Eyewall replacement cycle, Wikipedia April 04 - 2013

1. Eyewall replacement cycle 1
Eyewall replacement cycle
Eyewall replacement cycles, also called concentric eyewall cycles, naturally occur in intense tropical cyclones,
generally with winds greater than 185 km/h (115 mph), or major hurricanes (Category 3 or above). When tropical
cyclones reach this intensity, and the eyewall contracts or is already sufficiently small, some of the outer rainbands
may strengthen and organize into a ring of thunderstorms—an outer eyewall—that slowly moves inward and robs
the inner eyewall of its needed moisture and angular momentum. Since the strongest winds are in a cyclone's
eyewall, the tropical cyclone usually weakens during this phase, as the inner wall is "choked" by the outer wall.
Eventually the outer eyewall replaces the inner one completely, and the storm may re-intensify.
The discovery of this process was partially responsible for the end of the U.S. government's hurricane modification
experiment Project Stormfury. This project set out to seed clouds outside the eyewall, causing a new eyewall to form
and weakening the storm. When it was discovered that this was a natural process due to hurricane dynamics, the
project was quickly abandoned.[]
Almost every intense hurricane undergoes at least one of these cycles during its existence. Recent studies have
shown that nearly half of all tropical cyclones, and nearly all cyclones with sustained winds over 204 kilometres per
hour (127 mph; 110 kn), undergo eyewall replacement cycles.[] Hurricane Allen in 1980 went through repeated
eyewall replacement cycles, fluctuating between Category 5 and Category 3 status on the Saffir-Simpson Hurricane
Scale several times. Hurricane Juliette (2001) was a rare documented case of triple eyewalls.[] Typhoon June (1975)
was the first reported case of triple eyewalls.[] The reconnaissance flight that observed the triple concentric eyewalls
also recorded that this was the strongest typhoon up to that point.[1]
History
The first tropical system to be observed with concentric eyewalls was
Typhoon Sarah by Fortner in 1956, which he described as "an eye
within an eye".[] The storm was observed by a reconnaissance aircraft
to have an inner eyewall at 6 kilometres (3.7 mi) and an outer eyewall
at 28 kilometres (17 mi). During a subsequent flight 8 hours later, the
inner eyewall had disappeared, the outer eyewall had reduced to 16
kilometres (9.9 mi) and the maximum sustained winds and hurricane
intensity had decreased.[] The next hurricane observed to have
concentric eyewalls was Hurricane Donna in 1960.[] Radar from
1966 photo of the crew and personnel of Project
reconnaissance aircraft showed an inner eye that varied from 10 miles
Stormfury.
(16 km) at low altitude to 13 miles (21 km) near the tropopause. In
between the two eyewalls was an area of clear skies that extended
vertically from 3,000 feet (910 m) to 25,000 feet (7,600 m). The low-level clouds at around 3,000 feet (910 m) were
described as stratocumulus with concentric horizontal rolls. The inner eyewall was reported to reach heights near
45,000 feet (14,000 m) while the inner eyewall only extended to 30,000 feet (9,100 m). 12 hours after identifying a
concentric eyewalls, the inner eyewall had dissipated.[]
Hurricane Beulah in 1967 was the first tropical cyclone to have its eyewall replacement cycle observed from
beginning to end.[] Previous observations of concentric eyewalls were from aircraft-based platforms. Beulah was
observed from the Puerto Rico land-based radar for 34 hours during which time a double eyewall formed and
dissipated. It was noted that Beulah reached maximum intensity immediately prior to undergoing the eyewall
replacement cycle, and that it was "probably more than a coincidence."[] Previous eyewall replacement cycles had
been observed to decrease the intensity of the storm,[] but at this time the dynamics of why it occurred was not
known.[citation needed]

2. Eyewall replacement cycle 2
As early as 1946 it was known that the introduction of carbon dioxide ice or silver iodide into clouds that contained
supercooled water would convert the liquid water into ice. Today this is known as the Bergeron–Findeisen process.
It was thought that scientists could manipulate the size of the snow or ice particles to be either larger or smaller than
the original liquid water, and would either result in increased or decreased precipitation. By increasing the rate of
precipitation, the seeded cloud would result in dissipation of the storm.[] By early 1960, the working theory was that
the eyewall of a hurricane was inertially unstable and that the clouds had a large amount of supercooled water.
