Sun Photometer Data (AOD) 2011 from Zeppelin Station, Ny-Ålesund, Svalbard (AWIPEV)

Aerosol optical depth (AOD) is measured by a sun photometer, type SP1a by Dr. Schulz & Partner GmbH in 17 wavelengths between λ = 369nm to 1023nm with a field of view of 1° × 1° and a time resolution of 1 minute. In winter 2012/13 a new sun photometer was installed and just 10 of 17 wavelengths remained in the same wavelength range. With the nine out of ten wavelengths optical parameters like the AOD are computed. The one, which is devoted to water vapor is omitted. The instrument is calibrated regularly in pristine conditions at Izaña, Tenerife, via Langley method. A cloud screening based on short scale fluctuations of the AOD is used. The uncertainty for the AOD is generally said to be around 0.01. However, this is the maximum error of the instrument because the fluctuations are much smaller by comparing data minute by minute under low or constant aerosol conditions. The number of individual measurements differs between a few hundreds, especially in March and September, to up to 12,000 in early summer. No trend in each month can be seen comparing the amount of cloud-free measurements over the years. Only an annual cycle due to polar day and night is included in the data. Due to the instrument data is only available in clear sky conditions. In this regard the data should represent the real aerosol conditions. Only aerosols that are advected and processed within clouds or hygroscopic growth cannot be measured by this instrument. In this data set AOD, Angstrom-Exponent and modified Angstrom-Exponent (Graßl, Ritter 2019, Remote Sensing, https://doi.org/10.3390/rs11111362) are given for the sun photometer at Zeppelin Station, operated by AWIPEV, for the time 18. April 2011 until 05. October 2011. The variables are in netcdf format for each measurement day. The used instrument for the measurement period was SP1A13.气溶胶光学厚度（aerosol optical depth, AOD）由舒尔茨博士合伙有限公司（Dr. Schulz & Partner GmbH）生产的SP1a型太阳光度计（sun photometer）进行测量，该仪器覆盖369纳米至1023纳米的17个波段，视场角为1°×1°，时间分辨率为1分钟。2012/2013年冬季，该站点更换了一台新的太阳光度计，仅保留原17个波段中的10个，且波段范围未发生变化。利用该10个波段中的9个可计算得到气溶胶光学厚度等光学参数，用于水汽探测的1个波段则被剔除。该仪器会定期在特内里费岛伊萨尼亚（Izaña, Tenerife）的纯净大气环境中通过兰利法（Langley method）进行校准。研究采用基于气溶胶光学厚度短时波动的云筛查方法。通常认为气溶胶光学厚度的测量不确定度约为0.01，但该数值仅为仪器的最大误差：在气溶胶浓度较低或环境稳定的条件下，逐分钟比对观测数据可知，实际波动远小于该值。 单次观测的有效样本量差异显著，3月与9月的样本量仅数百个，而初夏时可多达12000个。对历年无云观测的样本量进行比对后，未发现月度趋势性变化，数据仅包含由极昼、极夜交替导致的年周期特征。由于该仪器仅能在晴空条件下获取观测数据，因此其记录的气溶胶状态可代表真实大气气溶胶状况。但该仪器无法探测在云内平流输送、发生云内转化或经历吸湿性增长的气溶胶粒子。 本数据集包含由AWIPEV运营的齐柏林站太阳光度计在2011年4月18日至2011年10月5日期间获取的气溶胶光学厚度、安斯特朗指数及修正安斯特朗指数，相关参考文献为：Graßl, Ritter 2019, Remote Sensing, https://doi.org/10.3390/rs11111362。所有变量以每日观测为单位存储为NetCDF格式，本次观测时段使用的仪器型号为SP1A13。