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11-1Ecological Monitoring Program Report, 1997 - 2005

Climate

Peter Holm and Charles Conner

ObjectivesThe protocol manual indicates that climate monitoring was to serve as “the primary integrative components of the Ecological Monitoring Program” (OPCNM 1995). Initial site selection for weather stations was based on the following criteria (Bennett and Kunzmann 1987):

1. identification of sensitive species habitat where a better understanding of climate related habitat factors is needed for protection of a species;

2. identification of habitat areas associated with long-term monitoring projects to establish climate parameters that may affect changes in naturally occurring populations;

3. identification of specific habitats (major vegetation types) where future research can utilize data collected as baseline and germane to the research project;

4. identification of major airsheds.

IntroductionClimate, particularly the spatial and temporal distribution of moisture and temperature, is a major forcing factor in determining the composition and dynamics of ecosystems (i.e., ecosystem driver). The distribution, productivity, and activity of plants and animals respond to climate variation through the genetically determined tolerances of each species. Detailed information about climate will help us to detect short and long-term changes in climate, identify climate-related variation in multiple biological and physical indicators, and better understand ecological processes including the local consequences of global climate change.

Climate of Southern ArizonaLike much of the Southwest, OPCNM has a bimodal annual rainfall distribution with winter precipitation peaking in December to March

and summer precipitation peaking in August. Pronounced seasonal droughts occur in the spring and fall, although the latter may be ameliorated by occasional tropical storms.

During the winter, winds over Arizona are generally out of the west to northwest. Winter precipitation depends on the path, moisture content, and duration of low pressure systems that may be associated with westerly cold fronts or cut off from major steering winds. Winter storms may be enhanced by an influx of tropical moisture such as from the Pacific Ocean subtropical jet stream.

During the summer, winds shift to a more south to southeast source. Summer precipitation, or the Mexican Monsoon, is largely dependent on high pressure systems over the Four-corners area and to the east (including the Bermuda high) to steer upper level moisture from the Gulf of Mexico to Arizona. Low level moisture, from the eastern Pacific and Gulf of California, is drawn into Arizona by low pressure.

Arizona climate, particularly winter precipitation, is associated with the El Niño Southern Oscillation, Pacific Decadal Oscillation, and Madden-Julian Oscillation, and ultimately linked to other global patterns.

MethodsProgram HistoryThe histories and configurations of weather stations and rain gauges are summarized in Tables 11-1 and 11-2. Work began in 1987 on the installation of 9 automated weather stations at sites in the monument designated as ecological monitoring sites. These stations, which used Omnidata “Datapod” recorders, were all operational by early 1988. Eight Forester rain gauges are also located throughout the

11-2 Organ Pipe Cactus National Monument

Figure 11-1. Climate monitoring sites, Organ Pipe Cactus N.M.


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SiteLetter Code

From Date

To Date Notes

Alamo Canyon ALAM Jan-82 present near campground

Arch Canyon ARCH Jan-82 present near parking area

Bates Well BATES Jan-82 Dec-87 operated by VIP’s, who left (age)

Bates Well BATES Feb-98 present at mouth of Growler Canyon, near mammal grids

Dos Lomitas DOLO Jan-82 Sep-96 rain gauge relocated from here due to theft

Dos Lomitas DOLO Nov-96 present new rain gauge location, near old

Dowling Ranch DOW Jan-82 present west of ranch

Dripping Springs

DRIP Jan-82 present near road

Armenta Ranch ARMR Jan-88 Dec-94 removed

Growler Valley GROW Jan-82 Oct-87 replaced with weather station

Mile Post 69.4 MP69 Jan-82 present ~1 mile to east

Pozo Nuevo POZO Oct-92 Feb-96 replaced with weather station

Quitobaquito QBQ Jan-82 present west of pond

Table 11-2. History of Forrester type rain gauges deployed at Organ Pipe Cactus N.M.

monument. Rain gauges have been in use at some sites since the early 1960s, though not consistently until 1982.

In 1995 and 1996, the array and composition of the 9 automated weather stations was upgraded. The new array consisted of 11 stations at or near the 11 Core I sites (see chapter about Study Sites). Two weather stations were eliminated (Headquarters and Gachado Well), seven weather stations were converted from Datapod recorders to Handar (now Vaisala) recorders at existing station sites (Aguajita Wash, Bull Pasture, East Armenta, Growler Valley, Acuña (=Neolloydia) Habitat, Salsola Site, and Senita Basin), and four stations were installed at new locations at Core I sites (Alamo Canyon, Middle Bajada, Pozo Nuevo, and Valley Floor. The instruments and recorders were all replaced with new late generation equipment, and all stations were set up with a full

complement of meteorological instruments. The above-ground configuration of instruments was identical from site to site; below-ground sensors for soil moisture and temperature were added to 7 sites in 1996-1997 (see Table 11-1 for site to site variation). The data at each station were recorded on one logger, the Handar 555A, and power was supplied by a solar panel and internal battery.

