<p>I find the statement in the question difficult to believe.Tides have a pretty cyclical period and I doubt the resulting effect is a day-night difference unless only S1 and S2 tidal constituents are important in that location, which I find very unlikely.</p>

<p>In fact, the portal
<a href="https://www.tide-forecast.com/locations/Fremantle-Australia/tides/latest" rel="nofollow noreferrer">https://www.tide-forecast.com/locations/Fremantle-Australia/tides/latest</a>
shows the high tide being larger during the day for the rest of the month of May 2018.<a href="https://i.sstatic.net/b4TM5.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/b4TM5.png" alt="may tide"></a>
That behavior changes in time as one would expect. The dominant frequencies at this location are diurnal tides (mostly a single high tide and low tide per day). The main diurnal tides have a period around 24 hours and in this case the dominant periods are slightly larger than 24 hours. </p>

<p>You can download the hourly data from: <a href="http://uhslc.soest.hawaii.edu/data/netcdf/fast/hourly/h175.nc" rel="nofollow noreferrer">http://uhslc.soest.hawaii.edu/data/netcdf/fast/hourly/h175.nc</a>
and the resulting time series goes from 1984 to now. Here is the time series for the year 2017. There is no time at which the tide "dissappears".
<a href="https://i.sstatic.net/NYhOs.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/NYhOs.png" alt="SL"></a>
The resulting harmonic analysis (using t_tide) shows that the tidal constituents with amplitudes over about 5 cm are:</p>

<pre><code>Constituent  Period (h)  Magnitude (m)
   O1         25.82      0.1206    
   K1         23.93      0.1667    
   M2         12.42      0.0525   
   S2         12.00      0.0465   
</code></pre>

<p>The dominant constituents are K1 and O1, with comparable amplitudes. The resulting effect of the two main diurnal frequencies is a period slightly over 24 hours. The effect of the semidiurnal constituents (M2, S2) is smaller and can be seen in the first time series as slight humps in May 24-27.</p>

<ul>
<li>T_tide: Pawlowicz, R., B. Beardsley, and S. Lentz, "Classical Tidal 
"Harmonic Analysis Including Error Estimates in MATLAB 
 using t_tide", Computers and Geosciences, 28, 929-937 (2002).</li>
</ul>

CC BY-SA 4.0
2018-05-24T08:51:30.800Z
Comments: University of Cambridge Forum 
https://www.thenakedscientists.com/forum/index.php?topic=73127.0
Юсуп
CC BY-SA 4.0
2018-05-24T11:05:39.127Z
@Юсуп This site is not a platform to ask questions with the goal of furthering your work (or the work of people you are connected with).  If you'd like to seek constructive input on these theories, you could try asking one direct question as to its validity.
JeopardyTempest
CC BY-SA 4.0
2018-05-24T11:12:37.907Z
I don't know if much of these practices are a language barrier causing some confusion, or if it's someone pushing more in line with pseudoscience. Unfortunately I never really touched much on oceanography besides certain ocean-atmospheric couplings (namely in ENSO). arkaia (and other oceanograhers) your input would help a lot... does the stuff that keeps getting posted by Юсуп have some connections to the field? Have you heard of the "Eastern European Scientific Journal"? Is [this wikipedia term/topic](https://en.wikipedia.org/wiki/Amphidromic_point) valid, or should it likewise be deleted?
JeopardyTempest
CC BY-SA 4.0
2018-05-24T11:20:01.143Z
Does look like amphidromic point shows up within the Journal of Oceanography a handful of times... so good to know.  Found it tough for me, someone with no knowledge of such topics to weigh the validity.  And for general public, likely harder.  Sorry, couldn't make heads or tails of the actions, and thought they might be detrimental hijacking attempts.  Can you confirm that's not the case, we can work towards trying to help the user through possible troubles with the language barrier?
JeopardyTempest
CC BY-SA 4.0
2018-05-24T17:50:40.123Z
I'm sorry!
The interpreter did not give a high-quality translation.
Юсуп
CC BY-SA 4.0
2018-05-25T01:48:05.950Z
The amphidromic points are quite REAL! The issue is that they are zero for one specific constituents out of the many constituents that form the tide. So it might be zero for the M2 tide, but the rest are not going to be zero at exactly that location. I'm not going to go into the discussion of questionable journals and all the pseudoscience stuff. Too much for me!
arkaia
CC BY-SA 4.0
2018-06-14T04:54:22.363Z
Frequently Asked Questions Concerning Tides: 
http://mypages.iit.edu/~johnsonpo/smart00/lesson4.htm#tidefaqs
1. It is believed that the cause of the second lunar hump is the barycenter. 
And what is the cause of the solar second hump?
2. Who is the author of the theory of tidal resonance and why this theory is not available on the Internet?
3. In the Atlantic Ocean from east to west, to the Gulf of Maine, a tidal current or tidal wave moves and at what speed.
Юсуп
CC BY-SA 4.0
2018-06-27T07:40:54.803Z
Why in some bays (Mont-Saint-Michel), with a frequency of 10-20 years, record high tides are formed.
"The Moon theory of tides," explains this phenomenon by increasing the force of gravity.But why gravity does not increase in other bays, moreover, in some bays, the amplitude of tides at the same time decreases on the contrary.
Юсуп
CC BY-SA 4.0
2018-05-23T20:43:28.740Z
2018-05-23T20:43:28.740Z
arkaia
<p>Can the tides at night be consistently higher than in the daytime in southwest Australia in the port of Fremantle?
Also, what is the explanation for the tides being significant during a part of the year, and then disappear.</p>

