SEA-LEVEL RISE AT KEY-WEST, FLORIDA, 1846-1992 - AMERICA LONGEST INSTRUMENT RECORD

The continuous series of sea level at Key West, Florida commenced in 1 913, but we have discovered sporadic measurements that date back to 18 46. From records at the U.S. Army Corps of Engineers and the U.S. Coas t and Geodetic Survey, the sea level series has been connected to a Su mmary (common) Datum. Thus, a gappy record of monthly and annual mean heights (H[t]), perhaps the United States' longest series over San Fra ncisco (ca. 1854) or New York (ca. 1856), can be tested to ascertain i f the rise in relative sea level at this site is stationary. Applying first and second order least squares and two-phase regression analyses , we find that dH/dt is 0.19+/-0.01 cm/yr, and that dH-2/dt2= [9.6+/-8 .6].10(-3) cm/yr; the two-phase regression shows H[t] rising 0.15+/-0. 03 cm/yr before ca. 1925 and 0.23+/-0.01 cm/yr afterwards. Neither the second-order regression coefficient nor dH-2/dt2 nor the two-phase ca lculation are significant above the 75% confidence level, but all thre e are weakly consistent with accelerated rise. For the epoch 1951-1987 , Key West sea level, corrected for post-glacial rebound, is best expl ained by concurrent measurements of 0-1,000 db dynamic height anomaly change.