Featured Images

Text Size

Hurricane Season 2011: Tropical Cyclone Thane (Northern Indian Ocean)
1.3.12
 
NASA's TRMM Satellite Sees Heavy Rainfall As Cyclone Thane Slams India › Larger image
These two 3-D images of Tropical Cyclone Thane were from Dec. 27 (left) and 29, 2011 (right), showing the heights of thunderstorms and rainfall rates. On Dec. 27, the 3-D image showed some convective thunderstorm towers were reaching to heights of over 16 kilometers (9.94 miles). Light to moderate rainfall, depicted in blue and green is falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour. Heavy rainfall, seen in red was occurring at a rate of 2 inches (50 mm) per hour.
Credit: SSAI/NASA, Hal Pierce
NASA's TRMM Satellite Sees Heavy Rainfall As Cyclone Thane Slams India › Larger image
This shows three days of Tropical Cyclone Thane's rainfall rates. TRMM provided a "top down" analysis of how fast rain was falling throughout the cyclone on Dec. 26 (left), Dec. 27 (center) and Dec. 29, 2011 (right). Light to moderate rainfall, depicted in blue and green is falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour. Heavy rainfall, seen in red was occurring at a rate of 2 inches (50 mm) per hour.
Credit: SSAI/NASA, Hal Pierce
NASA's TRMM Satellite Sees Heavy Rainfall As Cyclone Thane Slams India

At least 47 people were killed when tropical cyclone Thane with reported winds of up to 85 mph (137 kmh) hit Tamil Nadu on the southeastern coast of India Friday morning, December 30, 2011. The TRMM satellite saw the tropical cyclone several times from its birth in the Bay of Bengal to its growth to hurricane force before penetrating the Indian coast.

The Tropical Rainfall Measuring Mission satellite called TRMM has the unique ability to measure how fast rain is falling within a tropical cyclone from its orbit in space. TRMM is a joint satellite mission operated by NASA and JAXA, the Japanese Space Agency. TRMM flew over Tropical Cyclone Thane three of the four days it existed and captured rainfall rates and cloud heights, providing scientists with insight on its strength and behavior.

Thane was a tropical storm with winds of about 40 knots (46 mph/74 kmh) when TRMM passed above on June 26, 2011 at 1305 UTC (8:05 a.m. EST). The storm was starting to organize with TRMM Precipitation Radar (PR) revealing a large area of powerful storms surrounding the northern side. A TRMM Microwave Imager (TMI) rainfall analysis showed a large nearly circular eye like structure near the storm's center.

TRMM had another good look at Thane as the cyclone was strengthening on December 27, 2011 at 2159 UTC (2:59 p.m. EST). TRMM's PR showed continuous bands of intense convective storms occurring within bands around Thane. Some of these storms were returning values of over 50 dBZ to TRMM's Precipitation Radar (PR) instrument proving that heavy rainfall was falling in that area. "dBZ" means decibels of Z. It is measure of equivalent reflectivity (Z) of a radar signal that is reflected off a remote object (such as rainfall). TRMM data was used to create a 3-D image that showed some convective thunderstorm towers were reaching to heights of over 16 kilometers (9.94 miles).

Thane was a hurricane force tropical cyclone with winds of about 75 knots (~86 mph/139 mph) when the TRMM satellite again checked on December 29, 2011 at 1153 UTC (6:53 a.m. EST). TRMM PR showed multiple bands of intense convective storms southwest of Thane's center off the coast of India. Some of the rain in those powerful storms were showing reflectivity values of over 55dBZ, again giving proof of heavy rainfall. TRMM's Precipitation Radar (PR) data were again used to create a 3-D image of the structure of clouds within Thane.

Thane made landfall as the sun was rising on eastern India on December 30 at the coastal district of Cuddalore, and near the town of Pondicherry.

According to Reuters news, tens of thousands of people are in need of emergency aid In southeastern India as a result of Cyclone Thane's landfall. Thane caused large agricultural losses, took down trees, power lines and damaged homes as it came ashore.

