QUALITY ASSESSMENT OF SEA LEVEL DATA by the UH SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER JOINT ARCHIVE FOR SEA LEVEL updated: 01 Nov 2019 Station : Durban Latitude: 29 52.0S Country : South Africa Longitude: 031 03.0E JASL # : 181A Time Meridian: 030E (GMT + 2 hr) GLOSS # : 013 Originator #: DU NODC #: 32039101 Contributor : South Africa Navy Hydrographic Office (SANHO) Private Bag X1 Tokai 7966 South Africa Originator : same Original Data: analog (LEA,KENT); digital (SRD,radar) Instrmnt Type: 1) LEA float-type 1952 - 1971 2) KENT float-type 1970 - 1996. 3) SRD acoustic tide gauge November 1996 4) Ott Kalesto Radar gauge (2006-) Digitzd Intvl: hourly (LEA,KENT); 3 min (SRD); 1 min (radar) Present Data : Hourly, daily, and monthly values obtained by: Hourly : manually filtered raw data (LEA,KENT) average 9 min either side of hour (SRD, radar) 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 : 30 Sep 1970 - 31 Dec 2018 Gaps > 1 mon : 11 Feb - 07 May 1974; 30 Mar - 26 May 1981; 13 Jul - 23 Nov 1981;31 Dec 1981 - 31 Dec 1982 31 Dec 1984 - 31 Dec 1985;07 Apr - 16 May 1988 05 Sep - 26 Oct 1988;31 Dec 1989 - 31 Dec 1990 16 Jun - 30 Jul 1991;31 Dec 1991 - 31 Dec 1993 02 May - 21 Jun 1994;21 Jul - 02 Sep 1994 11 Jun - 17 Jul 1995;19 Dec 1996 - 22 May 1997 31 Dec 1997 - 14 Feb 2000;13 Nov 2000 - 11 Feb 2001 31 Dec 2003 - 25 Apr 2006;26 Jul 2010 - 31 Jan 2011 08 Aug 2011 - 25 Feb 2013 Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 Units : millimeters Missing Data Flag : 9999 Existing : Yes Operational : Yes Sat. Trans. : No Distribution : 1970-2018 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 benchmark: Trig survey BM 4121 at east end of Salibury Island. UTM Grid Reference 36 JUB 109930 BM getymeter = 2.679 above MSL BM 876B = 2.832m above MSL Tide Gauge Zero (TGZ) = South Africa Chart Datum TGZ = 0.838m below LLD (MSL) until 31 Dec 1978 TGZ = 0.900m below LLD (MSL) from 01 Jan 1979 TGZ = 0.904m below BM 4212 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 timing of the gauge appears to be off by a fraction of an hour in some instances as noted below in the questionable fluctuations. Location: In the tide gauge hut at the Tug Jetty (Small Craft Harbour) at the Point. In comparison of daily means with altimeter data, 1997 looks about 15 cm high. Data gap 8/2011-2/2013 due to re-construction in the harbor and other techinical difficulties. CI MISSING REPLACED GAPS QUESTIONABLE YEAR (%) DATA OR BAD DATA FLUCTUATIONS ---- --- -------------------- --------------- -------------------- 1970 25 none none 362-363 1971 100 none (22)232-(21)233 56-59,100-104,159- (22)236-(21)237 161,170-177,218-220, 223-224,232,260-263, 290-297,303-305,309, 320-325,351-353 1972 100 none (22)072-(21)073 1-3,14-17,31-34,44- 51,58,62-64,120-122, 147-149,179-184,248- 255,278-286,308-311, 337-339,366 1973 98 141-149 (22)033-(21)034 1-11,17-19,79-84, (22)217-(21)218 121-125,137-140,193- (22)223-(21)224 197,237-239,241,256, (22)229-(21)230 258-259,286-287,330, (22)234-(21)235 344-345,358-362 (22)239-(21)240 (22)246-(21)247 (22)250-(21)251 (22)256-(21)257 (22)262-(21)263 (23)281-(05)282 (23)282-(06)283 (22)288-(21)289 (22)324-(21)325 1974 73 42-127,238-246, (22)154-(21)155 