## 1 Introduction  
The word \"segment\" in sea level analyses was first used by [1] to denote segments of sea level changes that had to be characterized individually, in contrast to linear trends, ignoring the details of the observational records. [PERSON] [1] studied the tide gauges of Mumbai and Visakhapatnam, found on opposed sites of the Deccan Plateau, both characterized by the same four-parted segments, which they [1] interpreted as individual records of eustatic changes. More recently, [2; 3; 4], referred to interruptions in the tide gauge recording, artifacts by crustal movement, or changes in the tide gauge location, as different segments in a tide gauge record. This is what is discussed in the present paper. Many sea level records in the Permanent Service for Mean Sea Level (PSMSL) or the National Oceanic and Atmospheric Administration (NOAA) databases of tide gauges refer not to continual, but to segmented records due to interruptions in the recording for technical or social problems, earthquakes, or changes in the location of the tide gauge station. These segmented tide gauge records are wrongly used for assessing the sea level rate of rise and acceleration, the same as continuous records with no quality issues, supplying unreliable estimations. In the case of changes in the location of a tide gauge station, each segment may only be analyzed individually [5; 6]. This is the same if an earthquake or other perturbations have affected the record [7]. This paper proposes a technique to show errors in aligning the different segments of a segmented tide gauge record. While this technique may alleviate the misalignment issues, it certainly does not address the issues of changing sea and land contribution to the relative sea level signal or the effect of earthquakes and other perturbations. As shown in the method section, two regressions are applied to the measured monthly average mean sea levels (MSL) of a tide gauge record to compute the sea level rate of rise and acceleration. A linear regression returns the average rate of rise over the record length, and a parabolic regression returns the average acceleration over the record length. As the sea levels oscillate with well-known periodicities in the 60-year range, like other climate parameters [8; 9; 10; 11; 12; 13], more than 60 years of continuous recording from the same tide gauge, and without any major perturbation, are needed to compute a reliable rate of rise, and more than 100 years are needed to compute a reliable acceleration. While it is extremely important to have long records, care must be taken with segmented records, which should not be used to compute rates of rise or accelerations. Many works have reported sea level records that are not a single measurement, but a composition of different records [1; 2; 3; 4; 5; 6; 14; 15]. The combination of different tide gauge segments mostly produces very confusing results [1; 14], as only very rarely can two segments be combined satisfactorily. Most of the time, each segment may only be considered individually [1; 5; 6; 14]. When the data originates from different tide gauges, the different segments should not be coupled together but analyzed independently [1; 5; 6], because the sea and land contribution to the relative sea level signal may differ from one location to the other, and alignment may be inaccurate. Even neglecting the changes in sea and land contributions to the relative sea level signal, the misalignment of the tide gauge segments to each other may be misleading. A difference of just a few millimeters in the alignment of one segment versus another translates to substantial changes in the sea level rate of rise, and even much larger changes in the sea level acceleration. In the rest of the paper we will discuss segmented tide gauge records originating from different measurements performed by different tide gauge instruments in different locations with no overlapping, but gaps in between the measurements.