Climate Modeling

Challenges to Climate Modeling

A challenge with climate modeling is that in the real world, many processes of the climate system occur on different spatial or temporal scales. For example, the uplifting of mountain ranges may occur over millions of years while land–surface heating and cooling occur over seasonal and diurnal periods. In order to deal with different spatial and temporal scales, researchers must determine what type of climate model to apply to simulate the climate processes and time period of interest. To simulate a climate process such as a monsoon, researchers may run the model for a time scale of several months or 100 years over specific geographic region. To simulate changes with significant movements of the continents, researchers may run the model to simulate for millions of years for the entire globe.

Climate modeling became a researching tool in the mid-1960s. The most simple climate models are [Page 273]zero-dimensional models, or radiative equilibrium models. These models are used to gain an idea of a planet's radiative temperature based on an assumed constant amount of incoming solar radiation and the planet's mass. For earth, these models calculate a radiative surface temperature of 255 K (0 degrees F). These models omit some of the known climate processes such as warming from greenhouse gases, hence the actual average surface temperature for earth is actually 288 K (59 degrees F).

There are two general types of one-dimensional climate models: radiative-convective models and energy balance models. The radiative-convective models were developed in the mid-1960s to analyze the thermal equilibrium of the atmosphere. These models calculate the temperature for each layer of the atmosphere based on the incoming solar radiation, surface temperatures, surface reflectivity, cloud cover, atmospheric pressure, and moisture content. Radiative-convective models are useful to our understanding of climate processes of temperature decreases with altitude or local temperature inversions. They are also useful in understanding local climate processes such as thunderstorm development. Energy balance models were developed in the late 1960s to calculate the amount of solar radiation absorbed or reflected by clouds and the earth's surface. These calculations are based on the amount of incoming solar radiation, cloud cover, and reflectivity at different latitudes. Energy balance models demonstrate how temperature decreases with increasing distance from the earth's equator.

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