DOI: 10.26050/wdcc/lawr_uhh_hhg_v2
title: Multi-year X-band weather radar observations in Hamburg (LAWR HHG) (Version 2)

description: Project: Hamburg Local Area Weather Radars - Knowledge of small-scale rainfall variability is needed for several meteorological and hydrological applications. For this purpose, the University of Hamburg operates two local area weather radars (LAWR) and five micro rain radars (MRR) in the area of Hamburg. The low-cost, operational, single-polarized X-band weather radars provide measurements with high temporal (30 s), range (60 m), and sampling (1°) resolution within the 20 km scan radius. Studies on short time periods (several months) proofs the performance of this low-cost local area weather radar. For example, a case study on a tornado in a rain event demonstrates its refined resolution compared to the German nationwide C-band radars. A similar observational network of LAWRs and MRRs was deployed in an rural area and proofed its performance in the past. This project covers data sets related to these radar measurements.
Summary: 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.

Changes in Version 2:
- 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.