces. Windspeeds 

recorded during this event at two weather stations 

exceeded 150 km/h; anemometers at two other 

stations failed at similar windspeeds (Wilshire and 

others, 1981). 

Another. devastating event took place during the 

first winter storm to reach the southern High Plains in 

the Llano Estacado (Staked Plain) region of western 

New Mexico and eastern Texas in February 1977. 

During winter 1976-77, an unusually strong highpressure ridge formed at the surface and also aloft 

along the west coast of the United States. This 

persistent ridge pushed the ordinary Pacific storm 

tracks northward and caused severe winter conditions 

in the Northeastern States. The high-pressure ridge 

brought extended drought to the Western States and 

severely depleted both surface- and ground-water 

supplies. These conditions set up the southwestern 

High Plains for one of the greatest duststorms since 

the Dust Bowl days of the 1930's; it was, to our 

knowledge, the first duststorm of this magnitude to be 

monitored by a geostationary satellite. On 

February 21, the high-pressure ridge weakened and 

allowed the penetration of an initially mild storm that 

rapidly intensified as it moved eastward, and caused 

northwesterly winds. Two large dust plumes were then 

observed by the GOES-l-one in eastern Coloradowestern Kansas and another near the Texas-New 

Mexico State line-at 1700 G.m.t. on February 23. The 

dust pall from the southern plume spread across the 

entire State of Texas in about 6 hours; one of its point 

sources was in the Clovis-Portales area of eastern New 

6 Remote Monitoring of Processes That Shape Desert Surfaces: The Desert Winds Project 
Mexico. By 2030 G.m.t. on February 24, the pall had 

been decoupled f~om its source area; it covered at 

least 1 million km and totally obscured, to a height of 

about 3,000 m, most of the South-Central United 

States. By 1600 G.m.t. on February 26, a discrete but 

more diffuse dust pall was still visible as far eastward 

as the mid-Atlantic Ocean. 

The Clovis-Portales area has had a history of 

aridity and associated high winds from Tertiary time 

to the present; it has been identified by many authors 

as the center of the Dust Bowl of the 1930's. We were 

able to study the ravages of this storm about a week 

after the event by means of aerial and ground 

reconnaissance. Erosion of many plowed fields to 

depths of a meter created myriad small yardangs and 

blowouts; fine sand was deposited downwind in long 

lobate sheets that ranged from less than 1 em to 1 m 

in thickness. A conservative estimate of the total 

amount of material that was transported in suspension 

across the Southeastern United States and outward to 

the Atlantic Ocean is about 1 million t (Windom and 

Chamberlain, 1978). The erosion and deposition 

observed in the Clovis-Portales area probably occurred 

within about 6 hours. The weather station at Cannon 

Air Force Base, which is within the area affected, 

provided detailed meteorologic data (measured at 

hourly intervals) that greatly expedited our 

investigation. The above summary is from a more 

detailed report on this storm (McCauley and others, 

1981). This work kindled our interest and showed the 

need for the experimental array of Geomet stations 

that is now being deployed. 

Acknowledgments.-The Desert Winds Project is 

supported by the Geologic Framework Program of the 

U.S. Geological Survey; in its initial phases, this 

project was also supported by the Survey's Energy 

Lands and Climate Program. Some of the work in 

northern Arizona was funded by grants from the NASA 

Planetary Program in support of projects in eolian 

studies by the Survey and the Museum of Northern 

Arizona, Flagstaff. We thank Richard Paulson, 

William G. Shope, Jr., and Michael Field, all of the 

U.S. Geological Survey, for their advice in establishing 

our network of satellite-relay Geomet stations. We 

also are grateful to Richard MacCallum and Michael 

Nestlebush of the National Environmental Satellite 

Data Information Service (NESDIS, formerly NESS), 

and to Dale Gillette of NOAA, for many helpful 

discussions. 

THE DESERT WINDS PROJECT 

Equipment now being utilized 

Our remote-monitoring satellite telemetry 

system consists of four major elements: (1) Sensors 

that measure and detect changes in a given parameter, 

(2) encoders that convert the output of the sensors to 

suitable forms for telemetry, (3) a transmission system 

that provides the link to the GOES, and (4) a datareception and -distribution facility that sorts, decodes, 

checks, and distributes the data to our laboratory in 

Flagstaff, Ariz. (fig. 1). 

Each Geomet station consists of a convertible 

data-collection platform (CDCP) and various sensors, 

all mounted on a three-legged frame (figs. 6, 7). The 

CDCP is a self-timed system that performs multiple 

duties: It collects data from the sensors', encodes and 

converts data into calibrated values, stores data for 

transmission, and transmits the data to the GOES. At 

present, each station has identical sensors that 

measure windspeed, peak gusts, wind direction, air 

temperature, soil temperature, humidity, barometric 

pressure, and precipitation. 

The windspeed sensor, mounted on a crossarm at 

the top of a 6.1-m-high mast, is an analog sensor that 

consists of a three-cup anemometer with a permanent 

magnet, which operates a sealed magnetic reed 

switch. Rotation of the cups closes the reed switch 

Figure 6. Geometeorologic (Geomet) station of the 

Desert Winds Project undergoing testing and 

calibration on grounds of U.S. Geological Survey Field 

Center, Flagstaff, Ariz. Station is 6 m high. A, 

anemometer; B, transmitting antenna; C, solar panels; 

D, precipitation gauge; E, radiation shield containing 

air and relative-humidity sensors; F, storage 

compartment for electronic components (see fig. 7). 

Soil-temperature sensor is buried in ground nearby. 

The Desert Winds Project 7 
TOP I 

Figure 7. Inside view of storage compartment for 

electronic components (F, fig. 6) in Geomet station. 

A, signal-conditioning unit (SCU); B, convertible datacollection platform (CDCP), with clock timer and 

memory for data storage. Barometric-pressure sensor 

is also housed in this box. 

and provides a frequency of switch closures that is 

proportional to the windspeed. The data are recorded 

and converted to an average windspeed calculated over 

an update interval of 6 minutes; they are then stored 

for pretimed transmission once every hour. The peak 

gust within each 6-minute interval is recorded and 

transmitted at the same hourly intervals. 

