<p>I'll address this part of the question first:</p>
<p>&quot;Or a similar question can be: the weather measurements of how far ago can affect today's weather measurements? Does the weather forget about the weather events of long time ago? If so, how long is that window?&quot;</p>
<p>The answer is &quot;approximately two weeks&quot;. Even with <em>nearly perfect</em> knowledge of the atmospheric state (the distribution of pressure, moisture, aerosols, etc), the chaotic nature of fluids means that beyond two weeks, one would be better of predicting the weather from a climatological estimate (i.e, the average of the weather on that date for the last ~30 years). Research into this very question was foundational for the field of Chaos theory (Lorenz, 1963 is a famous example). This isn't just an artifact of the predictive models, but the natural system itself. The weather has effectively 'forgotten' what it was doing a few weeks before.</p>
<p>While the atmosphere has a short 'memory', other parts of the Earth have longer 'memories'. Notable examples are the Oceans and the Landsurface. A warm anomaly in the Ocean will stick around for a while, since ocean currents are much slower than air for mixing things around (and diffusing out the anomaly). The atmosphere is very influenced by what happens on the surface, so the warm/cool anomaly can affects the weather in various ways. This is what happens in the case of ENSO that you have mentioned. The land can also have an impact. The amount of saturation in the soil can have quite a big impact on weather, especially for things like thunderstorms and monsoon systems. Continental snow cover extent may also impact atmospheric predictability. Stratosphere/troposphere coupling mechanisms might also be a source of longer term predictability.</p>
<p>And this part:
&quot;I am wondering if there is long term (10 year, 7 year, 20 year) periodic patterns Similar to short term seasonal and periodic patterns in weather such as sea/land wind, monsoon, ENSO, ocean sea-saw, etc.&quot;</p>
<p>The most well known ~10 year climate oscillation is the Pacific Decadal Oscillation.</p>

CC BY-SA 4.0
2020-07-06T20:07:08.753Z
Thank you so much for detailed explanation. Is there a way to capture these patterns such as ENSO, etc in data analytics? Will they be captured automatically if I try to find the seasonalities within the data?
fof
CC BY-SA 4.0
2020-07-07T17:49:27.240Z
@fof-- The answer is 'it depends'. There might not be any correlation with between El Nino and precipitation whatsoever, depending on what part of world you're conducting your analysis. You probably want to start by looking at ENSO indices and seeing if your data correlates. https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php
William Rudisill
CC BY-SA 4.0
2020-07-06T18:27:50.513Z
2020-07-06T18:27:50.513Z
William Rudisill
<p>I am wondering if there is long term (10 year, 7 year, 20 year)  periodic patterns Similar to short term seasonal and periodic patterns in weather such as sea/land wind, monsoon, ENSO, ocean sea-saw, etc.
<br>
<strong>Specifically related to drought</strong><br>
I am trying to predict the rainfall using the weather data, I was wondering if different patterns that happen in weather changes through time are periodic?
Is there a periodic pattern in the pattern of weather changes?
Is there a general periodic pattern that may happen every 10 years or more? If so, how long is the window of this period?
Or a similar question can be: the weather measurements of how far ago can affect today's weather measurements?
Does the weather forget about the weather events of long time ago? If so, how long is that window?</p>
<p>If there is a <strong>journal paper</strong> or material that I can study please tell me. Thanks</p>
<p><strong>Additional Explanation:</strong>
I am a data scientist trying to predict rainfall using weather data. So I do not have earth science knowledge. So after I read @Fred's comment, I understood that what I have in mind is called 'Cycle' in earth sciences.
<br>
<strong>edited question:</strong> <em>What is the length of the cycles for rainfall patterns? (If I want to predict rainfall, how long is the length for cycles that affect rainfall? Or how many years of data I should use?! )</em></p>

