Multi-year X-band weather radar observations in Hamburg (LAWR HHG)

An operational, single-polarized X-band weather radar (WRX) provides measurements in Hamburg’s city center since 2013. This local area weather radar (LAWR) is located on the rooftop of the high-rise building "Geomatikum" in Hamburg (HHG), which is the location of the Meteorological Institute of the Universität Hamburg. The radar operates at one beam elevation angle with a high temporal 30 s, range 60 m, and sampling 1° resolution refining observations of the German nationwide C-band radars within a 20 km scan radius.
Several sources of radar-based errors were adjusted gradually improving the measurement variables, e.g. the radar calibration, alignment, attenuation, noise, non-meteorologial echoes. This experiment includes data sets of the equivalent radar reflectivity factor (dbz) in level 1 (without attenuation correction) and the rainfall rate (rr) in level 2 (applied attenuation correction). The WRX/LAWR HHG measurements were calibrated and evaluated with measurements of micro rain radars (MRR).
With this high-quality and -resolution weather radar product, refined studies on the spatial and temporal scale of urban precipitation will be possible. For example, the data sets will be used for further hydrological research in an urban area within the project Sustainable Adaption Scenarios for Urban Areas – Water from Four Sides of the Cluster of Excellence Climate Climatic Change, and Society (CliCCS).

This work was partly funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany‘s Excellence Strategy – EXC 2037 'CLICCS - Climate, Climatic Change, and Society' – Project Number: 390683824, contribution to the Center for Earth System Research and Sustainability (CEN) of Universität Hamburg.

Now a more recent version (Version 2) exists with the following changes:
- We provide daily instead of hourly files to reduce the number of files for better data handling. For the days 23.09.2014, 12.03.2015, 09.06.2015, 05.07.2017, and 01.02.2018 there are two files to avoid additional time dependencies of variables because of changes in calibration or alignment parameters.
- We changed the data type (double to int64) and the unit days since 1970-01-01 to seconds since 1970-01-01 of the time coordinate.
- We changed the standard names / long names of the variables azimuth, range and ele.
- We added the integer variable grid_mapping with the attributes grid_mapping_name ("radar_lidar_radial_scan"), latitude_of_projection_origin, longitude_of_projection_origin and height_of_projection_origin, as suggested by the CfRadial conventions. Since the grid_mapping variable provides the same information as the variables lat_center, lon_center and zsl_center, we removed them. We added the attribute grid_mapping to the variable rr and dbz.

自2013年起，一座位于汉堡市中心的高层建筑“Geomatikum”屋顶上运行的单一极化X波段天气雷达（WRX）已提供测量数据。该局部区域天气雷达（LAWR）位于汉堡（HHG）的汉堡大学气象研究所内。该雷达以30秒的高时间分辨率、60米的范围和1°的采样分辨率，在单一的波束仰角下运行，对德国全国范围内的C波段雷达的观测进行精细校正，其扫描半径为20公里。雷达测量误差的多个来源逐步调整，以优化测量变量，例如雷达校准、对准、衰减、噪声和非气象回波。本实验包括1级（未进行衰减校正）的等效雷达反射率因子（dbz）数据集和2级（应用衰减校正）的降雨率（rr）数据集。WRX/LAWR HHG的测量数据与微雨雷达（MRR）的测量数据进行校准和评估。凭借这一高质量和高分辨率的天气雷达产品，将能够进行关于城市降水时空尺度的深入研究。例如，这些数据集将被用于项目“城市区域可持续适应情景——卓越集群气候变化与社会（CliCCS）”的进一步水文研究。

本研究部分资助由德国研究基金会（DFG）提供，该项目属于德国卓越战略——EXC 2037 'CLICCS - 气候、气候变化与社会'——项目编号：390683824，为汉堡大学地球系统研究可持续发展中心（CEN）的贡献。

现有一个更新的版本（版本2），其中包含以下变更：
- 我们提供每日文件而非每小时文件，以减少文件数量，便于数据处理。对于2014年9月23日、2015年3月12日、2015年6月9日、2017年7月5日和2018年2月1日的日子，存在两个文件，以避免由于校准或对准参数变化而导致的变量额外的时序依赖。
- 我们将时间坐标的数据类型从double改为int64，并将单位从1970年1月1日以来的天数改为1970年1月1日以来的秒数。
- 我们更改了变量的标准名称/长名称，包括方位角、距离和仰角。
- 我们添加了整数变量grid_mapping，具有属性grid_mapping_name（"radar_lidar_radial_scan"）、latitude_of_projection_origin、longitude_of_projection_origin和height_of_projection_origin，如CfRadial约定所建议。由于grid_mapping变量提供了与变量lat_center、lon_center和zsl_center相同的信息，我们移除了它们。我们将grid_mapping属性添加到变量rr和dbz中。