NASA - National Aeronautics and Space Administration

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March 14, 2008

A Dying Jokwe in the Waters of the Mozambique Channel

On Friday, March 14, 2008, at 6:00 Zulu Time (2:00 a.m. EDT), a once deadly Cyclone Jokwe is now a dying Jokwe in the Mozambique Channel of the Indian Ocean. The Channel is the body of water between the island nation of Madagascar and the country of Mozambique on the African continent.

At that time, Jokwe had maximum sustained winds near 40 knots (46.mph), and was located near 25.4 degrees south latitude and 40.4 degrees east longitude, or approximately 425 nautical miles east of Maputo, Mozambique. Jokwe wasn't moving much, approximately 1 knot (1 mph), so the Joint Typhoon Warning Center classified its movement as "quasi-stationary." Jokwe is expected to dissipate in 12 hours time.

Credit: NASA/JPL
> Click for larger image This infrared image of Jokwe was created on March 13 at 22:35 Zulu Time (6:35 p.m. EDT) by data from the Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite. Jokwe is the purple and blue area located to the southwest of Madagascar.

This AIRS image (right) shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of Jokwe. The infrared signal of the AIRS instrument does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the surface of the Earth, revealing warmer temperatures (red).

Text credit: Rob Gutro/Goddard Space Flight Center

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March 11, 2008

Cyclone Jokwe Lashes Mozambique

Credit: Hal Pierce (NASA's Goddard Space Flight Center/Science Systems and Applications, Inc.)
> Larger image Jokwe, a powerful Category 3 cyclone, lashed parts of northern Mozambique with winds reported of up to 125 mph (200 kph). The cyclone is responsible for destroying thousands of homes and killing as many as 8 people. The northern Mozambique province of Nampula was hardest hit.

The Tropical Rainfall Measuring Mission satellite (known as TRMM) captured these images of Jokwe after it had raked the northern coast of Mozambique and was moving south in the central Mozambique Channel between Mozambique and Madagascar. (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 was taken at 11:15 UTC (2:15 pm local time) 10 March 2008 and shows the instantaneous rain rates 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 visible and infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). TRMM reveals that Jokwe has a rather large but well-defined eye with a band of intense rain located in the southeastern eyewall (dark red arc near the center of the image). Typically, tropical cyclones loose a lot of their structure after encountering land, but having only brushed along the coastline of Mozambique has allowed Jokwe to maintain its organization. The large eye is also somewhat characteristic of older cyclones that have undergone some form of weakening as this allows the wind field to expand.

Credit: Hal Pierce (NASA's Goddard Space Flight Center/Science Systems and Applications, Inc.)
> Larger image The second image was taken simultaneously with the previous and shows a unique 3D perspective of the cyclone courtesy of the TRMM PR. A ring of taller towers (highlighted in red), which compose the eyewall, surround the open center where the eye is located. To the right of the center, the cutaway view shows areas of more intense rain (in red) embedded within broader areas of less intense rain (yellow).

The less intense rain is associated with shallow portions of the storm (green tops), while the areas of intense rain tend to be collocated with deeper towers (red tops). Heavier rain is produced by stronger updrafts, which can then also carry cloud particles higher aloft. At the time these images were collected, Jokwe was a Category 2 cyclone with sustained winds estimated at 85 knots (98 mph) by the Joint Typhoon Warning Center.

Credit: Hal Pierce (NASA's Goddard Space Flight Center/Science Systems and Applications, Inc.)
> Larger image TRMM can also be used to calibrate rainfall estimates from other satellites. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center monitors rainfall over the global Tropics. MPA rainfall totals associated with the passage of Jokwe are shown here in relation to the storm's track (identified by the storm/cyclone symbols connected by a black line). The system first passed over the northern tip of Madagascar where it left behind little damage and rainfall amounts of up to 200+ mm (~8 inches, shown in orange) in isolated pockets long the coast but much lower totals farther inland. After making landfall in northern Mozambique, Jokwe turned towards the south parallel to the coastline. Here it left behind upwards of 300 mm (~12 inches, shown in darker red) of rain in the immediate coastal region right along its path. Amounts drop off quickly further inland.

Jokwe is expected to stall out in the southern Mozambique Channel in the coming days and slowly weaken. The tropical cyclone season is near its peak in the South Indian Ocean with March being a particularly active month.

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

Text credit: Steve Lang, NASA's Goddard Space Flight Center/Science Systems and Applications, Inc.