The wind-direction sensor, also on top of the 

mast, is an analog sensor consisting of an airfoil metal 

vane. The vane is coupled to a wire-wound 

potentiometer whose output voltage varies 

proportionally with the wind direction. The sensor is 

powered continuously, and an average wind direction is 

calculated over the 6-minute update interval. 

The air-temperature sensor is an analog sensor 

consisting of a solid-state linear three-element 

thermistor. The output of the sensor is a resistance 

proportional to the ambient temperature. The sensor 

is protected by a solar-radiation shield and is mounted 

1.5 m above the ground. 

The analog soil-temperature sensor is similar to 

the air-temperature sensor. The thermistor, contained 

in a metal dowel, is buried to a depth of 127 mm. 

The analog relative-humidity sensor is a polymer 

thin-film capacitor. The capacitor is composed of an 

upper and lower electrode with an organic polymer 

dielectric about 1 m thick. Water vapor is absorbed 

into the polymer, and the capacitance changes linearly 

as the moisture increases or decreases. The sensor is 

contained in the radiation shield along with the airtemperature sensor. 

The analog barometric-pressure sensor consists 

of an evacuated bellows that is sensitive to changes in 

absolute pressure. The measured resistance is 

proportional to the barometric pressure. 

The digital precipitation sensor consists of a 

funnel, 20 em in diameter, that collects water and 

delivers it to a twin tipping-bucket mechanism. Each 

time 0.2 mm of precipitation has been collected, the 

bucket tips and causes a mercury switch to close 

momentarily. The sensor is powered continuously to 

generate a count of switch closures during the update 

interval. 

Each sensor interfaces with the microprocessor 

of the CDCP by means of an input/output signalconditioning unit (SCU). Inside the SCU are signalconditioning cards that correspond to each sensor. The 

output from all the analog sensors is encoded to a 0- to 

5-V scale, and these analog voltages are sent to the 

microprocessor with the digital count from the 

precipitation sensor. The microprocessor, in turn, 

sends a signal through the SCU to the sensors every 6 

minutes to power those sensors not continuously 

powered and to record the information collected by 

each sensor. The power supply for the station includes 

a 12-V battery and two solar panels that recharge the 

battery continuously during sunlight hours. Various 

types of batteries have been used; no one type is 

presently preferred. 

Both the SCU and the microprocessor of the 

CDCP, which controls the activity of the entire 

platform, are housed in a metal box (fig. 7). A clock 

timer and the memory for data storage are also part of 

the CDCP. When the output from the sensors arrives 

(every 6 minutes) from the SCU, the microprocessor 

converts each reading into a "hexadecimal" number 

that is then stored in the memory. Each station has 

been assigned by the U.S. National Environmental 

Satellite Data Information Service (NESDIS) a 1-

minute window for transmission of data, and the clock 

timer in the CDCP is programmed to control 

transmission at the preassigned time. The ten 

6-minute updates are transmitted in "hexadecimal" 

format every hour. 

The GOES-6 that we are currently using is in 

circular orbit 36,000 km directly above the Equator, 

and so the speed of the spacecraft on its orbital path 

matches that of the Earth's rotation. This satellite is 

at long 135° W. and is available for stations in the 

Western United States. The small antennas on our 

stations are alined to transmit to this satellite, which 

receives the data on a preassigned channel and 

retransmits it to a central receiving station at Wallops 

Island, Va. From there, the data are sent by landline 

to Suitland, Md., sorted into user files, and retrieved 

by users with high-speed dedicated or low-speed dialup 

lines (fig, 1). The dialup low-speed (300 baud) teletype 

terminal also allows for instant access to the coded 

data for transmission or checking of time-slot errors. 

Software has been developed for extracting data 

from the user queue and for analyzing the data by way 

of a dialup line from the VAX-750 computer in 

Flagstaff, Ariz., to the NESDIS computer. The data 

are stored on disk in the computer for 1 month and 

then are written onto a tape that is stored in the U.S. 

Geological Survey tape library in Flagstaff, Ariz., and 

is available for future use. 

8 Remote Monitoring of Processes That Shape Desert Surfaces: The Desert Winds Project 
Special sensors and additional station-t"elated 

experiments 

The amount of dust passing through or 

originating from the area under surveillance is 

particularly significant. Because airborne dust 

particles smaller than 25 m in diameter move at the 

same speed and in the same direction as the wind, 

measurement of dust concentration and windspeed at a 

single point will provide a measure of the local dust 

flux (the rate at which dust is passing through a unit 

area perpendicular to the wind direction at the point 

of measurement). These measurements, however, do 

not indicate whether the material being measured is 

being eroded from local sources, is passing through, or 

is being deposited. A commercially available dustparticle counter, which actually counts the number of 

dust particles larger than a certain diameter that pass 

through a calibrated light beam, has been automated 

to make measurements that are transmitted 

simultaneously with other data from the Geomet 

stations. One of these experimental dust-flux sensors 

was deployed in early 1984. For reasons related to 

data capacity, only two size ranges were chosen for 

measurement: diameters of at least 0.5 m, and 

diameters of at least 5.0 m. If this device works 

successfully in the field, we will fit all our stations 

with similar devices. This application will be a 

pioneering effort in the adaptation of these units to 

remote low-powered stations. 

Sand-cloud properties are not so easily 

determined, primarily because the individual grains do 

not travel at the same speed and in the same direction 

as the wind. Moreover, even a sand cloud having 

grains of uniform size consists, at any one point, of 

grains moving with widely varying speeds both 

vertically and horizontally. Sand-flux measurements 

require knowledge of both the speed and mass (or size) 

of the sand grain. (The product of these two 

parameters is the particle momentum.) At present, 

there does not appear to be a simple, cost-effective 

method to measure, uniquely and independently, both 

parameters, either individually or collectively, in 

naturally occurring sand clouds. Dale Gillette of 

NOAA is attempting experiments with piezoelectric 

crystals configured to determine sand-flux 

properties. The crystals respond, upon particle 

impact, with an electrical pulse that is proportional to 

the sand particle's momentum. It remains to be seen 

whether differences can be distinguished between a 

slow-moving large particle and a fast-moving small 

particle, and whether coincident collisions 

significantly alter the momentum information that is 

contained in the crystals' electrical output. 

