U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2014–1247

Meteorological Data for Selected Sites along the 

Colorado River Corridor, Arizona, 2011–13
Cover: Southern view from a monitoring station in Furnace Flats, Grand Canyon National Park, Arizona. 

Photograph by Joshua Caster, U.S. Geological Survey Grand Canyon Monitoring and Research Center.
Meteorological Data for Selected Sites along the Colorado 

River Corridor, Arizona, 2011–13 

By Joshua Caster, Timothy Dealy, Timothy Andrews, Helen Fairley, Amy Draut, and Joel Sankey 

Open-File Report 2014-1247

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2014 

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Suggested citation:

Caster, J., Dealy, T., Andrews, T, Fairley, H., Draut, A., and Sankey, J., 2014, Meteorological data for selected

sites along the Colorado River Corridor, Arizona, 2011–13: U.S. Geological Survey Open-File Report 2014-1247, 

56 p., http://dx.doi.org/10.3133/ofr20141247.

ISSN 2331-1258 (online)

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report.
iii

Contents

Abstract ...................................................................................................................................................................... 1

Introduction and Purpose............................................................................................................................................ 1

Monitoring Locations and Period of Observation ........................................................................................................ 4

Materials and Methods ............................................................................................................................................... 6

Meteorological Parameters......................................................................................................................................... 7

Quality Control.......................................................................................................................................................... 10

Results...................................................................................................................................................................... 10

Discussion and Meteorological Context.................................................................................................................... 11

References Cited...................................................................................................................................................... 12

Appendixes............................................................................................................................................................... 55

Appendix 1. Explanation of Data Gaps within the Recording Period..................................................................... 55

Appendix 2. Potential Errors Identified during Quality Assessment....................................................................... 55

Appendix 3. Meteorological Data for Seven Weather Parameters, Glen Canyon Recreation Area, Arizona, 

January 2011—December 2013 ........................................................................................................................... 55

Appendix 4. Meteorological Data for Seven Weather Parameters, Grand Canyon National Park, Arizona, 

February 2007—December 2010.......................................................................................................................... 55

Figures

Figure 1. Map showing locations of weather monitoring sites the Colorado River Corridor through Glen and 

Grand Canyons, Arizona ........................................................................................................................................... 3

Figure 2. Photograph showing automated weather station ....................................................................................... 6

Figure 3. Polar plots showing seasonal wind speed means, maximum wind gusts, wind vector sums for wind 

speeds greater than 2 meters per second, and the total number (frequency) of 4-minute records by azimuth (in 

respect to true north). .............................................................................................................................................. 15

Figure 4. Graphs showing mean wind speeds recorded for 12-hour day (6 a.m.–6 p.m.) and night 

(6 p.m.–6 a.m.), January 1, 2011, through December 31, 2013 .............................................................................. 30

Figure 5. Graphs showing maximum wind gusts recorded for 12-hour day (6 a.m.–6 p.m.) and night 

(6 p.m.–6 a.m.), January 1, 2011, through December 31, 2013. ............................................................................. 34

Figure 6. Graphs showing mean air temperature recorded for 12-hour day (6 a.m.–6 p.m.) and night 

(6 p.m.–6 a.m.), January 1, 2011, through December 31, 2013 .............................................................................. 38

Figure 7. Graphs showing mean relative humidity recorded for 12-hour day (6 a.m.–6 p.m.) and night 

(6 p.m.–6 a.m.), January 1, 2011, through December 31, 2013 .............................................................................. 42

Figure 8. Graphs showing mean barometric pressure recorded for 12-hour day (6 a.m.–6 p.m.) and night 

(6 p.m.–6 a.m.), January 1, 2011, through December 31, 2013 .............................................................................. 46

Figure 9. Graphs showing cumulative daily rainfall and maximum daily 10-minute precipitation intensity, 

January 1, 2011, through December 31, 2013......................................................................................................... 50
iv

Tables

Table 1. Description of weather monitoring sites and stations, Colorado River Corridor, Grand Canyon, 

Arizona, 2011–13....................................................................................................................................................... 5

Table 2. Manufacturer’s stated accuracy and resolution for the VaisalaTM WXT510/520 Weather Transmitter 

(adapted from Vaisala, 2008)..................................................................................................................................... 8

Table 3. Weather parameters, instrumentation, collection methods, and expected range of values. ........................ 9

Table 4. Rainfall totals for the reporting period in millimeters per day ..................................................................... 11

Conversion Factors 

Inch/Pound to SI

Multiply By To obtain

inch (in.) 25.4 millimeter (mm)

inch of mercury at 32oF (in Hg) 33.8638867 millibars (mbar) 

mile (mi) 1.609 kilometer (km)

mile per hour (mi/h) 0.44704 meter per second (m/s) 

SI to Inch/Pound

Multiply By To obtain

millimeter (mm) 0.03937 inch (in.)

meter per second (m/s) 3.281 foot per second (ft/s) 

millibars (mbar) 0.02953 inch of mercury at 32oF (in Hg)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 × °C) + 32. 
1 

Meteorological Data for Selected Sites along the Colorado 

River Corridor, Arizona, 2011–13 

By Joshua Caster, Timothy Dealy, Timothy Andrews, Helen Fairley, Amy Draut, Joel Sankey, and David Bedford

Abstract

This report presents data from 14 automated weather stations collected as part of an ongoing 

monitoring program within the Grand Canyon National Park and Glen Canyon Recreation Area along

the Colorado River Corridor in Arizona. Weather data presented in this document include precipitation, 

wind speed, maximum wind gusts, wind direction, barometric pressure, relative humidity, and air 

temperature collected by the Grand Canyon Monitoring and Research Center at 4-minute intervals 

between January 1, 2011, and December 31, 2013, using automated weather stations consisting of a data 

logger and a weather transmitter equipped with a piezoelectric sensor, ultrasonic transducers, and 

capacitive thermal and pressure sensors. Data collection was discontinuous because of station additions, 

station removals, changes in permits, and equipment failure. A large volume of data was collected for 

each station. These data are part of a larger research effort focused on physical processes affecting 

landscapes and archaeological-site stability in the Colorado River Corridor—both natural processes 

(including meteorological events) and those related to the Glen Canyon Dam operations. Meteorological 

conditions during the study interval were warmer and drier than is typical, due to ongoing drought 

conditions during the time period studied. The El Niño/Southern Oscillation was primarily in a neutral 

state during the reporting period. 

