Data, data, data

ENVS 202 On-line Access

Human Impact on Climate does the data support that there is an effect?

Looking at more data to find significance or not:

Another Case: US Tornado Frequency:

This is the distribution of verified tornadoes in the American Midwest from the period of 1953--1993:

Is the apparent recent increase significant?

Another Case: Urbanization and the Weather

Does Urbanization produce a microclimate in the sense that urban areas are getting warmer.

Where the data is

Here are some results for Washington DC average Tempearture:

Note that the dispersions are all very similar in these periods. The square root of 120 (number of data samples) = 11.

  • Error in the mean for 1960-1970 = 8.8/11 = 0.80
  • Error in the mean for 1970-1980 = 8.3/11 = 0.75

  • (M1-M2)/1.5E1 = 15.25-14.26/(1.5*.8) = 1/1.2 = 0.83 --> no significant increase. A significant increase would be hard to detect in this data because the instrinsic dispersion is large.

    Let's look at the case for Berkeley CA:

  • The error in the mean is a lot less because the disperion is less. The mean error is approximately 3/11 = .27

    So for Berkeley we have: 14.32-13.67/1.5(.27) = .65/.40 = 1.65 --> still not significant but a lot more significant than the case for Washington DC.

    This indicates that Berkeley is a better site for this study than Washington DC since the natural climate variations in DC are more severe and hence the signature of a small effect will be much more difficult to get out of the data.

    Now, what do you make of this data?

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