title: seasonal decompose in python
body: <p>I have a CSV file that contains the average temperature over almost 5 years. After decomposition using <code>seasonal_decompose</code> function from <code>statsmodels.tsa.seasonal</code>, I got the following results. Indeed, the results do not show any seasonal! However, I see a clear <code>sin</code> in the trend! I am wondering why is that and how can I correct it? Thank you.</p>
  
  <pre><code>nresult = seasonal_decompose(nseries, model='additive', freq=1)
  nresult.plot()
  plt.show()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/uVprr.png" rel="noreferrer"><img src="https://i.stack.imgur.com/uVprr.png" alt="enter image description here"></a></p>