Introduction and Purpose

The Colorado River within the Grand Canyon National Park, Arizona, has been regulated since 

construction of the Glen Canyon Dam in 1963. To assess potential impacts on downstream cultural, 

environmental, and recreational resources caused by changes in the river flow regime and sediment 

supply, the Bureau of Reclamation (Reclamation) initiated the Glen Canyon Dam Adaptive 

Management Program (U.S. Department of the Interior, 1995). As part of this initiative, the U.S.

Geological Survey (USGS) Grand Canyon Monitoring and Research Center (GCMRC) and its 

cooperators monitor the effects of dam operations. 
2 

Monitoring efforts by the GCMRC have focused on a variety of parameters to assess 

downstream effects of Glen Canyon Dam. In 2003, meteorological data collection began as part of a 

study to relate geomorphic changes to meteorological events at and upslope of the active channel within 

the Colorado River Corridor. The weather data described here, and those collected previously, are part 

of a larger research effort focused on physical processes affecting archaeological-site stability in the 

Colorado River corridor—both natural processes (including meteorological events) and those related to 

dam operations. This research effort involves assessing relations between physical landscape processes, 

including meteorological events, and the physical integrity of archaeological sites. Measuring 

meteorological conditions and, in a separate but related effort, measuring sediment erosion and 

deposition in selected areas of the river-corridor landscape, allows researchers to identify natural and 

dam-induced changes to the river corridor. Meteorological data will be used in this larger research effort 

to evaluate the potential restorative effects of high-flow releases from the Glen Canyon Dam, including 

the monitoring of windblown sand supply from new river sandbars toward upland archaeological sites 

(Draut and Rubin, 2008; Draut and others, 2010a; Draut, 2012), precipitation-induced erosion (Collins 

and others, in press), gullying, and gully annealing by windblown sediment (Sankey and Draut, 2014). 

Weather data collection between 2003 and 2006 used spinning-cup anemometers and tippingbucket rain gages with an automated data logger to measure 4-minute wind direction, wind speed, 

maximum wind gusts, and precipitation at nine locations within the Grand Canyon, Arizona (Draut and 

Rubin, 2005; Draut and Rubin, 2006). The 4-minute time interval for data collection was selected as it 

provided the highest resolution information that would not exceed the data logger storage capacity 

between scheduled data collection operations. 

Beginning in February 2007, GCMRC installed 11 new weather stations at 9 sites within the 

Colorado River Corridor; 4 of the station locations were used during the previous study by Draut and 

others (2009a). These weather stations consisted of a data logger and an automated weather transmitter

with a piezoelectric sensor, ultrasonic transducers, and capacitive thermal and pressure sensors to collect

multiple weather parameters (wind direction, wind speed, maximum wind gusts, precipitation, 

temperature, barometric pressure, and relative humidity) at 4-minute intervals without moving parts. 

Data collected from these 9 weather monitoring sites for 2007, 2008, 2009, and 2010 have been 

presented in previous reports by Draut and others (2009, 2009b, 2010b) and Dealy and others(2014). 

Following a hiatus in data collection, 8 of the 11 stations were removed in 2012. The three remaining 

stations (AZ C:05:0031 Upper, AZ C:13:0346 Upper, AZ G:03:0072) as well as three new stations (AZ 

C:02:0071, AZ C:02:070, AZ B:10:0225) were activated in spring 2013 and are still operating as of 

spring 2014. 
3 

The purpose of this report is to present data collected by GCMRC weather stations between 

January 1, 2011, and December 31, 2013, and to establish a process for reporting future weather data.

Weather parameters during this period were collected from the 11 automated stations that were used for 

previous reports by Draut and others (2009a, 2009b, 2010b, and Dealy and others, 2014) that were in 

operation through fall 2011, three of which were reactivated in 2013, and three additional automated 

weather stations deployed in 2013 at sites AZ C:02:0071, AZ C:02:070, and AZ B:10:0225 (fig. 1). 

Reported meteorological data from these 14 automated weather stations were wind direction, wind 

speed, maximum wind gusts, air temperature, barometric pressure, relative humidity, and rainfall. 

Records from all 14 stations are fragmentary because of station removal, staggered station installation, 

equipment malfunction, and monitoring permit modification. Explanations of gaps within the data 

collected from the automated weather stations are included in this report and a detailed list is provided 

in appendix 1. 

Figure 1. Map showing locations of weather monitoring sites the Colorado River Corridor through Glen and Grand Canyons, 

Arizona. There are 14 automated weather stations within 11 monitoring sites. Sites AZ C:05:0031, AZ C:13:0365, and 

AZ C:13:0346 contained two stations prior to 2012. After summer 2011, all operational monitoring sites contained only one 

station. 
4 

Monitoring Locations and Period of Observation

GCMRC monitored 14 automated weather stations at 11 monitoring sites for at least a portion of 

the reporting period from January 2011 to December 2013. Site locations were selected based on the 

potential for gully erosion and aeolian influx of fluvial sand deposited upwind of the site along flood 

shorelines (Draut and Rubin, 2005). These weather monitoring sites were distributed along 

approximately 230 river miles of the Colorado River corridor within the Grand Canyon National Park 

and the Glen Canyon Recreation Area. Distances between monitoring sites ranged from 2 to 68 river 

miles. Three of these monitoring sites contained two weather stations for the purpose of assessing intrasite variability and quality control of readings. Monitoring sites have been designated with a 7-digit 

alpha-numeric code corresponding to previous reports (Draut and others, 2009a, 2009b, 2010b). Where 

two stations were present at a monitoring site, a qualifier of Upper, for the upstream station in respect to 

the Colorado River, or Lower, for the downstream station, was added to the designation. 

