1. Lesson: Observing Monsoon Weather Patterns with TRMM Data
Developed by the
Global Precipitation Measurement Mission
Education and Public Outreach Team
NASA Goddard Space Flight Center

2. Guiding Questions
Local Precipitation: How do we know if it’s raining? How do we know if it rained yesterday or will rain tomorrow?
Global Precipitation: How do we know if it’s raining in other parts of the world? Where can we get that data?
Satellites: How do satellites like TRMM measure precipitation? What else can they tell us?
Precipitation Patterns: What are some patterns in the worldwide precipitation? What about patterns in smaller regions?
Surface Temperature: How can looking at the Earth’s surface temperature help explain monsoon weather patterns?
This slide could be shown to students as a preview of the lesson, or used solely as a reference for the teacher.

3. How do you determine if it’s raining outside?
Engage
How do you determine if it’s raining outside?
How do you know if it rained yesterday? If it will rain tomorrow?
The images represent common answers students might give, as a way to guide the discussion: (image and text will appear one a time from top to bottom)
How do you determine if it’s raining outside? – go look out a window, or go outside to see
How do you know if it rained yesterday? – see if the ground is wet, use a rain gauge
How do you know if it will rain tomorrow? – listen/watch a weather forecast on the radio/TV/computer
Images from Microsoft Office ClipArt and
Images from Microsoft Office ClipArt,

4. What if we want to know if it has rained in other places in the world?
Engage, cont.
What if we want to know if it has rained in other places in the world?
Where does weather data come from?
The large text and image of The images represent common answers students might give, as a way to guide the discussion: (image and text will appear one a time from top to bottom)
What if we want to know if it has rained in other places in the world? – call a friend who lives there, check the computer
Where does weather data come from? – weather stations on the ground, radar (also on the ground) and satellites
Images from Microsoft Office ClipArt,
Images from Microsoft Office ClipArt,

5. Our focus today: satellite data, especially from the Tropical Rainfall Measuring Mission (TRMM)
As you learn about the instruments on TRMM, note important details on your capture sheet.
Students should write on the GPM Monsoon Weather Patterns and TRMM Data – Student Capture Sheet any important facts about TRMM and collecting precipitation data from spae.
Image from

6. Tracking Precipitation from Space
Satellites can provide a more complete picture of rain from space, allowing scientists to look at storms, rainfall totals, and changes throughout days to years
The Tropical Rainfall Measuring Mission (TRMM) has been providing rainfall data since 1998 in the tropics and mid latitudes
The Global Precipitation Measurement (GPM) Mission will extend observations of rain and snow up to the Arctic and Antarctic Circles
Image source (and for more information about TRMM):

7. Visible and Infrared Scanner (VIRS)
Instruments on TRMM
Visible and Infrared Scanner (VIRS)
Measuring infrared energy is measuring heat
The temperature of the clouds is related to their altitude, so you know how high they are
With VIRS, you see the top of the clouds only

8. TRMM Microwave Imager (TMI)
Instruments on TRMM
TRMM Microwave Imager (TMI)
Can measure water vapor, cloud water and rainfall intensity
Kind of like an x-ray of a cloud – shows the precipitation inside, but it’s a flat image

9. Precipitation Radar (PR)
Instruments on TRMM
Precipitation Radar (PR)
Show the 3-D structure of the clouds or a storm
Can see where the rain is heaviest
Only available over a narrow swath as TRMM passes over
Hurricane Sandy on Oct. 28, two days prior to landfall

10. Instruments on TRMM
The upper image shows the same 3-D view into Hurricane Sandy as the previous slide. (Click to go to an animation of the image). The lower image is microwave data showing rainfall totals, also for Sandy.
This slide shows how the instruments on TRMM can work together to give us data about a storm.
Link for animation:

11. Lighting Imaging Sensor (LIS)
Instruments on TRMM
Lighting Imaging Sensor (LIS)
An optical camera that can see where lighting is occurring.
Thanks to Dr. Scott Braun, TRMM Project Scientist and Dr. Dalia Kirschbaum, GPM Applicationas Scientist and Education & Public Outreach Lead, both at NASA Goddard Space Flight Center for help with the information on the previous slides.

