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Tide Gauge Details - Tonga Island - Nukualofa_TO

Device description

Name
Tonga Island - Nukualofa_TO
Country
Tonga Island
Group
TD UNESCO
Lat/Lon
-21.136801 / -175.180695

Last measured values

Time(UTC)
06 Feb 2026 07:59:00
Latency
1304
Level
1.35

Harmonics

Points count
6721718
First date
29 Apr 2011 19:11
Last date
06 Feb 2026 07:59

Click on following link to see data:

Harmonics Constatns
Comp # Period (day) Cos factor (m) Sin factor (m)
0 0.00000 1.13036E+0 0E+0
1 0.12877 7.80645E-5 -1.52255E-5
2 0.12886 1.9639E-4 1.55173E-4
3 0.12938 1.45736E-4 -1.07808E-4
4 0.14707 -9.56835E-5 2.70357E-5
5 0.16841 3.31486E-4 3.64277E-4
6 0.16857 -1.59744E-4 -1.09054E-3
7 0.17036 7.38657E-4 1.25575E-4
8 0.17052 -2.77355E-3 -1.33036E-3
9 0.17251 -1.06083E-3 1.12487E-3
10 0.17470 4.16251E-4 -2.72761E-4
11 0.19989 3.04258E-4 3.60191E-4
12 0.20545 7.48015E-4 -7.01183E-5
13 0.24966 -5.02891E-4 -2.35903E-5
14 0.25000 3.01868E-4 2.77393E-4
15 0.25395 -6.08449E-4 -3.9076E-4
16 0.25431 -6.39417E-5 1.07234E-3
17 0.25631 7.46966E-5 -8.84263E-5
18 0.25667 -2.17365E-4 7.39327E-6
19 0.25876 4.2176E-4 -4.74925E-4
20 0.26122 -2.28379E-4 8.25673E-4
21 0.33303 3.24559E-4 1.59841E-3
22 0.34071 1.04195E-3 -8.60469E-5
23 0.34135 6.0313E-4 -4.21188E-4
24 0.34502 -3.23016E-3 3.19852E-3
25 0.34943 5.16898E-5 1.86696E-4
26 0.48977 -6.17891E-5 8.77396E-4
27 0.49109 8.39766E-4 -1.82669E-4
28 0.49863 1.18821E-2 5.00471E-3
29 0.49932 -9.19605E-4 2.42969E-4
30 0.50000 -3.89232E-2 -4.08985E-2
31 0.50798 2.61795E-3 1.01672E-2
32 0.50924 2.13484E-3 -1.01767E-3
33 0.51606 -4.41696E-3 4.5427E-3
34 0.51679 2.51758E-3 4.10803E-3
35 0.51753 -4.02967E-1 3.06872E-1
36 0.51826 1.75456E-3 -6.52317E-3
37 0.52608 -2.06922E-2 1.50154E-2
38 0.52743 1.02386E-1 6.80335E-2
39 0.53632 1.55828E-2 1.2592E-2
40 0.53772 5.35852E-3 -1.55314E-2
41 0.54697 2.09778E-3 -4.36424E-3
42 0.54843 -1.75066E-3 -5.26211E-4
43 0.89909 9.61818E-5 2.46291E-4
44 0.92942 1.53688E-3 -1.60994E-3
45 0.93417 7.5039E-4 1.62518E-3
46 0.96244 -3.91755E-3 2.93728E-3
47 0.96696 2.93821E-4 1.76217E-5
48 0.99185 -5.33739E-4 4.22004E-4
49 0.99455 1.95706E-3 3.95797E-4
50 0.99727 4.65549E-2 4.56613E-2
51 1.00000 6.30409E-4 2.12255E-3
52 1.00275 1.10702E-2 1.61309E-2
53 1.00551 -4.00288E-4 8.86345E-4
54 1.02954 -9.01463E-5 1.89184E-3
55 1.03472 1.90321E-3 -1.98292E-3
56 1.04061 2.49241E-4 6.00311E-5
57 1.06951 -5.73447E-4 -1.108E-3
58 1.07581 3.33951E-2 -7.59594E-3
59 1.11346 3.25395E-4 1.21037E-3
60 1.11951 -2.24099E-3 -5.27089E-3
61 1.16035 4.92186E-4 -6.8035E-4
62 1.16693 -3.51872E-5 -3.67786E-4
63 1.21136 9.75521E-5 -1.76344E-4
64 13.66079 1.76106E-3 -9.15322E-3
65 14.76529 1.209E-3 2.35025E-3
66 27.55455 3.74742E-3 1.31177E-2
67 31.81193 -1.66643E-2 2.52736E-3
68 182.62118 -4.41338E-2 4.9293E-2
69 365.25998 6.21326E-2 9.98118E-2
Mathematical Formula
Tide calculation mathematical formula
Visual Basic Syntax
Function EstimateTideValues() As [Function]
                        Dim Pi As [Double] = Math.PI
                        Dim sum As [Double] = harmonics(0, 1)
                        For k As Int16 = 1 To harmonics.GetUpperBound(0)
                        Dim period As [Double] = 2 * Pi / harmonics(k, 0)
                        Dim coefCos As [Double] = harmonics(k, 1)
                        Dim coefSin As [Double] = harmonics(k, 2) 
                        sum = sum + coefCos * Math.Cos(time * period)
                        sum = sum + coefSin * Math.Sin(time * period)
                        Next
                        Return sum
                        End Function
C# Syntax
double EstimateTideValues()
                        {
                        double Pi = Math.PI;
                        double sum = harmonics[0, 1];
                        for (int k=1; k <= harmonics.GetUpperBound(0); k++)
                        {
                        double period = 2 * Pi / harmonics[k, 0];
                        double coefCos = harmonics[k, 1];
                        double coefSin = harmonics[k, 2];
                        sum += coefCos * Math.Cos(time * period);
                        sum += coefSin * Math.Sin(time * period);
                        }
                        return sum;
                        }

Axis ranges

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