None of the 14 automated weather stations collected data for the entire reporting period from 

January 1, 2011, through December 31, 2013. Data collection for all sites ceased between November 22, 

2011, and April 27, 2013, following a transitional period between the National Park Service research 

and monitoring permits. After the issuance of the 2013 permit, only three of the automated weather 

stations deployed in 2007 were re-activated (AZ C:05:0031Upper, AZ C:13:0346 Upper, AZ 

G:03:0072), and three new stations (AZ C:02:0071, AZ C:02:070, AZ B:10:0225) were installed. Four 

of the six stations in operation during 2013 retained a continuous record between installation and the 

end of the reporting period. Data collection was disrupted for sites AZ B:10:0225 and AZ G:03:0072 

because of power loss and station removal, respectively. A summary of station names, locations, and 

operational periods is presented in table 1 and a comprehensive list of gaps within the data is provided 

in appendix 1. 
5 

Table 1. Description of weather monitoring sites and stations, Colorado River Corridor, Grand Canyon, Arizona, 

2011–13. 

[Stations are listed in order from upstream (in respect to the Colorado River) to downstream] 

Monitoring 

site

Monitoring 

station

7.5 minute 

quadrangle

Geographic description Topographic 

description

Operational period

AZ C:02:0071 AZ C:02:0071 Ferry Swale Near the confluence of 

Ferry Swale Canyon and 

the Colorado River.

Within a shallow 

depression on a point 

bar.

Nov 5, 2013 to 

Dec 31, 2013

AZ C:02:0070 AZ C:02:0070 Lees Ferry Near the confluence of the 

Paria and the Colorado 

Rivers.

On a cobble bar. Jun 12, 2013 to 

Dec 31, 2013

AZ C:05:0031 AZ C:05:0031 

Upper

North Canyon 

Point

Near the confluence of 

Sheep Spring Wash and the 

Colorado River.

On the proximal 

portion of a debris fan.

Jan 1, 2011 to 

Jul 28, 2011 

Apr 27, 2013 to 

Dec 29, 2013

AZ C:05:0031 

Lower

Jan 1, 2011 to 

Jul 28, 2011

AZ C:13:0365 AZ C:13:0365 

Upper

Cape Solitude Near the confluence of 

Malgosa Creek and the 

Colorado River.

Along a minor 

distributary of Malgosa 

Creek.

Jan 1, 2011 to 

Jul 31, 2011

AZ C:13:0365 

Lower

Jan 1, 2011 to 

Jul 31, 2011

AZ C:13:0006 AZ C:13:0006 Cape Solitude Near the confluence of 

Sixtymile Creek and the 

Colorado River.

On the proximal 

portion of a debris fan.

Jan 1, 2011 to 

Jun 22, 2011

AZ C:13:0336 AZ C:13:0336 Cape Solitude Near the confluence of 

Palisades Creek and the 

Colorado River.

On the proximal 

portion of a 

reattachment bar.

Jan 1, 2011 to 

Aug 2, 2011

AZ C:13:0346 AZ C:13:0346 

Upper

Desert View Near the confluence of 

Basalt Creek and the 

Colorado River 

On a terrace in a 

largely inactive aeolian 

dune field.

Jan 1, 2011 to 

Aug 2, 2011 

May 2, 2013 to 

Dec 31, 2013

AZ C:13:0346 

Lower

Jan 1, 2011 to 

Nov 22, 2011

AZ B:10:0225 AZ B:10:0225 Fossil Bay Near the confluence of 

Fossil Canyon and the 

Colorado River.

On the proximal 

portion of a debris fan.

May 6, 2013 to 

Nov 1, 2013

AZ B:11:0281 AZ B:11:0281 Tapeats 

Amphitheater

Near the confluence of 

Bonita Creek and the 

Colorado River.

On the medial portion 

of a debris fan.

Jan 1, 2011 to 

Feb 27, 2011

AZ A:15:0033 AZ A:15:0033 Whitmore 

Point SE

Near the confluence of 

Spring Canyon and the 

Colorado River.

On the medial portion 

of a reattachment bar.

Jan 1, 2011 to 

Aug 6, 2011

AZ G:03:0072 AZ G:03:0072 Diamond 

Peak

Near the confluence of Two 

Hundred and Twentyfour 

Mile Canyon and the 

Colorado River.

On the medial portion 

of a debris fan.

Jan 1, 2011 to 

Aug 11, 2011 

May 11, 2013 to 

Jul 5, 2013
6 

Materials and Methods

Data collection was conducted using automated weather stations. Each station (fig. 2) consists of 

a transmitter and data logger mounted on a tripod and powered by a 12-volt deep cycle 55-amp-hour 

AGM Optima battery (model D34/78) enclosed in a plastic box at the base of the tripod. The battery is

charged by a 30 watt BP Solar multicrystalline photovoltaic module (BP SX30U). The solar module is

mounted to the tripod with an Ameresco Solar’s HPM18-30U horizontal pole mount system and is

regulated by Morningstar Corporation’s SunKeeperTM 6-amp 12 VDC solar charge controller. 

The transmitters used for each station are VaisalaTM type WXT510 or WXT520 that measure air 

temperature, barometric pressure, precipitation, relative humidity, wind speed, and wind direction. The 

VaisalaTM WXT510/520 transmitter was selected because it could collect multiple parameters without

moving parts that reduce visibility to canyon visitors and because of the potential for equipment 

malfunction associated with moving parts in a desert environment, such as interference from windblown 

sand. 

