The IOC/UNESCO just released the 5th volume of the Manual on sea level measurement and interpretation. This volume is devoted specifically to radar tide gauges. In the decade since Volume 4, they have been applied to measuring sea level at many locations. They have already replaced the previous tide gauge technologies in many countries. Their low cost (in most cases) and the fact that they are relatively easy to install and maintain mean that they have been the technology of choice whenever new sites have been instrumented or older ones refurbished.
Part 1 of this Volume 5 discusses topics such as how radar gauges can be mounted over the water to measure sea level. It considers how gauges can be calibrated, either in the laboratory before installation or in the field during routine maintenance visits. It describes how radar performs in comparison to other technologies and discusses how the measured radar levels can be biased in the presence of waves and, consequently, what other technologies must be used in parallel.
Part 2 of this Volume returns to some topics that have been presented in the previous Volumes 1-4 of the Manual. These are particularly important aspects of tide
gauge measurements, and so have been repeated each time, although in different ways. We suggest that new readers of the volumes would benefit from looking at Volumes 1-4 before reading the present Volume 5. Although the earlier volumes date from many years ago, and technology has evolved considerably in the meantime, much of the previous discussion is educational with regard to how the historical sea level data set has been obtained.
There are often dangers in exchanging one measuring system for another, in that different systematic methods can be introduced into a long-term time series, so an appreciation of how methods have changed is essential. It is clear that the same kind of mistakes in changing technologies could be occurring now, as radar systems replace others, so we must make attempts to understand them all as well as we can.
The online English version is available here.