The sand-flux sensor that we have recently 

deployed (along with the dust-flux sensor) at one of our 

stations is a modification of the type designed by 

Fryberger and others (1979). We have modified the 

sensor, for this project, by replacing the eight 

directionally divided storage bins with a tipping-bucket 

device similar to the precipitation sensor already in 

use. The amount of sand collected per unit time can 

then be directly related to specific meteorologic 

conditions. The directions from which the sand is 

collected, and the windspeeds, can be inferred from 

the wind-direction and -speed sensors on the Geomet 

stations. 

Other experiments involve data that are not 

digitized and relayed to the GOES; these data must be 

manually retrieved at irregular intervals. An example 

is the panoramic photographic coverage of different 

types of surfaces around each station. These 

photographs provide visual evidence of changes in 

surface geologic and topographic features and 

vegetation over time. In addition, at various heights 

on the frames of two of our stations, we have attached 

arrays of "virgin" quartz grains of various sizes 

mounted on aluminum plates. These grains, made from 

Brazilian quartz crystals, have been episodically 

removed and replaced for study of abrasion and 

possible solution effects, by use of the scanning 

electron microscope. Preliminary results (Krinsley and 

others, 1981) indicate substantial abrasion of the 

grains mounted at our Vicksburg, Ariz., station, 

probably as a result of the severe windstorms that 

struck the area in July and August 1981 (see discussion 

below). 

SITE SELECTION AND ASSOCIATED GEOLOGIC 

STUDIES 

The five Geomet stations ultimately planned for 

our array will be deployed to identify the greatest 

possible variance among the different types of deserts 

that exist in Arizona (fig. 8). Four stations are already 

operational: in the extremely arid lower Sonoran 

desert near Yuma (on a U.S. Marine Corps base), in the 

higher Sonoran desert at Vicksburg (fig. 9A), in the 

Great Basin Desert on the Navajo Indian Reservation 

at Gold Spring (fig. 9b), and in the easternmost Mojave 

Desert at Red Lake. A projected fifth site is in the 

Wilcox playa area of southeastern Arizona close to the 

northwest edge of the Chihuahuan Desert, which lies 

mostly in Mexico. Each of these deserts is known to 

have seasonally distinctive wind and rainfall patterns 

as well as distinctive geology, flora, and fauna. For 

example, the Mojave Desert is characterized by 

widespread winter rains, and the Sonoran Desert by 

sporadic, unevenly distributed summer cloudbursts. 

Within each of these areas, considerable time 

and care were expended to find a site that was 

representative of each desert type as a whole, where 

maximum security from possible vandalism could be 

obtained. To put the sites into context, detailed 

geologic field studies in the immediate vicinity of each 

machine, and a general synopsis of the regional 

geology, have been done or are planned. 

The preliminary geologic study of the Vicksburg 

site (fig. 9A) that follows exemplifies the type of 

geologic background needed to gain maximum benefit 

from the the quantitative meteorologic information 

generated by each machine. 

Vicksburg site 

A site southwest of Vicksburg on the Ranegras 

Plain, about 100 mi west of Phoenix, was chosen for 

studying the effects of wind and water erosion in the 

Gila Desert (figs. 8, 9 A). The Ranegras Plain is a 

Site Selection and Associated Geologic Studies 9 
110° 

• .·· : san 

p ... ··· Fro 

l..q1'£'.q ) Vo l can ic Fiel 

{) Humphreys 

0 40 

~ 

·;:) 

~a. (0 

.. ":~) 

~­( 

\ 

0 25 50mi . \ I --~ ( · .. 

~~<orv ~ \ : 

Figure 8. Locations of Geomet stations presently 

deployed in the deserts of Arizona. A, Gold Spring; B, 

Vicksburg; C, Yuma; D, Red Lake; E, station yet to be 

deployed at Wilcox Playa. These sites represent all 

five of the major desert environments in Arizona. 

Darkest areas receive the least precipitation, and 

white areas the most, as shown by precipitation 

isohyets (in millimeters per year). Annual sand roses 

(Fryberger and Dean, 1979) show directions of 

otv~ ·.. Nogales ' 1 

R,q -~2{----~-----_j 

potential sand-moving winds; length of sand-rose arms 

is proportional to frequency of occurrence of winds 

faster than about 25 km/h from each compass 

direction. Arrows show calculated resultant direction 

of potential sand drift. Sand roses are based on 

analysis of monthly summaries of wind measurements 

from U.S. National Weather Service weather stations 

at Yuma and Winslow, Ariz. Modified from Breed and 

others (1984). 

10 Remote Monitoring of Processes 'That Shape Desert Surfaces: The Desert Winds Project 
Figure 9. Geomet stations on sites near Vicksburg (A) 

and Gold Spring @), Ariz. Sites differ in geographic 

setting (intermontane basin in fig. 9!:.J high plateau in 

fig. 9_m, vegetation, surface geology, and types of 

A 

B 

storms (see figs. lZ, 13). Arrows denote location rods 

for photographic monitoring of surficial changes at 

sites. 

Site Selection and Associated Geologic Studies 11 
broad desert valley that surrounds Bouse Wash in 

northeastern Yuma County; it has a hot and arid 

climate and very little vegetation. The Geomet 

station is near a small dune field in the NE1/4SW1/4 

sec. 9, T. 4 N., R. 15 W. Topographic relief within a 

half-mile of the station is less than 3 m. 

Subsurface geology 

Although the subsurface geology of the Vicksburg 

site is little known, the known subsurface geology to 

the west and north near Bouse and Parker (Metzger 

and others, 1973) may extend throughout the 

subsurface of the Ranegras Plain. The deepest known 

sediment near Bouse and Parker is a pebble 

fanglomerate, possibly 300 to 400 m thick, whose 

composition resembles that of present-day alluvial 

fans. Beds in this basal fanglomerate generally dip 

from the mountains toward the basin and vary widely 

in thickness. The fanglomerate may be Pliocene in 

part; the overlying Bouse Formation has not been 

dated precisely. A possible maximum age, middle 

Miocene(?), can be inferred by correlating the 

fanglomerate with a similar unit west of Needles, 

Calif., that contains a fossil-vertebrate fauna. 

A sharp unconformity between the fanglomerate 

and the overlying Bouse Formation represents a change 

in environment from land-laid deposits to those 

deposited in an extension of the Gulf of California. 