Data Collection Each weather station recorded hourly data for all parameters (Table 11-1). Above-ground data collection included wind speed and direction at 3 m above ground surface, air temperature and humidity at 48 inches (122 cm) above ground surface, solar radiation, air temperature at 15 cm above ground surface, and precipitation. Below-ground sensors recorded soil moisture and temperature at various depths (Table 11-1).


Servicing a weather station consisted of downloading data onto a palmtop computer and checking for damaged or malfunctioning equipment. Data were downloaded from the palmtop to a PC at the office and entered into an Excel spreadsheet. Summary data were then generated for daily maximum, minimum, and average values for all relevant parameters, with monthly summary figures also generated. All data were backed up on disks and stored in a fire-proof vault.

Monthly rainfall data were gathered from the Forester rain gauges by measuring the amount of pre-measured transmission fluid (which prevented evaporation of water) and rain water in the bucket and subtracting the known quantity of transmission fluid. Then, fresh transmission fluid was measured and placed in the bucket. Water was separated out of the used transmission fluid so the fluid could be used again. Data from these rain gauges were entered into an Excel spreadsheet. Daily and monthly rainfall summaries were provided to monument staff seasonally and within a few days of the new year for a given year.

Regional climate data were obtained from Hastings and Humphrey (1969); Sellers, Hill, and M. Sanderson-Rae (1985); and from the Western Regional Climate Center web site (WRCC 2005) to compare with OPCNM stations. Sites included for elevation profiles included Ajo, Anvil Ranch, Arivaca, Casa Grande, El Riito (Sonora), Eloy, Gila Bend, Kitt Peak, Puerto Penasco (Sonora), Ruby, Santa Rosa School, Sasabe, Sells, Tacna, and Yuma (Citrus Station).

ResultsLong-term precipitation and temperature data for the headquarters area are presented in Figures 11-2, 11-3, and 11-4. A 10-year moving average (Figure 11-2) indicates that annual total precipitation has gone through 2 multi-decade cycles, and we appear to be in a major drought phase. The driest year in the 1943-2005 record was 2002 with 2.16 inches (55 mm), compared to

the wettest year in 1983 with 19.64 inches (499 mm) of rain. Mean annual precipitation for the period of record is 9.468 inches (240.5 mm).

Mean annual temperature has increased gradually over the period of record and so have the mean cold month (January) and warm month (July) temperatures (Figure 11-3 and Table 11-3). The coolest year on record was 1951 with an average temperature of 67.7 oF (19.8 oC) and the warmest was 1995 with an average 72.7 oF (22.6 oC). The number of freezing days has declined over the years (Figure 11-4), with a maximum of 34 occurring in 1949 and minimum of 2 occurring in 1995.

Annual and monthly summaries for precipitation and temperature are provided for each monitoring station and rain gauge, in Appendices C and D. Figure 11-5 provides a view of annual rainfall at 12 sites. Several significant rainfall events occurred from 1997 to 2005. Tropical Depression Marty stalled over the northern Gulf of California on September 23-25, 2003 and delivered 2.22 inches (56 mm) at Middle Bajada and 5.58 inches (142 mm) at Alamo Canyon. The spring 2005 wildflower season was exceptional because October 2004 – February 2005 rainfall sums ranged from 5.05 inches (128mm) at Growler Valley to 11.75 inches (298mm) at Arch Canyon. On average, these sites receive 3.78 inches (96mm) and 5.78 inches (147mm) for the period October – February.

Spatial variation is also evident within OPCNM and in comparison with other sites in the region. Annual rainfall increases with elevation (Fig. 11-5) and there is a general decline in rainfall at OPCNM from east to west. Based on Figure 11-5, annual rainfall between 15 and 20 inches (380 and 500mm) might be expected on Mount Ajo (elevation 1465m). Figure 11-6 shows mean annual temperatures declining with increasing elevation. Bull Pasture, the highest station in OPCNM, is warmer in winter than many valley bottom sites (Appendix D).


Table 11-3. Summary of regression statistics for climate trends at Organ Pipe Cactus N.M. headquar-ters. X = year for all.

0

5

10

15

20

25

1940 1950 1960 1970 1980 1990 2000 2010

Annual precipitation total 5-year moving average 10-year moving average

Figure 11-2. Annual precipitation (inches) recorded at Organ Pipe Cactus N.M. headquarters, 1943-2005.

