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Tropical Cyclone Daryl
| Title |
Tropical Cyclone Daryl |
| Description |
This pair of images shows the birth of Cyclone Daryl off the northwest coast of Western Australia on January 19, 2006. In the fifteen hours that elapsed between the time the Tropical Rainfall Measuring Mission (TRMM [ http://trmm.gsfc.nasa.gov/ ]) satellite captured the top image at 10:08 a.m. Australian Western Standard Time and when it captured the bottom image at 1:00 a.m., Daryl went from a weak, newly named storm to a mature storm roughly equivalent to a Category 1 hurricane on the Saffir-Simpson scale. The storm's center remained just offshore as it moved southwest along the coast, sparing coastal communities a direct hit. Both images show rain rates in the storm. In the top image, TRMM reveals that despite having a sizeable band of intense rain (dark red segment) centered in a broad area of light (blue areas) to occasionally moderate (green areas) rain, Daryl showed very little evidence of circulation. This lack of circulation indicated that Daryl was in the early stages of development. At the time of this image, Daryl was rated as a Category 1 cyclone by the Australian Bureau of Meteorology's Tropical Cyclone Warning Center, indicating peak wind gusts of less than 125 kilometers per hour (78 miles per hour)—equivalent to a tropical storm. The lower image was taken just 15 hours later at 17:00 UTC (1:00 a.m. Australian WST on January 20) and shows a very different-looking storm. Although Daryl did not have a well-defined closed eye, the heavy rain had separated into arcing bands (green and darker red arcs), indicating that Daryl had a more mature circulation than it did earlier. Daryl became a Category 3 cyclone the following day. Catching Tropical Cyclone Daryl in the act of building may provide new and critical data for understanding the complexities of storm intensification. Becuase storms tend to form and intensify well away from land, scientists are still trying to understand how cyclones intensify. Armed with both passive and active sensors, including the first and only precipitation radar in space, TRMM has proven itself to be a valuable tool for examining tropical cyclones. These images show rain rates as measured by a number of different sensors on the TRMM satellite. Rain rates in the center swath are from the TRMM Precipitation Radar, while rain rates in the outer swath are from the TRMM Microwave Imager. The rain rates are overlaid on infrared data from the TRMM Visible Infrared Scanner. Launched in November 1997 to measure rainfall over the global tropics, TRMM is a joint mission between NASA and the Japanese space agency, JAXA. Images produced by Hal Pierce (SSAI, NASA/GSFC) and captioned by Steve Lang (SSAI, NASA/GSFC). |
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Tropical Cyclone Daryl
| Title |
Tropical Cyclone Daryl |
| Description |
This pair of images shows the birth of Cyclone Daryl off the northwest coast of Western Australia on January 19, 2006. In the fifteen hours that elapsed between the time the Tropical Rainfall Measuring Mission (TRMM [ http://trmm.gsfc.nasa.gov/ ]) satellite captured the top image at 10:08 a.m. Australian Western Standard Time and when it captured the bottom image at 1:00 a.m., Daryl went from a weak, newly named storm to a mature storm roughly equivalent to a Category 1 hurricane on the Saffir-Simpson scale. The storm's center remained just offshore as it moved southwest along the coast, sparing coastal communities a direct hit. Both images show rain rates in the storm. In the top image, TRMM reveals that despite having a sizeable band of intense rain (dark red segment) centered in a broad area of light (blue areas) to occasionally moderate (green areas) rain, Daryl showed very little evidence of circulation. This lack of circulation indicated that Daryl was in the early stages of development. At the time of this image, Daryl was rated as a Category 1 cyclone by the Australian Bureau of Meteorology's Tropical Cyclone Warning Center, indicating peak wind gusts of less than 125 kilometers per hour (78 miles per hour)—equivalent to a tropical storm. The lower image was taken just 15 hours later at 17:00 UTC (1:00 a.m. Australian WST on January 20) and shows a very different-looking storm. Although Daryl did not have a well-defined closed eye, the heavy rain had separated into arcing bands (green and darker red arcs), indicating that Daryl had a more mature circulation than it did earlier. Daryl became a Category 3 cyclone the following day. Catching Tropical Cyclone Daryl in the act of building may provide new and critical data for understanding the complexities of storm intensification. Becuase storms tend to form and intensify well away from land, scientists are still trying to understand how cyclones intensify. Armed with both passive and active sensors, including the first and only precipitation radar in space, TRMM has proven itself to be a valuable tool for examining tropical cyclones. These images show rain rates as measured by a number of different sensors on the TRMM satellite. Rain rates in the center swath are from the TRMM Precipitation Radar, while rain rates in the outer swath are from the TRMM Microwave Imager. The rain rates are overlaid on infrared data from the TRMM Visible Infrared Scanner. Launched in November 1997 to measure rainfall over the global tropics, TRMM is a joint mission between NASA and the Japanese space agency, JAXA. Images produced by Hal Pierce (SSAI, NASA/GSFC) and captioned by Steve Lang (SSAI, NASA/GSFC). |
