Lesson 4: Graphing Albedo and Temperature DataStudents will use Microsoft Excel to graph the change in albedo and near surface temperatures following a forest fire.
In interlinked step-by-step lesson activities the learner will:
1. use Microsoft Excel to make a scatter graph of albedo before and after a forest fire;
2. use Microsoft Excel to make a line graph of near surface temperatures at two elevations after a forest fire; and
3. interpret the graphs showing changes in albedo and near surface temperatures in an area after a forest fire.
Computer with Microsoft Excel
Microsoft Excel file Albedo_Temp_data.xls
Albedo: If Earth were completely covered in ice it would have a high albedo of approximately 0.84, meaning 84% of the sunlight would reflect the sunlight back into space. If Earth were covered in a dark forest it would have a lower albedo, about 0.14. Satellite measurements made since the late 1970s estimate Earth’s average albedo to be about 0.30.
Earth’s total albedo is measured by satellites such as the Terra satellite which has collected the most up to date data using a sensor called: Moderate Resolution Imaging Spectroradiometer (MODIS). The image below was produced using MODIS data. Areas of the map colored red have the highest albedo (most reflective), while the areas in yellow and green indicate moderate values and blue shows dark surfaces (low albedo). White indicates no data was available and the image does not include albedo data regarding the ocean.
Wildfires are a part of the boreal forest ecosystem. They have both immediate and long-term impacts due to their effects on surface energy, water balance and underlying permafrost.
The thickness of the surface organic layer is an important factor controlling the degradation of permafrost. If the thickness of the organic layer is reduced, permafrost degradation can occur because of increased soil thermal conductivity. According to Dr. Kenji Yoshikawa, “Wildfire is one of the most important factors controlling the thickness of the organic layer in the boreal forest.” Following a fire the albedo can be reduced. Soil thickness reduction along with decreased albedo means that the soils can absorb more radiation, which result in higher ground temperatures, potentially degrading the permafrost.
This image shows the clear boundary of burned and unburned vegetation. The burned section will have a lower albedo and will be warmed by sun faster than the unburned vegetation.
Image courtesy Merritt Turetsky
