# Correcting for Mobile X-Band Weather Radar Tilt Using Solar Interference
## 6 Discussion and Conclusions
### Recommendations  
Based on the analysis presented here, we have the following recommendations, which are applicable to both NXPol-1 and weather radars in general, with a particular focus on higher latitudes. All weather radars should be monitored for potential errors in pointing accuracy--both mobile research systems and fixed-location operational systems--as demonstrated by this work along with previous studies. During installation/commissioning of radar systems, we recommend more traditional approaches to radar levelling are taken, including the use of manual level assessment using gunners quadrants or high-precision levels. [PERSON] et al. [34] provide detailed instructions that could be followed to manually assess the tilt of a radar system during deployment. To complement these techniques, we recommend offline raster scans be undertaken on multiple days covering a broad azimuth range to give the highest confidence that the system is level from the beginning. We would also recommend that the results from these raster scans be saved/recorded for further analysis, as demonstrated by [PERSON] et al. [10]. We would also encourage all radar manufacturers to add this functionality to their raster scan procedures in cases where it does not already exist. The online approaches detailed here do not provide results quickly enough to be sufficient for accurate installation. After installation, record as much data as possible by using a low minimum SNR (or collecting received power/equivalent reflectivity at every range gate if possible) to increase the number of solar hits obtained. This is particularly important for radar systems with a lower sensitivity due to receiver architecture or antenna gain (like X-band systems, which typically have smaller antennas). If collected, online solar hits provide a reliable method for assessing pointing accuracy. We recommend analysing these on an ongoing basis and under standard conditions. Tilt analysis can augment these results once a sufficiently long data sample has been collected. However, if a radar system is found to deviate beyond acceptable pointing accuracy limits using the ongoing monitoring, raster scans should be introduced to assess the potential for tilt more rapidly, as a drift in fixed offset through time and a change in tilt can both produce a comparable signal when assessing ongoing 2D Gaussian fits. Alternatively, site intervention may be the best option if a system is observed to drift in time. For radar systems at higher latitudes, solar hits may not be a sufficient option for monitoring--at least without additional information. This is particularly true during winter, where the possibility exists that some radars may observe few to no solar hits. For these systems, potential options are the use of indirect assessments, such as analysis of QPE error structures. The use of radar QPE may only be a viable option for verification in areas of complex topography, where partial beam blockage is a potential component of the QPE variability. In flatter regions, the impact of radar tilts of this magnitude on QPE would be significantly lower, though they may lead to an increase in ground clutter returns. This could potentially be monitored or evaluated using the relative calibration adjustment (RCA) technique of [PERSON] et al. [35], provided careful consideration of other sources of reflectivity fluctuation are also considered. Another option would be to use dedicated clutter scans of a fixed target such as a television tower or similar, [PERSON] [36] has been actively pioneering such an approach for dual-polarisation monitoring. It is also likely that independent monitoring of pedestal tilt would be advantageous through the use of a digital inclinometer, for example. While this would allow monitoring of pedestal tilt, it may not capture encoder errors and, therefore, should be viewed as an additional measure rather than a one-stop solution. **Author Contributions:** Conceptualization, D.D. and R.R.N.III; methodology, software, formal analysis and visualisation, D.D.