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PHILIPPINES HIT BY TWO CYCLONES
Two tropical cyclones recently struck the Philippines within a weeks time. On
the 19th of November 2007, then Tropical Storm Hagibis passed through the central
Philippines in the direction of Vietnam, leaving behind 13 dead. A week later
Typhoon Mitag hit northern Luzon where it was responsible for 17 fatalities. This
recent surge in tropical cyclone activity in the West Pacific may be related to an
active Madden-Julian Oscillation (or MJO). The MJO is a large, slow-moving area of
enhanced tropical convective (i.e., thunderstorm) activity that propagates eastward
from the Indian Ocean into the Pacific. It has been linked to modulations in
tropical cyclone formation.
The Tropical Rainfall Measuring Mission satellite (commonly known as TRMM) has now
completed 10 years of service, having been launched in November of 1997. Over the
past decade, TRMM has provided valuable images and information on tropical cyclones
around the Tropics using a combination of passive microwave and active radar sensors.
This unique image from TRMM shows Tropical Storm Hagibis (lower left corner, center
denoted by the tropical storm symbol) and Typhoon Mitag (upper right corner) both in
the same overpass. The image was taken at 23:00 UTC (6:00 pm EST) 25 November 2007.
It shows the horizontal distribution of rain intensity (top down view) within the
two cyclones as viewed by TRMM. Rain rates in the center of the swath are from the
TRMM Precipitation Radar (PR), a unique space-borne precipitation radar, while those
in the outer swath are from the TRMM Microwave Imager (TMI). These rain rates are
overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). At
the time of this image, Hagibis was in its weakening stages and just barely a tropical
storm with sustained winds estimated at just 35 knots (40 mph) by the Joint Typhoon
Warning Center. The center of circulation (denoted by the storm symbol) is completely
devoid of rain. Mitag, meanwhile, is a Category 1 typhoon with sustained winds of
75 knots (86 mph). It too is weakening after having made landfall about 6 hours
earlier. A broad band of moderate (green areas) intensity rain is seen spiraling
into the center with embedded areas of heavy rain (red areas). With the storm's
circulation having been disrupted by the terrain, the eye is hard to discern.
After re-emerging back over open water over the Luzon Strait north of Luzon, Mitag
is now following a northeast track away from major land areas and is expected to
continue weakening. Hagibis, however, which as one point was headed straight for
Vietnam after passing through the Philippines, made a U-turn and is now on its way
back to the Philippines. Fortunately, the system has already been
a
down-graded to tropical depression
and is expected to continue weakening, but it still poses a
threat for flooding. Efforts are still underway to locate crewman from a fishing
vessel as well as a search aircraft near the Spratly Islands located in the South
China Sea between the Philippines and Vietnam.
The image on the right was made using TRMM precipitation radar (PR)
data taken at the exact same time as the image above. The TRMM PR is a
one-of-a-kind space-borne radar that was used to see the 3-D vertical
precipitation structure in HAGIBIS and MITAG.
TRMM is a joint mission between NASA and the Japanese space agency JAXA.
Images by Hal Pierce (SSAI/NASA GSFC) and Caption by Steve Lang (SSAI/NASA GSFC)
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Two tropical cyclones recently struck the Philippines within a weeks time. On
the 19th of November 2007, then Tropical Storm Hagibis passed through the central
Philippines in the direction of Vietnam, leaving behind 13 dead. A week later
Typhoon Mitag hit northern Luzon where it was responsible for 17 fatalities. This
recent surge in tropical cyclone activity in the West Pacific may be related to an
active Madden-Julian Oscillation (or MJO). The MJO is a large, slow-moving area of
enhanced tropical convective (i.e., thunderstorm) activity that propagates eastward
from the Indian Ocean into the Pacific. It has been linked to modulations in
tropical cyclone formation.
