Maps, Graphs, and Data

Surface Temperature Graph by Latitude

Mean Zonal Trend Global Map for April 2018 of Surface Temperature

Land surface temperature is how hot the “surface” of the Earth would feel to the touch in a particular location. From a satellite’s point of view, the “surface” is whatever it sees when it looks through the atmosphere to the ground. It could be snow and ice, the grass on a lawn, the roof of a building, or the treetops in a forest. Thus, land surface temperature is not the same as the air temperature that is included in the daily weather report.

Note: Global temperature data are reported as anomalies, the measure of the amount of departure from a reference value or long-term average, or simply when the conditions depart from average conditions for a particular place at a given time of year. 

Some land surface temperature anomalies are simply random weather phenomena, not part of a specific pattern or trend. Others anomalies are more meaningful. Widespread cold anomalies may be an indication of a harsh winter with lots of snow on the ground. Small, patchy warm anomalies that appear in forests or other natural ecosystems may indicate deforestation or insect damage. Many urban areas also show up as hot spots in these maps because developed areas are often hotter in the daytime than surrounding natural ecosystems or farmland. Warm anomalies that persist over large parts of the globe for many years can be signs of global warming.

Let's compare global anomaly averages in zones of differing latitude. The zonal graph shows the global surface temperature anomaly trends (calculated using land-ocean temperatures) for April 2018.   The zones mean the different latitudinal zones: Arctic (90.0 - 64.2°N), N. Mid-Latitudes (64.2 - 23.6°N), Tropical (between 23.5N and 23.6°S), S. Mid-Latitudes (23.6 - 64.2°S), and Antarctic (64.2 - 90.0°S).

  • Trends: Temperature change (°C) of a specified mean period over a specified time interval based on local linear trends.

  • Mean period: Any monthly, seasonal (3 months or 6 months) or annual mean. The period is declared missing unless >50% of data are available.

  • Time interval: Years over which temperatures are averaged or trends are found.

Mini Lesson

  1. Describe the appearance of the July 2018 Zonal Mean vs. Latitude graph?
  2. How do the temperatures in the Tropics differ from the 64 – 90°N temperatures?  64 – 90°S?
  3. Based on the observed graph, what areas exhibit the most warming and cooling?
  4. What do you think causes these changes?
  5. What questions come to mind that you would like to research?  
  6. What datasets would you request to review to support these questions?