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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 Sep 2026 08:59:00
Latency
4115
Level
0.87

Harmonics

Points count
7034961
First date
29 Apr 2011 19:11
Last date
20 Sep 2026 08:59

Click on following link to see data:

Harmonics Constatns
Comp # Period (day) Cos factor (m) Sin factor (m)
0 0.00000 1.12576E+0 0E+0
1 0.12877 8.59154E-5 -9.57021E-6
2 0.12886 1.9142E-4 1.52337E-4
3 0.12938 1.56412E-4 -1.18748E-4
4 0.14707 -9.94753E-5 2.12959E-5
5 0.16841 3.12459E-4 3.80858E-4
6 0.16857 -1.49376E-4 -1.07123E-3
7 0.17036 7.30767E-4 1.14466E-4
8 0.17052 -2.75709E-3 -1.31667E-3
9 0.17251 -1.05534E-3 1.11916E-3
10 0.17470 4.14893E-4 -2.9115E-4
11 0.19989 3.22466E-4 3.74941E-4
12 0.20545 7.15552E-4 -9.02142E-5
13 0.24966 -4.57782E-4 -9.16331E-5
14 0.25000 2.26233E-4 3.04184E-4
15 0.25395 -5.17782E-4 -3.84773E-4
16 0.25431 -8.98825E-5 9.93459E-4
17 0.25631 7.8386E-5 -8.27328E-5
18 0.25667 -1.91259E-4 -1.72271E-5
19 0.25876 3.839E-4 -4.77615E-4
20 0.26122 -2.19047E-4 7.97365E-4
21 0.33303 3.47429E-4 1.6113E-3
22 0.34071 1.02421E-3 -7.35408E-5
23 0.34135 5.71161E-4 -4.2643E-4
24 0.34502 -3.19436E-3 3.20944E-3
25 0.34943 6.22077E-5 1.12832E-4
26 0.48977 -8.65031E-5 9.1071E-4
27 0.49109 8.35261E-4 -1.6384E-4
28 0.49863 1.21478E-2 4.90998E-3
29 0.49932 -9.90111E-4 1.71766E-4
30 0.50000 -3.89242E-2 -4.09132E-2
31 0.50798 2.77581E-3 9.99338E-3
32 0.50924 2.18033E-3 -1.03548E-3
33 0.51606 -4.23837E-3 4.42603E-3
34 0.51679 2.05366E-3 4.23037E-3
35 0.51753 -4.02346E-1 3.0695E-1
36 0.51826 1.56668E-3 -6.56562E-3
37 0.52608 -2.0536E-2 1.49122E-2
38 0.52743 1.02356E-1 6.81785E-2
39 0.53632 1.54407E-2 1.2577E-2
40 0.53772 5.35734E-3 -1.56315E-2
41 0.54697 2.10642E-3 -4.36616E-3
42 0.54843 -1.74358E-3 -5.16985E-4
43 0.89909 1.04361E-4 2.38731E-4
44 0.92942 1.56485E-3 -1.64684E-3
45 0.93417 6.84657E-4 1.61042E-3
46 0.96244 -3.93021E-3 2.94143E-3
47 0.96696 3.72573E-4 4.34E-5
48 0.99185 -4.94239E-4 4.81291E-4
49 0.99455 1.65213E-3 4.54875E-4
50 0.99727 4.70212E-2 4.57305E-2
51 1.00000 4.66439E-4 2.08474E-3
52 1.00275 1.10263E-2 1.60345E-2
53 1.00551 -2.83229E-4 9.19137E-4
54 1.02954 -8.40523E-5 1.82562E-3
55 1.03472 1.86969E-3 -1.94952E-3
56 1.04061 2.40304E-4 1.12626E-4
57 1.06951 -5.74335E-4 -1.03185E-3
58 1.07581 3.38084E-2 -7.3996E-3
59 1.11346 3.54319E-4 1.14864E-3
60 1.11951 -2.1842E-3 -5.31074E-3
61 1.16035 5.04435E-4 -7.16989E-4
62 1.16693 -4.63659E-5 -3.21355E-4
63 1.21136 1.62376E-4 -2.37206E-4
64 13.66079 1.2546E-3 -8.87368E-3
65 14.76529 1.16992E-3 2.32847E-3
66 27.55455 3.15743E-3 1.29108E-2
67 31.81193 -1.63165E-2 2.15403E-3
68 182.62118 -4.16674E-2 4.53607E-2
69 365.25998 6.29457E-2 9.56514E-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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