Data are collected from the VaisalaTM transmitter using a NexSensTM Technology data logger. 

The NexSens Technology, Incorporated Intelligent Sensor Interface and Control (iSIC) data logger is a 

2-megabyte remote data acquisition system that is housed in a weather-proof fiberglass enclosure and 

has an operating temperature range of -20 to 60 °C. 

Figure 2. Photograph showing automated weather station. Photograph by Joshua Caster, U.S. Geological Survey. 
7 

Each transmitter station is mounted on a tripod assembly made from a Ronard Industries, Inc. 

extra heavy duty tripod that was used to hold an electric metallic tube (EMT) conduit mast in place. The 

mast is attached with a Fernco coupler to a length of EMT that is driven between 0.5 and 1 m into the 

ground. The tripod and mast assembly is adjusted so that the transmitter is 2 m above ground. The 

transmitter is then oriented to true north based on magnetic declination collected from the National 

Oceanic and Atmospheric Administration’s (NOAA) National Geophysical Data Center’s Magnetic 

Field Calculator using the World Magnetic Model (Maus and others, 2010). 

The NexSensTM Technology, Inc. data loggers are programmed to collect data at 4-minute 

intervals until the maximum data storage capacity has been reached. The data loggers have potential to 

exceed maximum storage capacity after 5 months of continuous data collection for weather parameters 

at 4-minute intervals. To avoid loss, data are downloaded from the stations at least once every 4 months. 

Data are retrieved by directly connecting a field computer to the data logger using an analog cable. 

Meteorological Parameters

Seven meteorological parameters are collected at each automated weather station at 4-minute 

intervals. Wind parameters are collected by the VaisalaTM transmitter using three top-mounted 

ultrasonic transducers. Based on an assessment of ultrasonic wind readings by Wauben (2005), 

ultrasonic transducers have the potential to overestimate wind gusts when compared to cup 

anemometers. Wauben (2005) concluded that the VaisalaTM system was comparable with the 

conventional cup anemometer and vane system in wind speed and vector during field and wind tunnel 

tests, although wind speeds less than 5 m/s showed greater variation. 

Precipitation is measured by the VaisalaTM transmitter with a proprietary piezoelectric sensor 

(Salmi and others, 2008). Basara and others (2009) concluded that piezoelectric sensors have the 

potential to underestimate rainfall when compared to tipping-bucket units, depending on rainfall 

intensity. Despite these differences, R2 values greater than 0.95 between the VaisalaTM transmitter and 

the tipping-bucket unit were calculated by Basara and others (2009), suggesting comparable results. 

Air temperature, barometric pressure, and relative humidity are measured using a capacitive 

ceramic thermal sensor, a capacitive silicon pressure sensor, and a capacitive polymer moisture sensor, 

respectively, located inside a polycarbonate vented radiation shield. Based on manufacturer’s stated 

range of measurements, accuracy, and resolution for these parameters (table 2), these methods meet the 

measurement criteria for the National Weather Service’s Surface Observing Program (National Oceanic 

and Atmospheric Administration, 2010). 
8 

Table 2. Manufacturer’s stated accuracy and resolution for the VaisalaTM WXT510/520 Weather Transmitter 

(adapted from Vaisala, 2008). 

Range Accuracy Resolution

Air Temperature

-52 to 60 degrees Celsius (°C) ±0.3°C at 20°C 0.1°C

Atmospheric Pressure

600 to 1,100 Millibars (mbar) ±0.5 mbar at 0 to 30°C

±1 mbar at -52 to 60°C 0.1 mbar

Precipitation

- 5% 0.01 millimeters with a 

10-second duration

Relative Humidity

0 to 100 % Relative Humidity 

(RH)

±3% RH at 0 to 90% RH

±5% RH at 90 to 100% RH 0.1% RH

Wind Speed

0 to 60 meters per second (m/s) the greater of ±0.3 m/s or ±3% for 0 to 35 m/s

5% for 36 to 60 m/s 0.1 m/s

Wind Direction

0 to 360 degrees Azimuth (°) ±3.0° with a 0.25 second response time 1°
9 

Wind direction, wind speed, air temperature, relative humidity, and barometric pressure are 

collected for each interval as instantaneous records every 4 minutes. Wind gusts represent the maximum 

wind speed for each 4-minute interval based on 4-second composite data. Rainfall values are collected 

as a total sum of all rain recorded during a 4-minute interval. All meteorological parameters are

recorded in English units. To comply with scientific reporting standards, these data are converted to 

metric units using standard conversion factors. The method of data collection, the original English units 

for each parameter, the converted metric units, and a range of typical (expected) metric values are 

shown in table 3. 

Table 3. Weather parameters, instrumentation, collection methods, and expected range of values. 

[The expected ranges of values represent maximum and minimum 4-minute interval values, in the converted units, observed 

during the previous 4 years (2007–10) at the Grand Canyon Monitoring and Research Center and National Oceanic and 

Atmospheric Administration stations within the monitoring area. Values outside of this range do not necessarily indicate 

equipment error] 

Parameter Instrumentation Method of 

collection

Data collection 

units

Converted units Expected range 

of values*

Wind direction Ultrasonic 

transducer

Instantaneous degrees azimuth 

(true north)

not converted 0–360

Wind speed Ultrasonic 

transducer

Instantaneous miles per hour meters per 

second

0–18

Wind gusts Ultrasonic 

transducer

Maximum of 4-

minute composite

miles per hour meters per 

second

0–27

Air temperature Ceramic thermal 

sensor

Instantaneous degrees Fahrenheit degrees Celsius 0–54

Relative humidity Polymer moisture 

sensor

Instantaneous relative percentage not converted 0–100

Barometric 

pressure

Silicon pressure 

sensor

Instantaneous inches mercury millibars 845–1,015

Rainfall Piezoelectric sensor Total of 4-minute

composite

inches millimeters 0–25

*Values are in the converted units.
10

Quality Control 

Data collected from the 14 automated weather stations were analyzed for potential 

inconsistencies and spurious data through outlier identification, graphical analysis, and comparative 

analysis. Outlier identification was conducted by flagging weather parameter values that were outside of 

the expected range during the initial review of the 4-minute interval records of the seven collected

meteorological parameters (wind direction, wind speed, wind gust, temperature, barometric pressure, 

relative humidity, and rainfall). The expected range for each parameter is presented in table 3. The 

expected range for each parameter was determined based on the range of values within the 2007 through 

