QUALITY ASSESSMENT OF SEA LEVEL DATA by the UH SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER JOINT ARCHIVE FOR SEA LEVEL updated: 29 May 2001 Station : Charchanga Latitude: 22 13.0N Country : Bangladesh Longitude: 091 03.0E JASL # : 138A Time Meridian: 090E (GMT + 6 hr) GLOSS # : none TOGA #: none NODC #: 12092101 Contributor : Bangladesh Inland Water Transport Authority (BIWTA) Dept. of Hydrography 141-143, Motijheel C/A Dhaka - 1000 BANGLADESH Originator : same Original Data: analog Instrmnt Type: float and well type gauge (Munro) Digitzd Intvl: hourly Present Data : Hourly, daily, and monthly values obtained by: Hourly : original data are 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 Jan 1980 - 31 Dec 2000 Gaps > 1 mon : 14 Jul 1993 - 01 Dec 1993 Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 Units : millimeters Missing Data Flag : 9999 Existing : Yes Operational : Yes Sat. Trans. : No Distribution : 1980-2000 Refernce Levl: The sea level heights are referred to the zero point assigned to the tide staff. Bench mark information is available upon request from BIWTA. Comment : The daily and monthly means do not reveal any reference level shifts or trends, and the difference plots with Hiron Point suggest good quality level maintenance for both sites. The hourly residuals contain large periodic fluctuations. It is not clear whether this is due to phase shifts in the timing of the gauge or due to the inability of the tidal analysis to completely resolve all the tidal constituents at this shallow water site. The following periods contain a substantial amount of interpol- ation of 2-8 hour gaps occurring in succession (day/month/year): 11/02/1980-24/02/1980, 25/08/1980-22/09/1980,25/11/1981-31/08/1982, 17/03/1984-08/06/1984,22/09/1985-26/10/1985, 01/01/1992-31/12/2000. The interpolated short gaps do not appear to contaminate the low- frequency information. CI MISSING REPLACED GAPS QUESTIONABLE YEAR (%) DATA OR BAD DATA FLUCTUATIONS ---- --- -------------------- --------------- -------------------- 1980 100 none see comment see comment above 1981 100 none see comment see comment above 1982 100 none none see comment above 1983 100 none (18)364-(17)365 see comment above 1984 100 none none see comment above 1985 100 none none see comment above 1986 86 29-34,57-62,85-90, none see comment above 116-121,151-156,179- 184,207-212,242-247, 270-275,333-338 1987 100 none none see comment above 1988 100 none none see comment above 1989 100 none (01)085-(00)086 see comment above 1990 94 328-349 (13)280-(03)281 see comment above 1991 99 119-121 none see comment above 1992 100 none see comment see comment above 1993 62 195-335 see comment see comment above 1994 100 none see comment see comment above 1995 94 84-105 see comment see comment above 1996 99 51-52,119-121 see comment see comment above 1997 100 none see comment see comment above 1998 99 363-365 see comment see comment above 1999 100 none see comment see comment above 2000 99 59-60,177-178,366 see comment see comment above