21-24,271-273,286, 259-262,364-365 317-321,332-334 1975 85 1-27,104-133 none 135-139,141-144,231- 236,261-264,352-356 1976 86 271-278,286-292, none 2-4,17-18,30-32,48- 309-320,327-335, 54,74-77,86-89,103, 348-366 183-184,206-207,220- 223,238-242,266-268, 294-298,307-309,323- 324 1977 93 1-3,136-157 none 20-21,78,122-123 1978 100 none none 113-114,244-248,274- 278,345-352 1979 91 148-155,162-164, none 16,42-44,47,98,146- 225-248 148,160-162,165,167, 174-176,189-190,217, 279-281,291-295,308- 309,321-322,338-339 1980 100 none (12)196-(07)197 223,310-316 1981 48 89-146,194-327 none 152-153,357-362 1982 0 1-365 none none 1983 98 172-175,328-332 none 60,102-105,115-121, 144-147,204-207,233, 249-256,263,265-270, 277-283,290-299,307- 309,325-326,336-341, 353-355 1984 87 48-52,63-79, (11)018-(18)018 1-4,17,30,32-36,46- 161-163,310-335, (23)018-(08)019 47,51,60-62,89-99, 366 (10)019-(19)019 109,119-124,140,151- (22)019-(20)020 153,171-173,210-211, (01)021-(08)021 228-232,239,242-244, (06)115-(21)115 268-274,281,356-357 1985 0 1-365 none none 1986 78 99-105,118-119, (06)117-(22)117 22-24,52-61,81-84, 168-184,252-259, (05)326-(18)326 189-191,200,203-209, 270-287,295-301, (05)327-(17)327 217,224-225,233,250- 320-322,336-358, 250-252,259-264,269, 364-365 288-292,317-318,324, 332-336,362-363 1987 83 1-6,66-68, (06)020-(13)020 13-18,21,32-36,43- 90-105,160-167, (07)268-(09)268 52,60-62,71-76,105- 269-279,321-329, 109,116-118,159,223- 349-363 224,236-237,263-269, 281,295,308,329-332, 342-344 1988 59 43-49,60-61,71-82, (05)022-(20)022 65-68,242-244 98-137,151-153,159- (04)023-(20)023 187,249-300,355-366 (05)024-(21)024 (00)025-(11)025 (03)150-(19)150 1989 86 1-3,128-132,170-192, (14)025-(11)026 24-25,202,204,315- 286-298,351-363 (22)072-(12)073 318,335-350 1990 0 1-365 none none 1991 78 61-63,67-77,85-87, (22)064-(06)065 3-4,89-91 105-116,167-211,287- (17)221-(00)222 294,325-329 (21)223-(05)224 (17)253-(07)254 1992 0 1-366 none none 1993 0 1-365 none none 1994 59 84-98,122-172,202- (14)007-(21)007 none 245,251-256,259-263, (14)031-(21)031 272-276,280-286,290- 297,311-319,357-365 1995 76 1-9,26-30,125-129, (16)090-(23)090 91-92,123-125, 132-142,156-158,162- 161-162 198,244-254,282-290, 317-321,365 1996 85 1-2,14-16,24-26,41- none 212-213,266 44,92-95,127-141,277- 281,285-288,323-326, 346-352,354-366 1997 61 1-142,365 none none 1998 0 1-365 none none 1999 0 1-365 none none 2000 74 1-45,222-223,318-365 none none 2001 89 1-42 (00)328-(09)328 none 2002 100 none (01)001-(21)001 none (00)025-(08)025 (11)066-(22)066 (00)154-(13)154 (22)155-(06)156 (15)184-(01)185 2003 98 25-26,173-174,263- (13)084-(21)084 none 264 (10)085-(23)085 (12)337-(20)337 2004 0 1-366 none none 2005 0 1-365 none none 2006 69 1-115 none none 2007 99 148-150 (22)194-(21)195 none 2008 98 60-63,102-104, none none 118-121 2009 93 341-365 none none 2010 51 152-168,179-181, (13)089-(03)090 none 207-365 2011 48 1-31,138-153,220-365 none none 2012 0 1-366 none none 2013 68 1-56,78-96,105-106, (09)251-(07)252 none 144-149,154-172,175- (00)255-(08)255 177,245-247,277-287, (18)262-(08)263 306-311 (04)264-(12)264 2014 100 none none none 2015 99 259-264 none 152-186 2016 95 134-151 none none 2017 99 291-293,318-321 none none 2018 99 365 none none