2000 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| MAPS OF FALLING WATER: THREE YEARS OF TRMM DATA | G00-101 | 12/18/00 | 00:24:35 | Ever wonder about the rain? Beyond the practicality of needing an umbrella, climate researchers have wondered about the science of rainfall for a long time. But it's only in the past few years that they've begun to roll back some of its secrets. One of their tools for doing so is a powerful satellite called the Tropical Rainfall Measuring Mission, or TRMM. Now, after three years of continual operation, project scientists have released dramatic new maps of rainfall patterns gathered across a wide band of the Earth. And with measurements from one of the satellite's advanced sensors, meteorologists are now able to calibrate ground-based rain monitoring systems with greater precision than ever before.
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TAPE CONTENTS: |
| ITEM (1): The Flying Rain Gauge - For many people, rainfall is simply a subject for small talk. But it's serious science to the people who launched this: It's called TRMM--the Tropical Rainfall Measuring Mission, and it's changing the ways we think about how our planet works.
TRMM flies low for a research satellite--about 217 miles above the surface of the Earth. And just like shooting pictures with a camera, the closer you are to the subject, the better the image.
Here's one of them. We're looking at the living atmosphere, with ghostlike wisps of rain mottling the surface of the Earth. TRMM collected this data every day for the last three years--in fact, experts like Dr. Shepherd regard the joint Japanese/American satellite as a flying rain gauge.
This is important because tropical rainfall is one of the principle forces powering the atmosphere. As the atmosphere changes, so changes the climate, and a better understanding about how the climate works is fundamental to long term care of our planet.
Based on data collected over the last three years, TRMM is also changing what used to be possible with systems on the ground. Prior to launch, meteorologists expected to use ground-based instruments to calibrate the device onboard the satellite that measures rainfall. It turns out that the satellite system has performed so reliably that TRMM readings are instead being used to calibrate ground systems, offering the potential for significant refinements in forecasting techniques.
In part due to the rigors of flying in a low Earth orbit TRMM engineers designed the satellite only to last three years. But now on the far side of that birthday, the satellite appears to be capable of working well beyond its initial specs, and indications are good that this revolutionary laboratory will continue to deliver state of the art science for some time to come.
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| ITEM (2): Watching The Atmospheric Engine at Work: Three Year Rainfall Maps - A complete accounting of the world's total rainfall has long been a major goal of climate researchers. Rain acts as the atmosphere's fundamental engine for heat exchange; every time a raindrop falls, the atmosphere gets churned up and latent heat flows back into the total climate system. Considering that rainfall is the primary driving force of heat in the atmosphere, and that two thirds of all rain falls in the tropics, these measurements are significant for our understanding of overall climate. These images show three years of daily rainfall measurements taken by the satellite's unique precipitation radar. It's a revolutionary visualization in that it offers experts the first comprehensive, long duration observations of where it's raining and how much.
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| ITEM (3): What's Normal? Using TRMM to Generate Rainfall Averages - Just like the human body maintains a normal temperature that can fluctuate under different conditions, there tends to be a general rainfall average over much of the world. Whether those averages for different regions change through time due human factors is still an issue being debated. But TRMM is at least enabling experts to generate data for tropical rainfall averages taken over the past few years with a measure of accuracy never before possible. The following images show rainfall averages on a monthly time scale for territory beneath TRMM's ground track.
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| ITEM (4): Rainfall Anomalies: When it Rains, it Pours - About two thirds of all the Earth's rain falls in the tropics. Moreover, the energy released by that rain accounts for the vast majority of energy released in the atmosphere. As we come to better understand the rain on a planetary scale, we also begin to understand the processes describing localized rainfall events around the world.
The following visualizations show rainfall anomalies--that is, regions with rainfall amounts that significantly exceed or fall short of averages. Blue regions show low quantities, while yellows and reds show high quantities.
