1999 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| SCIENTISTS LISTEN TO RAIN FOR CLUES ON CLIMATE CHANGE (Acoustic Raindrops) | G99-105 | 02/28/00 | 00:11:19 | Those noisy raindrops that keep you awake at night may provide one of the best clues to how much rain falls over the ocean, an important factor in figuring out the Earth's complicated climate system. By listening to raindrops splash on the ocean surface with underwater microphones, scientists at the University of washington and NASA Goddard Space Flight Center, Greenbelt, MD., are exploring how the ocean and the atmosphere interact.
Acoustical oceanography is a new science deploying underwater microphones on oceanic moorings to measure rainfall. Scientists are interested because the ocean and our atmosphere continually interact in an intricate dance, which can trigger world climate change effecting marine biology, the ocean's food chain, and the global carbon cycle.
By listening and recording the rainfall data, important observations can be made to help meteorologists, oceanographers, and climatologists better understand the distribution and intensity of this important component of global rainfall patterns.
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TAPE CONTENTS: |
| ITEM (1): SMALL RAINDROP ANIMATION - When a small raindrop falls on the ocean, it produces sound underwater by its impact on the ocean surface and, more importantly, by sound created from a bubble trapped underwater during its splash. Different raindrop sizes produce distinctive sounds. When recorded underwater, small raindrops make a sound like a hiss. The following animation is first simulated as a real-time small raindrop, and then slowed down to demonstrate the distinct sound of impact and the subsequent ring of the higher frequency sound made by the bubble.
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| ITEM (2): MEDIUM RAINDROP ANIMATION
- Interestingly, the splash of a medium sized raindrop does not trap bubbles underwater and is consequently quiet, much quieter than small raindrops. The only acoustic signal from these drops is a weak impact sound as it hits the ocean surface. The following animation is first simulated as a real-time raindrop and then slowed to demonstrate how it does not make a bubble under the water.
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| ITEM (3): LARGE RAINDROP ANIMATION - For large and very large raindrops, the splash becomes energetic enough to create a wide range of bubble sizes trapped underwater, which produces a loud sound relatively low in frequency. The following animation is first simulated as a real-time large raindrop, and then slowed down to demonstrate the distinct sound of impact and the subsequent ring of the lower frequency sound made by the bubble.
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| ITEM (4): THE UNDERWATER SOUND OF A THUNDERSTORM - - This is a scientist's view of the underwater sound of a thunderstorm. This "sound" view is generated by a heavy thunderstorm recorded in Miami, Florida. During the heavy convective downpour, very large raindrops are present and the sound field is loud across the entire spectrum (1-50 kHz). At the end of the convective downpour, a long drizzle begins. This phase of the storm has few large drops. The sound generated by small drops dominates the sound field producing a distinctive 13-25 kHz peak associated with drizzle. At the end of the event, a few large drops are again present and once again the sound field becomes elevated below 10 kHz.
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| ITEM (5): ABOVE WATER RECORDING OF RAINDROPS
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| ITEM (6): UNDERWATER RECORDING OF SMALL RAINDROPS - This is the sound of drizzle. Note the high frequency "hiss."
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| ITEM (7): UNDERWATER RECORDING OF LARGE DROPS - Listen for "smacks" from the impact of the drops on the ocean and the subsequent lower frequency "gurgling."
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| ITEM (8): ACOUSTICAL RAIN GAUGE (ARG) "B" ROLL - Jeffrey Nysteum, a TRMM scientist aboard a NOAA ship, places an ARG into the Pacific Ocean. The ARG is attached to a mooring line and can be placed at any depth, only limited by the crushing strength of the instrument case. Every few minutes the ARG "wakes up", evaluates, and records the underwater sound field. After the gauge is extracted from its mooring, the recorded audio tract is downloaded to a computer where it can be viewed as data. In the future, real-time transmission of the data will be needed to provide useful data for weather forecasting.
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| ITEM (9): "ARG" IN A TANK - Comparative TRMM data is collected from a water tank on a lonely island in the Pacific Ocean during the Kwajalein Experiment in the fall of 1999. A scientist has removed the microphone's computer and prepares to download the recorded data.
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| ITEM (10): THE NOAA SHIP "B" ROLL - The Ronald Brown is a state-of-the-art oceanographic and atmospheric research vehicle, and the largest vessel in the NOAA fleet. The ship is
carrying out various TRMM experiments, including the ARG, in the Kwajalein Atoll in the Pacific Ocean.
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| ITEM (11): TRMM SATELLITE ANIMATION - The Tropical Rainfall Measuring Mission (TRMM) is a joint mission between NASA and the National Space Development Agency (NASDA) of Japan designed to monitor and study tropical rainfall and the associated release of energy that helps to power the global atmospheric circulation shaping both weather and climate around the globe.
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| ITEM (12): RAINBOWS AND OCEAN RAINFALL "B" ROLL
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| ITEM (13): THE KWAJALEIN ATOLL LOCATED IN THE PACIFIC OCEAN
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| ITEM (14): WORLD CLIMATE MYSTERY - Knowledge of rain distribution and intensity is important not only to farmers and flood control planners, but also to meteorologists, oceanographers and climatologists. This is because the formation of a raindrop releases energy into the air. This energy or heat release is one of the primary sources of energy driving atmospheric circulation. Understanding the global patterns of distribution and intensity of rainfall is needed to improve weather and climate forecasting.
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| ITEM (15): INTERVIEW EXCERPTS ON-BOARD THE SHIP, THE RON BROWN, DURING THE TRMM KWAJALEIN EXPERIMENT IN THE PACIFIC OCEAN -- JEFFREY NYSTEUN SENIOR OCEANOGRAPHER
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