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Tropical Cyclone Daryl
| Title |
Tropical Cyclone Daryl |
| Description |
This pair of images shows the birth of Cyclone Daryl off the northwest coast of Western Australia on January 19, 2006. In the fifteen hours that elapsed between the time the Tropical Rainfall Measuring Mission (TRMM [ http://trmm.gsfc.nasa.gov/ ]) satellite captured the top image at 10:08 a.m. Australian Western Standard Time and when it captured the bottom image at 1:00 a.m., Daryl went from a weak, newly named storm to a mature storm roughly equivalent to a Category 1 hurricane on the Saffir-Simpson scale. The storm's center remained just offshore as it moved southwest along the coast, sparing coastal communities a direct hit. Both images show rain rates in the storm. In the top image, TRMM reveals that despite having a sizeable band of intense rain (dark red segment) centered in a broad area of light (blue areas) to occasionally moderate (green areas) rain, Daryl showed very little evidence of circulation. This lack of circulation indicated that Daryl was in the early stages of development. At the time of this image, Daryl was rated as a Category 1 cyclone by the Australian Bureau of Meteorology's Tropical Cyclone Warning Center, indicating peak wind gusts of less than 125 kilometers per hour (78 miles per hour)—equivalent to a tropical storm. The lower image was taken just 15 hours later at 17:00 UTC (1:00 a.m. Australian WST on January 20) and shows a very different-looking storm. Although Daryl did not have a well-defined closed eye, the heavy rain had separated into arcing bands (green and darker red arcs), indicating that Daryl had a more mature circulation than it did earlier. Daryl became a Category 3 cyclone the following day. Catching Tropical Cyclone Daryl in the act of building may provide new and critical data for understanding the complexities of storm intensification. Becuase storms tend to form and intensify well away from land, scientists are still trying to understand how cyclones intensify. Armed with both passive and active sensors, including the first and only precipitation radar in space, TRMM has proven itself to be a valuable tool for examining tropical cyclones. These images show rain rates as measured by a number of different sensors on the TRMM satellite. Rain rates in the center swath are from the TRMM Precipitation Radar, while rain rates in the outer swath are from the TRMM Microwave Imager. The rain rates are overlaid on infrared data from the TRMM Visible Infrared Scanner. Launched in November 1997 to measure rainfall over the global tropics, TRMM is a joint mission between NASA and the Japanese space agency, JAXA. Images produced by Hal Pierce (SSAI, NASA/GSFC) and captioned by Steve Lang (SSAI, NASA/GSFC). |
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Tropical Cyclone Favio
| Title |
Tropical Cyclone Favio |
| Description |
) satellite on February 20 and February 22, 2007. TRMM was placed into its low-earth orbit in November 1997 to measure rainfall from space, however, it has also served as a valuable platform for monitoring tropical cyclones, especially over remote parts of the open ocean. The images show the rainfall intensity. Rain rates in the center of the swath are from the TRMM Precipitation Radar, while those in the outer portion are from the TRMM Microwave Imager. The rain rates are overlaid on infrared data from the TRMM Visible Infrared Scanner. TRMM shows that Favio was a well-organized storm on February 20 (top) with a central eye (dark blue area in the center) surrounded by an eyewall containing heavy rainfall (dark red areas). The storm is also very symmetric with good "banding" in the rain field, demonstrated by the tightly curved bands of moderate rain (green areas) spiraling in towards the center. These features are the hallmarks of a mature, intense tropical cyclone. Though the cyclone did not strike Madagascar, the red areas indicate that it dumped heavy rains on the southern tip of the island. As Favio crossed the Mozambique Channel it reached a peak intensity of 232 kilometers per hour (144 miles per hour, or 125 knots) on the