LIAISE_ELS-PLAN_LMD_Mobile-Lidar-station_L2

Time and space resolution: 8 s – 48 m
Time is local time (UTC +2).

Log(P.R2) at 2.05 µm in arbitrary unit [a.u.]
Radial wind speed in [m/s] (2.05 µm lidar)
Temperature in [K] (0.35 µm lidar)
Specific humidity in [g/kg] (0.35 µm lidar)

Scanning device (Doppler lidar): time, azimuth, elevation
Scanning device (Raman lidar): time, azimuth, elevation

Description:
Lidar data are 3D measurements following a one-hour cycle basis:
1) 4 vertical cross section of the atmosphere close to the ground (z ~ 0-100m), range-height indicator scanning (RHI). Azimut = 26.56°; Elevation = -0.54° - 5.46°. Speed = 0.05°/s
2) 1 horizontal cross section of the atmosphere close to the ground (z~10 m), plane polar indicator (PPI). Azimut = 11.56° - 41.56°; Elevation = 0.41°, Speed = 0.1°/s
3) 4 vertical cross section of the atmosphere close to the ground (z ~ 0-100m), range-height indicator scanning (RHI). Azimut = 26.56°; Elevation = -0.54° - 5.46°. Speed = 0.05°/s
4) The rest of the hour is dedicated to vertical measurement.

Specific information:
21/07/19: irrigation of maize field at Preixana
21/07/21: small rain event at 1h local time
21/07/26: significant rain event
21/07/27: Raman lidar works with 20 s time averaging from 21h 21/07/26 to 9h 21/07/27 local time
21/07/28: Raman lidar works without PPI: 10 RHI with vertical measurement the rest of the time

Data processing (V1)
Raman lidar data distance and temperature/ specific humidity offset has been calibrated with respect to radiosondes profiles. Doppler lidar data time and space offset has been corrected with respect to Raman lidar data. Then Raman lidar data have been interpolated to Doppler lidar measurements (slight variation of Raman lidar time vector with respect to 8s and slight difference of space resolution with respect to Doppler lidar one). The corrections are sufficient to enable statistic calculations (variance, covariance (i.e. fluxes), higher order moments, integral scales).
Scanning devices elevation and azimuth data have been referenced using Preixana and Bell Puig village bells and lidars altitude and latitude/longitude data.

Recommendations:
Caution has to be taken for the use of potential temperature gradient (electronic oscillation disturbance, bias at altitude lower than 400 m due to overlap lidar issue). Please contact LMD for further analysis. Specific humidity profile is not affected by these issues.
The horizontal and vertical scanning measurements are prototype measurements and some discrepancies with foreseen elevation and azimuth data may happen due to failure in scanning devices control. In case ones want to use it, please check the results with LMD people in contact. In addition some lag between lidars and scanning devices data may happen and has to be corrected.

时空分辨率：8秒 – 48米，时间采用当地时间（UTC+2）。
2.05μm波段下的Log(P.R2)（任意单位[a.u.]）、2.05μm多普勒激光雷达测得的径向风速（单位：米/秒[m/s]）、0.35μm激光雷达测得的气温（单位：开尔文[K]）与比湿（单位：克/千克[g/kg]）。

扫描设备（多普勒激光雷达）记录参数：时间、方位角、俯仰角；扫描设备（拉曼激光雷达）记录参数：时间、方位角、俯仰角。

数据集说明：
激光雷达数据为遵循1小时循环周期的三维测量结果，具体流程如下：
1) 4次近地面大气垂直剖面测量（高度范围约0-100米），采用距离高度指示扫描（Range-Height Indicator，RHI）模式，方位角固定为26.56°，俯仰角范围为-0.54°至5.46°，扫描速率为0.05°/秒；
2) 1次近地面大气水平剖面测量（高度约10米），采用平面位置指示扫描（Plane Polar Indicator，PPI）模式，方位角范围为11.56°至41.56°，俯仰角固定为0.41°，扫描速率为0.1°/秒；
3) 4次近地面大气垂直剖面测量（高度范围约0-100米），采用距离高度指示扫描（Range-Height Indicator，RHI）模式，方位角固定为26.56°，俯仰角范围为-0.54°至5.46°，扫描速率为0.05°/秒；
4) 该小时剩余时间用于垂直测量。

专项说明：
2019年7月21日：普雷萨纳（Preixana）玉米田开展灌溉作业；
2019年7月21日：当地时间1时发生小型降雨事件；
2019年7月26日：发生显著降雨事件；
2019年7月26日21时至2019年7月27日9时（当地时间）：拉曼激光雷达采用20秒时间平均模式进行观测；
2019年7月28日：拉曼激光雷达未开展PPI扫描，该时段内完成10次RHI扫描，剩余时间用于垂直测量。

数据预处理（V1版本）：
针对拉曼激光雷达数据，已通过无线电探空仪廓线数据对测距、气温与比湿的系统偏差进行校准；针对多普勒激光雷达数据，已通过拉曼激光雷达数据对其时、空偏移量进行校正。随后将拉曼激光雷达数据插值至多普勒激光雷达的测量坐标系下（因拉曼激光雷达的时间向量与8秒采样间隔存在细微差异，且空间分辨率与多普勒激光雷达存在小幅偏差）。上述校正已满足统计计算需求，可用于方差、协方差（即通量）、高阶矩、积分尺度等分析。
已通过普雷萨纳与贝尔普伊格（Bell Puig）村庄的钟楼信号对扫描设备的俯仰角、方位角数据进行基准校准，并同步校正激光雷达的海拔、经纬度坐标。

使用建议：
1. 取用潜在温度梯度数据时需谨慎：该数据存在电子振荡干扰，且在海拔低于400米区域因激光雷达重叠效应存在系统偏差，比湿廓线数据不受此类问题影响。如需进一步分析，请联系LMD团队；
2. 本次水平与垂直扫描测量均为原型试验数据，因扫描设备控制故障，部分实测俯仰角、方位角数据与预设值可能存在偏差。若需使用该部分数据，请先与LMD团队沟通核验结果。此外，激光雷达与扫描设备的时间序列可能存在滞后，需先行校正。