The Bouse Formation is a marine to brackish-water 

sequence composed of a basal limestone overlain by 

interbedded clay, silt, and sand. Several marine fossils 

were found in the Bouse Formation but are not 

diagnostic for age dating. The age of the Bouse can be 

established broadly as Pliocene on the basis of ages 

obtained from a thin overlying tuff (Metzger and 

others, 1973). The Bouse Formation is exposed about 

20 km northwest of the Vicksburg site, near Bouse, 

Ariz., where it exceeds 60 m in thickness; it probably 

also underlies the Ranegras Plain in the Vicksburg 

area. 

Metzger and others (1973, p. G16) reported that 

"* * * some of the well -cuttings in the Bouse 

contain small pebbles, for the most part enclosed by 

clay. Because the pebbles are 'floating' in the clay, it 

is inferred that they were probably dropped into the 

body of water from rafts of vegetation." This relation 

may be explained in another way by analogy to recent 

deposits near Vicksburg, where pebbles and gravel are 

presently accumulating in the clay playas. The pebbles 

are washed in by occasional flash floods of low 

velocity and high density. As the silt-laden 

floodwaters evaporate on the playas, the scattered 

pebbles and granular material are encased in clay. 

The Bouse Formation is easily eroded by stream 

action, and part of the Bouse was removed before 

deposition of about 40 to 300 m of recent alluvium. 

Several episodes of fluvial degradation and aggradation 

have occurred since deposition of the Bouse. 

Surficial geology 

Present-day drainage in Bouse Wash is 

ephemeral. The entire flood plain is inundated by 

slow-moving floods in wet intervals, which occur only 

a few times over a period of several years. The 

Ranegras Plain slopes less than 1° NW. and is cut by 

braided and manmade channels that are generally less 

than 1 m deep. The sediment in the channels consists 

largely of coarse sand. Clay or silt veneered with 

purple pea-size gravel and pebbles covers 90 percent 

of the plain. A few sparse low (0.3-3 m high) perennial 

creosote bushes and some larger (1.5-2 m high) 

mesquite and creosote trees and bushes are scattered 

along erosional channels. 

The Ranegras Plain may have had no external 

drainage during much of Pleistocene and Holocene 

time because drainage was cut off by aggressive 

alluvial-fan encroachment from the mountains on both 

sides of the valley. Playas were probably intermittent 

and small throughout the valley. The playa deposits 

consist of clay and sand, interbedded with alluvial-fan 

and stream deposits along the valley margins. In 

periods of dryer than normal conditions, windblown 

clay, silt, sand, and gravel gradually accumulated on 

the east edges of the playas. 

The small dune field near the Geomet site is not 

easily recognizable. The dunes are partly vegetated 

and form a series of parallel linear ridges trending 

north-south. The ridges have gentle slopes on their 

east and west sides. Dune elevations change gently in 

the direction of ridge elongation; the greatest relief is 

near the dune centers and decreases toward their 

extremities. No internal bedding structures were 

visible in the dunes where small trenches were dug, 

although horizontal and very low angle bedding does 

occur in the uppermost few inches of the dunes at 

some localities. In several places, runoff from the 

surrounding alluvial fans appears to have cut through 

-the larger sections of the dunes. Apparently the 

ephemeral-drainage gullies predate the dunes, which 

have established themselves across them and 

effectively blocked the smaller streamcourses, though 

not the persistent and larger ones. This interpretation 

implies that the dunes postdate the alluvial-fan 

drainage systems and, possibly, the Bouse Wash playas 

as well. The dunes have been extensively disturbed by 

various burrowing animals, notably the coyotes, 

rabbits, and mice who make their homes in the dune 

field. 

The dune-sand deposits are very poorly sorted; 

grain size ranges from granules (3.33 mm) to clay 

particles (<0.0020 mm). Skewness records excessive 

fines, and kurtosis is platykurtic. The average median 

grain size (based on four sieved samples) is 0.28 mm 

(1.87~), a tlledium sand. The corresponding threshold 

velocity Yt at the 6.1-m elevation of the wind sensor 

(calculated from the equations of Bagnold, 1941) is 8.5 

m/s. Grains of nearly all sizes are angular to 

subangular; several crystalline grains are composed of 

quartz, feldspar, and biotite. Dark minerals average 

16 percent of the dune grains, and light minerals 84 

percent. These characteristics imply a short time and 

distance of transport from the sources of these 

materials. The composition of the dune sediment 

indicates that the main source is the Little Harquahala 

and Granite Wash Mountains, about 10 km to the east; 

a minor source is the Plomosa and New Water 

Mountains, about 10 to. 20 km to the west. 

12 Remote Monitoring of Processes 'lbat Shape Desert Surfaces: The Desert Winds Project 
Surface geologic processes 

Ephemeral drainage on the present-day alluvial 

fan intersects the dune ridges perpendicularly from the 

east. Runoff along the gullies forms small playas 

before it is diverted around and between the dunes. 

Moderate to large amounts of eolian sand are observed 

in transport, as well as much eolian dust derived from 

the nearby barren alluvial plain of Bouse Wash. It is 

uncertain at this time whether the local dune field was 

formed by prevailing southwesterly and westerly winds 

or by opposing strong winds from the northwest and 

southeast; data from the Geomet station should help 

answer this question. The intermittent deposition of 

sand along the shores of the playas by water waves 

also may be an important factor in the formation of 

these dunes. 

Deposition of all the surficial units at the 

Vicksburg site reflects an interplay of wind with 

running and standing water. Surrounding the dunes and 

bordering the local playas is a mantle of alluvial 

deposits veneered by gravel. A desert pavement 

armors undisturbed surfaces of the alluvial deposits 

against deflation. Mud cracks and mud curls are 

common on the playa areas, which are a major source 

of windblown dust particles. Sand sheets and small 

sandpiles accumulate at the edges of the playas near 

the terminal ends of many alluvial-fan drainage 

gullies; eolian reworking of these deposits, in turn, 

begins to form small elongate dunes. A local 

environment of rapidly fluctuating water and wind 

currents, from almost slack to violently energetic 

activity, is reflected in the poor sorting of the dune 

material. 

