Clear-air Vertical Air Motion Within the Marine Boundary Layer

The Doppler lidars (DL) at the ARM observatories operate at 1.5-micrometer wavelength and record backscatter and mean Doppler velocity. The DL present at the ARM ENA site records these quantities at a 1-second temporal and 30-meter range resolution. Reported here are daily files containing gridded values of noise-filtered and calibrated backscatter, and noise-filtered mean Doppler velocity. In addition we also report the noise-filtered and calibrated gradient of backscatter that is used to derive estimates of cloud base height. All of the variables are reported at a uniform 5-second temporal resolution and 30-m range resolution. The instrument reported raw backscatter was first corrected for telescope focus function, filtered for noise, and then calibrated by exploiting the constant lidar ratio exhibited during nonprecipitating stratocumulus cloud conditions. Hence, the reported backscatter can be used to derive aerosol and hydrometeor properties. Daily files are reported for the summer Intensive Operational Period (IOP) of the Aerosol, and Cloud and Experiments in the Eastern North Atlantic (ACE-ENA) field campaign. Similar files can be produced for any DL at ARM observatories. Please find below the header of the NetCDF files. double time (time) ; time:Long_Name = "Time" ; time:units = "Seconds from 1970-1-1 0:00:00" ; double height (height) ; height:Long_Name = "Height" ; height:units = "meters" ; double dl_el (time) ; dl_el:Long_Name = "elevation" ; dl_el:units = "degrees"; double dl_beta (time, height) ; dl_beta:Long_Name = "Noise Filtered Calibrated Backscatter" ; dl_beta:units = "1 / (m * Sr)" ; double dl_velo (time, height); dl_velo:Long_Name = "Mean Doppler Velocity" ; dl_velo:units = "m/s" ; double dl_att (time, height) ; dl_att:Long_Name = "Gradient of Backscatter" ; dl_att:units = "1 / (m ^ 2 * Sr)" ; double base (time) ; base:Long_Name = "Cloud base height" ; base:units = "meters" ;

ARM观测台站的多普勒激光雷达（Doppler lidar, DL）工作波长为1.5微米，可记录后向散射系数与平均多普勒速度。设于ARM ENA站点的该类雷达以1秒的时间分辨率与30米的距离分辨率采集上述两类数据。
本数据集提供的每日文件包含经噪声滤波与定标的网格化后向散射数据、经噪声滤波的平均多普勒速度数据。此外，还包含经噪声滤波与定标的后向散射梯度数据，该数据可用于反演云底高度。所有变量均统一采用5秒的时间分辨率与30米的距离分辨率。
本次上报的原始后向散射数据首先经过望远镜聚焦函数校正、噪声滤波处理，随后利用非降水层积云条件下恒定的激光雷达比完成定标。因此，本数据集所提供的后向散射数据可用于反演气溶胶与水凝物的相关特性。
本次提供的每日文件对应东大西洋气溶胶与云实验（Aerosol, Cloud and Experiments in the Eastern North Atlantic, ACE-ENA）野外试验的夏季强化观测期（Intensive Operational Period, IOP）。ARM观测台站的其他多普勒激光雷达亦可生成同类数据集。
以下为该NetCDF文件的文件头：
double time (time) ; time:Long_Name = "时间" ; time:units = "自1970年1月1日00:00:00起的秒数" ;
double height (height) ; height:Long_Name = "高度" ; height:units = "米" ;
double dl_el (time) ; dl_el:Long_Name = "仰角" ; dl_el:units = "度";
double dl_beta (time, height) ; dl_beta:Long_Name = "经噪声滤波与定标的后向散射系数" ; dl_beta:units = "1/(m·Sr)" ;
double dl_velo (time, height); dl_velo:Long_Name = "平均多普勒速度" ; dl_velo:units = "m/s" ;
double dl_att (time, height) ; dl_att:Long_Name = "后向散射梯度" ; dl_att:units = "1/(m²·Sr)" ;
double base (time) ; base:Long_Name = "云底高度" ; base:units = "米" ;