early morning of February 22, making it a Category 4 storm. The cyclone then weakened slightly before slamming into southern Mozambique with sustained winds estimated at 204 km/hr (127 mph, 110 knots). TRMM took the lower image on February 22 soon after Favio made landfall in Mozambique. The image shows that although the eye was not as well defined as in the earlier image, the circulation is still robust, the spiral rainbands (green arcs) are still well defined. Maximum sustained winds were still estimated to be 167 km/hr (114 mph, 90 knots) at the time of this image but quickly diminished thereafter. The bands of heavy rain shown in this image triggered floods [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=14146 ] along rivers in Central Mozambique. Unfortunately for Mozambique, the storm-induced floods follow additional serious flooding on the Zambezi River [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=14125 ] to the north. TRMM is a joint mission between NASA and the Japanese space agency, JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC)., These images track Cyclone Favio as it brushed the southern tip of the island of Madagascar, and then continued on to Mozambique. The storm came ashore over southern Mozambique on February 22, 2007, as a strong Category 3 storm. As of February 28, news reports had attributed four fatalities to the storm in Vilanculos, a coastal tourist town where the storm made landfall. Favio began as a tropical disturbance on February 11, 2007, in the central Indian Ocean south of Diego Garcia in the Chagos Archipelago. Slow to intensify, the system finally became a tropical storm three days later on February 14. Favio remained a tropical storm for the next several days as it made its way through the west-central Indian Ocean east of Mauritius, and finally began to intensify as it neared Madagascar. It became a Category 1 cyclone on February 19. As it rounded the southern tip of Madagascar, Favio continued to intensify and reached Category 3 intensity on February 20. The cyclone then took a more northwesterly path as it entered the Mozambique Channel. These images of the storm were taken by the Tropical Rainfall Measuring Mission (TRMM [ http://trmm.gsfc.nasa.gov/ ] |
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Tropical Cyclone Favio
| Title |
Tropical Cyclone Favio |
| Description |
) satellite on February 20 and February 22, 2007. TRMM was placed into its low-earth orbit in November 1997 to measure rainfall from space, however, it has also served as a valuable platform for monitoring tropical cyclones, especially over remote parts of the open ocean. The images show the rainfall intensity. Rain rates in the center of the swath are from the TRMM Precipitation Radar, while those in the outer portion are from the TRMM Microwave Imager. The rain rates are overlaid on infrared data from the TRMM Visible Infrared Scanner. TRMM shows that Favio was a well-organized storm on February 20 (top) with a central eye (dark blue area in the center) surrounded by an eyewall containing heavy rainfall (dark red areas). The storm is also very symmetric with good "banding" in the rain field, demonstrated by the tightly curved bands of moderate rain (green areas) spiraling in towards the center. These features are the hallmarks of a mature, intense tropical cyclone. Though the cyclone did not strike Madagascar, the red areas indicate that it dumped heavy rains on the southern tip of the island. As Favio crossed the Mozambique Channel it reached a peak intensity of 232 kilometers per hour (144 miles per hour, or 125 knots) on the early morning of February 22, making it a Category 4 storm. The cyclone then weakened slightly before slamming into southern Mozambique with sustained winds estimated at 204 km/hr (127 mph, 110 knots). TRMM took the lower image on February 22 soon after Favio made landfall in Mozambique. The image shows that although the eye was not as well defined as in the earlier image, the circulation is still robust, the spiral rainbands (green arcs) are still well defined. Maximum sustained winds were still estimated to be 167 km/hr (114 mph, 90 knots) at the time of this image but quickly diminished thereafter. The bands of heavy rain shown in this image triggered floods [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=14146 ] along rivers in Central Mozambique. Unfortunately for Mozambique, the storm-induced floods follow additional serious flooding on the Zambezi River [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=14125 ] to the north. TRMM is a joint mission between NASA and the Japanese space agency, JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC)., These images track Cyclone Favio as it brushed the southern tip of the island of Madagascar, and then continued on to Mozambique. The storm came ashore over southern Mozambique on February 22, 