D 

LJ 

!II 

EXPLANATION 

Unexplained outage 

Outage due to machine 

maintenance or failure 

Outage due to Computer 

operations 

~ Outage due to NESS 

8 Machine fully operational 

For each desert area, we intend to use our 

meteorologic data, in combination with the type of 

background geologic information outlhled in the 

preceding section, to determine the efficiency of wind 

as a geologic agent and to assess the importance of 

other parameters in the overall erosional and 

depositional regime. The Vicksburg area is one of 

many source areas that give rise to intense duststorms 

that severely curtail visibility and hamper road traffic 

in the Phoenix area. Therefore, our long-term detailed 

studies ultimately should have practical value in 

determining the approximate frequency of occurrence 

of such events and the particular combination of 

geologic and meteorologic conditions that favor their 

occurrence. 

DATA ANALYSIS AND DISPLAY 

Methods are under study for systematic display 

and analysis of the data received from the four 

Geomet stations presently operational. We now have 

more than 3 years' data from our Gold Spring station. 

The stations near Vicksburg, near Yuma, and at Red 

Lake have been plagued with intermittent major and 

minor problems, the most serious of which has been 

drifting of the transmission frequency used to 

communicate with the GOES. Figure 10 summarizes 

the operational history of the stations and indicates 

the types of problems that cause gaps in the data. We 

believe that most of the technical problems have now 

been corrected and that ensuing records will be more 

continuous. Two examples of the records from recent 

separate wind events at Gold Spring and at Vicksburg 

are described below. 

All outages are rounded to the 

nearest day. Single lines represent 

one to four days of outages. 

GOLD SPRING 

Figure 10. Operational history of Geomet station network from late 1979 through late 1983. 

Data Analysis and Display 13 
Gold Spring, Ariz., event 

On March 25, 1981, an intense surface and upperlevel low-pressure center developed and dropped 

southward toward the Intermountain States (fig. 11). 

Data from the Gold Spring station (fig. 9b) showed 

moderate winds from the south-southwest. By the 

morning of March 26, the surface and upper-level lows 

were in an ideal position to cause strong winds in 

northern Arizona. Although the surface winds that 

morning were relatively light at Gold Spring, the winds 

aloft were extremely strong. In northern Arizona, few 

clouds were associated with this storm, and solar 

heating of the surface allowed turbulent interchange 

between the surface and upper air layers. The result 

was an explosive increase in winds after 1000 local 

standard time (l.s.t.). By the evening of March 26, the 

winds returned to moderate speeds and remained so 

throughout the next day. This type of event can cause 

severe sandstorms and duststorms if the ground 

surface is dry and a sufficient amount of loose clay- to 

sand-size material is available. 

Figure 12 plots the measurements obtained at 

Gold Spring on March 26. Wind intensity shows a 

symmetrical pattern, with a broad peak lasting from 

1100 to 1800 l.s.t. and a wide spread between peak 

gusts and the average wind velocity. During the period 

of highest peak winds, the wind direction was steady 

from about azimuth 260° (west-southwest). The peak 

of the windstorm coincided with a low in the relativehumidity curve, which also coincided with diurnal 

heating or the influx of dryer air. The period when the 

air and soil temperatures were equal, between about 

1330 and 1530 l.s.t., approximates the midpoint of the 

wind event; when the soil temperature exceeded the 

air temperature, the wind intensity was either 

increasing or decreasing. The calculated threshold 

velocity at Gold Spring, where the average grain size 

of the surface sand sheet is 0.135 mm (2.90), a fine 

sand, is about 13 mph (5.8 m/s, at the 6.1-m elevation 

of the windspeed sensor) according to Bagnold's (1941) 

equations; therefore, winds during this event were 

competent to move these surface sands under ideal 

conditions. We do not know, however, what sizes or 

amounts of sand actually moved, in the absence of fiux 

sensors at the time of the event. 

VickSburg, Ariz., event 

Several diverse but locally intense windstorms 

struck in the vicinity of our Vicksburg station in July 

1981. Figure 13 plots the data from one of these 

events. G. H. Billingsley visited the area on August 6, 

shortly after the storms had passed through, and 

provided the following report. 

My first stop was the house of Tom Lowe 

custodian of the Vicksburg station , where I took 

pictures of the wind damage that occurred during 

a storm on July 10, 1981. Only the four outside 

walls of the wooden-frame house were still 

standing; the roof, porch, windows, and doors 

were missing. Trees nearby were broken and 

shredded; some outbuildings were leaning over 

and badly damaged but not yet flattened. Parts 

1024 

HEIGHT OF 500 MILLIBAR 

PRESSURE SURFACE, 

IN FEET 

SURF ACE AIR PRESSURE, 

/,. --l?fJoo IN MILLIBARS 

WEDI'ESDAY. MARO-t 25, 1981 

~ 

--~-

----------19100 

lHURSDAY, MARO-t 26. 1981 

FRIDAY, MARO-t 27, 1981 

Figure 11. Surface and upper-air conditions over the 

Western United States that gave rise to strong wind 

event of late March 1981 at Gold Spring, Ariz. C, cold 

front; S, stationary front; O, occluded front. 

14 Remote Monitoring of Processes 'lbat Shape Desert Surfaces: 'lbe Desert Winds Project 
24.3 --- -- -r--- ----r ------J- ------<--- -----------.-------T--- ---+-------r------1--- ----:------- 1 I I I I I I I I I I 

I I I : I I : : : : 

: : I I I I 1 

_I_----- f-- ---- ~-- ----+-----~- ---- -~ -----+-----~----- --:-- ----- ,_ __ --TI----, : : : : I 

I 1 I I 

I I : : I : --1------+-- ____ T _____ --~-- ---- ~------ r------ 1 I I I 1 

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90 

80 ~ 

E-t 

QE-t 

70 -z 

~r:-.::1 

::>U 

::C:P=i r:-.::1 

r:-.::IP.. 

e:z 

E-tic:( 

~ 

r:-.::1 

p:j 

80 

70 

50 

30 

20 

0 

10 

0~--~~----~--~~----~--~~----~----~----~----._----~----._--~ 00 02 04 06 08 10 12 14 16 18 20 22 24 

LOCAL TIME, IN HOURS 

Figure 12. Condensed display of meteorologic data 

from Gold Spring Geomet station for March 26, 1981. 

During a period of 16 hours, windspeeds averaged over 

6-minu te intervals and peak gusts greatly exceeded 

fluid threshold v*locity y; (Bagnold, 1941) for eolian 

sand transport; .Y.t for average-size surface sand in this 

area is approximately 5.8 m/s (heavy dashed line). 