12. TRMM at 15
Link to video:
Video Description: 
When it rains it pours, goes the saying, and for the last 15 years, the data on tropical rainfall have poured in. NASA's Tropical Rainfall Measuring Mission (TRMM) was launched on Nov. 27, 1997, and for the last decade and a half has enabled precipitation science that has had far reaching applications across the globe.
In this video commemorating TRMM's 15th anniversary, Project Scientist Scott Braun looks back at the legacy of the Tropical Rainfall Measuring Mission and a few of the major scientific milestones the satellite has helped achieve.

13. Global Precipitation Measurement (GPM)
The GPM Core Observatory will provide improved measurements of precipitation from the tropics to higher latitudes
Main GPM website:
Click on the image for a link to an animation of the satellites in the GPM constellation and how they work together to give a precipitation reading every three hours.
Slide courtesy of Dr. Dalia Kirschbaum, NASA
GPM is an international mission which will use inputs from an international constellation of satellites to provide improved space and time coverage of precipitation (rain, snow) over the globe

14. Worldwide Precipitation Patterns
The images shows data combined from a number of sources (including TRMM) to get a worldwide view of monthly mean precipitation. Click on either image to go to an animation showing the whole year. What patterns do you notice in the data?
Students should write on the GPM Monsoon Weather Patterns and TRMM Data – Student Capture Sheet what they notice during the video to discuss afterward.
More information: (from )
The Global Precipitation Climatology Project (GPCP) is an element of the Global Energy and Water Cycle Experiment (GEWEX) of the World Climate Research program (WCRP). It was established by the WCRP in 1986 with the initial goal of providing monthly mean precipitation data on a 2.5°— 2.5°latitude -longitude grid. Monthly mean precipitation estimates are being produced beginning in 1979 and planned to go through The GPCP has accomplished this by merging infrared and microwave satellite estimates of precipitation with rain gauge data from more than 6,000 stations. Infrared precipitation estimates are obtained from GOES (United States), GMS (Japan) and Meteosat (European Community) geostationary satellites and National Oceanic and Atmospheric Administration (NOAA) operational polar orbiting satellites. Microwave estimates are obtained from the U.S. Defense Meteorological Satellite Program (DMSP) satellites using the Special Sensor Microwave Imager (SSM/I). These data sets will be used to validate general circulation and climate models, study the global hydrological cycle and diagnose the variability of the global climate system. Data sets have been expanded so that in addition to the monthly mean product available, the GPCP now has a 2.5°—2.5° degree pentad data set starting in 1979 and a 1°—1° daily data set starting in 1997. 

15. TRMM Precipitation Data – Eastern U.S.
Let’s zoom in on a part of the world that may be familiar – the Eastern United States. Watch the animation and look for any seasonal patterns you see in the data.
Students may notice some minor seasonal differences, but for the most part there is no clear pattern, except for the mostly continuous belt of heavy rain off the east coast of the U.S.

16. Focus on Southeast Asia
Now that we have something for comparison, let’s focus on one small area of the globe that has very interesting precipitation patterns: India.
Image from

17. TRMM Precipitation Data - India
As you watch, look for any patterns in precipitation. When does it looks like different parts of India get the heaviest rainfall? Does all of the country get rain at the same time? Are there times when there is little to no rainfall in India?
Students should be able to see quite clearly that India goes from very little rain over its land area, to very intense rain for a period of a few months, then back to little rain. The rain starts to come across the continent from the south in June, intensifying in July and August, and then beginning to retreat in September. The animation repeats the cycle several times, but it may be helpful to pause and point out the months, as the text may be hard to read from a distance.

18. What do we call this pattern of heavy precipitation during the summer months, and little to no precipitation during the rest of the year?
The image and word monsoon won’t appear until you click, giving you a chance to elicit responses from students if they are familiar with the term. This is also an opportunity to ask students if they have any experience with monsoon rains in Southeast Asia or elsewhere.
Click on the word monsoon for a link to a video of monsoon rains in Kerala, India,
A MONSOON!

