A Required Data Span to Detect Sea Level Rise

Altimetric measurements indicate that the global sea level rises about 3 mm/year, however, in various papers different data spans are adopted to estimate this value. The minimum time span of TOPEX/Poseidon (T/P) and Jason-1 (J-1) global sea level anomalies (SLA) data required to detect a statisti-cally significant trend in sea level change was estimated. Seeking the trend in the global SLA data was per-formed by means of the Cox-Stuart statistical test. This test was supported by the stepwise procedure to make the results independent of the starting data epoch. The probabilities of detecting a statistically significant trend within SLA data were computed in the relation with data spans and significance levels of the above-mentioned test. It is shown that for the standard significance level of 0.05 approximately 5.5 years of the SLA data are required to detect a trend with the probability close to 1. If the seasonal oscillations are removed from the combined T/P and J-1 SLA data, 4.3 years are required to detect a statistically significant trend with a probability close to 1. The estimated minimum time spans required to detect a trend in sea level rise are ad-dressed to the problem of SLA data predictions. In what follows, the above-mentioned estimate is assumed to be minimum data span to compute the representative sample of SLA data predictions. The forecasts of global mean SLA data are shown and their mean prediction errors are discussed.