TU Delft Cloud radar data - MARA Cabauw Vertical Profiles

<strong>Description:</strong>Vertical profiles of clouds and precipitation measured by 94 GHz cloud radar.<br>This dataset contains vertical profiles of clouds and precipitation observed using a dual-polarization frequency-modulated continuous-wave (FMCW) cloud radar located at the atmospheric site Cabauw. The radar, developed by Radiometer Physics GmbH (RPG-FMCW94-DP type) and named Mobile Atmospheric RAdar (MARA), operates at 94 GHz. It employs simultaneous transmission and simultaneous reception (STSR) mode and its beamwidth is 0.56°. There is a rain/snow/fog mitigation system, comprising a dew blower and a heater which prevent the accumulation of liquid drops and ice on the hydrophobic antenna radomes, therefore mitigating attenuation caused by the presence of liquid water on the antennas.<br>Measurements are collected at a fixed elevation angle (90°). MARA includes an embedded passive channel at 89 GHz, enabling Liquid Water Path (LWP) retrieval using the same receiving antenna. Additionally, it is coupled with a HATPRO G5 microwave radiometer (MARIO), providing collocated radiometric measurements at the same temporal resolution. A built-in weather station (Vaisala WXT536) also records ground-level meteorological conditions.<br>In terms of calibration, the transmit power is continuously monitored, and the radar receiver (including the receiving antenna) undergoes calibration every six months using liquid nitrogen calibration. Short-term calibration is provided through periodic Dicke switching. Prior to the semiannual calibration procedure, the hydrophobic antenna radomes are replaced.<br>This dataset is part of a broader collection from the Department of Geoscience and Remote Sensing (GRS) at TU Delft, published within the Ruisdael Observatory framework (https://ruisdael-observatory.nl/). This dataset will continue to be updated over time while the cloud radar remains operational.<br><strong>List of variables:</strong>* sensor and site parameters* measurement specifications* processing specifications* weather station measurements* LWP in the looking direction of the cloud radar * profiles of temperature, absolute and relative humidity (MARIO)* Doppler spectra (HH and VV) and covariance spectrum (LV0 files)* Equivalent reflectivity factor (LV1 files)* Doppler variables (LV1 files)* Polarimetric variables (LV1 files)<br><strong>Relevance:</strong>The dataset "Vertical profiles of precipitation, ice and mixed-phase clouds, and liquid water clouds at 94 GHz" provides important information for understanding cloud microphysics and atmospheric processes. By using radar reflectivity, Doppler variables and Doppler spectra at 94 GHz, the dataset enables detailed characterization of hydrometeor vertical structures, distinguishing between precipitation, ice, mixed-phase, and liquid water cloud layers. This high-frequency radar data is particularly sensitive to small cloud particles, making it highly relevant for studying cloud formation, phase transitions, and precipitation development. Such profiles are essential for validating satellite retrievals, improving weather and climate models, and enhancing our understanding of cloud–radiation interactions.

<strong>描述：</strong>本数据集收录了由94 GHz云雷达观测得到的云与降水垂直廓线。
该数据集包含部署于卡堡（Cabauw）大气观测站的双极化调频连续波（Frequency-Modulated Continuous-Wave, FMCW）云雷达所获取的云与降水垂直廓线观测数据。该雷达由辐射物理有限公司（Radiometer Physics GmbH, RPG）研发，型号为RPG-FMCW94-DP，命名为移动大气雷达（Mobile Atmospheric RAdar, MARA），工作频段为94 GHz。该雷达采用同步发射同步接收（Simultaneous Transmission and Simultaneous Reception, STSR）模式，波束宽度为0.56°。其配备雨雪雾防护系统，包含除湿风机与加热器，可防止液滴与冰晶附着在疏水天线罩上，从而减轻因天线表面积液引发的信号衰减。

观测采用固定仰角（90°）进行。MARA内置89 GHz无源通道，可通过同一接收天线实现液态水路径（Liquid Water Path, LWP）的反演。此外，该雷达还耦合了HATPRO G5微波辐射计（MARIO），可在相同时间分辨率下开展同步辐射观测。内置的维萨拉WXT536气象站还可记录地面气象条件。

在校准方面，发射功率会得到持续监测，雷达接收机（含接收天线）每六个月通过液氮校准流程完成一次校准；短期校准则通过周期性迪克开关（Dicke switching）实现。在每半年一次的校准流程开展前，需更换疏水天线罩。

本数据集是代尔夫特理工大学（TU Delft）地球科学与遥感系（Geoscience and Remote Sensing, GRS）的更大规模数据集的一部分，发布于Ruisdael天文台框架下（https://ruisdael-observatory.nl/）。只要该云雷达仍处于运行状态，本数据集将持续更新。

<strong>变量列表：</strong>
* 传感器与站点参数
* 测量规格
* 处理规格
* 气象站观测数据
* 云雷达观测方向上的液态水路径（LWP）
* 温度、绝对湿度与相对湿度廓线（MARIO）
* 多普勒谱（HH与VV极化）及协方差谱（LV0文件）
* 等效反射率因子（LV1文件）
* 多普勒变量（LV1文件）
* 极化变量（LV1文件）

<strong>研究价值：</strong>本数据集名为“94 GHz频段下降水、冰相、混合相云及液相云垂直廓线”，可为云微物理过程与大气环流机制的研究提供关键支撑。通过94 GHz频段的雷达反射率、多普勒变量与多普勒谱，该数据集可精准表征水成物的垂直结构，区分降水层、冰相云、混合相云与液相云层。该高频雷达对微小云粒子具有极高敏感性，因此在云形成、相变及降水发展的相关研究中具有重要价值。此类垂直廓线数据对验证卫星反演结果、优化天气与气候模式、深化云-辐射相互作用的认知均具有不可或缺的作用。