Rainfall anomalies also allow experts to study local or regional changes in climate. As we'll see in the next section, anomalous rainfall measurements can be harbingers of change, as in the case of desertification in parts of sub-Saharan Africa, or severe short term events, such as the intense floods of Mozambique in early 2000 or the pounding rains of Hurricane Mitch in 1998.
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| ITEM (5): Capturing Heavy Precipitation - The following visualizations focus on specific, localized rainfall events in different parts of the world. Notice how the relative rainfall intensity over each area suddenly increases around to the dates of each event. By studying events like these, experts hope to gain insight into better forecasting techniques, as well as provide broader analysis into regional and global climate change.
Mozambique Devastated by Floods - The worst flooding in nearly fifty years devastated large regions of Mozambique in late February and early March 2000. Intense flooding following heavy rains displaced hundreds of thousands of people and killed hundreds. As this visualization shows regions of heavy precipitation over Mozambique, consider that the southern part of that country received in the first three weeks of February as much rain as usually falls there in a whole year.
Hurricane Floyd Pounds North Carolina - In September of 1999, Hurricane Floyd precipitated massive flooding across wide stretches of North Carolina and other areas in the eastern United States. The hurricane moved slowly across the region, prompting heavy rains not only to fall over the area, but also to persist for days. Heavy rains from the storm caused waters to rise quickly in a large stretch of the region, while runoff and heavy sedimentation associated with it caused serious problems for residents and officials for weeks to come.
The Grinding Wake of Hurricane Mitch - It's been more than two hundred years since a storm killed as many people as Hurricane Mitch. In late October and early November of 1998, this monster storm dumped as much as one to two feet of rain per day for several days on parts of Central America. More than 11,000 people died during Hurricane Mitch, while it also caused billions of dollars of damage to fragile Central American economies.
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| ITEM (6): EL Nino And Tropical Rain: Causes And Effects - Generally tropical rains in the Pacific fall more heavily on the western part of the ocean. But as seen in this visualization, the El Nino event that recently came to an end caused an observable shift in average rainfall patterns south of the equator. Heavier than normal rains fell east of 150° West, while the western Pacific showed greatly diminished rainfall rates.
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| ITEM (7): Calibrating Ground Based Radar From Orbit (Animation) - Measurements are only as accurate as the instruments that take them. When U.S. and Japanese scientists designed TRMM, they expected to use ground based precipitation radar systems to calibrate the precipitation radar onboard the spacecraft. But after years of continual operation, the TRMM project has determined that the satellite's level of accuracy and consistency is great enough that ground-based systems can, in fact, be calibrated to the system on the spacecraft.
TRMM does not communicate directly with ground based systems. Satellite information actually helps experts develop algorithms and techniques, enabling them to refine land-based systems. But as a result of the TRMM team's efforts, those land-based systems can work at their peak efficiency, helping experts both study and forecast changes in the weather.
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| ITEM (8): A Legacy of Discovery - Everyone knows something about the rain. But one of the best parts about scientific research is discovering just how much we don't know. TRMM has been just such an instrument of discovery. In little more than three years, this Japanese and American joint effort has provided huge returns to the science community, from greater understanding of how tropical rainfall affects overall climate, to the energy budget surrounding global desert regions, to revolutionary ways for studying hurricanes. In this section we take a look at some of the TRMM program's most exciting work.
Rainfall Predictions -- Dramatic Improvements With The "Super-Ensemble" Model - TRMM has been highly successful in increasing meteorological forecasting capabilities. Using the new "super-ensemble"" forecasting technique, the following visualizations compare one day forecasts from September of that year to the collected daily observations of actual rainfall. This technique combines existing forecast models with satellite rainfall data. Tests show that the accuracy of tropical three-day rainfall forecasts can be improved as much as 100% by this method. In the following images gathered during September 1999, compare the month's collected one-day forecasts to the collected daily observations of actual rainfall. It was during that month that Hurricanes Floyd and Irene drenched much of the East Coast. In this representation the overall forecasting trend through time is more significant than precise matching of the rainfall areas depicted by the color map shown. The tropics are notoriously hard for daily precipitation prediction. This new forecasting technique is a major improvement over earlier methods.