Therefore, seeding the storm outside the eyewall would release more latent heat and cause the eyewall to expand.
The expansion of the eyewall would be accompanied with a decrease in the maximum wind speed though
conservation of angular momentum.[]
Project Stormfury
Project Stormfury was an attempt to weaken tropical cyclones by flying aircraft into them and seeding with silver
iodide. The project was run by the United States Government from 1962 to 1983.[]
The hypothesis was that the silver iodide would cause supercooled water in the storm to freeze, disrupting the inner
structure of the hurricane. This led to the seeding of several Atlantic hurricanes. However, it was later shown that
this hypothesis was incorrect.[] In reality, it was determined most hurricanes do not contain enough supercooled
water for cloud seeding to be effective. Additionally, researchers found that unseeded hurricanes often undergo the
same structural changes that were expected from seeded hurricanes. This finding called Stormfury's successes into
question, as the changes reported now had a natural explanation.[]
The last experimental flight was flown in 1971, due to a lack of candidate storms and a changeover in NOAA's fleet.
More than a decade after the last modification experiment, Project Stormfury was officially canceled. Although a
failure in its goal of reducing the destructiveness of hurricanes, Project Stormfury was not without merit. The
observational data and storm lifecycle research generated by Stormfury helped improve meteorologists' ability to
forecast the movement and intensity of future hurricanes.[]
Secondary eyewall formation
Secondary eyewalls were once considered a rare phenomenon. Since
the advent of reconnaissance airplanes and microwave satellite data, it
has been observed that over half of all major tropical cyclones develop
at least one secondary eyewall.[][] There have been many hypotheses
that attempt to explain the formation of secondary eyewalls. The
reason why hurricanes develop secondary eyewalls is not well
understood.[]
Identification
Qualitatively identifying secondary eyewalls is easy for a hurricane
analyst to do. It involves looking at satellite or RADAR imagery and Imagery from Tropical Rainfall Measuring
seeing if there are two concentric rings of enhanced convection. The Mission shows the beginning of an eyewall
outer eyewall is generally almost circular and concentric with the inner replacement cycle in Hurricane Frances.
eyewall. Quantitative analysis is more difficult since there exists no
objective definition of what a secondary eyewall is. Kossin et al.. specified that the outer ring had to be visibly
separated from the inner eye with at least 75% closed with a moat region clear of clouds.[]

3. Eyewall replacement cycle 3
While secondary eyewalls have been seen as a tropical cyclone is
nearing land, none have been observed while the eye is not over the
ocean. July offers the best background environmental conditions for
development of a secondary eyewall. Changes in the intensity of strong
hurricanes such as Katrina, Ophelia, and Rita occurred simultaneously
with eyewall replacement cycles and comprised interactions between
the eyewalls, rainbands and outside environments.[][] Eyewall
replacement cycles, such as occurred in Katrina as it approached the
Gulf Coast of the United States, can greatly increase the size of tropical
cyclones while simultaneously decreasing in strength.[2]
During the period from 1997–2006, 45 eyewall replacement cycles
were observed in the tropical North Atlantic Ocean, 12 in the Eastern
North Pacific and 2 in the Western North Pacific. 12% of all Atlantic
storms and 5% of storm in the Pacific underwent eyewall replacement
during this time period. In the North Atlantic, 70% of major hurricanes Typhoon Chanchu at peak intensity, during an
had at least one eyewall replacement, compared to 33% of all storms. eyewall replacement cycle
In the Pacific, 33% of major hurricanes and 16% of all hurricanes had
an eyewall replacement cycle. Stronger storms have a higher probability of forming a secondary eyewall, with 60%
of category 5 hurricanes underwent an eyewall replacement cycle within 12 hours.[]
During the years 1969-1971, 93 storms reached tropical storm strength or greater in the Pacific Ocean. 8 of the 15
that reached super typhoon strength (65 m/s), 11 of the 49 storms that reached typhoon strength (33 m/s), and none
of the 29 tropical storms (<33 m/s) developed concentric eyewalls. The authors note that because the reconnaissance
aircraft were not specifically looking for double eyewall features, these numbers are likely underestimates.[]
During the years 1949-1983, 1268 typhoons were observed in the Western Pacific. 76 of these had concentric
eyewalls. Of all the typhoons that underwent eyewall replacement, around 60% did so only once; 40% had more than
one eyewall replacement cycle, with two of the typhoons each experiencing five eyewall replacements. The number
of storms with eyewall replacement cycles was strongly correlated with the strength of the storm. Stronger typhoons
were much more likely to have concentric eyewalls. There were no cases of double eyewalls where the maximum
sustained wind was less than 45 m/s or the minimum pressure was higher than 970 hPa. More than three-quarters of
the typhoons that had pressures lower than 870 hPa developed the double eyewall feature. The majority of Western
and Central Pacific typhoons that experience double eyewalls do so in the vicinity of Guam.[]
Early formation hypotheses
Since eyewall replacement cycles were discovered to be natural, there has been a strong interest in trying to identify
what causes them. There have been many hypotheses put forth that are now abandoned. In 1980, Hurricane Allen
crossed the mountainous region of Haiti and simultaneously developed a secondary eyewall. Hawkins noted this and
hypothesized that the secondary eyewall may have been caused by topographic forcing.[] Willoughby suggested that
a resonance between the inertial period and asymmetric friction may be the cause of secondary eyewalls.[3] Later
modeling studies and observations have shown that outer eyewalls may develop in areas uninfluenced by land
processes.
