DNQ1与FD12型能见度仪观测比对及影响因子研究

DNQ1型前向散射能见度仪是目前我国气象站应用最多的能见度仪之一，但对其观测能力的评估及与国际上同类能见度仪间的比对研究较少。本文利用2015年1—3月北京上甸子国家大气本底站DNQ1和FD12型能见度仪观测资料开展比对研究，分析两种能见度仪的观测差异特征及与关键气象要素和大气成分的关系。结果表明：两种仪器观测的小时平均能见度的变化趋势较为一致，二者相关系数为0.98。除降雨外，DNQ1与FD12型仪器观测的能见度差值受不同天气状况（包括晴天、沙尘、雾、霾、降雨和降雪）的影响较小，但随能见度等级的增加，差值范围和离散程度均有所增大。能见度差值随相对湿度的增加呈指数递减关系，与气温呈线性正相关关系，与气压、风速和风向关系不明显。两种器测能见度与相对湿度呈明显负相关关系，与其他气象要素的关系不明显。DNQ1能见度相对FD12能见度在每日不同时刻的相对偏差平均低于±10%，满足观测需求；二者在夜间的相关性优于白天，可能与相对湿度和气温的日变化有关。

Comparison of visibility measurements using DNQ1 and FD12 visibility meters and their major influencing factors

The DNQ1 forward scattering visibility meter is currently one of the most widely used visibility meters at weather stations in China.However, rare studies have evaluated and compared the performance of DNQ1 visibility meters with other similar visibility instruments worldwide.Therefore, we conducted a comparative study using observation data of DNQ1 and FD12 visibility meters at the Shangdianzi National Atmosphere Watch Station from January to March 2015.The characteristics of observed differences between the two visibility meters and their relationships with major meteorological parameters and atmospheric components were analyzed in this study.The results indicated that hourly mean visibility measured by two instruments exhibits a consistent variation trend, with a correlation coefficient of 0.98.Except for rainfall, the difference in visibility observed by DNQ1 and FD12 instruments is less affected by different weather conditions (including sunny days, sand-dust, fog, haze, rainfall, and snowfall), but the difference range and dispersion increase as visibility level increases.The visibility difference shows an exponential decrease with the increase of relative humidity, a linear positive correlation with air temperature, and an insignificant relationship with air pressure, wind speed, and wind direction.The mean relative deviation between DNQ1-and FD12-measured visibility at different times of the day is on average less than ±10%, which indicates that the NDQ1 visibility meter meets observation needs.The correlation between the two visibility at night is better than that during the day, which may be related to the daily variation of relative humidity and temperature.