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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)
21 Mar 2026 02:02:00
Latency
2016
Level
0.44

Harmonics

Points count
6749312
First date
29 Apr 2011 19:11
Last date
25 Feb 2026 22:02

Click on following link to see data:

Harmonics Constatns
Comp # Period (day) Cos factor (m) Sin factor (m)
0 0.00000 1.12947E+0 0E+0
1 0.12877 7.39987E-5 -8.55183E-6
2 0.12886 2.04795E-4 1.56043E-4
3 0.12938 1.46303E-4 -1.16448E-4
4 0.14707 -1.00423E-4 2.42761E-5
5 0.16841 3.23039E-4 3.71207E-4
6 0.16857 -1.52874E-4 -1.0856E-3
7 0.17036 7.39328E-4 1.26479E-4
8 0.17052 -2.77173E-3 -1.32975E-3
9 0.17251 -1.06134E-3 1.12849E-3
10 0.17470 4.23555E-4 -2.76323E-4
11 0.19989 3.17049E-4 3.53739E-4
12 0.20545 7.39583E-4 -6.90138E-5
13 0.24966 -5.04311E-4 -2.69151E-5
14 0.25000 3.02718E-4 2.75993E-4
15 0.25395 -5.95445E-4 -3.8809E-4
16 0.25431 -5.90998E-5 1.05592E-3
17 0.25631 8.07937E-5 -7.51873E-5
18 0.25667 -2.08385E-4 -2.53266E-7
19 0.25876 4.13648E-4 -4.64681E-4
20 0.26122 -2.30656E-4 8.26978E-4
21 0.33303 3.19777E-4 1.59874E-3
22 0.34071 1.02741E-3 -8.97534E-5
23 0.34135 6.01277E-4 -4.09205E-4
24 0.34502 -3.22437E-3 3.19518E-3
25 0.34943 4.99327E-5 1.82688E-4
26 0.48977 -5.99915E-5 8.45176E-4
27 0.49109 8.03863E-4 -1.8316E-4
28 0.49863 1.1938E-2 4.97882E-3
29 0.49932 -9.05145E-4 1.87748E-4
30 0.50000 -3.89491E-2 -4.09489E-2
31 0.50798 2.6184E-3 1.01293E-2
32 0.50924 2.17315E-3 -9.99366E-4
33 0.51606 -4.43807E-3 4.63634E-3
34 0.51679 2.57476E-3 4.1913E-3
35 0.51753 -4.02866E-1 3.06892E-1
36 0.51826 1.8416E-3 -6.57832E-3
37 0.52608 -2.06563E-2 1.49749E-2
38 0.52743 1.02412E-1 6.80603E-2
39 0.53632 1.5553E-2 1.25927E-2
40 0.53772 5.35754E-3 -1.55645E-2
41 0.54697 2.09548E-3 -4.35545E-3
42 0.54843 -1.76265E-3 -5.22121E-4
43 0.89909 8.45242E-5 2.5108E-4
44 0.92942 1.52323E-3 -1.62157E-3
45 0.93417 7.42874E-4 1.63482E-3
46 0.96244 -3.91699E-3 2.93568E-3
47 0.96696 2.97181E-4 2.35886E-5
48 0.99185 -5.75981E-4 4.47921E-4
49 0.99455 1.94726E-3 4.50594E-4
50 0.99727 4.65895E-2 4.57047E-2
51 1.00000 6.84382E-4 2.13238E-3
52 1.00275 1.11137E-2 1.60984E-2
53 1.00551 -3.90991E-4 8.34009E-4
54 1.02954 -6.21809E-5 1.89836E-3
55 1.03472 1.88543E-3 -1.96638E-3
56 1.04061 2.55191E-4 7.97898E-5
57 1.06951 -6.19779E-4 -1.06559E-3
58 1.07581 3.34486E-2 -7.55587E-3
59 1.11346 3.53617E-4 1.14763E-3
60 1.11951 -2.18283E-3 -5.25207E-3
61 1.16035 4.8991E-4 -6.78618E-4
62 1.16693 -4.76339E-5 -3.72983E-4
63 1.21136 9.24941E-5 -1.61961E-4
64 13.66079 1.50829E-3 -8.84156E-3
65 14.76529 1.54504E-3 2.53541E-3
66 27.55455 3.11988E-3 1.32398E-2
67 31.81193 -1.68966E-2 1.68088E-3
68 182.62118 -4.38891E-2 4.75515E-2
69 365.25998 6.09014E-2 9.85256E-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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