QUALITY ASSESSMENT OF SEA LEVEL DATA by the UH SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER JOINT ARCHIVE FOR SEA LEVEL updated: 10 Oct 2019 Station : Walvis Bay Latitude: 22 57.0S Country : Namibia Longitude: 014 30.0E JASL # : 220A Time Meridian: 030E (GMT + 2 hr) GLOSS # : 314 Originator #: WB NODC #: 32012401 Contributor : South Africa Navy Hydrographic Office (SANHO) Private Bag X1 Tokai 7966 South Africa Originator : same Original Data: analog (FLT); digital (AWLR) Instrmnt Type: 1) float-type 1959 - 1998 (FLT) Kent: 1959-1966 Lea : 1966-1974 Ott : 1976-1995 2) AWLR acoustic tide gauge 1996-1998 3) Ott Kalesto radar gauge, 2008- Digitzd Intvl: hourly (FLT); 3 min (AWLR) Present Data : Hourly, daily, and monthly values obtained by: Hourly : manually filtered raw data (FLT); unconfirmed (AWLR) 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 : 01 Jan 1959 - 04 Dec 2015 Gaps > 1 mon : 10 Jan 1963 - 11 Feb 1963;31 Jan 1966 - 31 Dec 1966 01 Jan 1967 - 23 Nov 1976;06 Dec 1976 - 07 Feb 1977 30 May 1977 - 28 Feb 1978;21 Aug 1981 - 09 Oct 1981 31 Dec 1983 - 31 Dec 1984;19 Aug 1986 - 18 Sep 1986 08 Nov 1987 - 31 Jan 1988;19 Oct 1988 - 29 Nov 1988 30 Apr 1989 - 21 Nov 1991;20 Dec 1992 - 01 Feb 1993 11 Apr 1993 - 30 Nov 1993;04 Jan 1994 - 27 Jul 1994 30 Sep 1994 - 14 Nov 1994;31 Dec 1995 - 01 Jan 1997 15 Jul 1997 - 17 Nov 1997;23 Nov 1998 - 14 May 2008 24 Feb 2011 - 14 Jun 2011 Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 Units : millimeters Missing Data Flag : 9999 Existing : Yes Operational : Yes Sat. Trans. : No Distribution : 1959-2015 Refernce Levl: All tidal heights are given above Chart Datum, which is the datum to which all soundings on the largest scale navigational chart of the area have been reduced. Chart datum is now Lowest Astronomical Tide (LAT) in all ports of the Republic of South Africa and Namibia. The relationship between LAT and Lands Leveling Datum (LLD), referred to as Mean Sea Level (MSL) by land surveyors, is given below. Tide Gauge Zero (TGZ) = 0.913m below LLD (MSL) until 31 December 1978 TGZ = 0.900m below LLD (MSL) from 1 Jan 1979 TGZ was changed on 01 Jan 2003 onward as Mean Sea Level, which is the Land Leveling Datum. Comment : SANHO is the owner and copyright holder of the sea level data. Anyone downloading the information is to contact SANHO to request permission to use or reproduce the data. Permission can be requested via email to hydrosan@iafrica.com. The hourly residuals (observed data minus predicted tides) contain much high-frequency noise with 2 to 4 hour periods and about 10 cm amplitude during 1959 - 1981. The data between 1967 and 1978 have many gaps and uncertain leveling. The timing improves in 1996 with the new gauge. CI MISSING REPLACED GAPS QUESTIONABLE YEAR (%) DATA OR BAD DATA FLUCTUATIONS ---- --- -------------------- --------------- -------------------- 1959 97 227-231,278-281 (22)076-(21)077 74,81-88,92-94,97, 348-351 (22)157-(21)158 249,260-262,363-364 (22)360-(21)361 1960 91 31-35,144-148, none 27-28,163-164,265- 220-224,305-326 267,277-280,291-299, 305,354 1961 99 222-226 none 