Test Criteria for the South Central Coast Air Basin

This page last reviewed June 20, 2008

Effective February 1, 2003 the Air Resources Board Meteorology Section implemented new test criteria for the South Central Coast Air Basin (SCCAB). Burn decisions based on Title 17 criteria were previously made for three regions within the SSCAB:

1. Above 3,000 feet mean sea level (msl)
2. Below 3,000 feet msl in the South Section
3. Below 3,000 feet msl in the Northern Section.

Under the new test criteria, burn decisions will be made for four regions in the SSCAB, as follows:

1. Above 3,000 feet msl (no change)
2. Below 3,000 feet msl in the South Section (no change)
3. Below 3,000 feet msl in the Coastal Zone of the North Section
4. Below 3,000 feet msl in the Inland Zone of the North Section.

The Coastal and Inland Zones will affect a portion of Santa Barbara County and all of San Luis Obispo County only. In Santa Barbara County, the Coastal Zone extends to the west of Highway 101 from the Santa Barbara/San Luis Obispo County line south to the Santa Ynez Mountains ridgeline. The Inland Zone extends to the east of Highway 101 from the Santa Barbara/San Luis Obispo County line south to the Santa Ynez Mountains ridgeline. See map.

In San Luis Obispo County, the boundary for the Coastal and Inland Zones begins at the highest elevation of the coastal range of mountains at the San Luis Obispo/Monterey County line and runs southward along the coastal range at the highest elevation, with the City of Atascadero wholly in the Inland Zone. The boundary continues southward along the highest elevation of the coastal range to its intersection at Hi Mountain Road where it then follows the centerline of Hi Mountain Road southward. When Hi Mountain Road intersects Trout Creek, the boundary follows Trout Creek east and upstream until it intersects with the highest elevation of the coastal range. The boundary then continues southward along the highest elevation until it intersects the Huasna River and moves southward following the Huasna River. It then continues into Twitchell Reservoir following the centerline of the Reservoir to the San Luis Obispo/ Santa Barbara County line. See map.

Above 3,000 feet msl, a permissive burn day will be declared when both of the following criteria are met:

1. Near 4:00 a.m., the mean 500 millibar (mb) height over the Basin is less than the limiting mean height given in Table 2 of section 80320.
2. The expected 4:00 p.m. mean 500 mb height over the Basin is less than the limiting mean height given in Table 2 of section 80320.

Below 3,000 feet msl in the South Section, a permissive burn day will be declared when both of the following criteria are met (no change):

1. The maximum mixing depth is expected to be at least 1,500 feet msl.
2. The expected afternoon onshore airflow is expected to be at least five miles per hour.

Below 3,000 feet msl in the North Section of the Coastal Zone, a permissive burn day will be declared when both of the following criteria are met (no change):

1. The maximum mixing depth is expected to be at least 2,000 feet msl.
2. The expected afternoon onshore airflow is expected to be at least five miles per hour.

Below 3,000 feet msl in the North Section of the Inland Zone, a permissive brun day will be declared when all of the following criteria are met:

1. Near 4:00 a.m., the mean 500 millibar (mb) height over the Basin is less than the limiting mean height given in Table 2 of section 80320.
2. The expected 4:00 p.m. mean 500 mb height over the Basin is less than the limiting mean height given in Table 2 of section 80320.
3. The maximum mixing depth is expected to be at least 2,000 feet msl.
4. The expected afternoon onshore airflow is expected to be at least five miles per hour.

In cooperation with the South Central Coast Air Basin, the ARB has three years to develop new criteria or to use alternate criteria to those specified to establish burn days, no-burn days, and marginal burn days.

§ 80320. Table 2

Limiting Mean 500-Millibar Heights* by Month