N R R2Adjusted

R2F Sig

Number of days at or below 32 oF, 1949-2005 57 0.649 0.4210 0.4105 39.991 0.0000

Y = 641.445 - 0.317X

January average temperature, 1949-2005 57 0.462 0.2130 0.1987 14.887 0.0003

Y = 0.084X - 113.101

Annual average temperature, 1949-2005 57 0.623 0.3886 0.3775 34.960 0.0000

Y = 0.051X - 30.455

July average temperature, 1948-2005 58 0.331 0.1094 0.0935 6.881 0.0112

Y = 0.029X + 30.571

Annual precipitation, 1943-2005 63 0.172 0.0296 0.0137 1.858 0.1778

Y = 0.033X - 55.368

Annual precipitation, 1943-1999 57 0.280 0.0782 0.0614 4.663 0.0352Y = 0.059X - 106.540


Figure 11-3. Warm month, mean annual, and cold month temperatures (°F), recorded at Organ Pipe Cactus N.M.headquarters since 1948-49.

Figure 11-4. Annual number of freezing days (minimum temperatures of 32°F or less), recorded at Organ Pipe Cactus N.M.headquarters since 1949.

0

5

10

15

20

25

30

35

40

1940 1950 1960 1970 1980 1990 2000 2010

40

50

60

70

80

90

100

1940 1950 1960 1970 1980 1990 2000 2010

Warm month temperature Mean annual temperature Cold month temperature


Figure 11-5. Annual rainfall at 12 monitoring sites with the longest record at Organ Pipe Cactus N.M.

Figure 11-6. Mean annual precipitation and elevation at Organ Pipe Cactus N.M. and region. The high-est elevation site is Kitt Peak.

0

5

10

15

20

25

30

1980 1985 1990 1995 2000 2005 2010

Ann

ual r

ainf

all (

inch

es)

Alamo

Acuna

Arch

Bull

Dolo

Dowl

Drip

MP69.4

QBQ

Seni

Grow

Sals

0

5

10

15

20

25

0 1000 2000 3000 4000 5000 6000 7000 8000

Elevation (feet)

Mea

n A

nnua

l Pre

cepi

tatio

n (in

ches

)

OPCNM Regi on


DiscussionClimate data, especially rainfall, relates to many other resources of interest, including growth rates in cacti, relative abundance in wildlife populations, and groundwater levels (see other report chapters). Anecdotal information also relates climate to wildflower blooms (e.g., spring 2005, following wet winter of 2004-2005) and wildfire events (e.g., spring-summer 2005).

Climate data from all OPCNM stations provide a unique opportunity to develop high resolution models of climate variability. Such models, (e.g., Comrie and Broyles, 2002) can help understand and predict abrupt spatial variation related to local convection patterns.

Trends in precipitation, temperature, and number of freezing days were previously analyzed by Rowlands (2002). Using regression analysis, he obtained a significant increase in annual precipitation for the period 1943-1999 at monument headquarters. Since 1999, OPCNM has experienced a drought and a regression

analysis of the 1943-2005 data does not yield a significant increase (Table 11-3).

Organ Pipe Cactus N.M. lies in the transition between Arizona Upland and Lower Colorado Valley subdivisions of the Sonoran Desert. It also lies approximately 150 km north of the Central Gulf Coast subdivision and is well known for the high number of species characteristic of that desert. A comparison of OPCNM climate with regional stations suggests that OPCNM receives slightly less warm-season precipitation than the Central Gulf Coast and receives much more cool-season precipitation (Figure 11-7). Cold month temperatures are generally lower and warm month temperatures, generally higher, at OPCNM compared to the Central Gulf Coast (Figure 11-8).

The long-term changes in temperature and number of freezing days will ultimately affect the flora and fauna of this region. Frost-sensitive species, such as senita (Pachycereus schottii) and ashy jatropha (Jatropha cinerea), may expand their geographic distributions northward. Temperate

50

55

60

65

70

75

0 1000 2000 3000 4000 5000 6000 7000 8000

Elevation (feet)

Mea

n A

nnua

l Tem

pera

ture

(F

)

OPCNM Regi on

Figure 11-7. Mean annual temperature and elevation at Organ Pipe Cactus N. M. and region. The high-est elevation site is Kitt Peak.


0

20

40

60

80

100

120

140

160

180

200

20 70 120 170 220 270 320

Warm season precipitation ( mm)

Coo

l sea

son

prec

ipita

tion

(mm

)ARIZONA UPLAND CENTRAL GULF COAST LOWER COLORADO ORPI

Figure 11-8. Mean annual cool season (Oct-Mar) vs warm season (Apr-Sep) precipitation at Organ Pipe Cactus N.M. and other Sonoran Desert stations.

