Monitoring tropical cyclones in the Pacific Ocean - 2013-2019
2013-2019
This case study combines a number of examples of tropical cyclones that formed and travelled over the Pacific Ocean in the 2010s. We have tracked them using various satellite data and recorded some of the impacts they made in countries such as China, Japan and Taiwan.
20 March 2023
07 March 2023
Table of contents
| Hagibis | Krosa | Lekima | Wutip | Donna | Mindulle and Lionrock |
| Nepartak | Winston | Infa | Atsani | Linfa, Chan-Hom, Nangka | Hagupit |
| Vongfong | Halong | Amanda | Haiyan | Usagi |
2019
Hagibis
8-13 Oct, Japan
By Hayley Evers-King, Jochen Kerkmann, Sancha Lancaster, Ben Loveday and William Straka III (CIMSS)
Typhoon Hagibis was the worst storm to hit Japan for half a century, when it made landfall in mid-October 2019.
Typhoon Hagibis hit Japan on 12 October with wind speeds of 225km/h (140mph). At least 70 people were reported to have died and more than least 200 people were injured or missing.
More than 1m (3ft) of rain fell in the town of Hakone, the highest total ever recorded in Japan over 48 hours. The areas that had flooding were around Nagano, around Tokyo, in the Fukushima Prefecture, and in the Miyagi Prefecture (see the VIIRS/AHI flood map and full analysis). As a result of the typhoon several Rugby World Cup matches had to be cancelled, along with other sporting events, such as the practice session for the 2019 Japanese Grand Prix. In addition, the flooding was so severe that the Asian Disaster Reduction Center (ADRC) requested the International Charter Space and Major Disasters to be activated. The Charter allows Charter members, such as EUMETSAT and NOAA, to provide satellite imagery for disaster monitoring purposes.
The 19th named storm and the ninth typhoon of the 2019 Pacific typhoon season, Hagibis developed on 2 October, from a tropical wave located around 200 miles north of the Marshall Islands.
The system reached tropical storm status late on 5 October as it travelled westward, and was officially named Hagibis by the Japan Meteorological Agency (JMA). Soon afterwards Hagibis underwent a period of rapid intensification and on 7 October became a super typhoon, developing a pinhole eye and top wind speeds of 260km/h (160mph), clipping the uninhabited island of Anatahan in the Mariana Archipelago, as well as impacting the island of Saipan. Figure 1 shows the storm at Super Typhoon intensity, as seen by the OLCI instrument on Sentinel-3.
The moonlit imagery from the NOAA-20 Day Night Band (Figure 2) showed what you’d expect of an intense tropical cyclone: a well-defined eye along with copious amounts of tropospheric gravity waves, as well as some intense convection in the feeder bands. One other feature of the NOAA-20 pass is that the eye was not completely in shadow, with some mesovorticies within the eye, again a feature of an intense system. This can easily be seen in the zoomed in imagery of the eye (Figure 2, right).
NOAA-20 image comparison
Figure 2: Comparison of two NOAA-20 Day Night Band images from 9 October 2019 16:26 UTC, with the right hand image being zoomed in, highlighting the very clear eye of the storm.
After maintaining the peak intensity for about three days, Hagibis began to weaken, but was still a strong Category-2 equivalent storm when it made landfall along the Izu Peninsula.
Figures 3 and 4 are the Himawari-8 Airmass images of the typhoon a few hours before and a few hours after it made landfall. Figure 3, in particular, shows how large and widespread the system was. Figure 4 clearly shows the asymmetric structure of Hagibis as it made landfall, with the high level clouds in the west and north quadrants, with very few high clouds south and east of the storm. This was due to the influence of the mountains on the northern and western part of Honshu, the main island of Japan, slowly weakening the storm as it took away moisture from the centre of circulation.
The animation (Figure 5) shows Hagibis making landfall — the cyclone centre passed only just west of Tokyo. The impressive upper-level cirrus outflow on the western and northern sides is nicely shown. Most of the precipitation fell along the track of Hagibis and in the mountains west the track. The rains in the mountains caused flash flooding, including the loss of 10 high speed trains of Hokuriku Shinkansen Line in the city of Nagano, site of the 1998 winter Olympics.
After leaving a trail of destruction, Hagibis became extratropical the following day, with the remnants eventually influencing the Bering Sea a couple of days later.
The results of flooding caused by Hagibis can be seen in the impacts on nearshore turbidity in the ocean south of Tokyo.