Predicting Hurricane Intensity Far From Land - For years scientists have known of a strong correlation between sea surface temperature and the intensity of hurricanes. But one of the major stumbling blocks for forecasters has been the precise measurement of those temperatures when a storm begins to form. Traditional techniques for sea surface temperature measurement can not see through clouds. But researchers working with TRMM have developed a technique for looking through clouds with microwaves. This technique is likely to enhance forecasters' abilities to predict the intensity of hurricanes before the storms' massive energies fully develop.
Cause And Effect: Bonnie's Trail Weakens Danielle - A hurricane gathers energy from warm waters found in tropical latitudes. In this image we see Hurricane Bonnie cross the Atlantic, leaving a cooler trail of water in its wake. When Hurricane Danielle crosses Bonnie's path, the wind speed of the second storm drops markedly, as available energy to fuel the storm's engine drops off. But once Danielle crosses Bonnie's wake, notice how winds speed increase due to temperature increases in surface water around the storm.
Seing Surface Temperture Through Clouds - The clouds shown in this image were collected by the Geostationary Operational Environmental Satellite (GOES). Surface temperatures were gathered by TMI, the TRMM Microwave Imager. Notice how the ocean area directly following each storm registers as slightly cooler than surrounding ocean water. This is due to the nature of hurricanes in that they power themselves on heat found near the surface in tropical oceans.
Studying The Heartbeat of Hurricanes - Scientists using TRMM can now look inside hurricanes and better understand how they work by using a unique suite of active and passive sensors capable of measuring rainfall and sea surface temperature. Hurricanes act essentially as powerful engines, drawing energy up from warm tropical ocean waters to power the churning, swirling winds of their radial arms.
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| ITEM (10): "CAT" Scans And Crystal Towers - The following hurricane visualizations were developed using data from TRMM's precipitation radar. The images that dissect the storm into layers have come to be known informally as "CAT" scans for their resemblance to the medical technology that can peer inside a person's body. The term crystal towers for the 3-D, rotating images of the storms simply describes their majestic, prismatic spires rendered in electronic paint above the surface of a virtual ocean. High rates of rainfall appear in red, with lesser amounts appearing in blue. By mapping the structure of storms, experts can "take them apart" in the laboratory as they try to understand how they work. TRMM gathered data for these images of hurricanes Mitch, Georges, and Earl in 1998.
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| ITEM (11): Hurricane Bonnie - These images of Hurricane Bonnie come from the rain radar flying aboard TRMM. They show a cumulonimbus (storm) cloud towering 59,000 feet into the sky from the eyewall. Scientists believe that towering cloud structures like this are probably precursors to hurricane intensification. The satellite obtained these images on August 22, 1998.
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| ITEM (12): EL NINO Sea Surface Tempertures - Satellite observations trace the evolution of warmer than normal Pacific waters associated with El Nino (shown in red) from its peak in December 1997 through its decline in early 1998. TRMM's Microwave Imager collected the data for these observations.
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| ITEM (13): TRMM: Watching Rain to Help Explain - The Tropical Rainfall Measuring Mission (TRMM) is the first Earth Science mission dedicated to studying tropical and subtropical rainfall, precipitation that falls within 35 degrees north and 35 degrees south of the equator. Tropical rainfall comprises more than two-thirds of the world's total. The satellite uses several instruments to detect rainfall including radar, microwave imaging, and lightning sensors. Flying at a low orbital altitude of 217 miles (350 kilometers), TRMM's study of tropical rainfall and attendant processes will help improve our understanding and predictions of global climate change.
The Japanese space agency (NASDA) launched the satellite on an H-II rocket from Tanegashima Space Center on November 27, 1997.
TRMM data is available to researchers around the world; it is managed by a team at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
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| ITEM (14): Interview/Soundbites - Dr. Marshall Shepard, NASA, Research Meteorologist and Tropical Rainfall Measuring Mission (TRMM) Outreach Scientist
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