Abstract
This study reports the frequency of open burning, which was observed in two ways in Tsukuba-city, Ibaraki prefecture. First, the daily frequency between September and October, 2015, showed that the quantity increased before rainfall and that the rice residues, 57% of the total open burning, were burned in the order of hulls, then straw after harvesting. Secondary, the monthly frequency showed that the quantity tended to decrease from September, 2015, to August, 2016. The monthly frequency, which was taken by fixed point cameras on the top of Mt. Tsukuba, showed that the quantity tended to decrease from October, 2015, to May, 2016, and also showed that the quantity tended to increase on 10–11 am and 2–3 pm within a day. Based on these observations, a method to distribute the temporal emission ratio caused by rice straw open burning, which is expected to improve the accuracy of regional emissions and forecasting, has been developed. The regression coefficients indicated that the quantity of open burning increases before rain and decreases due to strong wind. Applying the model to the prefectural rice harvest terms and weather data, the prefectural daily PM (particulate matter) emission ratios are estimated.