CC BY-SA 4.0
2018-05-23T20:43:04.503Z
Given your past history with packaged/spam answers (deleted by moderation) to similar questions, are you interested in reasonable input?  Because I'm sure some great users would be glad to take their time to give such answers if you are interested in hearing them :)
JeopardyTempest
CC BY-SA 4.0
2018-05-23T20:44:31.473Z
@JeopardyTempest, I think we might try to edit the question to salvage it. I have provided what I believe can be a reasonable answer
arkaia
CC BY-SA 4.0
2018-05-23T21:13:38.833Z
@arkaia absolutely, I have no worries over the question, a little edit should be fine. Just noting we (including you) have had interaction with this user before, packaged answers put in many places including [here](https://earthscience.stackexchange.com/questions/8917/how-often-do-king-tides-perigean-spring-tides-occur) (only visible to users with 2000+ rep). As this looks now, seems only a useful question and answer... only want to alert to past issues, and note concern that this question may look to railroad to a hidden bias. But am very hopeful Юсуп is here with good intentions to learn!
JeopardyTempest
CC BY-SA 4.0
2018-05-24T00:55:48.157Z
@JeopardyTempest, I think we are on the same page
arkaia
CC BY-SA 4.0
2018-05-24T09:00:54.457Z
Are you asking about why tides are higher at night (as per the title), or are you asking why tides come and go over a year in Freemantle (as per the text)? Either way, can you provide any more information on the phenomenon that you're asking about? At the moment I'm voting to close as "unclear what you're asking", but I'd happily vote to re-open if there was a clear description of what you want to know.
Semidiurnal Simon
CC BY-SA 4.0
2018-05-24T12:08:03.417Z
Your question title (about day/night) and question text (about part of the year) do not match. Please [edit] your question to make clear what you are asking. And as *Semidiurnal Simon* says, provide some references showing that the phenomenon does indeed happen. For instance, if your question is about *tides at night higher than in the daytime*, that most certainly is **not** the case. One of the two daily tides is always higher than the other, and that higher tide shifts through 24 hours as the moon/month progresses.
Jan Doggen
CC BY-SA 4.0
2018-05-25T05:05:36.357Z
Thank you for editing the question for consistency. However, you're still asking "why is x?" for an x that is, at first glance, not the case. Can you provide a link or further information to illustrate what you mean? Then we might be able to answer as to why it happens.
Semidiurnal Simon
CC BY-SA 4.0
2018-05-26T00:58:17.383Z
As I don't think the original questioner is likely to edit the question, I am proposing some wording that might be more defendable and also useful for other users.
arkaia
CC BY-SA 4.0
2018-05-26T02:14:45.863Z
@arkaia Fair enough, certainly behind that.  Intriguing at least that the original asker did comment to you, but seems language may be a challenge :-/
JeopardyTempest
<ocean><tides>
Can tides at night by consistently higher than in the daytime?
Юсуп
# Can tides at night by consistently higher than in the daytime?

(Asked by: username_0 on 2018-05-23)

Can the tides at night be consistently higher than in the daytime in southwest Australia in the port of Fremantle?
Also, what is the explanation for the tides being significant during a part of the year, and then disappear.

**Tags:** ocean, tides

> **Comments:**
> **username_1**: Given your past history with packaged/spam answers (deleted by moderation) to similar questions, are you interested in reasonable input?  Because I'm sure some great users would be glad to take their time to give such answers if you are interested in hearing them :)  
> **username_2**: @username_1, I think we might try to edit the question to salvage it. I have provided what I believe can be a reasonable answer  
> **username_1**: @username_2 absolutely, I have no worries over the question, a little edit should be fine. Just noting we (including you) have had interaction with this user before, packaged answers put in many places including [here](https://earthscience.stackexchange.com/questions/8917/how-often-do-king-tides-perigean-spring-tides-occur) (only visible to users with 2000+ rep). As this looks now, seems only a useful question and answer... only want to alert to past issues, and note concern that this question may look to railroad to a hidden bias. But am very hopeful username_0 is here with good intentions to learn!  
> **username_2**: @username_1, I think we are on the same page  
> **username_3**: Are you asking about why tides are higher at night (as per the title), or are you asking why tides come and go over a year in Freemantle (as per the text)? Either way, can you provide any more information on the phenomenon that you're asking about? At the moment I'm voting to close as "unclear what you're asking", but I'd happily vote to re-open if there was a clear description of what you want to know.  
> **username_4**: Your question title (about day/night) and question text (about part of the year) do not match. Please [edit] your question to make clear what you are asking. And as *username_3* says, provide some references showing that the phenomenon does indeed happen. For instance, if your question is about *tides at night higher than in the daytime*, that most certainly is **not** the case. One of the two daily tides is always higher than the other, and that higher tide shifts through 24 hours as the moon/month progresses.  
> **username_3**: Thank you for editing the question for consistency. However, you're still asking "why is x?" for an x that is, at first glance, not the case. Can you provide a link or further information to illustrate what you mean? Then we might be able to answer as to why it happens.  
> **username_2**: As I don't think the original questioner is likely to edit the question, I am proposing some wording that might be more defendable and also useful for other users.  
> **username_1**: @username_2 Fair enough, certainly behind that.  Intriguing at least that the original asker did comment to you, but seems language may be a challenge :-/  

