Featured Images

Hurricane Season 2009: Aila (Bay of Bengal)
07.17.09
 
July 17, 2009

This image, taken at 21:20 UTC on May 23, 2009, shows the horizontal pattern of rain intensity within the storm. > Larger image
Aila was just becoming a tropical storm. This TRMM image was taken at 21:20 UTC, May 23, 2009 and shows the horizontal pattern of rain intensity within the storm.
Image Credit: NASA/SSAI, Hal Pierce
A large, well-defined eye is now visible, consistent with Aila's increased intensity. > Larger image
This TRMM image was taken at 12:55 UTC (6:25 pm local time) on May 25 and shows a much different looking storm. A large, well-defined eye is now visible, consistent with Aila's increased intensity.
Image Credit: NASA/SSAI, Hal Pierce
CYCLONE AILA MAKES LANDFALL IN INDIA

Aila recently became the first cyclone of the 2009 cyclone season in the North Indian Ocean just before making landfall in far eastern India in the northern Bay of Bengal. So far the storm is being blamed for 275 deaths in India and Bangladesh, but more are expected. Tropical Storm Bijli, which made landfall in eastern Bangladesh, was the first and only other named storm of the season back in mid April. Although the cyclone season in the North Indian Ocean is long, stretching from April through December, there are typically just over 5 named storms per year with 2 becoming full tropical cyclones.

Aila evolved from a tropical disturbance in the central Bay of Bengal. The disturbance slowly organized over a period of 2 to 3 days and became a tropical storm on the morning (local time) of May 23rd as it moved northward. The Tropical Rainfall Measuring Mission satellite (known as TRMM) was placed into service in November of 1997. From its low-earth orbit, TRMM can provide valuable images and information on tropical cyclones around the Tropics using a combination of passive microwave and active radar sensors.

The first image shows Aila just as it was becoming a tropical storm. The image was taken at 21:20 UTC 23 May 2009 (2:50 am 24 May local time) and shows the horizontal pattern of rain intensity within the storm. Rain rates in the center swath are from the TRMM Precipitation Radar (PR), the first 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 this stage, the center is not very well defined; however, the developing cyclonic circulation is evident by the curvature in the rain bands. Aila would officially became a tropical storm less than 3 hours after this image was taken.

Over the next day, the system slowly strengthened as it continued northward towards the coastline of eastern India and western Bangladesh along the northern Bay of Bengal. Aila finally became a Category 1 cyclone around noon (local time) on the 25th just as the center was crossing the far eastern coast of India. The next image from TRMM was taken at 12:55 UTC (6:25 pm local time) on May 25 and shows a much different looking storm. A large, well-defined eye is now visible, consistent with Aila's increased intensity. A sizeable area of moderate to light rain (shown in green and blue, respectively) extends mainly out ahead of the storm. Areas of locally heavier rain are shown in red.

At the time of this image, Aila had been downgraded to a strong tropical storm with sustained winds estimated at 55 knots (63 mph). In addition to the 275 fatalities, the storm has displaced millions of people. Because the coastal topography is so shallow, the region is susceptible to storm surge. Coupled with the fact that the low-lying coastal areas are densely populated, makes storms in this region extremely dangerous. Last year there was only one cyclone, Nargis, but it was a Category 4 storm and was responsible for over 146,000 fatalities in Burma (Myanmar).

Text Credit: Hal Pierce, SSAI/Goddard Space Flight Center



June 1, 2009

Aila was becoming a tropical storm on May 23 > Larger image
Aila was becoming a tropical storm on May 23
Image Credit: NASA/SSAI, Hal Pierce
Aila is more powerful and organized on May 25, as a large, well-defined eye is now visible > Larger image
Aila is more powerful and organized on May 25, as a large, well-defined eye is now visible.
Image Credit: NASA/SSAI, Hal Pierce
NASA'S TRMM SATELLITE CAPTURES DEADLY CYCLONE AILA'S RAINFALL

Aila recently became the first cyclone of the 2009 cyclone season in the North Indian Ocean just before making landfall in far eastern India in the northern Bay of Bengal. So far the storm is being blamed for 275 deaths in India and Bangladesh, but more are expected.

Tropical Storm Bijli, which made landfall in eastern Bangladesh, was the first and only other named storm of the season back in mid April. Although the cyclone season in the North Indian Ocean is long, stretching from April through December, there are typically just over 5 named storms per year with 2 becoming full tropical cyclones.

Aila evolved from a tropical disturbance in the central Bay of Bengal. The disturbance slowly organized over a period of 2 to 3 days and became a tropical storm on the morning (local time) of May 23 as it moved northward. The Tropical Rainfall Measuring Mission satellite (known as TRMM) was placed into service in November of 1997. From its low-earth orbit, TRMM can provide valuable images and information on tropical cyclones around the Tropics using a combination of passive microwave and active radar sensors.

The first image shows Aila just as it was becoming a tropical storm. The image was taken at 21:20 UTC May 23, 2009 (2:50 a.m. May 24 local time) and shows the horizontal pattern of rain intensity within the storm. Rain rates in the center swath are from the TRMM Precipitation Radar (PR), the first 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 this stage, the center is not very well defined; however, the developing cyclonic circulation is evident by the curvature in the rain bands. Aila would officially became a tropical storm less than 3 hours after this image was taken.