2010 datasets (Draut and others, 2009a, 2009b, 2010b; Dealy and others, 2014) and on historical

maximum and minimum values published by the NOAA National Climatic Data Center (NCDC) for 

Page, Arizona (station GHCND:USW00053164), Paria Point, Arizona (station 

GHCND:USR0000APAR), and Phantom Ranch, Arizona (station GHCND:USC00026471). 

To identify potentially spurious data within the expected range of parameter values, deviations 

from natural trends were identified by graphical analysis. Graphical analysis was conducted by plotting 

values within Microsoft® Excel and MatlabTM R2013b. Records with values that deviated from diurnal, 

nocturnal, or seasonal trends were inspected to examine whether they represented real phenomena or 

were likely spurious data. Comparative analysis was conducted on parameters, such as rainfall, that do 

not necessarily follow daily or monthly trends. This analysis involved comparisons of graphical and 

tabular data for each weather station and the nearest upstream and downstream sites. Records with 

potentially spurious data were further inspected. Determination, justification, and rectification of 

anomalies have been included in appendix 2. 

Results

Meteorological data collected by GCMRC at each of the 14 automated weather stations within 

the Colorado River Corridor for the reporting period are provided in appendix 3. Appendix 3 contains 

4-minute interval data for each of the automated weather stations, tab separated by parameter (wind 

direction, wind speed, wind gusts, air temperature, relative humidity, barometric pressure, and rainfall. In 

addition to the data collected during the reporting period, appendix 4 provides, for the first time in 

digital format, previously reported 4-minute interval data collected by the automated weather stations 

from February 2007 through December 2010. 

A summary of meteorological data presented in appendix 3 is provided graphically in time-series 

plots in figures 3–9. Figure 3 presents mean wind speed and maximum wind gusts by wind direction. 

Mean and maximum wind speeds are affected by the frequency of wind direction change. For 

comparison, the number (frequency) of 4-minute records used to calculate these statistics was included, 

by azimuth, in the time-series plot as well as wind vector sums. Wind vector sums were calculated for 

winds greater than 2 m/s, a minimum threshold for sand transport (Draut and others, 2009a, 2009b, 

2010b; Dealy and others, 2014). Time-series plots in figure 3 are presented by season based on typical 

solstice/equinox dates and the available data recorded. For 2011, winter was defined as from January 1 

(first record) to March 20, spring was from March 20 to June 21, summer was from June 21 to 

September 22, and fall was from September 22 to November 22 (last record). For 2013, spring was 

defined as from April 27 (first record) to June 21, summer was from June 21 to September 22, fall was 

from September 22 to December 21, and winter was from December 21 to December 31 (last record). 
11

As gaps within the seasonal data were present, the percentage of data used for the wind speed-direction 

polar plots has been included in the figure description. Figures 4–8 present maximum wind gusts and 

mean wind speed, air temperature, relative humidity, and barometric pressure summarized by daily and 

nightly values. Daily 12-hour summary values were derived from parameters collected between 6 a.m. 

(0600) and 6 p.m. (1800), and nightly 12-hour summary values were derived from parameters collected 

between 6 p.m. (1800) and 6 a.m. (0600). Figure 9 presents cumulative daily rain totals with the 

maximum daily 10-minute rainfall intensity, a metric for precipitation-induced erosion (Collins and 

others, in press). Values for 10-minute intensity (in millimeters per hour) were calculated from the 4-

minute interval rainfall data using the following equation adapted from Ward and Elliot (1995): 

I = �r1 + r2 +

r3

2� ∗ 6

Where r1, r2, and r3 are consecutive 4-minute intervals of total rainfall, in millimeters. 

A summary of the daily rainfall totals for the reporting period is provided in table 4. 

Table 4. Rainfall totals for the reporting period in millimeters per day. 

[Table 4 is a Microsoft® Excel file available for download at http://pubs.usgs.gov/of/2014/1247] 

Discussion and Meteorological Context

Weather conditions during the reporting period are expected to be atypical because regional 

weather patterns in the Southwestern United States were warmer and drier than average (National 

Oceanic and Atmospheric Administration National Climatic Data Center, 2011, 2012, 2013). In 2011, 

much of the Southern United States experienced some degree of drought. Below-average rainfall and 

above-average air temperatures during the monsoon season (July–October) contributed to local areas of 

severe to extreme drought in northern Arizona (National Oceanic and Atmospheric Administration 

National Climatic Data Center, 2011). These conditions persisted through much of 2012, with the 

Lower Colorado River Basin experiencing the 24th driest year on record (National Oceanic and 

Atmospheric Administration National Climatic Data Center, 2012). Monsoon season temperatures 

continued to be high through 2013, and precipitation totals during this season exceeded normal 

conditions (116-year average) (National Oceanic and Atmospheric Administration National Climatic 

Data Center, 2013). Above-average precipitation during the summer and fall of 2013 was sufficient to 

alleviate some, but not all, of the drought conditions within the Lower Colorado River Basin ( National 

Oceanic and Atmospheric Administration National Climatic Data Center, 2013, 2014). Based on the 

Palmer Hydrologic Drought Index, short-term analysis suggests drought conditions will persist into 

2014 (National Oceanic and Atmospheric Administration National Climatic Data Center, 2014).

