On Sea-Level Variability on the Eastern Seaboard of the United States

摘要

Sea level variability along the eastern seaboard of the US is studied using continuous time series of data collected at seven NOAA NOS NWLON stations. The conventional notion of a global number representing the assumed rise in sea level is shown to be approximately correct but with a great deal of variability even over a relatively small stretch of coastline; Atlantic City NJ to Charleston SC. However the notion that sea level is continually rising is shown to be only correct when discussing the overall record length trend. Sea level variability has many modes of variability and from year to year sea level may rise or may fall; relatively speaking. The message is: one year of highs and lows are not representative of the true variability either locally, regionally or along an ocean basin margin. A significant finding has to do with the reporting of the data. If one uses monthly averaged data, versus hourly data, then one cannot extract a deterministic fundamental 19 year cycle in the time series; even over an eight decade period. The message is: you must be careful of your sampling rates or reporting periods to ensure that the resolution of the data is sufficient to not miss important physics. Another significant finding is that on average water level is the order of a foot (30 cm) higher in September and October than it is in January. The difference can be much higher and much lower but the difference exists on average. The message is: do not use January average water level heights to establish the height of a water barrier; rather, use September-October heights. Finally the annual absorption of heat coupled with the strength, location and persistence of atmospheric pressure systems play important roles in establishing water level bases on annual bases.