18,105-106,176-177, 182-183,210-212,237- 240,279-280,295,343- 345 1962 97 109-116,305-309 (22)136-(06)137 298-299,341,344-345 (22)137-(06)138 (22)139-(08)140 (22)141-(10)142 (22)142-(10)143 1963 83 10-42,45-49, none 228 65-70,182-184, 229-233,319-334 1964 99 202-205 none 257-258,322-325 1965 95 226-236,247-253 none 1-2,16-17,30-32,64- 65,77,93-95,108-113, 121-124,126-128,133- 134,148-149,240-242, 266,268-270 1966 09 31-365 none 19 1967 0 1-365 none none 1968 0 1-366 none none 1969 0 1-365 none none 1970 0 1-365 none none 1971 0 1-365 none none 1972 0 1-366 none none 1973 0 1-365 none none 1974 0 1-365 none none 1975 0 1-365 none none 1976 4 1-328 none none 1977 25 1-38,41-46, none none 84-101,150-365 1978 65 1-59,83-88, (09)099-(07)100 349-354 151-153,232-235, (21)105-(08)106 242-263,277-278, (20)206-(07)207 303-329,348-349, 355-365 1979 93 1-11,69-77,85-89, (03)053-(11)053 152-154 125-127,158-160 (18)099-(07)100 (11)136-(06)137 1980 99 61-62,96-97 (11)061-(10)062 21,107-108 1981 80 120-128,233-282, (02)066-(12)066 147,156,349-352 320-335 (22)151-(21)152 (22)180-(21)181 (17)185-(10)186 (22)357-(07)358 1982 99 155-159 (11)061-(10)062 72,107,153,175-178, 195,229-236,260-263, 273-278,283,287-289, 291-292,294,296-297, 302-306,331-333,345- 346,350-351,360-361 1983 97 10-18,123-125, (22)269-(14)270 32,56-57,131,142- 321-323 (21)319-(17)320 145,159-161,190,251, 263,265,307 1984 0 1-365 none none 1985 97 23-35 none 66,239-242,258-259, 262 1986 88 67-78,231-261, (22)204-(14)205 362-365 272-273,356-358 (02)301-(12)301 (15)328-(06)329 1987 71 48-70,179-181, (22)030-(21)031 1-4,16-19,32-37,42- 207-218,240-251, (13)097-(06)098 48,162,258,304-306 262-266,276-280 (17)262-(07)263 341-365 1988 64 1-31,52-55,81-85, (17)346-(06)347 51,75-81,240-242, 117-131,148-157,185- 249,258 194,201-207,250-257, 280-286,293-334 1989 29 8-17,34-36,63-67, (08)027-(06)028 none 120-365 (00)093-(10)093 1990 0 1-365 none none 1991 28 1-264,325-326 (07)349-(17)349 none (00)358-(19)358 1992 89 17-19,73-100,355-366 (07)047-(21)047 127-135,183-187 (05)127-(15)127 (05)155-(21)155 (01)209-(16)209 1993 26 1-32,35-36,63-64, none 335-365 101-334,341-342 1994 26 4-209,236-248,273- none 1-2,209-236,261-265, 318,346-356 337-339 1995 76 27-29,57-62,65-76, (22)252-(21)253 15-27,43-51,76-79, 79-104,108-110,132- (02)266-(15)266 107,118-131,192-195, 148,161-168,196-199, 221-227,246-252,312- 227-229,256-258,285- 316,338-342 289,296-301,321-322, 336-338 1996 0 1-366 none none 1997 65 28-29,196-321,365 (20)190-(07)191 none 1998 66 1-27,33-55,106-128, (16)075-(03)076 none 145-147,207-208,278- (02)215-(13)215 280,313-319 1999 0 1-365 none none 2000 0 1-366 none none 2001 0 1-365 none none 2002 0 1-365 none none 2003 0 1-365 none none 2004 0 1-366 none none 2005 0 1-365 none none 2006 0 1-365 none none 2007 0 1-365 none none 2008 63 1-135 (13)172-(20)172 none (23)220-(06)221 2009 99 285-289 (22)165-(21)166 none (09)238-(05)239 2010 99 188-190 (07)266-(22)266 none 2011 69 55-165,166-168 none none 2012 97 52-58,198-201 (23)281-(21)282 none (22)331-(21)332 2013 100 none none none 2014 100 none none none 2015 89 51-62,253-254 none none