Oceanic temperature cycles in the Pacific known as El Niño/Southern Oscillation (ENSO) can 

have a role in weather conditions within the Southwestern United States (Kumar and Hoerling, 1998), 

particularly in strong El Nino (warm) years, where cool season precipitation is typically above average, 

and in strong La Niña (cool) years, where annual precipitation is typically below average (McPhaden 

and Others, 2006; Wolter and Timlin, 2011). During the reporting period, ENSO was likely a minor 

factor in regional weather because the Pacific Ocean was in a weak to neutral ENSO state (National 

Oceanic and Atmospheric Administration National Climatic Data Center, 2011, 2012). In 2011, a weak 

La Niña (cool) state was present for most of the year (National Oceanic and Atmospheric 

Administration National Climatic Data Center, 2011). By April 2012, the ENSO had transitioned to a 

neutral state, where it remained through 2013 (National Oceanic and Atmospheric Administration 

National Climatic Data Center, 2012, 2013). 
12

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15

Figure 3. Polar plots showing seasonal wind speed means, maximum wind gusts, wind vector sums for wind speeds greater 

than 2 meters per second, and the total number (frequency) of 4-minute records by azimuth (in respect to true north). 

Seasonal statistics were calculated for 2011 based on the following dates—winter from January 1 (first record) to March 20 

(28,440 possible records), spring from March 20 to June 21 (33,480 possible records), summer from June 21 to September 

22 (33,480 possible records), and fall from September 22 to November 22 (last record) (21,746 possible records). Seasonal 

statistics were calculated for 2013 based on the following dates— spring was from April 27 (first record) to June 21 (33,480 

possible records), summer from June 21 to September 22 (33,480 possible records), fall from September 22 to December 21

(32,400 possible records), and winter from December 21–December 31 (last record) (3,600 possible records). Data were not

collected between November 22, 2011, and April 27, 2013. All polar plots represent the maximum number of possible 4-

minute records unless otherwise stated. 
16

2011 2013

Station AZ C:02:0071

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

No Data Recorded in 2011

Spring

Mar 20-Jun 21

No Data Recorded in 2011 No Data Recorded in 2013

Summer

Jun21-Sep 22

No Data Recorded in 2011 No Data Recorded in 2013

Fall

Sep 22-Dec 21

No Data Recorded in 2011

Figure 3. (a) Station AZ C:02:0071 seasonal wind speed-direction plots. In 2013, 52 percent of the possible records were 

collected during fall 
17

2011 2013

Station AZ C:02:0070

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

No Data Recorded in 2011

Spring

Mar 20-Jun 21

No Data Recorded in 2011

Summer

Jun21-Sep 22

No Data Recorded in 2011

Fall

Sep 22-Dec 21

No Data Recorded in 2011

Figure 3. (b) Station AZ C:02:0070 seasonal wind speed-direction plots. In 2013, 17 percent of the possible records were 

collected during spring and 89 percent were collected during winter. 
18

2011 2013

Station AZ C:05:0031 Upper

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

Spring

Mar 20-Jun 21

Summer

Jun21-Sep 22

Fall

Sep 22-Dec 21

No Data Recorded in 2011

Figure 3. (c) Station AZ C:05:0031 Upper seasonal wind speed-direction plots. In 2011, 40 percent of the possible records 

were collected during summer. In 2013, 20 percent of the possible records were collected during winter, 92 percent were 

collected during spring, 68 percent were collected during summer, and 57 percent were collected during fall. 
19

2011 2013

Station AZ C:05:0031 Lower

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013) 

No Data Recorded in 2013

Spring

Mar 20-Jun 21

No Data Recorded in 2013

Summer

Jun21-Sep 22

No Data Recorded in 2013

Fall

Sep 22-Dec 21

No Data Recorded in 2011 No Data Recorded in 2013

Figure 3. (d) Station AZ C:05:0031 Lower seasonal wind speed-direction plots. In 2011, 40 percent of the possible records 

were collected during summer. 
20

2011 2013

Station AZ C:13:0365 Upper

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 

(2013)

No Data Recorded in 2013

Spring

Mar 20-Jun 21

No Data Recorded in 2013

Summer

Jun21-Sep 22

No Data Recorded in 2013

Fall

Sep 22-Dec 21

No Data Recorded in 2011 No Data Recorded in 2013

Figure 3. (e) Station AZ C:13:0365 Upper seasonal wind speed-direction plots. In 2011, 42 percent of the possible 

records were collected during summer.
21

2011 2013

Station AZ C:13:0365 Lower

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

No Data Recorded in 2013

Spring

Mar 20-Jun 21

No Data Recorded in 2013

Summer

Jun21-Sep 22

No Data Recorded in 2013

Fall

Sep 22-Dec 21

No Data Recorded in 2011 No Data Recorded in 2013

Figure 3. (f) Station AZ C:13:0365 Lower seasonal wind speed-direction plots. In 2011, 42 percent of the possible records 

were collected during summer. 
22

2011 2013

Station AZ C:13:0006 

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 

(2013)

No Data Recorded in 2013

Spring

Mar 20-Jun 21

No Data Recorded in 2013

Summer

Jun21-Sep 22

No Data Recorded in 2013

Fall

Sep 22-Dec 21

No Data Recorded in 2011 No Data Recorded in 2013

Figure 3. (g) Station AZ C:13:0006 seasonal wind speed-direction plots. In 2011, 4 percent of the possible records were 

collected during summer.
23

2011 2013

Station AZ C:13:0336 

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

No Data Recorded in 2013

Spring

Mar 20-Jun 21

No Data Recorded in 2013

Summer

Jun21-Sep 22

No Data Recorded in 2013

Fall

Sep 22-Dec 21

No Data Recorded in 2011 No Data Recorded in 2013

Figure 3. (h) Station AZ C:13:0336 seasonal wind speed-direction plots. In 2011, 45 percent of the possible records were 

collected during summer.
24

2011 2013

Station AZ C:13:0346 Upper 

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

Spring

Mar 20-Jun 21

Summer

Jun21-Sep 22

Fall

Sep 22-Dec 21

No Data Recorded in 2011

Figure 3. (i) Station AZ C:13:0346 Upper seasonal wind speed-direction plots. In 2011, 45 percent of the possible records 

were collected during summer. In 2013, 92 percent of the possible records were collected during spring. 
25