4

6

8

10

12

14

16

18

20

25 27 29 31 33 35 37

Warm month temperature ( oC)

ARIZONA UPLAND CENTRAL GULF COAST LOWER COLORADO ORPI

Col

d M

onth

Tem

pera

ture

( o C

)

Figure 11-9. Mean annual cold month vs warm month temperature (oC) at Organ Pipe Cactus N.M. and other Sonoran Desert stations.


zone species may disappear from the small mountain-top communities in southwestern Arizona. Most vulnerable, may be populations with an age structure and biogeographic distribution that is distinctly relictual. Some populations of redberry juniper (Juniperus coahuilensis) consist entirely of ragged-looking old adults and are confined to protected north-facing slopes at high elevations where the most cool-mesic environments occur. Documenting such trends could help increase public awareness of the effects of global climate change on local ecosystems.

Sonoran Desert Network (SODN)Climate is one of 25 vital signs selected by the network for a regional monitoring program (Mau-Crimmins et al. 2005). An excerpt from the SODN Phase III Monitoring Plan summarizes the significance and objectives of broad and meso-scale climate monitoring:

Broad-scale ClimateThe climate of a region drives ecosystem processes, dictating species’ distributions, governing nutrient cycling, and driving changes in other abiotic components of the system. 1. Determine long-term trends in temperature, precipitation, and synthetic variables (PET, drought indices, etc) in the Sonoran Desert region.

2. Determine how broad-scale climate is related to other vital signs.

Meso-scale ClimateThe local (mesoscale) climate within a park drives localscale ecosystem processes, dictatingspecies’ distributions, governing nutrient cycling, and driving changes in other abiotic components of the system.

1. Evaluate spatial and temporal trends in temperature, precipitation, wind speed,wind direction, relative humidity, snow depth, and variables appropriate for

understanding other vital signs in SODN parks.

2. How do local weather conditions influence biotic and abiotic processes (e.g.,leaf-out, flowering, invasion by nonnative species, fire threat?)

3. How do climatic variables vary over complex topography within the scale of apark unit?

In October 2005, OPCNM and SODN staff met to discuss integration of EMP and network projects. Several goals were identified including the development of metadata and protocols that meet current NPS standards. The existing OPCNM climate data set is vast and will require extensive analysis to realize its full utility and determine the best configuration for future climate monitoring. The network was provided with a complete copy of the data set and the integration process is moving forward.

Recommendations• Continue to integrate EMP climate

monitoring with the Sonoran Desert Network. Work with the network to determine how many climate monitoring sites are needed and develop procedures for routine data analysis and reporting. Also, evaluate current and future needs for upgrade of climate monitoring equipment.

• Climate monitoring has generated a large data set that has not been thoroughly analyzed. The data should be formatted for analysis and placed on a website where it can be accessed by researchers.

• Monitor selected species and communities at high elevation, cool-mesic sites to track impacts of global warming. Long-term changes are expected to be slow and monitoring can take place at wide intervals, such as every 10 years.

Acknowledgements Field assistance was provided by Ami Pate.


Literature Cited

Bennett, P. S. and M.R. Kunzman. 1987. Organ Pipe Cactus National Monument biosphere reserve sensitive ecosystems program. Special Report Number 7, Cooperative Park Studies Unit, The University of Arizona, Tucson. 82 pp.

Comrie, A.C., and B. Broyles. 2002. Variability and spatial modeling of fine-scale precipita-tion data for the Sonoran Desert of south-west Arizona. Journal of Arid Environments 50: 573-592.

Hastings, J.R., and R.R. Humphrey. 1969. Cli-matological data and statistics for Sonora and northern Sinaloa. Technical Reports on the Meteorology and Climatology of Arid Regions No. 19. University of Arizona Institute of At-mospheric Sciences.

Mau-Crimmins, T., A. Hubbard, D. Angell, C. Filippone, and N. Kline. 2005. Sonoran Desert Network Vital Signs Monitoring Plan: Phase III. Sonoran Desert Network. Tucson, Arizona. Technical Report NPS/IMR/SODN-003. 174pp.

Rowlands, P.G. 2002. Low Temperature and Other Climatic Trends at Organ Pipe Cactus National Monument: Depiction and Relevance to Long-Term Ecological Monitoring. Unpub-lished PowerPoint Presentation.

Sellers, W.D., R.H. Hill, and M. Sanderson-Rae. 1985. Arizona climate. The first hundred years. University of Arizona.

WRCC. 2005. Western Regional Climate Center. Arizona Climate Summaries. http://www.wrcc.dri.edu/summary/climsmaz.html.

IntroductionMethodsResultsDiscussionLiterature Cited

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