Global Atmospheric Circulation Patterns - Analyzing TRMM Data

Eugenio Y. Arima, Hobart and William Smith Colleges


In this lab exercise, students interpret precipitation data obtained from NASA's Tropical Rainfall Measuring Mission (TRMM) in order to understand global atmospheric circulation and climate patterns. In the process, students learn GIS raster algebra.


Type and level of course
This lab assignment can be used in a second-level GIS course that emphasizes raster data models and raster algebra in particular, or in an introductory climatology class.

Geoscience background assumed in this assignment
Students should have a basic understanding of Earth's climate system and general circulation patterns of the atmosphere such as Hadley cells and summer monsoons (e.g. W. F. Ruddiman – Earth's Climate book, chapter 2)

GIS/remote sensing skills/background assumed in this assignment
Students should know basic ArcGIS commands such as open/close, add/remove layers, zoom in/out, change symbology (e.g. colors, categories, etc) and have notions of coordinate systems and cartography.

Software required for this assignment/activity:
Software required: ArcGIS 9.3 or later with Spatial Analyst Extension; Winzip or Izarc or similar software to unzip files.

Time required for students to complete the assignment:
90 minutes


GIS/remote sensing techniques students learn in this assignment
Students will learn how to use raster calculator to perform simple raster algebra operations such as addition, subtraction, and division.

Other content/concepts goals for this activity
Students will visualize the major precipitation patterns in the world and connect those patterns to atmospheric circulation patterns. Concepts such as Hadley cells, ITCZ, orographic precipitation & rain shadow, zones of high/low pressures, etc. are emphasized throughout the assignment.

Higher order thinking skills goals for this activity
Students will describe 'what if' scenarios to strengthen their understanding about energy and circulation patterns and relate to actual climatological phenomena such as the El Ninõ Southern Oscillation.

Description of the activity/assignment

Prior to this assignment, students read Chapter 2 (Earth's Climate System Today) of W. Ruddiman's Earth's Climate book and online information about the TRMM dataset. In the computer lab, students download the instructions and the pre-processed dataset from course website. The lab assignment consists of GIS raster algebra operations used to generate average precipitation rasters and to calculate anomalies. Throughout the assignment, students are asked to interpret and explain global precipitation patterns.

Determining whether students have met the goals

Students prepare a lab report with answers to the questions and maps that illustrate their answers.
More information about assessment tools and techniques.

URLs and References

If you want to download the complete monthly dataset from 1998 to 2010, including original HDF files, pre-processed TIF files, and IDL scripts, please click on the link below (1.2 GB)

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