Program highlights

The fall burn officially began September 15, 2003 and ran through November 28, 2003, a total of 75 days. Total rice acreage burned was 33,908 acres, down from 37,373 acres in 2002. Other agricultural burning, such as orchard prunings, totaled 18,995 acres, an increase from 11,478 acres the previous year. A few other facts from 2003 include:

• Average daily burn - 705 acres
• Average daily allotment - 1,993 acres
• Most acreage burned - November 6 (4,299 acres); November 14 (3,245 acres); and November 5 (2,704 acres)
• Declared "no burn" days - one
• Measurable precipitation - 13 days

Weathernews is the Chico-based firm under contract with the Rice Research Board to provide real-time meteorological information from a network of 19 remote weather stations to county air pollution control officials. County air pollution control officials decide the amount and location of acreage to be burned, depending on weather conditions and prescribed allotments. Existing law limits rice straw burning for disease control to the lesser of 25 percent of each grower's planted acreage up to an annual total of 125,000 acres in the Sacramento Valley Air Basin. Of the 125,000-acre total, a maximum of 90,000 acres can be burned during the fall.

The information from the automated weather stations is made available to all rice growers in the Sacramento Valley on a year-round basis at the Rice Research Board's password-protected Web site. Here growers can also use the data to calculate growing degree-days, phenology models and determine field temperatures to assess blanking and other weather-related rice issues.

Monthly Weather Review

In September 2003 a well-developed marine layer pushed onshore at the onset of the fall burn period, providing cool southerly breezes through the Delta and up the Sacramento Valley. However, a strong ridge of high pressure quickly took over, providing more stable wind conditions and warmer temperatures. The hot weather lasted a week before another marine layer intruded into the Valley toward month's end. High pressure at this time of the year typically produces stagnant air, trapping pollutants near the surface and minimizing the amount of field burning taking place.

In October 2003 dry and unseasonably warm temperatures persisted with light winds and poor atmospheric dispersion. Wet, colder weather did not materialize until the last day of the month. A dry front passed through the Valley on October 4, sufficiently mixing the atmosphere to permit the first 1,000+ acre burn day. Gusty winds and favorable burning conditions also occurred on October 8. The most acreage burned in October occurred on the 22nd, when a marine intrusion allowed for 1,284 acres to be burned.

In November 2004 a frequently wet weather pattern developed across the north state. Most of these storms produced fairly light precipitation, which boded well for burning activities. Good two-day burn periods occurred November 5,6 and November 13, 14. However, it was an extended period of dry, seasonably mild weather occurring November 18-26 that led to the longest period of most consistent burning in the 2003 fall burn.

The burn program finished during the Thanksgiving weekend, when more robust storm activity and less effective drying in between systems loomed on the horizon.

 

Fall burn acreage

Air quality concerns

The number of citizen complaints has been recorded each fall since the program began in 1981. This may be one measure of the program's success each year but not necessarily the most reliable measure. Compared to previous years, the state Air Resources Board recorded very few complaints. Of the complaints recorded, most came from Butte, Colusa and Placer counties. Glenn, Yolo, Sacramento and Tehama counties recorded the fewest.

During the fall 2003, field burning was limited on days of poor air quality and poor atmospheric dispersion and maximized during days of good air quality and good atmospheric dispersion. This greatly minimizes the impact of agricultural burning on the air quality in the Sacramento Valley Air Basin, just as intended. The air quality during the fall is often more influenced by other sources of pollution - such as wildfires, vehicular traffic and residential burning - than by the burning of rice fields.