In the True Colour RGB from 9 October (Figure 6, left), clear skies allowed for the OLCI instrument aboard Sentinel-3 to capture an image showing blue ocean around Japan, prior to the arrival of the cyclone. The second True Colour RGB, from 13 October (Figure 6, right), shows the same area after the cyclone. In this image the impact of the flooding caused by rainfall during the storms passage is clear as plumes of brown, sediment-laden run off from the coast into the ocean.
Sentinel-3 image comparison
Figure 6: A comparison of Sentinel-3 OLCI enhanced True Colour RGB images before and after the cyclone made landfall
The images in Figure 7 show estimates of the concentrations of total suspended matter derived from the same data used to create the images in Figure 6. The darker brown colour indicates higher derived estimates of total suspended matter, after the cyclone caused devastating flooding on land.
Before and after comparison
Figure 7: A comparison of Sentinel-3 OLCI Total Suspended Matter product, before and after the floods
Further analysis
Super Typhoon Hagibis - October 6-13 2019, William's full analysis of the event
Media reports
The aftermath of Typhoon Hagibis – in pictures (The Guardian)
Typhoon Hagibis: Japan deploys 110,000 rescuers after worst storm in decades (BBC News)
The landslide impact of Typhoon Hagibis in Japan The Landslide Blog
Ten Hokuriku Shinkansen Line trains worth ¥32.8 billion sustain damage after yard is flooded in Typhoon Hagibis (Japan Times)
Other image sources
Super Typhoon Hagibis (NASA Earth Observatory)
Super Typhoon Hagibis in the West Pacific Ocean (CIMSS Satellite Blog)
Krosa
6-16 Aug, Japan
By HansPeter Roesli
Typhoon Krosa developed from a tropical storm and started to be tracked while it was in the Philippine Sea on 5 August. It reached typhoon strength between 7 August 18:00 UTC and 10 August 06:00 UTC, jumping briefly to Category-3 equivalent on 8 August, while still being over open seas.
It then moved towards southern Japan as a tropical storm, crossing the country on 15 August, before dissolving over the Sea of Japan.
The animation (Figure 9) documents Krosa’s path between 6 and 15 August, tracked by six-hourly positions given as dots, coloured from blue (tropical depression/storm) through cyan and brown to orange (Category 3 typhoon).
The track is overlaid with 12-hourly interleaved images from VIS0.64 (at 00:00 UTC) and IR10.4 (at 12:00 UTC) of Himawari-8. The other track, west of Krosa, is from Typhoon Lekima that headed almost simultaneously, in similar way, towards the Chinese mainland.
Krosa’s passage through Japan, between 14 August 12:00 UTC and 15 August 12:00 UTC, can be followed in detail in the animation of the IR10.4 band at 2.5 minute time resolution (Figure 1).
Among the many convective events that occurred over the area, one stood out prominently between about 04:00 and 08:00 UTC on 15 August (see red arrow on Figure 8).
The vigorous dynamics of this particular convective event over open waters, west of the town of Matsuyama, is best seen in a zoomed-in, accelerated animation of both the VIS0.64 and IR10.4 bands (Figure 11). The first upwelling was very fast and took just 10 minutes to reach the top of the troposphere. Subsequently, new convective towers emerged below the new cloud deck that manifested in protruding tops or gravity waves in the VIS0.4 images, and as darker red (colder) spots in the IR10.4.
Lekima
4-11 Aug, China, Japan, Taiwan
By HansPeter Roesli
Super Typhoon Lekima scraped past Krosa, a concurrent typhoon, in the Western Pacific Ocean in August 2019. Lekima then went on to cause devastation in parts of China.
Starting as a tropical depression in the Philippine Sea (North Pacific Ocean) on 4 August, Lekima reached typhoon and super typhoon strength (tropical storm category 4) when passing between Taiwan and Okinawa on 8 August.
On the way to the Chinese mainland it weakened slightly to category 2 and made landfall just south of the Hangzhou Bay on 9/10 August. From there, following the coast northwards, it weakened to a tropical storm and then a depression. Its track ended on 11 August at 12:00 UTC where the coastline turns east.
The sequence of six-hourly images of band IR10.4 of Himawari-8, overlaid over the six-hour track points (Figure 13), shows the full life cycle of Lekima, from 4 August 00:00 UTC to 11 August 12:00 UTC. The numbers on the imagery indicate the typhoon category, from 1 (cyan) to 4 (red). The blue dots show the storm's positions prior to and after the typhoon phase.
