title: How do I calculate standard deviation of two arrays in python?
body: <p>I have two arrays: one with 30 years of observations, and one with 30 years of historical model runs. I want to calculate the standard deviation between observations and model results, to see how much the model deviates from observations. How do I go about doing this?</p>
  
  <p><strong>Edit</strong></p>
  
  <p>Here are the two arrays (Each number represents a year(1971-2000)): </p>
  
  <pre><code>obs = [ 2790.90283203  2871.02514648  2641.31738281  2721.64453125
  2554.19384766  2773.7746582   2500.95825195  3238.41186523
  2571.62133789  2421.93017578  2615.80395508  2271.70654297
  2703.82275391  3062.25366211  2656.18359375  2593.62231445
  2547.87182617  2846.01245117  2530.37573242  2535.79931641
  2237.58032227  2890.19067383  2406.27587891  2294.24975586
  2510.43847656  2395.32055664  2378.36157227  2361.31689453  2410.75
  2593.62915039]
  
  model = [ 2976.01928711  3353.92114258  3000.92700195  3116.5078125   2935.31787109
  2799.75805664  3328.06225586  3344.66333008  3318.31689453
  3348.85302734  3578.70800781  2791.78198242  4187.99902344
  3610.77124023  2991.984375    3112.97412109  4223.96826172
  3590.92724609  3284.6015625   3846.34936523  3955.84350586
  3034.26074219  3574.46362305  3674.80175781  3047.98144531
  3209.56616211  2654.86547852  2780.55053711  3117.91699219
  2737.67626953]    
  </code></pre>