A Köppen Climate Classification Systematic Matrix
by M. Mustoe Ph.D.
For My Students at Eastern Oregon University, La Grande Oregon
6 March 2004

INTRODUCTION
The Köppen Climate Classification System is a very complex system that classifies climate types based on a variety of variables. Basically it works as a matrix in which the user starts with some specific data and then applies this data to various parameters within the Köppen model. As the user sifts through the matrix the ultimate outcome is a two or three letter classification connoting, amongst other things the over all type of climate it is, the type of seasonal concentration of precipitation it has, and the its temperature parameter.

Thus, keeping to the idea of a matrix, I have taken a simplified model of the Köppen system developed by R. Gabbler, R. Sager, and D. Wise, found in the text, Essentials of Physical Geography, 1999, and have adapted this to a series of hyperlinked web pages. There are a number of pages associated with the whole site, which contain links that allow the user to step from one classification characteristic to another and ultimately arriving at a complete classification of the climate.

For further information on climate see the Climate Resource Page.


What is the Köppen Climate Classification System?
The Köppen Climate Classification system is a model which helps in the identification and understanding the nature of various kinds of climates. It is based around letters which define broad areas of climates. These major letters are:

Note: A highland (mountain) climate is also a part of this system which is part of this classification model.

Who was Vladimir Köppen
Vlad. Köppen was a Russian botanist who developed the model in the late 1800s. Although it has been modified many times it is still a viable method of classifying climates today.


How to classify a climate
Here are a series of questions which you can ask yourself as you go through the classification process. Tap on the hot link which might be applicable for the climate inquiry you are making.

Prior Information That You Will Need.

*According to the Köppen system there are TWO SEASONS; Summer and Winter. Summer is April May June July August September and Winter is January February March and October, November, and December. A concentration of precipitation is defined as 70% of the total precipitation for the year falling in either Summer or Winter. For example, if you have 30% of the total precipitation of a station falling in summer, thus you must have 70% falling in winter, (30%+70%=100%) so consequently, according to Köppen, this station is defined as having a Winter Concentration of precipitation.



Reading Data
NOTE: DO NOT CONFUSE THE UNITS. IF YOU START A CLASSIFICATION OFF IN ENGLISH UNITS KEEP TO THAT SYSTEM OF UNITS.
ALSO REMEMBER IF YOU CLASSIFY CLIMATES IN THE SOUTHERN HEMISPHERE SEASONS ARE OPPOSITE THAT OF THE NORTHERN HEMISPHERE.
Normally you would obtain data from any climatic data source, for example. Ultimately what you might have is a chart that looks something like this:
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
°C 1.3 4.5 8.1 11.4 15.4 19.7 23.1 22.5 17.5 11.7 5.8 1.7 11.9
°F 34.3 40.1 46.6 52.5 59.7 67.5 73.6 72.5 63.5 53.1 42.4 35.1 53.4

These are the AVERAGE temperatures for each month at Milton Freewater, Oregon in both °C and °F. The average total for the year is calculated at the end of the chart on the right under Year. The above information is for temperature, but for Köppen's Classification you will also need precipitation. Those data might look something like this:

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
mm 40.3 31.4 35.0 34.1 34.1 28.7 10.7 14.0 21.5 29.0 45.2 43.5 368.5
inches 1.6 1.2 1.4 1.3 1.3 1.1 0.4 0.6 0.8 1.1 1.8 1.7 14.5

In this case the data is in mm and inches and shows the averages of precipitation for each month and the total for the year. In order to complete a classification you would have to first determine where the concentration of this precipitation falls. The total in inches for Jan, Feb, Mar, Nov, Dec, and Dec, (the winter months according to Köppen) is 8.8 inches, Since 14.5 inches is the total precipitation, this means that     (8.8 / 14.5 X100=%)    about 60% of the precipitation at Milton Freewater falls in winter. And thus 40% falls in summer, and, since neither of these measures suggest a Köppen defined concentration of precipitation, the station is considered to have a climate with a non-concentrated pattern of precipitation.



Ready To Classify?
With the data you have determine the following information before you start:

To keep your data in order, here is a page you can use and print out. Data Page.

STEP ONE
DETERMINING THE
FIRST LETTER
Start Here