CC BY-SA 4.0
2020-07-03T22:18:09.067Z
have you done any steps to find information about this subject,it might help you in making more focused questions.
trond hansen
CC BY-SA 4.0
2020-07-04T00:21:39.333Z
@a_donda Based on the title only, one could tell a little something about solar cycles and Milankovitch cycles.
Joscha Fregin
CC BY-SA 4.0
2020-07-04T01:33:22.650Z
With climate, many thing come into play. As others have stated, [Milankovitch Cycles](https://en.wikipedia.org/wiki/Milankovitch_cycles), resulting from the Earth's axial, precession & eccentricity creates climate cycles that have cycles for 1000s of years. Additionally, amongst other cycles, there are also [drought cycles](https://earthobservatory.nasa.gov/world-of-change/AustraliaNDVI), with shorter intervals.  You might find [*Climate: The Key To Understanding Business Cycles*](https://cyclesresearchinstitute.org/cycles-research/weather/wheeler/) interesting, if you can find a copy. ...
Fred
CC BY-SA 4.0
2020-07-04T03:18:27.533Z
I can't tell if you are asking about [climate](https://en.wikipedia.org/wiki/Climate) or [weather](https://en.wikipedia.org/wiki/Weather) and there are several different questions here. Can you narrow this down to something a little more specific? I think this is a great line of questioning and you can always ask more questions, but it's better to keep each one well-focused so that it can have a fairly short, clear answer if possible. Thanks!
uhoh
CC BY-SA 4.0
2020-07-04T13:18:27.870Z
@trondhansen Yes, I have done, but I still do not have a more focused question. Since Earth Science is not my area of expertise and I am doing a project in this area, I needed some information. But I will explain my project in the descriptions so that maybe it clarifies what information I need.
fof
CC BY-SA 4.0
2020-07-04T13:21:49.943Z
@Fred Thanks for your information! That is the type of answer that I need. Specially drought cycles is exactly the one that I am looking for.
fof
CC BY-SA 4.0
2020-07-04T13:50:05.043Z
@uhoh I am talking about weather. My main question is the one that I asked as a question (Are weather changes periodic?) and other questions I made in the description is to help others understand what specifically I have in mind.
fof
CC BY-SA 4.0
2020-07-04T13:58:41.593Z
@Fred It seems like the period for weather cycles, is 100 years from what I can tell in https://cyclesresearchinstitute.org/cycles-research/weather/wheeler/ . So if I am doing data analysis and I have only the data for the past 40 years, I should not be worried about that, am I correct? Or is there other short term cycles, for example 10 years cycle?
By the way, since your respond is the closest to what I wanted, you can post it as the answer and I confirm it as the answer to the question.
fof
CC BY-SA 4.0
2020-07-04T14:59:27.583Z
@a_donda Thanks ECMWF is good information. I am predicting long term rainfall, so midterm seasonality, specially related to drought.
fof
CC BY-SA 4.0
2020-07-06T15:43:01.213Z
By chance you mean, https://en.wikipedia.org/wiki/El_Ni%C3%B1o%E2%80%93Southern_Oscillation and https://en.wikipedia.org/wiki/Pacific_decadal_oscillation?
Buttonwood
<weather-forecasting><precipitation><rainfall>
Are weather changes periodic? (Do the same weather patterns repeat over years?) (Cycles) (Journal paper suggestion)
fof
# Are weather changes periodic? (Do the same weather patterns repeat over years?) (Cycles) (Journal paper suggestion)

(Asked by: username_0 on 2020-07-03)

I am wondering if there is long term (10 year, 7 year, 20 year) periodic patterns Similar to short term seasonal and periodic patterns in weather such as sea/land wind, monsoon, ENSO, ocean sea-saw, etc.
  
**Specifically related to drought**  
I am trying to predict the rainfall using the weather data, I was wondering if different patterns that happen in weather changes through time are periodic?
Is there a periodic pattern in the pattern of weather changes?
Is there a general periodic pattern that may happen every 10 years or more? If so, how long is the window of this period?
Or a similar question can be: the weather measurements of how far ago can affect today's weather measurements?
Does the weather forget about the weather events of long time ago? If so, how long is that window?

If there is a **journal paper** or material that I can study please tell me. Thanks

**Additional Explanation:**
I am a data scientist trying to predict rainfall using weather data. So I do not have earth science knowledge. So after I read @username_3's comment, I understood that what I have in mind is called 'Cycle' in earth sciences.
  
