|Rice Straw Burning
Program - 96
Don Schukraft, Certified Consulting Meterologist, Weather Network, Inc
|Last year was a good year for the rice straw burning program.
Favorable meteorological conditions allowed growers to burn substantially more acreage
than in the three previous seasons. And complaints to the Air Resources Board dropped to
the lowest level since 1989.
The 1996 fall burn ran from September 15 through November 18, a total of 64 days. During this period 128,380 acres were burned. Nearly 256,000 acres were left ready to burn. There were only nine "no burn" days declared - compared to 21 the previous year. Six of these days occurred from November 7 through November 12, when the atmosphere became quite stable and air quality deteriorated in the basin.
Improved Weather Monitoring
Preparations for the 1996 fall rice straw burning program began in summer with maintenance checks of the sensors, modems and dataloggers at the automated meteorological observing stations (AMOS) scattered throughout the Sacramento Valley. Radios and antennas were adjusted and computer software changes were made to improve operations and communications of weather data.
For the first time, meetings on the bum program were held at each county air pollution control office to provide greater opportunity for local input. Held during the end of August and the first part of September, these meetings were attended by personnel from the county air pollution control offices, the state Air Resources Board, Weather Network and Fife Environmental. A general meeting with all parties was then held in Yuba City on September 12 to review the program, its procedures and its objectives. Communication among all program participants at meetings such as this and during daily operations throughout the burn period is key to the success of the program.
A Fairly Good Weather Pattern
During most of September burning conditions were marginal. Burning averaged only 1,160 acres per day. Burning activity continued to progress slowly the first half of October. On October 24, however, a cold front approaching the Sacramento Valley provided excellent conditions for smoke dispersal. A total of 11,847 acres were burned on this day and the coefficient of haze (COH), a measure of air quality, averaged only 1.41 for this 24-hour period. Increasing south winds and an unstable atmosphere allowed 9,161 acres to be burned on October 28. Again the air quality over a 24-hour period remained quite good, with COH averaging only 1.37. (A COH reading of 3.0 or higher is considered a poor air quality day.)
Weather conditions turned unfavorable for burning between November 7 and November 12. Although no authorized rice straw burning took place, a high pressure system and little wind caused the COH values to rise to more than 5.0 on November 9 and November 12. "No burn" conditions were lifted the afternoon of Nov. 13, as the air quality and atmospheric stability improved due to changes in the weather pattern.
With a series of weather systems over the North Pacific moving toward California, rice straw burning became quite active on November 14, 15 and 16. During this three-day period, a total of 30,379 acres were burned, accounting for 76 percent of all the acreage burned in November. Rain from a storm that began moving into the state on November 16 forced an end to the burning program on November 18.
The good weather allowed growers to burn more acreage and hear fewer complaints about it in some time. A total of 17 complaints were recorded at the Air Resources Board, although more than 100 additional complaints were recorded at county air pollution control offices. Ironically, the greatest number of local complaints occurred on September 30, a day when only 2,560 acres were burned and the COH was only 1.13. When more than 30,000 acres were burned the last three days of the fall burn, only two complaints were recorded.
How The Burning Program Works
The nice straw burning program has been in place since 1981. A "burn plan" is submitted to the Sacramento Valley Basin Control Council and is approved each year by the California Air Resources Board (ARB). The plan provides for burning rice fields in the fall and during the spring months prior to planting. The primary objective of the program is to manage the burning of rice straw to take place with a minimum impact on the air quality and the citizens in the Sacramento Valley air basin, including rice farmers and their families.
Under contract with the Rice Research Board, Weather Network supplies detailed weather information daily to the ARB, county air pollution control offices and to Fife Environmental, which manages centralized computer operations. The ARB is responsible for making the final decision on whether to allow burning or not. Weather factors that affect this decision include the day's forecast, surface winds, transport winds, inversion strength and temperatures needed to break inversions. From this information a burn impact rating is set for each of the Valley's 35 burn zones. This rating is used in an algorithm to generate the number of acres each county is allocated to burn. Weather conditions are monitored and updated to local air pollution control officials several times each day.
There are six different levels of "burn days", ranging from a no-burn day, to prunings only day, to a "regular" burn day. If a regular "burn day" is declared, a basin-wide acreage allocation is issued. This acreage figure is then parceled out to each county according to a formula and predicted weather conditions. Each county then distributes assignable acreage to a list of growers who have indicated they are ready to burn. Weather conditions, field moisture and field location are all critical factors weighed in the decision-making process. Thus a grower near the top of the bum list may be passed over if wind conditions are unfavorable or if the field is too wet.
The data from 1996, as well as previous years, shows that the program is accomplishing its aims: maximizing burning on days with favorable atmospheric conditions and minimizing or eliminating burning on days when conditions are less than favorable.