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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)
19 Aug 2026 00:56:00
Latency
5034
Level
1.31

Harmonics

Points count
6995210
First date
29 Apr 2011 19:11
Last date
19 Aug 2026 00:56

Click on following link to see data:

Harmonics Constatns
Comp # Period (day) Cos factor (m) Sin factor (m)
0 0.00000 1.12612E+0 0E+0
1 0.12877 8.91525E-5 -6.93653E-6
2 0.12886 1.91295E-4 1.48845E-4
3 0.12938 1.52566E-4 -1.22712E-4
4 0.14707 -9.69052E-5 2.18837E-5
5 0.16841 3.2032E-4 3.80591E-4
6 0.16857 -1.5402E-4 -1.07724E-3
7 0.17036 7.36658E-4 1.18591E-4
8 0.17052 -2.75658E-3 -1.32491E-3
9 0.17251 -1.06005E-3 1.11964E-3
10 0.17470 4.11315E-4 -2.88731E-4
11 0.19989 3.34827E-4 3.86271E-4
12 0.20545 7.20832E-4 -8.68079E-5
13 0.24966 -4.61825E-4 -5.60396E-5
14 0.25000 2.57694E-4 2.85407E-4
15 0.25395 -5.4247E-4 -3.93249E-4
16 0.25431 -8.14362E-5 1.02214E-3
17 0.25631 6.4976E-5 -8.70539E-5
18 0.25667 -1.92835E-4 -4.24278E-6
19 0.25876 3.96887E-4 -4.74939E-4
20 0.26122 -2.1754E-4 8.02508E-4
21 0.33303 3.59763E-4 1.60559E-3
22 0.34071 1.02829E-3 -6.7701E-5
23 0.34135 5.7156E-4 -4.35327E-4
24 0.34502 -3.20473E-3 3.2098E-3
25 0.34943 6.4642E-5 1.30204E-4
26 0.48977 -7.11522E-5 9.12706E-4
27 0.49109 8.29057E-4 -1.793E-4
28 0.49863 1.21412E-2 4.93489E-3
29 0.49932 -1.01772E-3 1.55565E-4
30 0.50000 -3.88944E-2 -4.09358E-2
31 0.50798 2.76514E-3 1.005E-2
32 0.50924 2.14224E-3 -1.04622E-3
33 0.51606 -4.16182E-3 4.36226E-3
34 0.51679 2.08984E-3 4.32794E-3
35 0.51753 -4.02452E-1 3.06941E-1
36 0.51826 1.61991E-3 -6.65797E-3
37 0.52608 -2.05588E-2 1.48978E-2
38 0.52743 1.02377E-1 6.8144E-2
39 0.53632 1.54766E-2 1.25694E-2
40 0.53772 5.36369E-3 -1.55912E-2
41 0.54697 2.11116E-3 -4.35266E-3
42 0.54843 -1.75747E-3 -5.17054E-4
43 0.89909 8.19925E-5 2.77669E-4
44 0.92942 1.55273E-3 -1.65249E-3
45 0.93417 6.8252E-4 1.62464E-3
46 0.96244 -3.93571E-3 2.96626E-3
47 0.96696 3.55761E-4 2.99359E-5
48 0.99185 -4.36047E-4 4.29572E-4
49 0.99455 1.6817E-3 5.32935E-4
50 0.99727 4.6935E-2 4.57213E-2
51 1.00000 5.13058E-4 2.00988E-3
52 1.00275 1.10794E-2 1.61065E-2
53 1.00551 -3.68727E-4 9.36187E-4
54 1.02954 -6.71799E-5 1.8203E-3
55 1.03472 1.8785E-3 -1.93949E-3
56 1.04061 2.37559E-4 1.04234E-4
57 1.06951 -5.28836E-4 -1.06328E-3
58 1.07581 3.37455E-2 -7.41767E-3
59 1.11346 3.53721E-4 1.17589E-3
60 1.11951 -2.20519E-3 -5.32527E-3
61 1.16035 5.1051E-4 -7.16439E-4
62 1.16693 -4.17217E-5 -3.15888E-4
63 1.21136 1.48917E-4 -2.20619E-4
64 13.66079 1.39863E-3 -8.92305E-3
65 14.76529 1.09794E-3 2.25773E-3
66 27.55455 3.27833E-3 1.28068E-2
67 31.81193 -1.63109E-2 2.36633E-3
68 182.62118 -4.20707E-2 4.59593E-2
69 365.25998 6.25761E-2 9.50172E-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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