广州帽峰山林区空气负离子和气象因素全年时尺度变化及关系

Changes and Relationships in Hourly Scales throughout the Year for the Negative Air Ions and Meteorological Factors in Maofeng Mountain Forest Areas,Guangzhou

目前,空气负离子(NAI)浓度水平已成为反映城市林区空气质量及康养效应的重要指标之一。基于广州市帽峰山林区空气负离子、气象因素的连续定位观测,对2018年林区NAI浓度及气象因素在时尺度的变化和关系进行了系统的研究解析。结果表明:林区全年NAI时均浓度变化在380—14618 ion·cm−3间、年平均为1144.2 ion·cm−3;10月NAI浓度最高达1375 ion·cm−3、是相应最低的5月的1.73倍;林区全年NAI浓度≥4000 ion·cm−3均出现在9次降雨过程中,且每次降雨的最大雨强前1小时的NAI浓度最高,表明在强对流降雨过程中雷电电离对NAI浓度影响在最大雨强前的1小时最为显著。除去全年的降雨天外,林区NAI浓度与总辐射量的昼变化节律一致性高、两者间呈极显著的二次回归关系(P=1.2×10−9),且总辐射量在310—530 W·m−2间的NAI浓度相对较高。林区全年NAI时均浓度与对应的气温、空气湿度、气压间存在极显著的多元线性关系(P=4.3×10−254);由于时尺度的单气象因素在等值点对应的NAI浓度离差较大,使两者的回归关系精度偏低;因此,以各气象因素的等值点、小梯度递增与对应的多NAI浓度值均予平均处理后,获得的回归关系的精度被显著提高,回归模式更适宜林区NAI的平均浓度估算应用。

At present,the concentration level of negative air ions(NAI)has become one of the important indexes to reflect the air quality and health effects in urban forest areas.Based on the continuous location observation for the NAI and meteorological factors in Maofeng mountain forest areas of Guangzhou,we systematically evaluated the association and changes between the NAI concentration and meteorological factors of the forest areas in 2018 in hour scales.The results showed that the NAI hourly mean concentration was 1144.2 ion·cm−3 while the NAI concentration ranged from 380 to 14618 ion·cm−3 for the forest areas in all year.The highest NAI mean concentration in October was 1375 ion·cm−3,which was 1.73 times higher than that in May.Furthermore,we found that extreme high concentration(NAI≥4000 ion·cm−3)all appeared in the course with nine rainfalls of the forest areas for the whole year,and the maximum level of NAI was observed within 1 hour before the maximum rain intensity for each rainfall.And that indicated that the influence of lightning ionization on the NAI was most significant before the maximum rain intensity in each heavy convective rainfall process.In addition to the rain days for all year,hourly mean change of daylight for the NAI concentration and total radiation in the forest areas was highly consistent during the dry and rainy seasons;in addition the NAI concentration was relatively high when total radiation ranged from 310 to 530 W·m−2.From this,it was also quantified that the quadratic relationship between NAI concentration and total radiation.There was a significant multiple linear relationship between the hourly NAI concentration and corresponding air temperature,air humidity and air pressure in the forest areas for the all year,which was aligned with the attributes of meteorological factors.As the regression relationship between the hourly NAI and single meteorological factor was affected by the NAI large dispersion on the equal points of the latter.Therefore,the regression accuracy was significantly improved for the two based on the mean treatment that the NAI on the equal points or incremental gradient for each meteorological factor.Conducting the effect models of single meteorological factor on the NAI mean concentration will be more plausible to assess the air quality in the forest areas.