---

## 1 answers

### Answer by username_2 on 2018-05-23. Score: 3

I find the statement in the question difficult to believe.Tides have a pretty cyclical period and I doubt the resulting effect is a day-night difference unless only S1 and S2 tidal constituents are important in that location, which I find very unlikely.

In fact, the portal
<https://www.tide-forecast.com/locations/Fremantle-Australia/tides/latest>
shows the high tide being larger during the day for the rest of the month of May 2018.[![may tide](https://i.sstatic.net/b4TM5.png)](https://i.sstatic.net/b4TM5.png)
That behavior changes in time as one would expect. The dominant frequencies at this location are diurnal tides (mostly a single high tide and low tide per day). The main diurnal tides have a period around 24 hours and in this case the dominant periods are slightly larger than 24 hours.

You can download the hourly data from: <http://uhslc.soest.hawaii.edu/data/netcdf/fast/hourly/h175.nc>
and the resulting time series goes from 1984 to now. Here is the time series for the year 2017. There is no time at which the tide "dissappears".
[![SL](https://i.sstatic.net/NYhOs.png)](https://i.sstatic.net/NYhOs.png)
The resulting harmonic analysis (using t\_tide) shows that the tidal constituents with amplitudes over about 5 cm are:

```
Constituent  Period (h)  Magnitude (m)
   O1         25.82      0.1206    
   K1         23.93      0.1667    
   M2         12.42      0.0525   
   S2         12.00      0.0465   

```

The dominant constituents are K1 and O1, with comparable amplitudes. The resulting effect of the two main diurnal frequencies is a period slightly over 24 hours. The effect of the username_3 constituents (M2, S2) is smaller and can be seen in the first time series as slight humps in May 24-27.

* T\_tide: Pawlowicz, R., B. Beardsley, and S. Lentz, "Classical Tidal
  "Harmonic Analysis Including Error Estimates in MATLAB
  using t\_tide", Computers and Geosciences, 28, 929-937 (2002).

> **Comments:**
> **username_0**: Comments: University of Cambridge Forum  https://www.thenakedscientists.com/forum/index.php?topic=73127.0  
> **username_1**: @username_0 This site is not a platform to ask questions with the goal of furthering your work (or the work of people you are connected with).  If you'd like to seek constructive input on these theories, you could try asking one direct question as to its validity.  
> **username_1**: I don't know if much of these practices are a language barrier causing some confusion, or if it's someone pushing more in line with pseudoscience. Unfortunately I never really touched much on oceanography besides certain ocean-atmospheric couplings (namely in ENSO). username_2 (and other oceanograhers) your input would help a lot... does the stuff that keeps getting posted by username_0 have some connections to the field? Have you heard of the "Eastern European Scientific Journal"? Is [this wikipedia term/topic](https://en.wikipedia.org/wiki/Amphidromic_point) valid, or should it likewise be deleted?  
> **username_1**: Does look like amphidromic point shows up within the Journal of Oceanography a handful of times... so good to know.  Found it tough for me, someone with no knowledge of such topics to weigh the validity.  And for general public, likely harder.  Sorry, couldn't make heads or tails of the actions, and thought they might be detrimental hijacking attempts.  Can you confirm that's not the case, we can work towards trying to help the user through possible troubles with the language barrier?  
> **username_0**: I'm sorry! The interpreter did not give a high-quality translation.  
> **username_2**: The amphidromic points are quite REAL! The issue is that they are zero for one specific constituents out of the many constituents that form the tide. So it might be zero for the M2 tide, but the rest are not going to be zero at exactly that location. I'm not going to go into the discussion of questionable journals and all the pseudoscience stuff. Too much for me!  
> **username_0**: Frequently Asked Questions Concerning Tides:  http://mypages.iit.edu/~johnsonpo/smart00/lesson4.htm#tidefaqs 1. It is believed that the cause of the second lunar hump is the barycenter.  And what is the cause of the solar second hump? 2. Who is the author of the theory of tidal resonance and why this theory is not available on the Internet? 3. In the Atlantic Ocean from east to west, to the Gulf of Maine, a tidal current or tidal wave moves and at what speed.  
> **username_0**: Why in some bays (Mont-Saint-Michel), with a frequency of 10-20 years, record high tides are formed. "The Moon theory of tides," explains this phenomenon by increasing the force of gravity.But why gravity does not increase in other bays, moreover, in some bays, the amplitude of tides at the same time decreases on the contrary.  

---

