QUALITY ASSESSMENT OF SEA LEVEL DATA by the UH SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER JOINT ARCHIVE FOR SEA LEVEL updated: 03 Sep 1998 Station : Durban Latitude: 29 53.0S Country : South Africa Longitude: 031 02.0E JASL # : 181A Time Meridian: 030E (GMT + 2 hr) GLOSS # : 013 TOGA #: I012 NODC #: 32039101 Contributor : Directorate of Hydrography Maritime Headquarters Private Bag Retreat 7965 South Africa Originator : same Original Data: analog (LEA,KENT); digital (SRD) Instrmnt Type: 1) LEA float-type 1952 - 1971 2) KENT float-type 1970 - 1996. 3) SRD acoustic tide gauge November 1996 Digitzd Intvl: hourly (LEA,KENT); unconfirmed (SRD) Present Data : Hourly, daily, and monthly values obtained by: Hourly : manually filtered raw data (LEA,KENT); unconfirmed (SRD) 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 - 19 Dec 1996 Gaps > 1 mon : 11 Feb - 07 May 1974; 30 Mar - 18 May 1981; 13 Jul - 23 Nov 1981; 31 Dec 1984 - 16 Jul 1985 07 Apr - 16 May 1988; 05 Sep - 26 Oct 1988; 08 Mar - 18 Jul 1990; 16 Jun - 30 Jul 1991; 13 Apr - 01 Jun 1992; 02 May - 21 Jun 1994; 21 Jul - 02 Sep 1994; 11 Jun - 17 Jul 1995 Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 Units : millimeters Missing Data Flag : 9999 Existing : Yes Operational : Yes Sat. Trans. : No Distribution : 1970-1996 Refernce Levl: All heights have been referred to the station tide staff zero which is linked to fixed bench marks. The original data were adjusted at JASL with leveling information provided by the contributors to the 1987 data as follows: period value added to ( (hour)day/month/year ) original (mm) ------------------------ --------------- *(00)30/09/70-(20)18/06/73 -100 (21)18/06/73-(23)13/05/75 -250 (00)14/05/75-(12)13/08/80 100 *(13)13/08/80-(23)30/03/81 -150 (00)31/03/81-(06)24/04/84 150 (07)24/04/84-(23)28/11/84 -320 *(00)29/11/84-(00)15/07/85 -120 *(00)01/01/88-(23)23/10/92 240 *(00)24/10/92-(20)29/06/93 485 *(21)29/06/93-(23)19/12/96 240 *adjustment of shift in reference level deduced from the plot of hourly residuals, daily and monthly means, and differences with the corrected monthly means of the Permanent Service for Mean Sea Level. These adjustments are contain uncertainty to a few centimeters. Benchmarks (brass pegs): * BM 483: 2.789 m above MSL. * BM 875: 2.839 m above MSL. * BM Getymeter: 2.679 M above MSL. * "New GPS": 2.8235 m above MSL. Comment : 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. 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 50 89-138,194-327 (16)073-(03)074 152-153,357-362 (16)074-(03)075 1982 100 none (14)221-(09)222 24,248,254,255,328, 348-353 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)038-(00)039 268-274,281,356-357 (06)039-(05)040 1985 46 1-197 (09)201-(16)201 200,234,242-243,258- (10)202-(16)202 262,268-273,297-304, 327-337,343,347-351, 360-361,363 1986 78 99-105,118-119, (06)117-(22)117 22-24,52-61,81-84, 168-184,252-259, (04)323-(21)323 189-191,200,203-209, 270-287,295-301, (05)326-(18)326 217,224-225,233,250- 320-322,336-358, (05)327-(17)327 250-252,259-264,269, 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- (05)024-(21)024 187,249-300,355-366 (03)150-(19)150 (01)245-(08)245 1989 86 1-3,128-132,170-192, (14)025-(11)026 24-25,202,204,315- 286-298,351-363 (12)061-(23)061 318,335-350 1990 51 43-46,50-60,67-199, (08)047-(16)047 25-42,335-338 226-260 (07)049-(14)049 (04)355-(11)355 1991 78 61-63,67-77,85-87, none 3-4,89-91 105-116,167-211,287- 294,325-329 1992 82 104-153,167-174,181- none 156-158 184,198-202,296-300 1993 88 66-68,134-152,169- none none 173,184-188,201-207, 211-222 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- (01)091-(15)091 161-162 198,244-254,282-290, 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