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Cyclones in the Pacific
| Title |
Cyclones in the Pacific |
| Description |
This colorful image superimposes measurements of wind direction on top of wind speed. NASA's microwave scatterometer, QuickSCAT, collected the image on February 15, 2005, over the South Pacific where two large cyclones are moving steadily closer to one another in a potentially dangerous dance. It is very unusual for cyclones to be so close together in the South Pacific, and it's hard to predict how the storms will interact. One possibility is that the weaker storm will be tugged off course by the large-scale atmospheric circulation of the other. Eventually the weaker storm will seem to "orbit" the stronger storm. The second possibility is that the outflow from one storm will impede the outflow from the other storm, weakening the second storm. Regardless of the interaction, the storms pose a potentially deadly threat to American Samoa and the Cook Islands, which are shown as small grey dots. At the time this image was acquired, Olaf was a strengthening Category 4 cyclone, with steady winds of 135 knots and gusts up to 165 knots. Nancy was beginning to weaken with winds of 85 knots and gusts of 115 knots. The strongest winds, shown in pink, circle the center of the storms. Even without any sort of interaction, the two large storms could pack a dangerous one-two punch to the island nations of the South Pacific. NASA image courtesy Timothy Liu, Wendy Tang, and Xiaosu Xie, of the QuikSCAT Science Team at the Jet Propulsion Laboratory. |
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Cyclones in the Pacific
| Title |
Cyclones in the Pacific |
| Description |
This image of the South Pacific on February 16, 2005, shows Cyclone Olaf and a weakening Cyclone Nancy one day before Olaf passed over the island of American Samoa as a Category 5 storm. Although the island received a direct hit, there were no reported causalities on land. However, some fishing vessels may have been lost. To the north of Olaf, a band of large thunderstorms stretches across the top of the scene. The line of storms is probably an outer spiral band of the cyclone, at the eastern end, the line of storms can be seen bending southward toward the core of the storm. The area of clear skies between the main part of the storm and the outer band of thunderstorms in the north is known as a "moat". A moat is zone of sinking air between bands of convection (rising air that fuels thunderstorms.) Image courtesy the MODIS Rapid Response Team [ http://rapidf,ire.ci.gsfc.nasa.gov ], NASA-GSFC |
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Cyclones in the Pacific
| Title |
Cyclones in the Pacific |
| Description |
Two cyclones, Olaf a powerful Category 4 cyclone and Nancy a weaker but still strong Category 2 cyclone, are together threatening the Cook Islands and the islands of Samoa in the South Pacific. This spectacular image from TRMM, the Tropical Rainfall Measuring Mission satellite, shows Cyclone Olaf in the upper left as it is approaching the islands of Samoa and Cyclone Nancy in the lower right as it heads towards Rarotonga in the Cook Islands. The image was taken at 15:34 UTC on February 15, 2005, and shows the horizontal distribution of rain intensity as seen from above by the TRMM satellite. 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). At the time of this image, Olaf was a Category 4 storm with maximum sustained winds estimated at 120 knots (138 mph) by the Joint Typhoon Warning Center and was in the process of intensifying. Nancy, meanwhile, was a Category 2 storm with maximum sustained winds estimated at 95 knots (109 mph) and was beginning to weaken. These characterizations are supported by TRMM, which shows that Olaf has much better banding in the rain field as evidenced by the green arcs of moderate rain intensity and a tight, closed eye (green circle). Nancy exhibits no well-defined eye, and the banding is much less evident. When two cyclones come within close proximity and their circulations begin to interact with each other, two possible interactions can occur. One interaction is known as the Fujiwara effect, wherein the cyclones begin circling around each another. The other possibility is that the outflow from one storm impedes the outflow from the other storm, weakening it. TRMM is a joint mission between NASA and the Japanese space agency JAXA. Image 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 |
On February 27, 2005, Tropical Cyclone Percy continued to gather steam as it struck Swain?s Island, a tiny island in American Samoa. Tropical Cyclone Percy is the fourth large cyclone to sweep across the South Pacific in as many weeks, and at the time this image was taken at 10:05 a.m., local time, the storm was the equivalent of a Category 3 Hurricane with winds of 195 kilometers per hour (121 mph) and gusts to 240 kph (150 mph). By March 1, Percy would reach Category 4 status on the Saffir-Simpson Hurricane Scale, with winds of 213 kph (132 mph) and gusts to 260 kph (161 mph). The Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA?s Terra [ http://terra.nasa.gov/ ] satellite captured this true-color image of the storm on February 27. NASA image created by Jesse Allen, Earth Observatory, using data obtained from the Goddard DAAC. |
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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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Tropical Cyclone Percy: Natu
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nasa, nasanaturalhazards
* eoimages.gsfc.nasa.gov/ima
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percy_TRM_2005061
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2005-03-02 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
percy_TRM_2005061 |
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Cyclones in the Pacific: Nat
…
nasa, nasanaturalhazards
Two cyclones, Olaf a powerfu
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nancyolaf_TRM_2005015
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2005-02-15 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
nancyolaf_TRM_2005015 |
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Tropical Cyclone Percy: Natu
…
nasa, nasanaturalhazards
On February 27, 2005, Tropic
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cookis_tmo_27feb05
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2005-02-27 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
cookis_tmo_27feb05 |
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Tropical Cyclones Olaf and N
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nasa, nasaimageofthedaygalle
…
This colorful image superimp
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nancyolaf_QST_2005046
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2005-02-15 |
| creator |
NASA -- NASA image courtesy Timothy Liu, Wendy Tang, and Xiaosu Xie, of the winds.jpl.nasa.gov/ QuikSCAT Science Team at the Jet Propulsion Laboratory. |
| identifier |
nancyolaf_QST_2005046 |
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Cyclones in the Pacific: Nat
…
nasa, nasanaturalhazards
The MODIS instrument onboard
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Olaf_Nancy_2005047
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2005-02-16 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Olaf_Nancy_2005047 |
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Cyclones in the Pacific: Nat
…
nasa, nasanaturalhazards
This image of the South Paci
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Olaf.TMOA2005047
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2005-02-16 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Olaf.TMOA2005047 |
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