2007, as a strong Category 3 storm. As of February 28, news reports had attributed four fatalities to the storm in Vilanculos, a coastal tourist town where the storm made landfall. Favio began as a tropical disturbance on February 11, 2007, in the central Indian Ocean south of Diego Garcia in the Chagos Archipelago. Slow to intensify, the system finally became a tropical storm three days later on February 14. Favio remained a tropical storm for the next several days as it made its way through the west-central Indian Ocean east of Mauritius, and finally began to intensify as it neared Madagascar. It became a Category 1 cyclone on February 19. As it rounded the southern tip of Madagascar, Favio continued to intensify and reached Category 3 intensity on February 20. The cyclone then took a more northwesterly path as it entered the Mozambique Channel. These images of the storm were taken by the Tropical Rainfall Measuring Mission (TRMM [ http://trmm.gsfc.nasa.gov/ ] |
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Tropical Cyclone Gonu
| Title |
Tropical Cyclone Gonu |
| Description |
At one time, Cyclone Gonu was a powerful Category 5 storm packing sustained winds of 255 kilometers per hour (160 miles per hour), according to the Joint Typhoon Warning Center, [ https://metocph.nmci.navy.mil/jtwc.php ] and on a course towards Oman. This made it the most powerful cyclone ever to threaten the Arabian Peninsula since record keeping began back in 1945. Tropical cyclones do on occasion form in the Arabian Sea, but they rarely exceed tropical storm intensity. In 2006, Tropical Storm Mukda was the only system to form in the region, and it remained well out to sea before dissipating. Gonu became a tropical storm in the morning (local time) of June 2, 2007, in the east-central Arabian Sea. After some initial fluctuations in direction, the storm settled on a northwesterly track and began to intensify. Gonu went from tropical storm intensity to a Category 2 Tropical Cyclone [ http://www.nhc.noaa.gov/aboutsshs.shtml ] on the night of June 3. Overnight, it developed into a Category 4 storm with winds estimated at 210 km/hr (132 mph). The Tropical Rainfall Measuring Mission (TRMM) [ http://trmm.gsfc.nasa.gov/ ], captured this image of Gonu as the storm was moving northwest over the central Arabian Sea. The image was taken at 6:23 a.m. local time (03:23 UTC) on June 4, 2007, when Gonu was a Category 4 storm. It shows the horizontal distribution of rain intensity looking down on the storm. The distribution of rain within the storm reveals the storm's structure, and in this case, Gonu displays all of the tell-tale signs of a potent storm. Not only did Gonu have a complete, well-formed, symmetrical eye surrounded by an intense eyewall (innermost red ring), this inner eyewall was surrounded by a concentric outer eyewall (outermost red and green ring). This double eyewall structure only occurs in very intense storms. Eventually the outer eyewall will contract and replace the inner eyewall, a process known as eyewall replacement. The image was made with data from several sensors on the TRMM satellite. Rain rates in the center of the swath are from the TRMM Precipitation Radar, while those in the outer portion are from the TRMM Microwave Imager. The rain rates are overlaid on infrared data from the TRMM Visible Infrared Scanner. Several hours after this image was taken, Gonu reached Category 5 intensity, the very peak of possible storm strengths. The system remained in this high state through the day, then began weakening during the night of June 4 as it continued to approach the coast of Oman. The center remained just offshore of the northeast coast of Oman as a Category 1 storm before turning northward towards Iran, where it was expected to make landfall as a tropical storm, according to forecasts made on June 6, 2007. The TRMM satellite was placed into service in November 1997. From its low-earth orbit, TRMM provides valuable images and information on storm systems around the tropics using a combination of passive microwave and active radar sensors, including the first precipitation radar in space. TRMM is a joint mission between NASA and the Japanese space agency, JAXA. NASA image produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC). |
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Tropical Cyclone Gonu
| Title |
Tropical Cyclone Gonu |
| Description |