**edited question:** *What is the length of the cycles for rainfall patterns? (If I want to predict rainfall, how long is the length for cycles that affect rainfall? Or how many years of data I should use?! )*

**Tags:** weather-forecasting, precipitation, rainfall

> **Comments:**
> **username_1**: have you done any steps to find information about this subject,it might help you in making more focused questions.  
> **username_2**: @a_donda Based on the title only, one could tell a little something about solar cycles and Milankovitch cycles.  
> **username_3**: With climate, many thing come into play. As others have stated, [Milankovitch Cycles](https://en.wikipedia.org/wiki/Milankovitch_cycles), resulting from the Earth's axial, precession & eccentricity creates climate cycles that have cycles for 1000s of years. Additionally, amongst other cycles, there are also [drought cycles](https://earthobservatory.nasa.gov/world-of-change/AustraliaNDVI), with shorter intervals.  You might find [*Climate: The Key To Understanding Business Cycles*](https://cyclesresearchinstitute.org/cycles-research/weather/wheeler/) interesting, if you can find a copy. ...  
> **username_4**: I can't tell if you are asking about [climate](https://en.wikipedia.org/wiki/Climate) or [weather](https://en.wikipedia.org/wiki/Weather) and there are several different questions here. Can you narrow this down to something a little more specific? I think this is a great line of questioning and you can always ask more questions, but it's better to keep each one well-focused so that it can have a fairly short, clear answer if possible. Thanks!  
> **username_0**: @username_1 Yes, I have done, but I still do not have a more focused question. Since Earth Science is not my area of expertise and I am doing a project in this area, I needed some information. But I will explain my project in the descriptions so that maybe it clarifies what information I need.  
> **username_0**: @username_3 Thanks for your information! That is the type of answer that I need. Specially drought cycles is exactly the one that I am looking for.  
> **username_0**: @username_4 I am talking about weather. My main question is the one that I asked as a question (Are weather changes periodic?) and other questions I made in the description is to help others understand what specifically I have in mind.  
> **username_0**: @username_3 It seems like the period for weather cycles, is 100 years from what I can tell in https://cyclesresearchinstitute.org/cycles-research/weather/wheeler/ . So if I am doing data analysis and I have only the data for the past 40 years, I should not be worried about that, am I correct? Or is there other short term cycles, for example 10 years cycle? By the way, since your respond is the closest to what I wanted, you can post it as the answer and I confirm it as the answer to the question.  
> **username_0**: @a_donda Thanks ECMWF is good information. I am predicting long term rainfall, so midterm seasonality, specially related to drought.  
> **username_5**: By chance you mean, https://en.wikipedia.org/wiki/El_Ni%C3%B1o%E2%80%93Southern_Oscillation and https://en.wikipedia.org/wiki/Pacific_decadal_oscillation?  

---

## 1 answers

### Answer by username_6 on 2020-07-06. Score: 0 | Accepted answer

I'll address this part of the question first:

"Or a similar question can be: the weather measurements of how far ago can affect today's weather measurements? Does the weather forget about the weather events of long time ago? If so, how long is that window?"

The answer is "approximately two weeks". Even with *nearly perfect* knowledge of the atmospheric state (the distribution of pressure, moisture, aerosols, etc), the chaotic nature of fluids means that beyond two weeks, one would be better of predicting the weather from a climatological estimate (i.e, the average of the weather on that date for the last ~30 years). Research into this very question was foundational for the field of Chaos theory (Lorenz, 1963 is a famous example). This isn't just an artifact of the predictive models, but the natural system itself. The weather has effectively 'forgotten' what it was doing a few weeks before.

While the atmosphere has a short 'memory', other parts of the Earth have longer 'memories'. Notable examples are the Oceans and the Landsurface. A warm anomaly in the Ocean will stick around for a while, since ocean currents are much slower than air for mixing things around (and diffusing out the anomaly). The atmosphere is very influenced by what happens on the surface, so the warm/cool anomaly can affects the weather in various ways. This is what happens in the case of ENSO that you have mentioned. The land can also have an impact. The amount of saturation in the soil can have quite a big impact on weather, especially for things like thunderstorms and monsoon systems. Continental snow cover extent may also impact atmospheric predictability. Stratosphere/troposphere coupling mechanisms might also be a source of longer term predictability.

And this part:
"I am wondering if there is long term (10 year, 7 year, 20 year) periodic patterns Similar to short term seasonal and periodic patterns in weather such as sea/land wind, monsoon, ENSO, ocean sea-saw, etc."

The most well known ~10 year climate oscillation is the Pacific Decadal Oscillation.

> **Comments:**
> **username_0**: Thank you so much for detailed explanation. Is there a way to capture these patterns such as ENSO, etc in data analytics? Will they be captured automatically if I try to find the seasonalities within the data?  
> **username_6**: @username_0-- The answer is 'it depends'. There might not be any correlation with between El Nino and precipitation whatsoever, depending on what part of world you're conducting your analysis. You probably want to start by looking at ENSO indices and seeing if your data correlates. https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php  

---