Two other typhoons are visible in the animation — Franciso crossed south west Japan and dissolved over Korea on 7 August, and on 7 August Krosa entered the image sequence at the same latitude as Lekima, but further to the east.
The animation in Figure 14 shows the evolution of the Krosa-Lekima couple in the local day time on 8 August, side-by-side in True Colour RGB and false-coloured IR10.4 band from Himawari-8.
The closeness of the couple begged the question whether they would undergo the Fujiwhara effect, an example of the effect can be found in the case The Fujiwhara effect on extratropical cyclones. In fact, the distance at local noon (03:00 UTC) on 7 and 8 August was 1476km and 1509km, respectively (Figure 15), ie very close to the 1400km point, below which interactions between tropical storms can occur. The movie does not show any sign of interaction; Super Typhoon Lekima just scraped past Krosa, with Krosa moving away untouched after the close encounter.
Other image sources
Super Typhoon Lekima in the West Pacific Ocean (CIMSS Blog)
Lekima – Northwestern Pacific Ocean (NASA Blog)
Typhoon Lekima Nears China (NASA Earth Observatory)
Media reports
Lekima kills dozens and displaces millions in eastern China (AccuWeather)
Wutip
25-26 Feb, Guam
By Jochen Kerkmann
In late February 2019 Typhoon Wutip became the strongest February typhoon on record in the Northwest Pacific basin.
After forming as a topical depression 18 February, Wutip intensified into a tropical storm on 20 February, before intensifying into a typhoon later the next day.
On 23 February, while passing Guam, Typhoon Wutip became the strongest February typhoon on record in the Northwest Pacific basin, when it intensified further, reaching its initial peak intensity as a super typhoon with maximum 10-minute sustained winds of 185km/h (115mph), one-minute sustained winds of 250km/h (155mph), and a minimum pressure of 925hPa (mbar).
After weakening slightly, it resumed strengthening and early on 25 February reached peak intensity with maximum 10-minute sustained winds of 195km/h (120mph), one-minute sustained winds of 260km/h (160mph), and a minimum central pressure of 915hPa (mbar) (Figure 16).
Over the following days it weakened, before dissipating on 2 March.
Himawari image comparison
Figure 17: Comparison of Himawari-8 Natural Colour RGB and Cloud Phase RGB, 26 February 2019 00:00 UTC (Credit: EUMeTrain ePort)
Figure 17 shows a comparison of the Himawari-8 AHI Natural Colour RGB and the Cloud Phase RGB.
On the Natural Colour RGB, ice clouds are normally shown in cyan colour and water clouds in pink colours. However, this only works for water clouds with small droplets (large reflectivity in the NIR1.6 band). Water clouds with large droplets (low reflectivity in the NIR1.6 band) have a cyan colour, very similar to ice clouds, which makes the discrimination of water and ice clouds over the oceans (pristine air, cumulus and stratocumulus clouds with large droplets) very difficult.
As shown in this comparison, the distinction between water clouds and ice clouds is much easier in the Cloud Phase RGB that uses the new 2.3 micron band on the green beam, instead of the 0.8 micron band. In this RGB, ice clouds are shown in cyan (small ice) or blue colours (large ice), and water clouds are shown in magenta colours.
On the western side of the eyewall, small ice particles can be seen. This is confirmed when we look at the Convection RGB that shows the cold ice clouds with small ice particles, yellow in colour, see the comparison of the Convection RGB and the IR-VIS sandwich product (Figure 18).
Convection RGB and infrared comparison
Figure 18: Comparison of Himawari-8 Convection RGB and infrared-visible sandwich, 26 February 2019 00:00 UTC (Source: EUMeTrain ePort)
Other image sources
Detailed story of the development of Wutip , including a 2.5-minute rapid scan loop (CIMSS Blog)
NASA-NOAA satellite analyzes Typhoon Wutip (PhysOrg)
Typhoon Wutip - Visible satellite imagery views (Force Thirteen/YouTube)
2017
Donna
3-8 May, Australia, Vanuatu
By Sancha Lancaster, Jose Prieto and HansPeter Roesli
Tropical Cyclone Donna was an out-of-season cyclone that broke records in May 2017.
Donna started as a disturbance before being officially classed as a Tropical Cyclone by the Joint Typhoon Warning Center (JTWC) on 2 May.
By 06:00 UTC on 3 May it had reached Category 1 on the Australian tropical cyclone scale and was named 'Donna' by the Fiji Meteorological Service (FMS). Figure 19 is the Metop-A AVHRR view of the cyclone over Vanuatu and the Solomon Islands, east of Australia, on 3 May at 23:16 UTC.
