Seasonal Variations in High Arctic Free Tropospheric Aerosols Over Ny-Alesund, Svalbard, Observed by Ground-Based Lidar
Seasonal Variations in High Arctic Free Tropospheric Aerosols Over Ny-Alesund, Svalbard, Observed by Ground-Based Lidar
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陆基激光雷达观测到的斯瓦尔巴群岛新奥勒松上空高北极自由对流层气溶胶的季节变化
DOI：
10.1029/2018jd028973
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Toshiaki TAKANO
中科院分区：
文献类型：
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作者：
Takashi Shibata;Koichi Shiraishi;Masataka Shiobara;Suginori Iwasaki;Toshiaki TAKANO
从2014年3月起，在Ny‐ Ellesund（78.9°N，11.9°E）通过激光雷达观测了高北极上空的自由对流层气溶胶约4年。根据这些观测结果，得到了532和1,064 nm两个波长气溶胶后向散射系数的垂直廓线，以及532 nm一个波长的退偏比。气溶胶后向散射系数、粒子退偏振比和色比（两个波长处后向散射系数的比值）分别与气溶胶粒子的质量浓度、非球形度和尺寸大致成正比。气溶胶后向散射系数表明，气溶胶月平均浓度在1 km左右的自由对流层最低处最大，在10 km左右的高度处小一个数量级，气溶胶浓度在春末至夏季最高，在夏末至秋季最低。在四个观测年中，对流层的去极化率小于百分之几。退偏振比和色比在冬春季最大，夏秋季最小。月平均非球形度和大小的最大值出现在月平均浓度的最大值之前几个月，表明气溶胶粒子的形态或特征存在季节性变化。小于百分之几的小粒子退偏振比是一致的，与以前的研究结果，北极自由对流层气溶胶粒子在春季是由液相硫酸盐和煤烟颗粒的混合物。
Free tropospheric aerosols over the high Arctic were observed by lidar for about 4 years from March 2014 at Ny‐Ålesund (78.9°N, 11.9°E). Vertical profiles of aerosol backscattering coefficients at two wavelengths, 532 and 1,064 nm, and depolarization ratio at one wavelength, 532 nm, are derived from these observations. The aerosol backscattering coefficient, the particle depolarization ratio, and the color ratio (the ratio of the backscattering coefficients at the two wavelengths) are roughly proportional to mass concentration, nonsphericity, and size of the aerosol particles, respectively. The aerosol backscattering coefficients indicate that monthly averaged concentration of aerosols was largest in the lowest free troposphere at about 1 km in altitude and was an order of magnitude less at an about 10 km in altitude and that the concentration of aerosols was highest from late spring to summer and lowest from late summer to fall. The depolarization ratio was less than a few percent in the troposphere during the four observed years. The depolarization ratio and the color ratio were greatest from winter to spring and smallest from summer to fall. The maxima in the monthly averaged nonsphericity and size precede the maxima in the monthly averaged concentration by a few months, indicating a seasonal change in the morphology or the characteristics of the aerosol particles. The small particle depolarization ratio of less than a few percent is consistent with previous findings that Arctic free tropospheric aerosol particles in spring are composed of a mixture of liquid phase sulfate and soot particles.