There have been many hypotheses suggesting a link between synoptic scale features and secondary eyewall
replacement. It has been observed that radially inward traveling wave-like disturbances have preceded the rapid
development of tropical disturbances to tropical cyclones. It has been hypothesized that this synoptic scale internal
forcing could lead to a secondary eyewall.[] Rapid deepening of the tropical low in connection with synoptic scale
forcing has been observed in multiple storms,[] but has been shown to not be a necessary condition for the formation

4. Eyewall replacement cycle 4
of a secondary eyewall.[] The wind-induced surface heat exchange (WISHE) is a positive feedback mechanism
between the ocean and atmosphere in which a stronger ocean-to-atmosphere heat flux results in a stronger
atmospheric circulation, which results in a strong heat flux.[] WISHE has been proposed as a method of generating
secondary eyewalls.[] Later work has shown that while WISHE is a necessary condition to amplify disturbances, it is
not needed to generate them.[]
Vortex Rossby wave hypothesis
In the vortex Rossby wave hypothesis, the waves travel radially outward from the inner vortex. The waves amplify
angular momentum at a radius that is dependent on the radial velocity matching that of the outside flow. At this
point, the two are phase-locked and allow the coalescence of the waves to form a secondary eyewall.[][]
β-skirt axisymmetrization hypothesis
In a fluid system, β (beta) is the spatial, usually horizontal, change in the environmental vertical vorticity. β is
maximized in the eyewall of a tropical cyclone. The β-skirt axisymmetrization (BSA) assumes that a tropical cyclone
about develop a secondary eye will have a decreasing, but non-negative β that extends from the eyewall to
approximately 50 kilometres (31 mi) to 100 kilometres (62 mi) from the eyewall. In this region, there is a small, but
important β. This area is called the β-skirt. Outward of the skirt, β is effectively zero.[]
Convective available potential energy (CAPE) is the amount of energy a parcel of air would have if lifted a certain
distance vertically through the atmosphere. The higher the CAPE, the more likely there will be convection. If areas
of high CAPE exist in the β-skirt, the deep convection that forms would act as a source of vorticity and turbulence
kinetic energy. This small-scale energy will upscale into a jet around the storm. The low-level jet focuses the
stochastic energy a nearly axisymmetric ring around the eye. Once this low-level jet forms, a positive feedback cycle
such as WISHE can amplify the initial perturbations into a secondary eyewall.[][]
Death of the inner eyewall
After the secondary eyewall totally surrounds the inner
eyewall, it begins to affect the tropical cyclone
dynamics. Hurricanes are fueled by the high ocean
temperature. Sea surface temperatures immediately
underneath a tropical cyclone can be several degrees
cooler than those at the periphery of a storm, and
therefore cyclones are dependent upon receiving the
energy from the ocean from the inward spiraling winds.
When an outer eyewall is formed, the moisture and
angular momentum necessary for the maintenance of the inner eyewall is now being used to sustain the outer
eyewall, causing the inner eye to weaken and dissipate leaving the tropical cyclone with one eye that is larger in
diameter than the previous eye.
