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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)
20 Aug 2026 03:02:00
Latency
2016
Level
1.04

Harmonics

Points count
6996440
First date
29 Apr 2011 19:11
Last date
20 Aug 2026 00:59

Click on following link to see data:

Harmonics Constatns
Comp # Period (day) Cos factor (m) Sin factor (m)
0 0.00000 1.12611E+0 0E+0
1 0.12877 8.76037E-5 -6.3609E-6
2 0.12886 1.92201E-4 1.50216E-4
3 0.12938 1.5334E-4 -1.21274E-4
4 0.14707 -9.64804E-5 2.28404E-5
5 0.16841 3.20945E-4 3.8163E-4
6 0.16857 -1.53205E-4 -1.07803E-3
7 0.17036 7.35411E-4 1.18395E-4
8 0.17052 -2.7566E-3 -1.3237E-3
9 0.17251 -1.06104E-3 1.11883E-3
10 0.17470 4.10713E-4 -2.87527E-4
11 0.19989 3.36607E-4 3.86953E-4
12 0.20545 7.21752E-4 -8.88274E-5
13 0.24966 -4.61545E-4 -5.98704E-5
14 0.25000 2.53877E-4 2.85611E-4
15 0.25395 -5.40241E-4 -3.90154E-4
16 0.25431 -7.86359E-5 1.01951E-3
17 0.25631 6.13044E-5 -8.78525E-5
18 0.25667 -1.92785E-4 -4.79724E-7
19 0.25876 3.96554E-4 -4.71237E-4
20 0.26122 -2.20012E-4 7.99745E-4
21 0.33303 3.59766E-4 1.60388E-3
22 0.34071 1.02949E-3 -6.55328E-5
23 0.34135 5.736E-4 -4.36952E-4
24 0.34502 -3.20461E-3 3.21271E-3
25 0.34943 6.33386E-5 1.3326E-4
26 0.48977 -7.39424E-5 9.18375E-4
27 0.49109 8.35008E-4 -1.77664E-4
28 0.49863 1.21392E-2 4.92918E-3
29 0.49932 -1.0119E-3 1.57187E-4
30 0.50000 -3.88997E-2 -4.09328E-2
31 0.50798 2.75958E-3 1.00525E-2
32 0.50924 2.14359E-3 -1.05207E-3
33 0.51606 -4.15674E-3 4.36519E-3
34 0.51679 2.0844E-3 4.33036E-3
35 0.51753 -4.02451E-1 3.06936E-1
36 0.51826 1.62273E-3 -6.65276E-3
37 0.52608 -2.05566E-2 1.48923E-2
38 0.52743 1.0238E-1 6.81493E-2
39 0.53632 1.54789E-2 1.25749E-2
40 0.53772 5.35804E-3 -1.55927E-2
41 0.54697 2.10572E-3 -4.3544E-3
42 0.54843 -1.75277E-3 -5.20137E-4
43 0.89909 7.92078E-5 2.78078E-4
44 0.92942 1.5539E-3 -1.65548E-3
45 0.93417 6.79293E-4 1.62403E-3
46 0.96244 -3.93947E-3 2.96562E-3
47 0.96696 3.58462E-4 2.72928E-5
48 0.99185 -4.33925E-4 4.33354E-4
49 0.99455 1.67744E-3 5.32495E-4
50 0.99727 4.69382E-2 4.57182E-2
51 1.00000 5.13377E-4 2.01435E-3
52 1.00275 1.10756E-2 1.61039E-2
53 1.00551 -3.6419E-4 9.34918E-4
54 1.02954 -6.32412E-5 1.81677E-3
55 1.03472 1.87893E-3 -1.93428E-3
56 1.04061 2.4279E-4 1.0277E-4
57 1.06951 -5.28822E-4 -1.05719E-3
58 1.07581 3.37518E-2 -7.4188E-3
59 1.11346 3.60989E-4 1.17522E-3
60 1.11951 -2.2092E-3 -5.31896E-3
61 1.16035 5.05261E-4 -7.09818E-4
62 1.16693 -4.3859E-5 -3.24231E-4
63 1.21136 1.477E-4 -2.30045E-4
64 13.66079 1.37812E-3 -8.90114E-3
65 14.76529 1.12298E-3 2.27463E-3
66 27.55455 3.30042E-3 1.28279E-2
67 31.81193 -1.63409E-2 2.37134E-3
68 182.62118 -4.20646E-2 4.593E-2
69 365.25998 6.25959E-2 9.50395E-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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