2011 2013

Station AZ C:13:0346 Lower 

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

No Data Recorded in 2013

Spring

Mar 20-Jun 21

No Data Recorded in 2013

Summer

Jun21-Sep 22

No Data Recorded in 2013

Fall

Sep 22-Dec 21

No Data Recorded in 2013

Figure 3. (j) Station AZ C:13:0346 Lower seasonal wind speed-direction plots. In 2011, 94 percent of the possible records 

were collected during winter, 99 percent were collected during spring, 89 percent were collected during summer, and 61 

percent were collected during fall.
26

2011 2013

Station AZ B:10:0225

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

No Data Recorded in 2011 No Data Recorded in 2013

Spring

Mar 20-Jun 21

No Data Recorded in 2011

Summer

Jun21-Sep 22

No Data Recorded in 2011

Fall

Sep 22-Dec 21

No Data Recorded in 2011

Figure 3. (k) Station AZ B:10:0225 seasonal wind speed-direction plots. In 2013, 83 percent of the possible records were 

collected during spring and 44 percent were collected during fall. 
27

2011 2013

Station AZ B:11:0281

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

No Data Recorded in 2013

Spring

Mar 20-Jun 21

No Data Recorded in 2011 No Data Recorded in 2013

Summer

Jun21-Sep 22

No Data Recorded in 2011 No Data Recorded in 2013

Fall

Sep 22-Dec 21

No Data Recorded in 2011 No Data Recorded in 2013

Figure 3. (l) Station AZ B:11:0281 seasonal wind speed-direction plots. In 2011, 73 percent of the possible records were 

collected during winter.
28

2011 2013

Station AZ A:15:0033

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

No Data Recorded in 2013

Spring

Mar 20-Jun 21

No Data Recorded in 2013

Summer

Jun21-Sep 22 

No Data Recorded in 2013

Fall

Sep 22-Dec 21

No Data Recorded in 2011 No Data Recorded in 2013

Figure 3. (m) Station AZ A:15:0033 seasonal wind speed-direction plots. In 2011, 49 percent of the possible records were 

collected during summer.
29

2011 2013

Station AZ G:03:0072

Winter

Jan 1-Mar 20 (2011), Dec 21-Dec 31 (2013)

No Data Recorded in 2013

Spring

Mar 20-Jun 21

Summer

Jun21-Sep 22

Fall

Sep 22-Dec 21

No Data Recorded in 2011 No Data Recorded in 2013

Figure 3. (n) Station AZ G:03:0072 seasonal wind speed-direction plots. In 2011, 54 percent of the possible records were 

collected during summer. In 2013, 75 percent of the possible records were collected during spring and 15 percent were 

collected during summer.
30

2011 2013

Station AZ C:02:0071

No Data Collected in 2011

Station AZ C:02:0070

No Data Collected in 2011

Station AZ C:05:0031 Upper

Figure 4. Graphs showing mean wind speeds recorded for 12-hour day (6 a.m.–6 p.m.) and night (6 p.m.–6 a.m.), January 1, 

2011, through December 31, 2013. Data were not collected between November 22, 2011, and April 27, 2013.
31

2011 2013

Station AZ C:05:0031 Lower

No Data Collected in 2013

Station AZ C:13:0365 Upper 

No Data Collected in 2013

Station AZ C:013:0365 Lower

No Data Collected in 2013

Station AZ C:013:0006

No Data Collected in 2013

Figure 4.—Continued
32

2011 2013

Station AZ C:013:0336

No Data Collected in 2013

Station AZ C:13:0346 Upper Station AZ C:13:0346 Lower

No Data Collected in 2013

Station AZ B:10:0225

No Data Collected in 2011

Figure 4.—Continued
33

2011 2013

Station AZ B:11:0281

No Data Collected in 2013

Station AZ A:15:003

No Data Collected in 2013

Station AZ G:03:007

Figure 4.—Continued
34

2011 2013

Station AZ C:02:0071

No Data Collected in 2011

Station AZ C:02:0070

No Data Collected in 2011

Station AZ C:05:0031 Upper Station AZ C:05:0031 Lower

No Data Collected in 2013

Figure 5. Graphs showing maximum wind gusts recorded for 12-hour day (6 a.m.–6 p.m.) and night (6 p.m.–6 a.m.), January 

1, 2011, through December 31, 2013. Data were not collected between November 22, 2011, and April 27, 2013.
35

2011 2013

Station AZ C:13:0365 Upper

No Data Collected in 2013

Station AZ C:013:0365 Lower

No Data Collected in 2013

Station AZ C:013:0006

No Data Collected in 2013

Station AZ C:013:0336

No Data Collected in 2013

Figure 5.—Continued
36

2011 2013

Station AZ C:13:0346 Upper Station AZ C:13:0346 Lower

No Data Collected in 2013

Station AZ B:10:0225

No Data Collected in 2011

Station AZ B:11:0281

No Data Collected in 2013

Figure 5.—Continued
37

2011 2013

Station AZ A:15:003

No Data Collected in 2013

Station AZ G:03:007

Figure 5.—Continued
38

2011 2013

Station AZ C:02:0071

No Data Collected in 2011

Station AZ C:02:0070

No Data Collected in 2011

Station AZ C:05:0031 Upper Station AZ C:05:0031 Lower

No Data Collected in 2013

Figure 6. Graphs showing mean air temperature recorded for 12-hour day (6 a.m.–6 p.m.) and night (6 p.m.–6 a.m.), January 

