Arizona State and Local Government Documents Collection

The purpose of the ambient air monitoring network is to sample air pollution in a variety of settings, assess the health and welfare effects, and assist in determining sources of air pollution. In general, six basic monitoring objectives and five measuring scales are used to determine the network design. Since it is physically and fiscally impossible to monitor the air in every location, representative samples must be obtained. These samples are determined by using the monitoring objectives and the spatial measurement scales. The network must be dynamic enough to maintain a current representative sample of the air quality. Air quality issues such as eight-hour ozone non-attainment boundaries and permits for new sources are diverse and controversial subjects for the citizens of Maricopa County. With its robust air monitoring network and mobile monitoring tools, the department strives to provide the most reliable and relevant air monitoring data to the public.

Pima County Department of Environmental Quality monitors ambient (outdoor) air pollutants throughout eastern Pima County, including the Tucson metropolitan area and Green Valley. There are six principal pollutants, called “criteria” pollutants that are monitored in accordance with the National Ambient Air Quality Standards set by the Environmental Protection Agency to comply with the Federal Clean Air Act. These standards were established to protect public health and the environment from harmful levels of air pollution.

The Pima County Department of Environmental Quality has prepared this document to be submitted to the U.S. Environmental Protection Agency, Region IX. The purpose of the Ambient Air Monitoring Network Plan is to determine if the network is achieving the air monitoring objectives specified in 40 CFR Part 58 Appendix D, which mandate adherence to certain number, type and location requirements of monitoring sites and specific site criteria such as monitoring inlet height. The review should also determine if modifications should be made to the network (e.g. through the termination or relocation of unnecessary stations or addition of new stations). In addition, the review is necessary in order to ensure that the residents of Pima County are provided adequate, representative and useful air quality data, and to provide adequate protection to public health.

The study had three main goals: (1) to assess the vulnerability of groundwater-dependent agriculture to climate variability, (2) to identify historical and current processes of adaptation to the vagaries of climate in the region— these refer to both system wide adaptations and individual farmer’s adaptations, and, (3) to assess the use of and needs for seasonal climate forecast information in agricultural decision making. The report is targeted at institutional stakeholders (i.e., agricultural extension personnel), physical scientists (particularly climatologists), and policymakers (at the level of NOAA and other federal agencies). Specific recommendations are made to these groups in order to improve the delivery of seasonal forecasts, set research priorities, and inform public policy.

The information presented here highlights the findings of a drought history study in support of the Governor's Drought Task Force activities, such as determining triggers for drought mitigation and response actions, based on observed hydroclimatic and other information. The material is intended to provide the relevant climatology background for non-specialists, and it is presented in a top ten or frequently asked question format. The questions and answers cover the major climate-related aspects of drought including long-term averages, seasonality, interannual and long-term spatial and temporal drought variations, extremes, and causes of climatic variability. The answers to each question include bulleted Quick Answers followed by a concise explanation of more detailed information. Example figures are presented within the text.

This paper summarizes the current state of knowledge concerning the climate of the Southwest. Low annual precipitation, clear skies, and year-round warm weather over much of the Southwest are due in large part to a quasi-permanent subtropical high-pressure ridge over the region. However, the Southwest is located between the mid-latitude and subtropical atmospheric circulation regimes, and this positioning relative to shifts in these regimes is the fundamental reason for the region's climatic variability. El Niño, which is an increase in sea surface temperature of the eastern equatorial Pacific Ocean with an associated shift of the active center of atmospheric convection from the western to the central equatorial Pacific, has a well developed teleconnection with the Southwest, usually resulting in wet winters. La Niña, the opposite oceanic case of El Niño, usually results in dry winters for the Southwest. Another important oceanic influence on winter climate of the Southwest is a feature called the Pacific Decadal Oscillation, which has been defined as temporal variation in sea surface temperatures for most of the Northern Pacific Ocean. The major feature that sets climate of the Southwest apart from the rest of the United States is the North American monsoon, which, in the US, is most noticeable in Arizona and New Mexico. Up to 50% of the annual rainfall of Arizona and New Mexico occurs as monsoonal storms from July through September.