NSCAT First Images

First Wind Data from NSCAT Captures Pacific Typhoons

Violet and Tom Typhoons at Japan
Synoptic View of Ocean Surface Winds
Typhoon Violet at Japan
Average Wind Speed
Pacific Surface Winds
Typhoon Violet and Tom

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Violet and Tom Typhoons at Japan
NASDA,NASA/JPL
September 21,22 1996

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Synoptic View of Ocean Surface Winds
NASDA,NASA/JPL
September 21,22 1996

This image shows ocean surface wind speeds and directions over the Pacific Ocean on 21 September 1996 as they were measured by the NASA Scatterometer (NSCAT) onboard Japan's Advanced Earth Observing Satellite (ADEOS). The background color indicates wind speed and the white arrows show the direction of the wind. The basin-wide wind field is representative of near-Equinox atmospheric circulation. The strong Trade Winds (red) blow steadily from the cooler subtropical ocean to the warm water of the Intertropical Convergence Zone (ITCZ) located just north the Equator. Instead of blowing in the north-south direction, the winds are deflected westward by the Corriolis Force due to the Earth's rotation. The air rises over the warm water of ITCZ and sinks in the subtropics at the Horse Latitudes, forming the Hadley Circulation. Both the convergence area at the ITCZ and the divergence area at the Horse Latitudes are indicated by low wind speed of blue color. In the mid-latitudes, the high vorticity due to the Corriolis Force generates cyclones (yellow spirals) moving in the eastward direction. Two typhoons are observed in the western Pacific. Typhoon Violet is just south of Japan. After these data were taken, Typhoon Violet struck the East Coast of Japan causing damage and deaths. Typhoon Tom is located further east and did not land.

The image is based on preliminary processing of the first set of NSCAT observations, using prelaunch model function and calibration. Improvement is expected after the standard calibration and beam balancing procedures. The image is produced by objective interpolation as described by Tang and Liu [JPL Publication 96-19, 1996] based entirely on NSCAT data. This preliminary analysis clearly demonstrates that the high spatial resolution of NSCAT data improves the monitoring of sever storms, such as typhoons, which are usually grossed over by conventional methods. It also shows that the repeated global coverage provides a better description of atmospheric circulation over ocean that is not adequately sampled in the past.

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Typhoon Violet at Japan
September 20, 1996

This image shows typhoon Violet, along with surrounding winds measured by the NSCAT scatterometer, near Japan on September 20, 1996. The cloud imagery is from the Infrared channel of the GMS-5 Japanese meteorological satellite. Overlayed on top of the cloud data are the surface vector winds as measured by NSCAT. In the NSCAT data, the measured wind direction is shown by arrows, and the measured speed by color: blue representing low wind speeds and red the highest wind speeds. An apparent drop in wind speed near the center of the storm is most likely due to access rain attenuation of the scatterometer radar signal. This image is typical of the operational data that will be generated using NSCAT and made available to meteorologists. NSCAT will provide regular measurements of ocean surface wind velocity from space, which will enhance the ability to forecast the behavior of storms such as Violet.

Average Wind Speed

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Pacific Surface Winds
Measured by NSCAT
September 20, 1996

This animation shows ocean surface wind speeds and directions over the Pacific as measured by the NSCAT scatterometer on September 20, 1996. Here, wind speed is depicted by the color of the ocean background: blue for low winds, red for moderate winds, and yellow for high winds. The movement of the white arrows shows the direction of the wind at about 00:00 GMT. The underlying wind field was constructed from eight orbits worth of NSCAT data by using a successive correction interpolation scheme. Noteworthy features manifested in this scene include: typhoons Violet and Tom in the North-Western Pacific near Japan, the trade winds and inter-tropical convergence zone near the equator, and strong winter storm activity in the Southern Hemisphere.

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Typhoons Violet and Tom
Measured by NSCAT
September 20, 1996

This animation shows ocean surface wind speeds and directions in the Pacific ocean near Japan as measured by the NSCAT scatterometer on September 20, 1996. Here, wind speed is depicted by the color of the ocean background: blue for low winds, red for moderate winds, and yellow for high winds. The movement of the white arrows shows the direction of the wind at about 02:00 GMT. The underlying wind field was contructed from four orbits worth of NSCAT data by using a successive correction interpolation scheme. Typoon Tom is in the upper right hand corner. Typhoon Violet is just South of Japan. Typhoon Violet eventually moved up and struck the East Coast of Japan causing damage and deaths.

The first images of winds over the oceans taken by the NASA Scatterometer (NSCAT) science instrument onboard Japan's Advanced Earth Observing Satellite (ADEOS) show two typhoons in the northwest Pacific Ocean as they were seen on September 20.

Typhoon Violet eventually ran into the coast of Japan, killing several people and causing severe property damage. Typhoon Tom was observed in the open ocean east of Japan. The scatterometer measured winds in the storms at about 60 miles per hour.

"We are very pleased with the quality of these first images." said Jim Graf, NSCAT project manager at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA. "These images are typical of the operational data that will be generated using NSCAT and then made available to meteorologists all over the world. NSCAT will provide regular measurements of ocean surface wind speeds from space, which will enhance the ability of weather forecasters to predict the behavior of storms such as Typhoon Violet. In addition, Earth science researchers will use NSCAT data to better understand climate changes occurring on our planet."

The scatterometer takes 190,000 wind measurements per day, mapping more than 90 percent of the world's ice-free oceans every two days. The instrument will provide more than 100 times the amount of ocean wind information currently available from ship reports. Since the scatterometer is a radar instrument, it is capable of taking data day or night, regardless of sunlight or weather conditions.

"This preliminary analysis of the first set of NSCAT data clearly demonstrates that the high resolution of the NSCAT instrument improves the monitoring of severe storms, such as typhoons. It also shows that the repeated global coverage provides a better description of atmospheric circulation over the oceans, which has not been adequately sampled in the past, and it contributes to a better understandng of air-sea interactions," said Dr. W. Timothy Liu, NSCAT project scientist at JPL.

Information gathered by the scatterometer is being used by the National Weather Service, an office of the National Oceanic and Atmospheric Administration (NOAA), and the Japanese Meteorological Agency. NOAA processes the data from the scatterometer and distributes related products to researchers around the globe. The ocean surface wind measurements, used in numerical computer models, will help weather forecasters more accurately predict the path and intensity of hurricanes, winter storms and other weather systems that form over the oceans.

ADEOS is an international global change research mission of the National Space Development Agency of Japan (NASDA), which includes instruments from the United States, Japan and France, with investigators from many other countries. The satellite is a key part of an international environmental research effort that includes NASA's Mission to Planet Earth (MTPE) program, a long-term, coordinated research effort to study the Earth as a global environmental system. The goal of MTPE is to develop a better scientific understanding of natural environmental changes and to distinguish between natural and human-made changes and impacts.

MTPE-related data, which NASA distributes to researchers worldwide, is essential to helping people make better informed decisions about the environment. NSCAT data will be distributed by NASA and NASDA.

The Jet Propulsion Laboratory developed, built and manages the NSCAT instrument for NASA's Office of Mission to Planet Earth, Washington, DC.

Earth Observation Research Center

Comments to: adeossupport@eorc.nasda.go.jp
Last Update: 07 October 1996