Data Analysis and Display 15 
~-

~ 2.4 :::::> 

til 

til 

~ til 2.2 ~ ~ 

ll..::t 

{){) 

..... z 2.0 

~-E-< z ~ 

~ 1.8 

0 

~ 

II( 

I:Q 1.6 

350 

300 

90 

80 

70 

50 

30 

------,------ ,------- -~-- ----, ---- --~----- -~- ---- -~----- -,----- -,--------.----

: : : : : : : : : I I : : : I : : : : : ------~--- --- -~- -----;-------+-------t ------+------1------t----- -~--- ---i : : I : I : PRECIPITATION : 

: : : : : : : I I : I ------!---- ---------1--------- ----+-------.- -----r------~- ------1------T ----- -r-- ----- 1 I 1 : I I 1 1 I I I 

: ! : I : : I i : : I 1 I I I 1 I I 

------+------1---- - ------l------:-------: I I I I 

LOCAL TIME, IN HOURS 

----T-----

1 

I 

I 

I 

I 

I 

-I 

: --r------

---r----- 1 

I 

I 

I 

--,------ 1 

I 

I 

I 

--~------

1 

I 

I 

I -~-------

1 

I 

I 

2.4 

2.2 

z 

Otll 

E-<::c -~ 

2.0 II({) 

~z ll.. ..... 

oz 

1.8 ~-

~ 

ll.. 

1.6 

Figure 13. Condensed display of meteorologic data 

from Vicksburg Geomet station for August 8, 1981. 

This storm differed from Gold Spring event illustrated 

by figures 10 and 11 in its relative brevity and 

intensity and in its evening rather t\an midday 

occurrence. Fluid-threshold velocity .Y.t; (Bagnold, 

1941) for eolian transport of average-size dune sand at 

this locality is approximately 8.5 m/s (heavy dashed 

line). Note increase in precipitation shortly after 

onset of extremely high winds after 1900 l.s. t.; this 

pattern is typical of desert "haboobs" (Idso, 1976). 

16 Remote Monitoring of Processes That Shape Desert Surfaces: The Desert Winds Project 
of the roof were scattered over a distance of 

about 0.4 km to the east of the house and came 

very close to our Geomet station. According to 

Mrs. Grace Lowe, who provided the eyewitness 

report given below, a tornado hit the house, but 

there was so much dust and confusion that it is 

uncertain whether a funnel cloud was actually 

present. 

The station was essentially undamaged, but 

the legs of the frame were noticeably 

sandblasted to a height of about a meter on their 

west-facing sides. New granule ripples with a 

spacing of about 10 em were observed on the 

formerly nat pea gravel near the station. In 

addition, the scattered ground shrubs in the area 

were stripped clean of their leaves. Although 

the data from this event were recorded and 

transmitted by the station, they were lost 

somehow in the downlink transmission from 

GOES to the NESS receiving facility. 

Two days after Billingsley's visit, another storm 

hit the area and overturned one of the two house 

trailers being used by the Lowe family as temporary 

shelter. The data from this event (fig. 13) were 

received by telemetry and showed peak gusts of almost 

144 km/h accompanied by extreme variation in wind 

direction and, during an interval of little more than an 

hour, 1.5 em of precipitation. Another storm hit 

between 2300 l.s.t. August 10 and 0200 l.s.t. August 

11, this one from the east. Our records show peak 

gusts of about 80 km/h, with winds of more than 48 

km/h over at least a 3-hour period. No further damage 

was reported by the Lowes, possibly because 

everything in the vicinity was so badly damaged 

already. 

The following eyewitness account by Mrs. Lowe 

of some of the events that affected the Vicksburg area 

was provided in a letter dated August 17, 1981, to G. 

H. Billingsley. 

First I'll explain about the storm which hit 

us on July lOth at about 4:20p.m. It came out of 

the west, and when the wind got wild it came in 

all directions. The kids and I were in the house 

when the roof came off. We heard the wind 

come up, then the windows broke out on the west 

side of the house, then the doors started 

slamming, then opened and slammed shut again. 

It was raining very hard when the roof came 

off. We ran outside to the pick-up and sat there 

for about 2-1/2 hrs. until the rain stopped. At 

one time it stopped raining like someone turned 

off a faucet for about 5 to 10 minutes, when it 

started again the wind seemed stronger, and it 

rocked the truck from side to side * * *. 

Well, we were just getting settled in the 

trailer when on August 8th about 7:00 p.m. we 

were hit with another storm, which came out of 

the northeast and did the same as the last one. 

It lasted about 2 hrs. and, would you believe it, 

flipped the trailer on its side. We are finally 

getting settled again. On the lOth of Aug. we 

had another windstorm, not much rain but a lot 

of wind which came out of the east. 

Surprisingly, no damage this tim e. 

This series of storms that struck the Vicksburg 

area provides a very different meteorologic picture 

from that of the storms which affected the Gold 

Spring area, as typified by the event on March 26, 

1981. The Gold Spring storm (fig. 11) was marked by a 

gradual increase in wind intensity (with peak gusts 

exceeding 96 km/h toward mi~day and a gradual 

decrease to velocities below .Yt_ (fluid threshold) at 

night. During the height of this storm, the wind 

direction was relatively constant from the westsouthwest, parallel to the axial trend of the linear 

dunes that characterize the Gold Spring area; there 

was no measurable precipitation. 

The Vicksburg storms, however, were more short 

lived, more intense, less rhythmic diurnally, and varied 

more widely in wind direction (fig. 13). The Vicksburg 

data are consistent with those expected from the 

passage of "haboobs," described in Arizona and 

elsewhere by Idso (1976). This type of storm is 

commonly caused by downdrafts of cool air from a 

single large cumulonimbus cloud. The density current 

generated by the relatively small scale disturbances 

creates a highly turbulent, churning near-ground flow 

pattern that commonly causes small whirlwinds which 

can damage buildings. Loose dust is picked up into a 

towering mass of cool air, within which visibility is 

generally a few hundred meters or less. Passage of the 

cool turbulent downdraft is commonly followed by a 

period of short but intense precipitation (fig. 13). 

Local storms of this type are reported about a dozen 

times per year in the vicinity of Phoenix. 

To begin to assess the geologic responses of 

various desert surfaces to complex meteorologic 

processes, a theoretical measure of the potential sandmoving capacity of the wind has been developed (D. J. 