Despite weakening from a Category 5 to a Category 1 cyclone as it neared the Arabian Peninsula, Tropical Cyclone Gonu was responsible for at least 28 fatalities in the region, mostly as a result of flooding, said news reports. In Oman's capital city of Muscat, torrential rains turned streets into rivers of water in this normally arid region. In addition to the 25 confirmed fatalities in Oman, at least 26 other people were reported missing. Iran had reported 3 deaths as a result of the storm as of June 7, 2007. This visualization shows rainfall totals from May 31 through June 7, 2007, from the Multi-satellite Precipitation Analysis (MPA). Although the center of Gonu never made landfall in Oman, it came very close to the northeast coastline where it dumped upwards up 200 millimeters of rain (8 inches, shown in dark red). The capital region of Muscat is on the coast where some of the heaviest rain fell. Despite further weakening as it traversed the Gulf of Oman between Oman and southern Iran, Gonu dumped substantial amounts of rain in southern Iran (broad green area) with locally heavy amounts. The mountainous terrain near the coast of Oman and Iran posed an additional hazard to coastal regions. Heavy rain falling on the steep mountains sent torrents of fast-moving floodwater down to the coastal areas. The MPA is computed at NASA Goddard Space Flight center in near-real time using data from the Tropical Rainfall Measuring Mission (TRMM). [ http://trmm.gsfc.nasa.gov/ ] The TRMM satellite was placed into service in November 1997. From its low-earth orbit, TRMM provides valuable images and information on storm systems around the tropics using a combination of passive microwave and active radar sensors, including the first precipitation radar in space. TRMM is a joint mission between NASA and the Japanese space agency, JAXA. NASA image produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC). |
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Tropical Cyclone Monica
| Title |
Tropical Cyclone Monica |
| Description |
Cyclone Monica became the strongest storm of the 2006 Australian cyclone season with wind gusts reaching 350 kilometers per hour (215 miles per hour) as reported by the Australian Bureau of Meteorology's Cyclone Warning Centre. The Category 5 cyclone hit along the sparsely populated coastline of the Northern Territory, sparing the city of Darwin. Monica originated in the Coral Sea below the southeastern tip of Papua New Guinea, becoming a minimal tropical storm on April 17, 2006. The storm tracked due west towards the Cape York Peninsula in Queensland, where it came ashore just south of Lockart River on the afternoon of April 19 as a Category 3 cyclone. Monica weakened as it crossed the peninsula, but when it reached the warm waters of the Gulf of Carpentaria on the other side, it re-organized and re-intensified. The image above shows Cyclone Monica during this re-intensification. The visualization combines data from several different instruments from the Tropical Rainfall Measuring Mission (TRMM) satellite, which observed the storm at 16:08 UTC on April 22, 2006 (1:38 a.m., April 23, Australian CST). With an active radar and a passive microwave sensor, TRMM can peer into the core of these storms and relay important details on storm structure and location to forecasters. In this case, TRMM showed a pattern of very heavy rain (red) forming an intense symmetric eyewall around a small, complete eye with tightly curved rainbands spiraling into the center—the signature of a mature, intense tropical cyclone. Rain rates in the center swath are from the TRMM Precipitation Radar, and rain rates in the outer swath are from the TRMM Microwave Imager. The rain rates are overlaid on infrared data from the TRMM Visible Infrared Scanner. At the time of this TRMM overpass, Monica's sustained winds were estimated to be 230 kilometers/hour (144 mph) or equivalent to a Category 4 hurricane on the Saffir-Simpson scale. Soon after these images were taken, Monica reached Category 5 status with sustained winds estimated at 285 km/hr (178 mph). The cyclone tracked westward, skirting the northern coastline of Australia before coming ashore west of Maningrida in the Northern Territory just after 8 p.m. local time. The storm quickly lost strength as it moved inland and passed by the main population center of Darwin. TRMM is a joint mission between NASA and the Japanese space agency, JAXA. TRMM made several passes over Monica, during both the early and the mature stages of the storm. Since its launch in 1997, TRMM has provided valuable information on tropical storms. With an active radar and a passive microwave sensor, TRMM can peer into the core of these storms and relay details on storm structure and location to forecasters. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC). |
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Tropical Cyclone Percy
| Title |
Tropical Cyclone Percy |
| Description |