19. And while rain can be fun (and be a welcome break from the heat . . .
Image source: (Dinesh Baraja, CreativeCommons license)

20. Lots of rain all at once can cause heavy flooding as well.
Kashmor, Pakistan
Mumbai, India
Mumbai image source: (Michael Kohli, CreativeCommons license)
Pakistan image source: (NASA’s Earth Observatory)

21. Average Monsoon Onset for India
Image from

22. AIR AIR What causes winds?
We’ll look at some more satellite data about India shortly, but before that, just a reminder about what causes winds . . .
When air is heated, it rises, causing low pressure.
When air is cooled, it sinks, causing high pressure.
AIR
So winds blow from high to low pressure.
When you click, a short animation of high and low pressure will play, then the images above will appear.
Images from
AIR

23. Earth Surface Temperature for India
Now let’s look at WHY India experiences a monsoon weather pattern. Keep the cause of wind in mind, as well as the fact that wind will pick up extra moisture when it blows across water. Here’s another animation of satellite data – this time of the Earth’s skin surface temperature. Make note of the patterns you observe.
The animation plays through twice, both starting and ending with December monthly averages. Because of the way the images were created, during the first run-through, the scale adjusts slightly in each frame based on the range of temperatures depicted. This shows very clearly when the land is warmer than the ocean in summer months and cooler in the winter months, but gives a bit of a false impression of how much the sea surface temperature changes. The second time the animation plays through, the scale is consistent throughout, showing better that the ocean is not really changing temperature as quickly or as much as it appeared, but instead the land is warming and cooling much faster in comparison. This is a great opportunity to discuss the importance of paying attention to the scale or key when interpreting a graphical data display or map.

24. NOVA: “Earth From Space” – Monitoring Earth’s Water Vapor
Why do monsoons occur?
NOVA: “Earth From Space” – Monitoring Earth’s Water Vapor
“In this video excerpt from NOVA: “Earth From Space,” observe the global pattern of water vapor circulation and learn how it connects the Sun, oceans, atmosphere, and life. Animations show how satellites in geostationary orbit provide a global view of the movement of water vapor. As water vapor produced near the equator travels toward Earth’s poles, it transports energy and creates weather. Variations in the topography of different regions result in different outcomes (for example, the Asian monsoon, an arid desert, or sweltering conditions).”
Text and video source:
Duration 5:29 - the portion specifically dealing with monsoons runs from ~2:00 to 3:40.

25. BBC: Monsoons Flood in Pakistan
Why do monsoons occur?
BBC: Monsoons Flood in Pakistan
“Life in many parts of South Asia depends on the rains which arrive during the monsoon season. The monsoon of 2010, however, delivered exceptionally high rainfall across areas of northern Pakistan. This resulted in widespread flooding across the entire country in the days and weeks which followed. The report includes graphics and satellite images showing the size and development of the monsoon rains over the region. This clip was first published on BBC News Online on 2 August Please note this clip is only available in Flash.”
Text and video source:
Duration 2:39

26. Why do monsoons occur?
Monsoons are massive, seasonally changing sea breeze circulations that form due to temperature differences between land and ocean.
This slide if for the final wrap-up to make sure students understand before writing their own explanation for monsoons. More information, and an excellent summary, can be found at
Image source: via (also source of text)

27. Evaluate
Explain what you’ve learned about monsoons! Write a well-written paragraph or two describing why India has the weather pattern it does. Be sure to include:
What the weather pattern is called (monsoon!) and what the weather would be like if you lived there
Why a monsoon weather pattern occurs (hint: be sure you talk about seasons and changes in temperature of the land and ocean)
The patterns you saw in the satellite data for precipitation and surface temperature over India, and how that relates to the reason for monsoons
How a satellite (especially TRMM) collects data and how that helps us understand monsoons

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Precipitation Education Website: pmm.nasa.gov/education