MacKinnon and others, t.mpub. data, 1984). Figure 14 

shows some preliminary results of this work. The 

upper bar graph represents the daily total potential 

mass of sand that the measured wind might be capable 

of transporting across a 1-cm-wide line perpendicular 

to the wind's direction, under ideal conditions (absence 

of soil moisture and vegetation). The total potential 

sand-moving capacity of the wind for each day is 

derived from the empirical Lettau and Lettau sandnux equation (Fryberger and Dean, 1979, p. 145), into 

which has been mathematically folded the measured 

wind data; these data have been Gaussianly distributed 

about the average, with a variance proportional to the 

peak-gust speed for each measurement, and 

accumulated for each day. This modified sand-flux 

equation incorporates the sand-grain-size-distribution 

information for each Geomet site. Figure 14 also 

shows the daily total precipitation (in millimeters) on 

the lower bar graph. Precipitation data are included 

to provide quick recognition of the presence of soil 

moisture, which affects the cohesion of sand particles; 

soil moisture is a major factor that affects the 

movement of sand by wind (Chepil, 1956). Soil 

moisture remains difficult to measure directly and is 

not included among the parameters presently measured 

by Geomet stations. 

The primary use of an erosion-potential chart is 

to screen large amounts of data so that events of 

potential sand-moving significance can be identified 

for detailed graphic treatment and analysis (figs. 12, 

13). The long-term purpose of more complete models 

Data Analysis and Display 17 
>< 

E-< 

u 

-< 

p.. 

-< 

u 

10,000~ 

1000~ 

~ 100~ 

~ 

10.,... 

100~ 

101-

I I 

-

I I I 

I -

I I I I I I I I I I I I I I 

5 10 15 20 I I I I I 

25 30 

DAYS OF MONTH (AUGUST, 1981) 

Figure 14. Erosion-potential semilog chart showing 

daily precipitation (in millimeters) and total daily 

theoretical capacity of winds to move sand (in grams 

per centimeter) in August 1981 at Vicksburg, Ariz., 

Geomet site. Compare graphs of wind capacity and 

precipitation for August 8 with those of meteorologic 

data (fig. 13) that show occurrence of precipitation in 

relation to highest windspeeds and peak gusts. 

will be to compare the potential wind capacity 

predicted by a theory, such as is illustrated by figure 

14, with the actual movement of sand and dust 

detected by the flux sensors. Differences between the 

theoretical and actual capacity of the measured winds 

at each site may then be attributed to such variables 

as moisture and vegetation. 

SUMMARY 

Although short-term measurements have been 

made and much local lore and speculation exist about 

wind processes in deserts, the need for long-term 

quantitative studies in these regions has been 

neglected. The less arid regions are far better 

understood in terms of the geologic processes that 

shape their surfaces. Throughout geologic time but 

more demonstrably in the recent past, deserts have 

cyclically expanded and contracted. Their present-day 

expansion, due to natural causes abetted by human 

misuse of marginal areas (desertification), threatens 

the productivity of the American West (Sheridan, 

1981). 

Our Geomet monitoring system should help 

provide detailed quantitative data on wind behavior in 

relation to other parameters in various desert 

environments. The automatic solar-powered highresolution stations can be emplaced in truly remote 

desert areas of special interest. Once operational, 

these low-maintenance stations are not constrained by 

periodic service requirements and laborious analog 

data-reduction procedures. 

Our immediate objective is a long-term study of 

the geologic role of wind, relative to other geologic 

agents, in the five distinctive desert regions of 

Arizona, using our data-collection platforms coupled 

with an array of off-the-shelf meteorologic devices. 

This relatively low-cost, non-labor-intensive array 

could be expanded later, as necessary, to address 

desertification problems in the American West as a 

whole. 

Four of our Geomet stations in Arizona are now 

operational: at Gold Spring on the Navajo 

Reservation; near Vicksburg, on the Ranegras Plain 

west of Phoenix; near Yuma; and at Red Lake. Each 

station was located after extensive site studies; 

detailed mapping of the surficial geology around each 

site has been completed or is in progress. 

Photographic stations have been established on various 

surficial units around each station to provide longterm repetitive coverage of physical changes and their 

relation to the Geomet data. 

Although the U.s. Geological Survey's computer 

facilities in Flagstaff, Ariz., record the complete time 

histories of the meteorology at each station, our 

emphasis, to date, has been on severe windstorms. We 

have discussed here the results of two diverse types of 

windstorms, each in a different desert environment. 

We are currently planning to fit all our stations with 

sand- and dust-flux sensors to help assess the geologic 

effects of each event. Measured amounts of sand and 

dust flux produced under monitored meteorologic and 

geologic conditions will then be used to test the 

equations of wind transport based on theoretical 

considerations. 

Analyses of quantitative meteorologic data, 

acquired over several years, will be combined with 

detailed geologic field studies and repetitive 

photographic coverage at each Geomet site to provide 

a basis for comparing wind effectiveness in deserts of 

differing geologic and climatic types. These 

quantitative data, unlike those obtained by existing 

weather stations, should be of sufficient resolution and 

timespan to contribute to a better understanding of 

desert processes in general and of the role of wind in 

particular. Varying patterns of wind activity and 

surface response are already evident from the data 

recorded from the various subtypes of the Arizona 

desert being monitored. These differences indicate 

the complexity of desert environments in general and 

the difficulty of applying any single theoretical or 

experimental model to the formation of desert 

landforms. 

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Bagnold, R. A., 1941, The physics of blown sand and 

desert dunes: London, Chapman and Hall, 265 p. 

Breed, C. S., Fryberger, S. C., Andrews, Sarah, 

McCauley, C. K., Lennartz, Frances, Gebel, 

Dana, Horstman, Kevin, 1979, Regional studies 

of sand seas using Landsat (ERTS) imagery, in 

McKee, E. D., ed., A study of global sand seas: 

U.S. Geological Survey Professional Paper 1052, 

P• 305-397. 

Breed, C. S., McCauley, J. F., Breed, W. J ., Billingsley, 

G. H., and McCauley, C. K., 1983, Eolian 

landscapes, in Smiley, T. L., and others, eds., 

Landscapes of Arizona-the geologic story: New 

York, Academic Press [in press]. 