Percy, a powerful Category 4 cyclone, is the latest cyclone to threaten the South Pacific. In early February Cyclone Meena hit the Cook Islands, and in mid-February Cyclone Nancy also skirted the Cook Islands while Cyclone Olaf brushed the islands of Samoa and American Samoa. Percy started out as a tropical depression on February 24, 2005, near Tuvalu, just east of the international dateline. The system moved east-southeast staying north of Samoa and steadily increased in strength. It became a cyclone on February 25 and, two days later, grew into a powerful Category 4 cyclone with sustained winds estimated at 115 knots (132 mph) by the Joint Typhoon Warning Center. Percy then slowed down, weakened slightly and battered the atolls of Nassau and Pukapuka in the northern Cook Islands before turning south on February 28. Percy regained Category 4 strength on March 1, and then further intensified into a powerful Category 5 storm on the 2nd with maximum sustained winds estimated at 140 knots (161 mph). In November of 1997, the Tropical Rainfall Measuring Mission, or TRMM satellite, was launched to measure rainfall over the global tropics. TRMM has also turned out to be an excellent observational platform for studying and monitoring tropical cyclones, as shown by this series of images of Cyclone Percy. The top left image, taken at 08:29 UTC on February 28, just as Percy was raking the Nassau and Pukapuka atolls, shows the horizontal distribution of rain intensity. Rain rates in the center swath are from the TRMM Precipitation Radar (PR), the first and only precipitation radar in space, while rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). TRMM shows an asymmetrical eye with intense rain (dark red area) in the northern part of the eyewall. This rain indicates where heat is being released into the storm. Known as "latent heat," it is the heat released when water vapor condenses into liquid cloud droplets. It is most effective in driving the cyclone's circulation when it is released near the center as is the case shown here by TRMM. The right image was taken at the same time by the TRMM Precipitation Radar (PR), and shows a vertical cross section through the center of the storm looking east. The intense rain (darker red area) is associated with the tallest towers in the northern eyewall. The broad yellow area indicating moderate rain is associated with an outer rainband. At the time of these images, Percy was a Category 3 storm with sustained winds estimated at 105 knots (121 mph). The lower left image was taken at 08:18 UTC on March 2, 2005. At this time Percy was a strong Category 4 cyclone with maximum sustained winds estimated at 130 knots (150 mph). The center of the storm does not fall within the PR swath, which has a higher horizontal resolution than the TMI. However, the TMI is still able to show what appears to a double, eyewall. Mature, intense tropical cyclones undergo what it known as eyewall replacement cycles wherein an outer eyewall forms as a ring surrounding the inner eyewall. The outer eyewall eventually contracts and replaces the inner eyewall. The two eyewalls are evident as the two concentric rings of moderate rain intensity (green areas).TRMM [ http://trmm.gsfc.nasa.gov/ ] is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC). |
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Tropical Cyclone Percy
| Title |
Tropical Cyclone Percy |
| Description |
Percy, a powerful Category 4 cyclone, is the latest cyclone to threaten the South Pacific. In early February Cyclone Meena hit the Cook Islands, and in mid-February Cyclone Nancy also skirted the Cook Islands while Cyclone Olaf brushed the islands of Samoa and American Samoa. Percy started out as a tropical depression on February 24, 2005, near Tuvalu, just east of the international dateline. The system moved east-southeast staying north of Samoa and steadily increased in strength. It became a cyclone on February 25 and, two days later, grew into a powerful Category 4 cyclone with sustained winds estimated at 115 knots (132 mph) by the Joint Typhoon Warning Center. Percy then slowed down, weakened slightly and battered the atolls of Nassau and Pukapuka in the northern Cook Islands before turning south on February 28. Percy regained Category 4 strength on March 1, and then further intensified into a powerful Category 5 storm on the 2nd with maximum sustained winds estimated at 140 knots (161 mph). In November of 1997, the Tropical Rainfall Measuring Mission, or TRMM satellite, was launched to measure rainfall over the global tropics. TRMM has also turned out to be an excellent observational platform for studying and monitoring tropical cyclones, as shown by this series of images of Cyclone Percy. The top left image, taken at 08:29 UTC on February 28, just as Percy was raking the Nassau and Pukapuka atolls, shows the horizontal distribution of rain intensity. Rain rates in the center swath are from the TRMM Precipitation Radar (PR), the first and only precipitation radar in space, while rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). TRMM shows an asymmetrical eye with intense rain (dark red area) in the northern part of the eyewall. This rain indicates where heat is being released into the storm. Known as "latent heat," it is the heat released when