QUALITY ASSESSMENT OF SEA LEVEL DATA by the UH SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER JOINT ARCHIVE FOR SEA LEVEL updated: 20 Aug 2020 Station : Midway Latitude: 28 13.0N Country : USA Trust Longitude: 177 22.0W JASL # : 050A Time Meridian: 165W (GMT - 11 hr) GLOSS # : 106 Originator #:1619910 NODC #: 72178701 Contributor : National Ocean Service (NOS) National Ocean. and Atmos. Administration (NOAA) N/OES22 SSMC4, STATION 7109 1305 East West Highway Silver Spring, MD. 20910-3233 Originator : US Coastal Geodetic Survey (1947-1972); NOS (1973+) Original Data: analog (standard); digital (adr and NG) Instrmnt Type: standard mechanical (1947-1974);analog-to-digital (adr) recorder (1975-1991); Aquatrak acoustic gauge NOAA Next Generation Water Level Measuring System (NG) (1992-) Digitzd Intvl: hourly (standard); six-minute (adr and NG) NG sampling is three-minute average Present Data : Hourly, daily, and monthly values obtained by: Hourly : The original digitizing interval was hourly (standard); spot sampling on the hour (adr and NG) Daily : 119-point convolution filter (Bloomfield, 1976) centered on noon applied to the hourly data with respective periods of the 95, 50, and 5% amplitude points at 124.0, 60.2, and 40.2 hours Monthly: Simple average of all daily values; calculated if 7 or fewer days are missing Span of data : 08 Feb 1947 - 31 Dec 2019 Gaps > 1 mon : 10 Nov 1948 - 01 Jan 1949;04 Jun 1949 - 05 Jul 1949 09 Jul 1949 - 09 Aug 1949;02 Apr 1950 - 23 Jun 1950 01 Aug 1963 - 01 Sep 1963;01 Jan 1973 - 27 Dec 1973 10 May - 14 Jun 1974;02 Apr - 5 May 1976; 20 May - 18 Aug 1976; 2 Aug - 5 Sep 1977; 1 Nov 1978 - 6 Mar 1979; 2 Jun - 7 Aug 1985 15 Sep 2002 - 04 Dec 2002;24 Mar 2005 - 24 Apr 2005 Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 Units : millimeters Missing Data Flag : 9999 Existing : Yes Operational : Yes Sat. Trans. : Yes Distribution : 1947-2019 Refernce Levl: All heights have been referred to the station tide staff zero which is linked to fixed bench marks. While standard mechanical or ADR instrument was the primary gauge, leveling calibration factors were applied monthly based on tide staff comparisons. Comment : Large fluctuations during Nov - Apr for most years are associated with meteorological events. Step- function signatures in the hourly residuals suggest level shifts on 27 Sep 1968 and on 01 Aug 1974. However, the mean level and differences with the PSMSL holdings have not warranted an adjustment. Notable episodic events: 04-06 Nov 1952: Tsunami from Kamchatka 09-10 Mar 1957: Tsunami from C. Aleutians 23-25 May 1960: Tsunami from S.C. Chile 28 Mar 1964: Tsunami from Alaska 11 Mar 2011: Tsunami from Japan CI MISSING REPLACED GAPS QUESTIONABLE YEAR (%) DATA OR BAD DATA FLUCTUATIONS ---- --- -------------------- --------------- -------------------- 1947 87 190-199 (14)156-(10)157 none (06)189-(19)189 1948 86 315-366 none none 1949 76 1,152-186,190-234, (11)119-(10)120 none 238-244 1950 77 92-174 none none 1951 100 none none none 1952 95 95-115 none none 1953 100 none none none 1954 100 none none none 1955 96 351-365 none none 1956 99 1-6 none none 1957 100 none none none 1958 100 none none none 1959 96 254-261,268-275 none none 1960 88 93-122,162-169, none none 274-281 1961 100 none none none 1962 100 none none none 1963 92 213-244 none none 1964 100 none none none 1965 100 none none none 1966 100 none none none 1967 100 none none none 1968 100 none none none 1969 100 none none none 1970 100 none none none 1971 100 none none none 1972 100 none none none 1973 2 1-361 none none 1974 80 1-10,11-32,42-44,45- (08)035-(00)036 none 49,123-125,130-165 (15)188-(09)189 (11)189-(18)189 1975 93 62-86,154-156 (06)153-(12)153 none (17)158-(09)159 1976 66 93-126,141-231 none none 1977 90 214-248 (11)305-(04)306 none 1978 77 232-234,244-262, (10)091-(22)091 none 305-366 1979 67 1-66,244-246, none none 316-365 1980 89 1-42 none none 1981 95 149-168 none none 1982 90 60-97 none none 1983 100 none none none 1984 100 none none none 1985 82 153-219 none none 1986 100 none none none 1987 100 none none none 1988 100 none none none 1989 100 none none none 1990 100 none none none 1991 93 114-139 none none 1992 100 none none none 1993 100 none none none 1994 100 none (10)210-(18)212 none 1995 100 none none none 1996 100 none none none 1997 100 none none none 1998 100 none none none 1999 100 none none none 2000 100 none none none 2001 100 none none none 2002 78 258-338 none none 2003 100 none none none 2004 100 none none none 2005 88 83-114,323-334 (18)357-(04)358 none 2006 97 306-318 none none 2007 100 none none none 2008 94 282-305,309-310 none none 2009 100 none none none 2010 100 none none none 2011 100 none none none 2012 100 none none none 2013 100 none none none 2014 100 none none none 2015 100 none none none 2016 100 none none none 2017 100 none none none 2018 100 none none none 2019 100 none none none