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


Dec. 30, 2011

Image of Thane by Aqua› Larger image
NASA's Aqua satellite MODIS instrument captured this visible image of Cyclone Thane on Dec. 30 at 0818 UTC (3:18 a.m. EST) after it made landfall south of Chennai. Thane's cloud cover takes up almost the entire southern peninsula. Credit: NRL/NASA
Cyclone Thane Makes Landfall in Eastern India

NASA's Aqua satellite passed over Cyclone Thane just after its center made landfall in eastern India, south of Chennai.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellite captured a visible image of Cyclone Thane on Dec. 30 at 0818 UTC (3:18 a.m. EST). Thane's cloud cover took up almost the entire southern peninsula.

The Joint Typhoon Warning Center (JTWC) issued their final advisory on the system on Dec. 30 at 0600 UTC (1 a.m. EST). AT that time, Thane's maximum sustained winds were of tropical storm strength, near 40 knots (46 mph/74 kmh). Its center was near 11.7 North and 79.1 East about 110 nautical miles southwest of Chennai, India. It continued to move west at 8 knots (9 mph/15 kmh).

Infrared satellite imagery, such as that from the Atmospheric Infrared Sounder that flies aboard NASA's Aqua satellite, showed that Thane's cloud tops were warming, indicating weakening in the uplift that helps create and power the thunderstorms that make up a tropical cyclone. The bands of thunderstorms that were seen around Thane's center before landfall have also fallen apart and are now fragmented, another sign of weakening.

According to Weather Underground, the forecast for Madurai, India, located south of Chennai, calls for afternoon and evening thunderstorms from Tropical Cyclone Thane with gusty winds. Madurai is located about 120 miles south of Thane's center.

JWTC expects Thane to dissipate by Dec. 31 over land, although it will be monitored for signs of regeneration as is moves toward the Arabian Sea.

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


Dec. 27, 2011

TRMM provided a › View larger image
TRMM provided a "top down" rainfall analysis of Cyclone Thane on Dec. 26 at 1305 UTC. Light to moderate rainfall, depicted in blue and green is falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour. Heavy rainfall, seen in red was occurring at a rate of 2 inches (50 mm) per hour. TRMM noticed hot towering clouds as high as 8.7 miles.
Credit: SSAI/NASA, Hal Pierce
NASA Satellite Sees Tropical Cyclone Thane Strengthening

The Tropical Rainfall Measuring Mission satellite called TRMM passed over newly formed Tropical Cyclone Thane in the Northern Indian Ocean and saw an organized storm with heavy rainfall and "hot towering" clouds that hint at further intensification.

On Dec. 26 at 1305 UTC (8:05 a.m. EST) the TRMM satellite passed over Tropical Cyclone Thane, formerly known as 06B and measured its rainfall rates. TRMM measured heavy rainfall rates in the northwestern quadrant of the storm near 1.7 inches (45 millimeters) per hour. TRMM also noticed several hot towering clouds around Thane's center that topped out around 8.7 miles (14 kilometers), indicating a lot of power in this tropical storm's heat engine. The low-level center appears to be on the eastern edge of the heaviest rainfall because of light east-southeasterly vertical wind shear.

Hot Towers are towering clouds that emit a tremendous amount of latent heat (thus, called "hot"). NASA research indicates that whenever a hot tower is spotted, a tropical cyclone will likely intensify within six hours.

On Dec. 27 at 1500 UTC (10 a.m. EST), Tropical Cyclone Thane had maximum sustained winds near 60 knots (69 mph/111 kmh). Thane was located about 375 nautical miles (431 miles/694 kilometers) east of Chennai, India, near 12.3 North and 86.3 East. Thane is moving to the west-northwest at 4 knots (5 mph/7 kmh).

According to the Joint Typhoon Warning Center, "Animated multispectral satellite imagery continues to indicate a consolidating low-level circulation center with improved deep convective (thunderstorm) banding wrapping into the center.

The Joint Typhoon Warning Center forecasts Thane to strengthen over the next day and then weaken before it makes landfall just south of Chennai late on Dec. 29 or early Dec. 30.

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