硫酸盐直接辐射强迫的在线与固定转化率模拟方法的对比研究

COMPARISON OF ON-LINE COUPLED AND CONSTANT TRANS- MISSION SIMULATION METHODS FOR DIRECT RADIATIVE FORCING OF ANTHROPOGENIC SULFATE

以2000年1、4、7、10月为例,利用区域气候模式,比较了模拟硫酸盐气溶胶分布和直接辐射强迫的在线模拟方法与固定SO2到硫酸盐转化率方法,并与全球模式的结果进行了对比检验.结果表明:在线模拟得到的主要结果与全球平均结果符合得很好,但固定转化率方法存在明显偏差;两种方法硫酸盐柱含量的差异在-4～12 mg/m2范围内,占在线模拟柱含量的42%以上,7月份差异最显著,1月份差异最小;大气顶辐射强迫差异在-1.8～0.4 W/m2之间,此差别占在线辐射强迫的26%以上;采用36.7%的固定转化率对冬季过大、夏季偏小,只有春秋季的江南部分地区适合.由于固定转化率方法不能反映温度、辐射、水汽、云水等气象要素的季节性变化对硫酸盐生成率的影响,因而对硫酸盐含量和分布的季节变化模拟存在偏差,这是导致上述差异的重要原因.

Two methods, on-line coupled and constant transmission, for radiative forcing simulation of anthropogenic sulfate over China area have been compared within Jan., Apr., Jul. and Oct. 2000. The following results can be figured out based on the comparison： （1） The results of on-line coupling are consistent with global averaged results from GCMs. （2） Both column burden and radiative forcing at TOA of anthropogenic sulfate have obvious differences between the two simulation methods. （3） The maximum difference range of sulfate burden is from -4 to 12 mg/m^2. Its maximum emerges in July and minimum value in January. The relative difference to that of on-line sulfate burden is more than 42% on the whole simulated area scale. If partial area averages are compared, their values are more than that of the whole area scale. （4） The difference of radiative forcing at TOA is within -1.8-0.4W/m^2. The relative difference to that of on-line radiative forcing at TOA is more than 26% on the whole simulated area scale. （5） The results of constant transmission method differ from on-line or off-line methods fairly, and it is hard to give the fact of sulfate burden and radiative forcing.