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March 10, 2008

Credit: NASA/JPL
> Larger image A Deadly Jokwe in Mozambique

Powerful Tropical Cyclone Jokwe has caused thousands of people in Mozambique to flee their homes, and has already killed seven people, according to BBC News.

Reports indicate that more than 500 buildings have been damaged, and electricity is out in Mozambique. The Northern Nampula province received the brunt of the storm, as did historic Mozambique Island.

On March 10 at 6:00 Zulu Time (2:00 a.m. Eastern Daylight Time) Cyclone Jokwe was located near latitude 20.3 south, and longitude 39.5 east, approximately 430 miles west-southwest of Antananarivo, Madagascar, in the Indian Ocean.

Jokwe is moving south-southeast near 7 knots (8 mph), parallel to the coastline. Jokwe's maximum sustained winds increased to near 85 knots (98 mph) with gusts to 105 knots (120 mph), making it a category two hurricane on the Saffir-Simpson scale. Jokwe's strong winds were generating 32 foot-high waves.

This visible image of Jokwe was created on March 10 at 11:11 Zulu Time (7:11 a.m. EDT) by data from the Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite. Jokwe is located in the bottom center of the image. Madagascar is to the right of the storm, while Mozambique is to the storm's left.

Why Such an Active Season in the Southwestern Indian Ocean?

The Southwestern Indian Ocean has been extremely active this season. In fact, the 2008 cyclone season has seen the highest number of storms in a decade. Some meteorologists attribute the higher frequency to the current La Nina. La Nina is unusually cold ocean temperatures in the eastern equatorial Pacific Ocean that cause a ripple effect on weather around the world.

NASA's CloudSat Satellite Provides a Sideways View of Jokwe

Credit: Naval Research Laboratory-Monterey
> Larger image NASA's CloudSat satellite's Cloud Profiling Radar captured a sideways look across Cyclone Joke on March 10. The top image is from NASA's Aqua satellite and the image was supplied through the U.S. Naval Research Laboratory.

The image on the bottom is from NASA's CloudSat satellite. The red line through the GOES satellite image shows the vertical cross section of radar, basically what Jowke's clouds looked like sideways. The colors indicate the intensity of the reflected radar energy. The top of Jokwe's clouds reach almost up to 15 kilometers, or approximately 9.3 miles high. These high cloud tops indicate a strong storm.

The blue areas along the top of the clouds indicates cloud ice, while the wavy blue lines on the bottom center of the image indicate intense rainfall. Notice that the solid line along the bottom of the panel, which is the ground, disappears in this area of intense precipitation. It is likely that in the area the precipitation rate exceeds 30mm/hr (1.18 inches/hour) based on previous studies.

For NASA's La Niña/El Niño Watch Web site, visit http://sealevel.jpl.nasa.gov/elnino/index.html

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

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March 6, 2008

Tropical Cyclone Jokwe Lashing the Coast of Madagascar

Credit: NASA/JPL
> Larger image The powerful winds of Tropical Cyclone Jokwe were clipping the northwestern tip of the island nation of Madagascar on March 6 at 12:00 Zulu Time (7:00 a.m. EDT) on its way into the Mozambique Channel.

At that time, Jokwe, or tropical cyclone 22S was located near latitude 13.7 south, and longitude 46.9 east, approximately 315 miles north of Antananarivo, Madagascar, in the Indian Ocean.

Jokwe is moving west-southwest near 12 knots (13 mph), parallel to the Malagasy northwestern coastline. Jokwe had maximum sustained winds near 75 knots (86 mph) with gusts to 90 knots (103 mph), making it a category one hurricane on the Saffir-Simpson scale.

Proximity to land will limit further intensification, but the cyclone is expected to remain offshore off central Mozambique. RSMC La Reunion projects a turn away from the coast in the longer term.

Jokwe's strong winds were generating 22 foot-high waves. Tropical storm force winds (greater than 37 mph) extended out to about 85 miles from Jokwe's center, or cover a total area of around 170 miles. Hurricane force winds are more concentrated in the center, and reach 20 miles out from the eye.

This visible image of Jokwe was created on March 6 at 9:59 UTC (4:59 a.m. EDT) by data from the Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite. Jokwe is located in the bottom left of the image, and the country of Somalia is located in the land that juts out far to the north of the storm. Madagascar is actually below the storm, but is somewhat difficult to see in this satellite image.

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