Over the next day, the system slowly strengthened as it continued northward towards the coastline of eastern India and western Bangladesh along the northern Bay of Bengal. Aila finally became a Category 1 cyclone around noon (local time) on the 25th just as the center was crossing the far eastern coast of India. The next image from TRMM was taken at 12:55 UTC (6:25 pm local time) on the 25th of May and shows a much different looking storm. A large, well-defined eye is now visible, consistent with Aila's increased intensity. A sizeable area of moderate to light rain (shown in green and blue, respectively) extends mainly out ahead of the storm. Areas of locally heavier rain are shown in red. At the time of this image, Aila had been downgraded to a strong tropical storm with sustained winds estimated at 55 knots (63 mph).

In addition to the 275 fatalities, the storm has displaced millions of people. Because the coastal topography is so shallow, the region is susceptible to storm surge. Coupled with the fact that the low-lying coastal areas are densely populated, makes storms in this region extremely dangerous. Last year there was only one cyclone, Nargis, but it was a Category 4 storm and was responsible for over 146,000 fatalities in Burma (Myanmar).

TRMM is a joint mission between NASA and the Japanese space agency JAXA.

Text credit: Steve Lang, Goddard Space Flight Center/SSAI



May 27, 2009

NASA's Terra satellite saw Aila on May 25 over India and Bangladesh > Larger image
NASA's Terra satellite saw Aila on May 25 over India and Bangladesh
Image Credit: NASA/MODIS Rapid Response
NASA Satellites Captured Views of Aila, the Year's Deadliest Cyclone

Residents in eastern India and Bangladesh are still assessing damages from Cyclone Aila after it made landfall as a minimal Category One hurricane/cyclone on May 25. On May 27, estimates from both countries place the total death toll at 130 people, and that number is expected to rise. That makes Aila the deadliest tropical cyclone so far in 2009.

NASA's Terra and Aqua satellites were both flying overhead on May 25 and captured a visible and infrared image of the storm, the day Aila made its deadly landfall.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured a visible image of Aila at 12:55 a.m. EDT (4:55 UTC) on Monday, May 25 while it was moving inland.

The city of Kolkata (also known as Calcutta) - the second largest city in India, suffered heavy damage. Aila made landfall with sustained winds between 65 and 75 mph (74 mph is the lowest threshold for a Category one hurricane). When landfall occurred, it brought with it a deadly storm surge between 10-13 feet high along the east Indian and western Bangladesh coastlines.

Aila's heavy rains and storm surge flooded many areas, destroying homes and mud huts, and leaving others stranded on rooftops or rafts. Drinkable water has been an issue of concern, but the Indian army is now operating 278 water purification machines according to a report on DNAindia.com.

Aila's cold clouds were captured by NASA's Aqua satellite > Larger image
Aila's cold clouds were captured by NASA's Aqua satellite.
Image Credit: NASA JPL, Ed Olsen
NASA's Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured an infrared image of Aila on May 25 at 4:11 p.m. EDT (20:11 UTC). Aila is the round area of blue and purple (high clouds) on the border of eastern India and Bangladesh.

The infrared image clearly shows a large temperature difference between the storm's cloud-tops and the warm land temperatures of central India. In this image, the orange temperatures are 80F (300 degrees Kelvin) or warmer.

Cyclone Aila's lowest temperatures (in purple) are associated with high, cold cloud tops. Those temperatures are as cold as or colder than 220 degrees Kelvin or minus 63 degrees Fahrenheit (F). The blue areas are around 240 degrees Kelvin, or minus 27F.

Aila has since dissipated over land.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center



May 26, 2009

Cyclone Aila dissipating over eastern India on May 26 > Larger image
Tropical Cyclone Aila dissipating over eastern India on May 26.
Image Credit: U.S.Navy/JTWC/NASA
Deadly Cyclone Aila Dissipates After a Landfall in Eastern India

Cyclone Aila formed in the Bay of Bengal on May 24 and made a quick landfall the next day in eastern India. The storm killed up to 120 people in eastern India and neighboring Bangladesh combined. Aila has now dissipated inland over eastern India.

Cyclone 02B, later named Aila when it became a tropical storm, formed in the early morning hours of May 24 about 240 miles south of Kolkata, India. Aila strengthened quickly into a tropical storm later that day, then made landfall near Calcutta, India on Sunday, May 25 at 0900 Zulu Time (5 a.m. EDT) as a Category One Cyclone. It had sustained winds near 65 knots (74 mph) at the time of landfall. The threshold for a Category One Cyclone (or hurricane) starts at 74 mph and goes to 95 mph. Aila has since dissipated inland over eastern India.

According to a Reuters news report, Bangladesh's Daily Star newspaper reported at least 89 deaths as the search continues for others there. Meanwhile, 29 people were reported dead in the West Bengal State of eastern India. Aila's heavy rains caused agricultural damage to rice crops that were about to be harvested. The rains also raised river levels and broke through mud embankments. Winds downed trees, power lines and even collapsed houses. Hundreds of thousands of people fled into shelters.

The last warning from the Joint Typhoon Warning Center was issued on May 25 at 0900 Zulu Time (5 a.m. EDT), when Aila had sustained winds near 40 knots (46 mph). At that time, the center of circulation was located about 105 miles north-northwest of Kolkata, India, near 24.2 north and 88.5 east.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Aqua satellite captured this image of cyclone Aila at 2:13 a.m. EDT (7:13 Zulu Time) on Monday, May 26, 2009. The storm was already dissipating at that time, and this image confirmed that, because the storm wasn't circular anymore.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center