The U.S. Environmental Protection Agency, the National Park Service, and the Texas Commission on Environmental Quality sponsored the Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study, with technical support provided by the Electric Power Research Institute (EPRI). The BRAVO Study involved a four-month intensive monitoring period from July through October 1999 collecting 24 hour and semi-continuous aerosol, optical and gaseous data. The 24 hour data included speciated PM2.5 data following the IMPROVE protocol at 37 sites throughout Texas. The study also released perfluorocarbon tracers from four locations and monitored them throughout Texas.

Ambient concentrations of gases and particles as measured by filter packs.

Chemical speciation concentration data from aerosol filter packs at local conditions.

The Interagency Monitoring of Protected Visual Environments (IMPROVE) program is a cooperative measurement effort governed by a steering committee of representatives from Federal, state, and regional organizations. The IMPROVE monitoring program was established in 1985 to facilitate the creation of Federal and State implementation plans for the protection of visibility in Class I areas (156 national parks and wilderness areas) as stipulated by the 1977 amendments to the Clean Air Act.

An IMPROVE monitoring site can have missing data for various reasons, e.g. a power outage at the monitoring site. In some instances, there is enough missing data that the monitoring site fails the completeness criteria to calculate a valid haze metric for the Regional Haze Rule (RHR) baseline period (2000-2004). The RHR guidance documents has procedures for filling in some missing values with “patched” data; however this criteria is strict and few values are actually filled in. A number of States have developed different procedures to fill in additional missing values and submitted these data to the VIEWS database. These data are referred to as “substituted” data to differentiate them from the RHR “patched” data. Currently substituted data are available from 19 monitoring sites. These sites were selected because they either did not have the required 3 years of valid data to calculate the RHR haze metrics for the baseline period or they did not have complete data for the year 2002. The Regional Planning Organizations modeled the year 2002 and monitoring data was needed to evaluate and use the modeling results.

Total Wet Deposition Reported in Kilograms per Hectare

Data files containing daily, annual and five year average values of composite aerosol concentrations and light extinction and haze metrics following the calculating procedures in the regional haze guidance documents using the new and old IMPROVE light extinction algorithms. In addition, the means of the best 20% visibility days (G10), worst 20% visibility days (G90), and all visibility days (G100)for the 5 year Regional Haze Rule baseline period (2000-2004) are provided. The baseline values were calculated following the RHR guidance documents using the new IMPROVE algorithm both with and without the State supplied substituted data.

Precipitation-Weighted Mean Concentrations Reported in Milligrams/Liter

Total Wet Deposition Reported in Kilograms per Hectare

This file contains the second version of the natural haze level II estimates based on the work of the Natural Haze Levels II Committee. These data fix a minor error in the first version of the natural haze level II estimates. The first version of these data did not include values for monitoring sites with less than three complete years of monitoring data. States have provided substituted data for missing data values at these sites that represent haze in class I areas. For these sites the natural haze levels are estimated using only the measured data and using measured data and substituted data values.

NPS W126 Ozone Metrics

Ambient aerosol field measurements were conducted at Reserve, KS, in Fall/Winter 2002 to provide insights into aerosol climatology in the CENRAP domain. The monitoring platform site was next to an IMPROVE Protocol monitoring station which commenced operations in Summer 2002. The measurement strategy featured two intensive periods – each nominally six weeks in duration - with a battery of semi-continuous monitors and integrated samplers. Several of the semicontinuous monitors were also operated during the weeks between these two intensive periods. The data set includes all data collected during the deployment, including prior to, between, and following the two intensive studies.