water vapor condenses into liquid cloud droplets. It is most effective in driving the cyclone's circulation when it is released near the center as is the case shown here by TRMM. The right image was taken at the same time by the TRMM Precipitation Radar (PR), and shows a vertical cross section through the center of the storm looking east. The intense rain (darker red area) is associated with the tallest towers in the northern eyewall. The broad yellow area indicating moderate rain is associated with an outer rainband. At the time of these images, Percy was a Category 3 storm with sustained winds estimated at 105 knots (121 mph). The lower left image was taken at 08:18 UTC on March 2, 2005. At this time Percy was a strong Category 4 cyclone with maximum sustained winds estimated at 130 knots (150 mph). The center of the storm does not fall within the PR swath, which has a higher horizontal resolution than the TMI. However, the TMI is still able to show what appears to a double, eyewall. Mature, intense tropical cyclones undergo what it known as eyewall replacement cycles wherein an outer eyewall forms as a ring surrounding the inner eyewall. The outer eyewall eventually contracts and replaces the inner eyewall. The two eyewalls are evident as the two concentric rings of moderate rain intensity (green areas).TRMM [ http://trmm.gsfc.nasa.gov/ ] is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC). |
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Tropical Cyclone Percy
| Title |
Tropical Cyclone Percy |
| Description |
Percy, a powerful Category 4 cyclone, is the latest cyclone to threaten the South Pacific. In early February Cyclone Meena hit the Cook Islands, and in mid-February Cyclone Nancy also skirted the Cook Islands while Cyclone Olaf brushed the islands of Samoa and American Samoa. Percy started out as a tropical depression on February 24, 2005, near Tuvalu, just east of the international dateline. The system moved east-southeast staying north of Samoa and steadily increased in strength. It became a cyclone on February 25 and, two days later, grew into a powerful Category 4 cyclone with sustained winds estimated at 115 knots (132 mph) by the Joint Typhoon Warning Center. Percy then slowed down, weakened slightly and battered the atolls of Nassau and Pukapuka in the northern Cook Islands before turning south on February 28. Percy regained Category 4 strength on March 1, and then further intensified into a powerful Category 5 storm on the 2nd with maximum sustained winds estimated at 140 knots (161 mph). In November of 1997, the Tropical Rainfall Measuring Mission, or TRMM satellite, was launched to measure rainfall over the global tropics. TRMM has also turned out to be an excellent observational platform for studying and monitoring tropical cyclones, as shown by this series of images of Cyclone Percy. The top left image, taken at 08:29 UTC on February 28, just as Percy was raking the Nassau and Pukapuka atolls, shows the horizontal distribution of rain intensity. Rain rates in the center swath are from the TRMM Precipitation Radar (PR), the first and only precipitation radar in space, while rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). TRMM shows an asymmetrical eye with intense rain (dark red area) in the northern part of the eyewall. This rain indicates where heat is being released into the storm. Known as "latent heat," it is the heat released when water vapor condenses into liquid cloud droplets. It is most effective in driving the cyclone's circulation when it is released near the center as is the case shown here by TRMM. The right image was taken at the same time by the TRMM Precipitation Radar (PR), and shows a vertical cross section through the center of the storm looking east. The intense rain (darker red area) is associated with the tallest towers in the northern eyewall. The broad yellow area indicating moderate rain is associated with an outer rainband. At the time of these images, Percy was a Category 3 storm with sustained winds estimated at 105 knots (121 mph). The lower left image was taken at 08:18 UTC on March 2, 2005. At this time Percy was a strong Category 4 cyclone with maximum sustained winds estimated at 130 knots (150 mph). The center of the storm does not fall within the PR swath, which has a higher horizontal resolution than the TMI. However, the TMI is still able to show what appears to a double, eyewall. Mature, intense tropical cyclones undergo what it known as eyewall replacement cycles wherein an outer eyewall forms as a ring surrounding the inner eyewall. The outer eyewall eventually contracts and replaces the inner eyewall. The two eyewalls are evident as the two concentric rings of moderate rain intensity (green areas).TRMM [ http://trmm.gsfc.nasa.gov/ ] is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC). |
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