In the moat region between the inner and outer eyewall, observations by dropsondes have shown high temperatures
and dewpoint depressions. The eyewall contracts because of inertial instability.[] Contraction of the eyewall occurs if
the area of convection occurs outside the radius of maximum winds. After the outer eyewall forms, subsidence
increases rapidly in the moat region.[]
Once the inner eyewall dissipates, the storm weakens; the central pressure increases and the maximum sustained
windspeed decreases. Usually the new eyewall will contract and intensify the storm such that it is stronger than
before the start of the eyewall replacement cycle. Rapid changes in the intensity of tropical cyclones is a typical
characteristic of eyewall replacement cycles.[] Compared to the processes involved with the formation of the

5. Eyewall replacement cycle 5
secondary eyewall, the death of the inner eyewall is fairly well understood.
Some tropical cyclones with extremely large outer eyewalls do not experience the contraction of the outer eye and
subsequent dissipation of the inner eye. Typhoon Winnie (1997) developed an outer eyewall with a diameter of 200
kilometres (120 mi) that did not dissipate until it reached the shoreline.[] The time required for the eyewall to
collapse is inversely related to the diameter of the eyewall which is mostly because inward directed wind decreases
asymptotically to zero with distance from the radius of maximum winds, but also due to the distance required to
collapse the eyewall.[]
Throughout the entire vertical layer of the moat, there is dry descending air. The dynamics of the moat region are
similar to the eye, while the outer eyewall takes on the dynamics of the primary eyewall. The vertical structure of the
eye has two layers. The largest layer is that from the top of the tropopause to a capping layer around 700 hPa which
is described by descending warm air. Below the capping layer, the air is moist and has convection with the presence
of stratocumulus clouds. The moat gradually takes on the characteristics of the eye, upon which the inner eyewall
can only dissipate in strength as the majority of the inflow is now being used to maintain the outer eyewall. The
inner eye is eventually evaporated as it is warmed by the surrounding dry air in the moat and eye. Models and
observations show that once the outer eyewall completely surrounds the inner eye, it takes less than 12 hours for the
complete dissipation of the inner eyewall. The inner eyewall feeds mostly upon the moist air in the lower portion of
the eye before evaporating.[]
Evolution into an annular hurricane
Annular hurricanes have a single eyewall that is larger and circularly symmetric. Observations show that an eyewall
replacement cycle can lead to the development of an annular hurricane. While some hurricanes develop into annular
hurricanes without an eyewall replacement, it has been hypothesized that the dynamics leading to the formation of a
secondary eyewall may be similar to those needed for development of an annular eye.[] Hurricane Daniel (2006) was
an example where a storm had an eyewall replacement cycle and then turned into an annular hurricane.[] Annular
hurricanes have been simulated that have gone through the life cycle of an eyewall replacement. The simulations
show that the major rainbands will grow such that the arms will overlap, and then it spiral into itself to form a
concentric eyewall. The inner eyewall dissipates, leaving a hurricane with a singular large eye with no rainbands.[]
References
Further reading
Books
• Paul V. Kislow (2008). Hurricanes: background, history and bibliography. Nova Publishers. p. 50.
ISBN 1-59454-727-0.
• Kshudiram Saha (2009). Tropical Circulation Systems and Monsoons. Springer. p. 76. ISBN 3-642-03372-5.
Web pages
• "Satellite examples of eyewall replacement cycles" (http://cimss.ssec.wisc.edu/goes/blog/?s=eyewall+
replacement+cycle). CIMSS Satellite Blog. Retrieved 28 August 2010.
• Jeff Haby. "Answers: How hurricanes replace their eyewalls" (http://www.theweatherprediction.com/
habyhints2/412/). Haby's Weather Forecasting Hints. Retrieved 19 November 2009.
• Chris Cappella (31 August 2004). "Answers: How hurricanes replace their eyewalls" (http://www.usatoday.
com/weather/resources/askjack/2003-11-15-eyewall-replacement_x.htm). USA Today. Retrieved 19 November
2009.

6. Eyewall replacement cycle 6
• R.L. Deal (20 April 2006). "Eye Wall Replacement In Tropical Cyclones" (http://casil.met.fsu.edu/~rdeal/
documents/Deal_Met3300.pdf) (PDF). MET3300 Project. The Florida State University. Retrieved 19 November
2009.