18 Remote Monitoring of Processes That Shape Desert Surfaces: The Desert Winds Project 
Chepil, W. S., 1956, Influence of moisture on 

erodibility of soil by wind: Soil Science Society 

Proceedings; v. 20, no. 2, p. 288-292. 

Cotera, A. S., and McCauley, C. K., 1977, 

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sources for wind deposits abs. , in Eolian 

processes, chap. 7 of Arvidson, R~ E., and 

W ahmann, compilers, Reports of Planetary 

Geology Program, 1976-1977: U.S. National 

Aeronautics and Space Administration Technical 

Memorandum TM X-3511, p. 153-154. 

Fryberger, S. G., Ahlbrandt, T. S., and Andrews, Sarah, 

1979, Origin, sedimentary features, and 

significance of low-angle eolian "sand sheet" 

deposits, Great Sand Dunes National Monument 

and vicinity, Colorado: Journal of Sedimentary 

Petrology, v. 49, no. 3, p. 733-749. 

Fryberger, S. G., and Dean, Gary, 1979, Dune forms 

and wind regime, in McKee, E. D., ed., A study 

of global sand seas: U.S. Geological Survey 

Professional Paper 1052, p. 137-169. 

Goldsmith, Victor, 1973, Internal geometry and origin 

of vegetated coastal sand dunes: Journal of 

Sedimentary Petrology, v. 43, no. 4, p. 1128-

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Haynes, C. V., Jr., 1980, Quaternary geology and 

archaeological observations, in El-Baz, Farouk, 

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H., El-Etr, H. A., Embabi, N. S., Grolier, M. J., 

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1978: Geographical Journal, v. 146, no. 1, p. 59-

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Idso, S. B •• 1976, Dust storms: Scientific American, v. 

235, no. 4, p. 108-114. 

Krinsley, D. H., Marshall, John, McCauley, J. F., 

Breed, C. S., and Grolier, M. J ., 1981, Production 

of fine silt and clay during natural eolian 

abrasion abs. , in Aeolian processes and 

landforms, chap. 5 .2! Holt, H. E., compiler, 

Reports of Planetary Geology Program-1981: 

U.S. National Aeronautics and Space 

Administration Technical Memorandum 84211, p. 

251-254. 

Lyles, Leon, 1976, Wind patterns and soil erosion on 

the Great Plains, in Tinus, R. W ., ed., 

Shelterbelts on the Great Plains: Great Plains 

Agricultural Council Publication 78, p. 22-30. 

McCauley, C. K., and Breed, W. J., 1980, 

Topographically controlled dune systems on 

Earth and Mars abs. , in Aeolian processes and 

landforms, chap. 6 of Wirth, P., Greeley, Ronald, 

and D'Alli, R. E., compilers, Reports of 

Planetary Geology Program, 1979-1980: U.S. 

National Aeronautics and Space Administration 

Technical Memorandum 81776, p. 255-256. 

McCauley, J. F., Breed, C. S., El-Baz, Farouk, 

Whitney, M. I., Grolier, M. J., and Ward, A. W., 

1979a, Pitted and fluted rocks in the Western 

Desert of Egypt-Viking comparisons: Journal of 

Geophysical Research, v. 84, no. B14, p. 8222-

8232. 

McCauley, J. F., Breed, C. S., Grolier, M. J., and 

MacKinnon, D. A., 1981, The U.S. dust storm of 

February 197 7, in Pewe, T. L., ed., Desert dust: 

Origin, characteristics, and effect on Man: 

Geological Society of America Special Paper 

186, p. 123-147. 

McCauley, J. F., Breed, C. S., Grolier, M. J., Whitney, 

M. I., Ward, A. W., and Greeley, Ronald, 1979b, 

Wind tunnel simulation studies of airflow 

patterns around pitted and fluted ventifacts from 

the Western Desert of Egypt abs. , in Eolian 

processes, chap. 6 E.!, Boyce, J. M., and Collins, 

P. S., compilers, Reports of Planetary Geology 

Program, 1978-1979: U.S. National Aeronautics 

and Space Administration Technical 

Memorandum 80339, p. 288-289. 

McCauley, J. F., Grolier, M. J., and Breed, C. S., 1977, 

Yardangs, in Doehring, D. 0., ed., 

Geomorphology in arid regions: Annual 

Geomorphology Symposium, 8th, Binghamton, 

N.Y., 1977, Proceedings, p. 233-269. 

McKee, E. D., 1979a, Ancient sandstones considered to 

be eolian, in McKee, E. D., ed., A study of global 

sand seas: U.S. Geological Survey Professional 

Paper 1052, p. 187-238. 

1979b, Sedimentary structures in dunes, in 

McKee, E. D., ed., A study of global sand seas: 

U.S. Geological Survey Professional Paper 1052, 

p. 83-134. 

McKee, E. D., and Douglass, J. R., 1971, Growth and 

movement of dunes at White Sands National 

Monument, New Mexico, in Geological Survey 

research, 1971: U.S. Geological Survey 

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Metzger, D. G., Loeltz, 0. J., and Irelna, Burdge, 1973, 

Geohydrology of the Parker-Blythe-Cibola area, 

Arizona and California: U.S. Geological Survey 

Professional Paper 486-G, p. G1-Gl30. 

Olson, J. W., 1979, Desert glass: Aramco Magazine, v. 

30, no. 5, p. 2-5. 

Pimentel, David, Terhune, E. C., Dyson-Hudson, Rada, 

Rochereau, Stephen, Samis, Robert, Smith, E. A., 

Denman, Daniel, Reifschneider, David, and 

Shepard, Michael, 1976, Land degradation: 

effects on food and energy resources: Science, 

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Reiche, Parry, 1938, An analysis of cross-laminationthe Coconino Sandstone: Journal of Geology, v. 

46, no. 7, p. 905-932. 

Sheridan, David, 1981, Desertification of the United 

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Office, 142 p. 

Whitney, M. I., 1978, The role of vorticity in 

developing lineation by wind erosion: Geological 

Society of America Bulletin, v. 89, no. 1, p. 1-18. 

Wilshire, H. G., Nakata, J. K., and Hallett, Bernard, 

1981, Field observations of the December 1977 

windstorm, San Joaquin Valley, California, in 

Pewe, T. L., ed., Desert dust: Origin, 

characteristics, and effect on Man: Geological 

Society of America Special Paper 186, p. 233-

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References Cited 19 
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