1, 2011, through December 31, 2013. Data were not collected between November 22, 2011, and April 27, 2013.
39

2011 2013

Station AZ C:13:0365 Upper

No Data Collected in 2013

Station AZ C:013:0365 Lower

No Data Collected in 2013

Station AZ C:013:0006

No Data Collected in 2013

Station AZ C:013:0336

No Data Collected in 2013

Figure 6.—Continued
40

20112013

Station AZ C:13:0346 Upper Station AZ C:13:0346 Lower

No Data Collected in 2013

Station AZ B:10:0225

No Data Collected in 2011

Station AZ B:11:0281

No Data Collected in 2013

Figure 6.—Continued. 
41

2011 2013

Station AZ A:15:003

No Data Collected in 2013

Station AZ G:03:007

Figure 6.—Continued
42

2011 2013

Station AZ C:02:0071

No Data Collected in 2011

Station AZ C:02:0070

No Data Collected in 2011

Station AZ C:05:0031 Upper Station AZ C:05:0031 Lower

No Data Collected in 2013

Figure 7. Graphs showing mean relative humidity recorded for 12-hour day (6 a.m.–6 p.m.) and night (6 p.m.–6 a.m.), 

January 1, 2011, through December 31, 2013. Data were not collected between November 22, 2011, and April 27, 2013.
43

2011 2013

Station AZ C:13:0365 Upper

No Data Collected in 2013

Station AZ C:013:0365 Lower

No Data Collected in 2013

Station AZ C:013:0006

No Data Collected in 2013

Station AZ C:013:0336

No Data Collected in 2013

Figure 7.—Continued
44

2011 2013

Station AZ C:13:0346 Upper Station AZ C:13:0346 Lower

No Data Collected in 2013

Station AZ B:10:0225

No Data Collected in 2011

Station AZ B:11:0281

No Data Collected in 2013

Figure 7.—Continued
45

2011 2013

Station AZ A:15:003

No Data Collected in 2013

Station AZ G:03:007

Figure 7.—Continued
46

2011 2013

Station AZ C:02:0071

No Data Collected in 2011

Station AZ C:02:0070

No Data Collected in 2011

Station AZ C:05:0031 Upper Station AZ C:05:0031 Lower

No Data Collected in 2013

Figure 8. Graphs showing mean barometric pressure recorded for 12-hour day (6 a.m.–6 p.m.) and night 

(6 p.m.–6 a.m.), January 1, 2011, through December 31, 2013. Data were not collected between November 22, 2011, and 

April 27, 2013.
47

2011 2013

Station AZ C:13:0365 Upper

No Data Collected in 2013

Station AZ C:013:0365 Lower

No Data Collected in 2013

Station AZ C:013:0006

No Data Collected in 2013

Station AZ C:013:0336

No Data Collected in 2013

Figure 8.—Continued
48

2011 2013

Station AZ C:13:0346 Upper Station AZ C:13:0346 Lower

No Data Collected in 2013

Station AZ B:10:0225

No Data Collected in 2011

Station AZ B:11:0281

No Data Collected in 2013

Figure 8.—Continued
49

2011 2013

Station AZ A:15:003

No Data Collected in 2013

Station AZ G:03:007

Figure 8.—Continued
50

2011 2013

Station AZ C:02:0071

No Data Collected in 2011

Station AZ C:02:0070

No Data Collected in 2011

Station AZ C:05:0031 Upper Station AZ C:05:0031 Lower

No Data Collected in 2013

Figure 9. Graphs showing cumulative daily rainfall and maximum daily 10-minute precipitation intensity, January 1, 2011, 

through December 31, 2013. Data were not collected between November 22, 2011, and April 27, 2013.
51

2011 2013

Station AZ C:13:0365 Upper

No Data Collected in 2013

Station AZ C:013:0365 Lower

No Data Collected in 2013

Station AZ C:013:0006

No Data Collected in 2013

Station AZ C:013:0336

No Data Collected in 2013

Figure 9.—Continued
52

2011 2013

Station AZ C:13:0346 Upper Station AZ C:13:0346 Lower

No Data Collected in 2013

Station AZ B:10:0225

No Data Collected in 2011

Station AZ B:11:0281

No Data Collected in 2013

Figure 9.—Continued
53

2011 2013

Station AZ A:15:003

No Data Collected in 2013

Station AZ G:03:007

Figure 9.—Continued
54

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55

Appendixes

Appendixes 1 and 2 are Microsoft® Excel files that can be downloaded from 

http://pubs.usgs.gov/of/2014/1247. Appendixes 3 and 4 are Microsoft® Excel files or Comma-separated 

value (CSV) files that can be downloaded from http://pubs.usgs.gov/of/2014/1247. 

Appendix 1. Explanation of Data Gaps within the Recording Period

Appendix 2. Potential Errors Identified during Quality Assessment

Appendix 3. Meteorological Data for Seven Weather Parameters, Glen Canyon Recreation Area, 

Arizona, January 2011—December 2013

Appendix 4. Meteorological Data for Seven Weather Parameters, Grand Canyon National Park, 

Arizona, February 2007—December 2010
56

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Publishing Network, Menlo Park and Tacoma Publishing Service Centers

For more information concerning the research in this report, contact the

SBSC staff, Southwest Biological Science Center

U.S. Geological Survey

2255 N. Gemini Drive

Flagstaff, AZ 86001

http://sbsc.wr.usgs.gov/
Caster and others—Meteorological Data for Selected Sites along the Colorado River Corridor, Arizona, 2011–13—Open-File Report 2014–1247

ISSN 2331-1258 (online)

http://dx.doi.org/10.3133/ofr20141247