• "Eyewall Replacement Cycles" (http://www.meted.ucar.edu/tropical/textbook/ch10/tropcyclone_10_4_5_3.
html). (Requires free registration). University Corporation for Atmospheric Research. 2007. Retrieved 19
November 2009.
• J.P. Kossin and D.S. Nolan. "Tropical Cyclone Structure and Intensity Change Related to Eyewall Replacement
Cycles and Annular Storm Formation, Utilizing Objective Interpretation of Satellite Data and Model Analyses"
(http://www.onr.navy.mil/sci_tech/32/reports/docs/07/mmkossin.pdf) (PDF). Retrieved 19 November
2009.
• Jon Hamilton (1 March 2007). "Why Katrina Became a Monster and Rita Fizzled" (http://www.npr.org/
templates/story/story.php?storyId=7672274). All Things Considered. National Public Radio. Retrieved 19
November 2009.
Journal articles
• Willoughby, H. E. (1979). "Forced Secondary Circulations in Hurricanes". J. Geophys. Res. 84 (C6): 3173–3183.
Bibcode 1979JGR....84.3173W (http://adsabs.harvard.edu/abs/1979JGR....84.3173W). doi:
10.1029/JC084iC06p03173 (http://dx.doi.org/10.1029/JC084iC06p03173).
• Kossin, J.P.; Schubert, W.H; Montgomery, M.T. (2000). "Unstable Interactions between a Hurricane's Primary
Eyewall and a Secondary Ring of Enhanced Vorticity". J. Atmos. Sci. 57 (24): 3893–3917. Bibcode
2000JAtS...57.3893K (http://adsabs.harvard.edu/abs/2000JAtS...57.3893K). doi:
10.1175/1520-0469(2001)058<3893:UIBAHS>2.0.CO;2 (http://dx.doi.org/10.1175/
1520-0469(2001)058<3893:UIBAHS>2.0.CO;2).
• Sitkowski, M.; Barnes, G.M. (2009). "Low-Level Thermodynamic, Kinematic, and Reflectivity Fields of
Hurricane Guillermo (1997) during Rapid Intensification". Mon. Wea. Rev. 137 (2): 645–663. Bibcode
2009MWRv..137..645S (http://adsabs.harvard.edu/abs/2009MWRv..137..645S). doi:
10.1175/2008MWR2531.1 (http://dx.doi.org/10.1175/2008MWR2531.1).
• Zhang, Qing-hong; Kuo, Ying-hwa; Chen, Shou-jun (2005). "Interaction between concentric eye-walls in super
typhoon Winnie (1997)". Quarterly Journal of the Royal Meteorological Society 131 (612): 3183–3204. Bibcode
2005QJRMS.131.3183Z (http://adsabs.harvard.edu/abs/2005QJRMS.131.3183Z). doi: 10.1256/qj.04.33
(http://dx.doi.org/10.1256/qj.04.33).
• Emanuel, K (2003). "Tropical Cyclones". Annu Rev Earth Planet Sci 31 (1): 75. Bibcode 2003AREPS..31...75E
(http://adsabs.harvard.edu/abs/2003AREPS..31...75E). doi: 10.1146/annurev.earth.31.100901.141259
(http://dx.doi.org/10.1146/annurev.earth.31.100901.141259).
• Oda, M.; Nakanishi, M.; Naito, G. (2006). "Interaction of an Asymmetric Double Vortex and Trochoidal Motion
of a Tropical Cyclone with the Concentric Eyewall Structure". J. Atmos. Sci. 63 (3): 1069–1081. Bibcode
2006JAtS...63.1069O (http://adsabs.harvard.edu/abs/2006JAtS...63.1069O). doi: 10.1175/JAS3670.1 (http:/
/dx.doi.org/10.1175/JAS3670.1).
• Zhao, K.; Lee, W.-C.; Jou, B. J.-D. (2008). "Single Doppler radar observation of the concentric eyewall in
Typhoon Saomai, 2006, near landfall". Geophys. Res. Lett. 35 (7): L07807. Bibcode 2008GeoRL..3507807Z
(http://adsabs.harvard.edu/abs/2008GeoRL..3507807Z). doi: 10.1029/2007GL032773 (http://dx.doi.org/
10.1029/2007GL032773).
