QUALITY ASSESSMENT OF SEA LEVEL DATA by the UH SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER JOINT ARCHIVE FOR SEA LEVEL Station : Dar Es Salaam Latitude: 06 49.2S Country : Tanzania Longitude: 039 17.3E JASL # : 102A Time Meridian: 045E (GMT + 3 hr) GLOSS # : none TOGA #: I007 NODC #: 30036902 Contributor : UH Sea Level Center 1000 Pope Rd. MSB 317 Honolulu, Hawaii 96822 Originator : UH Sea Level Center in collaboration with Institute of Marine Sciences University of Dar Es Salaam P. O. Box 668 Zanzibar, Tanzania Original Data: analog Instrmnt Type: Leupold and Stevens, model A-71, float gauge Digitzd Intvl: one hour spot reading Present Data : Hourly, daily, and monthly values obtained by: Hourly : The original digitizing interval was hourly 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 : 06 Jul 1986 - 30 Sep 1990 Gaps > 1 mon : 20 Aug - 22 Sep 1986; 16 Aug - 28 Sep 1987 11 Sep - 16 Oct 1989 Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 Units : millimeters Missing Data Flag : 9999 Existing : Yes Operational : Yes Sat. Trans. : No Distribution : 1986-1990 Refernce Levl: Heights are referred to the station tide staff zero, which is linked to land-based benchmarks. This reference zero is unique to this station and is not an official datum (chart, national, etc.) and is not relative to local tidal parameters, such as mean lower low water. See the Originators for benchmark descriptions, maps, and the geodetic levelling history. Comment : In comparison of daily values with Zanzibar and Mombasa, April 1987 appears about 5 cm low. However, no evidence of a shift could be isolated in the tide staff readings or hourly residuals. Otherwise, the daily and monthly means do not reveal any reference level shifts and agree well with Zanzibar and Mombasa. Timing errors of about +/- 7 minutes in the hourly data were common throughout. CI MISSING REPLACED GAPS QUESTIONABLE YEAR (%) DATA OR BAD DATA FLUCTUATIONS ---- --- -------------------- --------------- -------------------- 1986 40 232-265 none 203-206,219-227,229- 232,272-282,290-311, 347-348,357,361-362 1987 79 30-34,157-182, (21)106-(11)107 2-5,56-67,71-79,86- 228-271,339-346 96,100-107,115-118, 122-124,131-135,141- 157,204-208,220-228, 279-283,292-301,322- 329,336-339,360-365 1988 90 2-5,52-61,144- (03)270-(00)271 1-2,5-7,21-23,34-42, 147,183-188, 45-47,49-51,63-69, 200-212,260-263, 90-101,108-112,118- 333-335 125,135-144,163-183, 212-215,221-222,244- 246,264-265,272-275, 324-333,342-348 1989 88 58-61,66-70, none 7-16,20,35-42,52-57, 254-289,334-336, 65-66,70-73,76-83, 97-101,168-187,193- 210,227-232,289-292, 309-323,329-334, 359-365 1990 71 140-143,146-157 none 1-4,10-15,25-32,41- 48,53-61,83-90,104, 111-120,125-140,170- 172,176,178,189,194- 195,203-204,221,232- 235,272-273