QUALITY ASSESSMENT OF SEA LEVEL DATA by the UH SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER JOINT ARCHIVE FOR SEA LEVEL updated: 12 Nov 2019 Station : Zanzibar Latitude: 06 09.3S Country : Tanzania Longitude: 039 11.4E JASL # : 151A Time Meridian: 045E (GMT + 3 hr) GLOSS # : 297 Originator #: 151 NODC #: 30036901 Contributor : UH Sea Level Center 1000 Pope Rd. MSB 317 Honolulu, Hawaii 96822 Originator : UH Sea Level Center in collaboration with Commission of Lands and Environment PO Box 811 Zanzibar, Tanzania Original Data: analog (STD); digital (others) Instrmnt Type: 1) 03/1984-10/1993, Float type, R.W. Munro, London, I.H. 109 (STD); 2) 02/1993-, Handar Encoder 436A (ENC) 3) 02/1993-06/2006, Handar Encoder 436B (ENB) with datalogger (ENO) 3. 8/2006- radar (RAD) gauge (Vega Vegapuls 62) 4. 8/2006- pressure transducer (PRS) backup Primary channel used in JASL set: 1984-10/1993: STD 3/1993-2018: (ENC) *short gaps in primary channel filled with other channels as available; see UHSLC for specific dates Digitzd Intvl: one hour (Munro); 4 min (ENC); 15 min (ENB,ENO) 3 min (RAD); 2 min (PRS) 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 : 01 Mar 1984 - 31 Dec 2018 Gaps > 1 mon : 30 Mar 2008 - 28 Jan 2009;10 Jul 2014 - 17 Sep 2014 Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 Units : millimeters Missing Data Flag : 9999 Existing : Yes Operational : Yes Sat. Trans. : Yes Distribution : 1984-2018 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. The Old Tide Gauge Benchmark (TGBM) is about 30m from the tide gauge (521209E,9319992N). Benchmark I (BMI) at Malindi roundabout = 3.80 above Land Survey Datum (1984, 1987). Mean Sea Level is 2.08m above Chart Datum. The gauge was relocated in Zanzibar Harbor during 1990. Comment : The daily and monthly means do not reveal any reference level shifts and agree fairly well with adjacent stations, Mombasa, Kenya and Dar Es Salaam, Tanzania. Occasionaly, timing errors were evident in the hourly data. Numerous daily gaps Oct 2006 - Mar 2008. JASL Nov 2019 update replaces 2016- 05 Sep 2017. CI MISSING REPLACED GAPS QUESTIONABLE YEAR (%) DATA OR BAD DATA FLUCTUATIONS ---- --- -------------------- --------------- -------------------- 1984 84 none (02)363-(08)363 79,230,281-282 1985 99 67-68,192-193 (20)164-(08)165 20,47,66-67,96,98, (05)294-(11)294 125-127,129,179 1986 100 none none 25-27,31,193 1987 100 none none 122-124,132-135, 180-181 1988 100 none none 105,158-160,240-242 1989 100 none none 49-51,67-69,82-84, 91-93,314-316,349- 350 1990 95 208-226 none 96-100,140-150,173- 175,227-230,282,309- 310,337-340 1991 100 none none 1-3,89-92,153,164- 165 1992 100 none none none 1993 98 8-16 none none 1994 100 none none none 1995 100 none (13)184-(12)185 none 1996 100 none none none 1997 98 330-339 none none 1998 99 329-330 (21)203-(17)204 none 1999 100 none none none 2000 100 none none none 2001 100 none none none 2002 100 none none none 2003 100 none none none 2004 100 none none none 2005 98 173-181,353-355 (13)167-(11)168 none (11)170-(00)171 (23)177-(07)178 (16)199-(23)199 (11)234-(23)234 2006 97 301-305,311-317 (10)065-(08)066 none (06)086-(23)086 (06)207-(13)207 (11)276-(21)276 (12)277-(20)277 (05)278-(16)278 (11)279-(21)279 (09)280-(16)280 (11)285-(21)285 (11)287-(02)288 (11)291-(19)291 (13)292-(21)292 (11)294-(01)295 (11)295-(23)295 (11)296-(23)296 (07)297-(16)297 (11)299-(18)299 (07)318-(14)318 (07)321-(15)321 (07)324-(14)324 (06)328-(15)328 (07)330-(15)330 (06)331-(15)331 (07)332-(14)332 (08)336-(15)336 (07)337-(15)337 (07)338-(15)338 (07)339-(15)339 (07)340-(15)340 (07)341-(14)341 (07)342-(14)342 (06)343-(15)343 (08)344-(15)344 (08)345-(15)345 (07)347-(15)347 (07)348-(15)348 (07)349-(15)349 (07)350-(15)350 (07)351-(14)351 (07)352-(15)352 (07)353-(15)353 (07)354-(15)354 (07)355-(14)355 (07)361-(14)361 (08)001-(15)001 2007 100 none (08)003-(15)003 none (08)009-(15)009 (08)011-(15)011 (08)012-(15)012 (08)013-(15)013 (08)016-(15)016 (08)017-(15)017 (08)018-(15)018 (08)021-(15)021 (08)027-(15)027 (08)034-(15)034 (08)040-(15)040 (08)045-(15)045 (08)046-(15)046 (08)047-(15)047 (06)055-(19)055 (08)060-(15)060 (08)062-(15)062 (08)063-(15)063 (08)065-(15)065 (08)066-(15)066 (08)067-(15)067 (08)070-(15)070 (08)075-(15)075 (08)079-(15)079 (08)084-(15)084 (08)085-(15)085 (07)087-(14)087 (07)094-(15)094 (07)095-(15)095 (07)096-(15)096 (07)097-(15)097 (08)098-(15)098 (07)099-(14)099 (07)100-(14)100 (07)102-(14)102 (07)110-(14)110 (07)111-(14)111 (07)112-(14)112 (07)115-(14)115 (07)117-(14)117 (07)118-(14)118 (07)119-(14)119 (07)140-(14)140 (07)145-(14)145 (07)147-(14)147 (07)159-(14)159 (07)160-(14)160 (07)161-(14)161 (07)162-(14)162 (07)163-(14)163 (07)167-(14)167 (07)179-(14)179 (07)180-(14)180 (07)186-(14)186 (07)191-(14)191 (07)192-(14)192 (07)193-(14)193 (07)194-(14)194 (07)195-(14)195 (07)196-(14)196 (07)200-(14)200 (07)202-(14)202 (07)203-(14)203 (07)204-(14)204 (07)205-(14)205 (07)209-(14)209 (07)210-(14)210 (07)211-(14)211 (07)212-(14)212 (07)217-(14)217 (07)218-(14)218 (07)219-(14)219 (07)220-(14)220 (07)221-(14)221 (07)222-(14)222 (07)223-(14)223 (07)225-(14)225 (07)226-(14)226 (07)235-(14)235 (07)236-(14)236 (07)238-(14)238 (07)239-(14)239 (07)241-(14)241 (07)242-(14)242 (07)245-(14)245 (07)247-(14)247 (07)251-(14)251 (07)313-(14)313 (07)335-(14)335 (07)342-(14)342 (07)343-(14)343 (07)344-(14)344 (06)349-(14)349 (06)350-(14)350 (06)351-(14)351 (07)352-(14)352 (06)353-(14)353 (07)355-(14)355 (07)357-(14)357 (07)358-(15)358 (07)359-(14)359 (07)360-(15)360 (07)361-(14)361 (07)364-(14)364 (07)365-(14)365 2008 25 90-366 (06)032-(14)032 none (07)033-(15)033 (07)035-(14)035 (06)037-(14)037 (07)073-(14)073 (06)074-(14)074 (06)075-(14)075 (07)077-(17)077 (06)078-(14)078 (06)079-(14)079 (06)080-(14)080 (07)081-(14)081 (06)082-(14)082 (05)083-(14)083 (06)084-(13)084 (07)085-(14)085 (06)087-(14)087 (06)088-(13)088 (07)089-(14)089 (06)090-(14)090 2009 93 1-28 (07)123-(23)123 none 2010 100 none (12)089-(04)090 none (21)253-(05)254 (20)256-(04)257 (21)257-(04)258 (19)259-(04)260 (21)269-(05)270 (22)272-(05)273 (21)273-(04)274 (22)274-(05)275 (22)275-(05)276 (20)276-(05)277 (21)277-(05)278 (22)278-(05)279 (22)279-(05)280 (22)280-(05)281 (22)281-(05)282 (21)282-(05)283 (22)283-(05)284 (22)284-(05)285 (20)285-(05)286 (19)286-(05)287 (22)287-(05)288 (21)288-(05)289 (20)289-(04)290 (20)290-(05)291 (21)291-(04)292 (21)292-(04)293 (21)293-(05)294 (19)294-(05)295 (18)295-(05)296 (19)296-(05)297 (19)297-(05)298 (20)298-(07)299 (00)335-(07)335 2011 100 none (11)181-(18)181 none (01)286-(15)286 (21)286-(05)287 (12)288-(02)289 (22)289-(13)290 (16)290-(00)291 2013 100 none (12)174-(23)174 none 2014 79 179-182,191-227,234- (21)049-(06)050 none 260,268-282 2015 100 none (00)209-(08)209 none 2016 100 none none none 2017 100 none none none 2018 100 none none none