• Kuo, H.C.; Schubert, W.H.; Tsai, C.L.; Kuo, Y.F. (2008). "Vortex Interactions and Barotropic Aspects of
Concentric Eyewall Formation". Mon. Wea. Rev. 136 (12): 5183–5198. Bibcode 2008MWRv..136.5183K (http://
adsabs.harvard.edu/abs/2008MWRv..136.5183K). doi: 10.1175/2008MWR2378.1 (http://dx.doi.org/10.
1175/2008MWR2378.1).

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• Rozoff, C.M.; Kossin, J.P.; Schubert, W.H.; Mulero, P.J. (2009). "Internal Control of Hurricane Intensity
Variability: The Dual Nature of Potential Vorticity Mixing". J. Atmos. Sci. 66: 133–147. Bibcode
2009JAtS...66..133R (http://adsabs.harvard.edu/abs/2009JAtS...66..133R). doi: 10.1175/2008JAS2717.1
(http://dx.doi.org/10.1175/2008JAS2717.1).
• Zhu, T.; Zhang, D.L.; Weng, F. (2004). "Numerical Simulation of Hurricane Bonnie (1998). Part I: Eyewall
Evolution and Intensity Changes". Mon. Wea. Rev. 132: 225–241. Bibcode 2004MWRv..132..225Z (http://
adsabs.harvard.edu/abs/2004MWRv..132..225Z). doi:
10.1175/1520-0493(2004)132<0225:NSOHBP>2.0.CO;2 (http://dx.doi.org/10.1175/
1520-0493(2004)132<0225:NSOHBP>2.0.CO;2).
• Nong, S.; Emanuel, K. (2003). "A numerical study of the genesis of concentric eyewalls in hurricanes". Quarterly
Journal of the Royal Meteorological Society 129 (595): 3323–3338. Bibcode 2003QJRMS.129.3323N (http://
adsabs.harvard.edu/abs/2003QJRMS.129.3323N). doi: 10.1256/qj.01.132 (http://dx.doi.org/10.1256/qj.
01.132).
• Kuo, H.C.; Lin, L.Y.; Chang, C.P.; Williams, R.T. (2004). "The Formation of Concentric Vorticity Structures in
Typhoons". J. Atmos. Sci. 61 (22): 2722–2734. Bibcode 2004JAtS...61.2722K (http://adsabs.harvard.edu/abs/
2004JAtS...61.2722K). doi: 10.1175/JAS3286.1 (http://dx.doi.org/10.1175/JAS3286.1).
• Terwey, W.D.; Montgomery, M.T. (2008). "Secondary eyewall formation in two idealized, full-physics modeled
hurricanes". J. Geophys. Res. 113: D12112. Bibcode 2008JGRD..11312112T (http://adsabs.harvard.edu/abs/
2008JGRD..11312112T). doi: 10.1029/2007JD008897 (http://dx.doi.org/10.1029/2007JD008897).
• Maclay, K.S.; DeMaria, M.; Vonder Haar, T.H. (2008). "Tropical Cyclone Inner-Core Kinetic Energy Evolution".
Mon. Wea. Rev. 136 (12): 4882–4898. Bibcode 2008MWRv..136.4882M (http://adsabs.harvard.edu/abs/
2008MWRv..136.4882M). doi: 10.1175/2008MWR2268.1 (http://dx.doi.org/10.1175/2008MWR2268.1).

8. Article Sources and Contributors 8
Article Sources and Contributors
Eyewall replacement cycle Source: http://en.wikipedia.org/w/index.php?oldid=520479418 Contributors: Anthony Appleyard, Cherkash, Chris the speller, Debresser, Earth100, Favonian,
Headbomb, Hellbus, Hmains, Hurricanehink, Jason Rees, Jersey emt, Juliancolton, LilHelpa, Miller17CU94, Mortense, Müdigkeit, Nathan Johnson, Rjwilmsi, Soapthgr8, Victor Diovanni, Xeno,
15 anonymous edits
Image Sources, Licenses and Contributors
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File:TRMM Frances 30aug1021 utc lrg.jpg Source: http://en.wikipedia.org/w/index.php?title=File:TRMM_Frances_30aug1021_utc_lrg.jpg License: Public Domain Contributors: NASA
images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC), NASA's Tropical Rainfall Measuring Mission.
File:Typhoon Chanchu16-05-06.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Typhoon_Chanchu16-05-06.jpg License: Public Domain Contributors: Jeff Schmaltz, MODIS
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