Despite some evidence of wind shear along the northern fringes of the storm, it began to clear an eye late on 4 May and on 6 May at 00:00 UTC Donna reached its first peak as a Category 4 cyclone (equivalent to a Category 3 hurricane), see the Himawari-8 band 14 image (Figure 20). Tropical Cyclone Donna's progress can be followed in the Himawari-8 Band 14 (11 µm) animation from 3 May 20:20 UTC–6 May 03:50 UTC.
By 7 May the cyclone had a solid ring of deep convection surrounding a well-defined 55km (35m) eye.
The FMS upgraded Donna to a Category 5 cyclone (equivalent to a Category 4 hurricane) at 00:00 UTC on 8 May, estimating that the storm possessed 10-minute sustained winds of 205km/h (127mph).
As a result, Donna became the strongest off-season tropical cyclone on record during the month of May in the South Pacific basin.
The eye is clearly defined on the Himawari-8 Visible imagery, see Figure 21 and the animation from 3 May 03:00–06:20 UTC.
Other image sources
Tropical Cyclones Donna and Ninteen (EUMETSAT Flickr)
Cyclone Donna in the South Pacific Ocean (CIMSS Blog)
2016
Mindulle and Lionrock
21-30 Aug, Japan
By Scott Bachmeier (CIMSS), Jochen Kerkmann and Curtis Seaman (CIRA)
Within just 10 days, two tropical storms slammed into Japan, first Mindulle, which hit the larger Tokyo area, and then Lionrock that hit Japan's already tsunami-hit north-east coast.
On Sunday 21 August, Himawari-8 imagery captured an interesting sight near Japan — a trio of tropical systems spinning near the country (Figure 22).
One of those three systems, Mindulle, made landfall near Tokyo on Monday 22 August, lashing the greater Tokyo area (Figure 23). It dumped heavy rain and left at least one person dead and 29 injured in storm-related incidents. On Monday evening Mindulle headed north, where it hit the Tohoku region and Hokkaido later on Tuesday 23 August.
The other two tropical systems located near Japan were Tropical Storm Lionrock, off of Japan's southwest coast and Tropical Storm Kompasu, to the north near Hokkaido Island, which had dissipated by early Monday morning.
On 24 August, Typhoon Lionrock intensified quickly to Category 3. During this period of intensification, 2.5 minute interval rapid-scan Himawari-8 Visible (0.64µm) imagery (Figure 24) revealed complex patterns of cloud-top radial and transverse banding. Surface mesoscale vortices were also seen at times within the open eye feature.
On 26 August, Lionrock briefly intensified to Category 4 during the north-eastward motion segment of its rather unusual track (Credit: CIMSS Storm Archive) — the intensity estimate from the Advanced Dvorak Technique peaked at 112.4kts (208km/h). It again intensified to Category 4 on 28 August.
Figure 25 shows Typhoon Lionrock on the evening on 27 August. Looking at the area between the typhoon and the Philippines, one can see polluted Asian air (from Eastern China and the Philippines) floating over the Pacific into the tropical cyclone.
Note that for this Natural Colour RGB, in contrast to the EUMETSAT definition, the green-wavelength visible band (AHI band 2) is used instead of the traditional red band (AHI band 3).
This saves on computation time (deals with only 1km bands, not the high-resolution visible band) and increases the sensitivity to smoke/smog and other aerosols.
Finally, on 30 August, after a long and unusual journey, Lionrock made landfall in Northern Japan, leaving at least 11 people dead (see Figure 26). Rivers in Iwate and Hokkaido island flooded, inundating residential areas and blocking roads.
While Japan is often struck by typhoons, Lionrock is the first to make a direct hit on the country’s north from the Pacific Ocean since records began in 1951, according to the Japan Meteorological Agency. It caused damage in regions that usually feel the aftermath of typhoons rather than their strongest force.
"The typhoons this year are making landfall in a way that doesn't happen in normal years," Land and Transport Minister Keiichi Ishii said in an interview. “The rain is falling in a violent way that didn’t happen before, possibly from the effects of global warming.”
He added that Japan's typhoon vigilance needs to be broadened to cover regions previously thought to be at low risk.
*Note: in the True Colour RGB images, the input images have been “Rayleigh corrected” to correct for the molecular scatter of sunlight by gases in the atmosphere which is significant, particularly in the blue band (band 1 of AHI). These corrections are a non-linear function of solar and satellite geometry, i.e. they require a simplified radiative transfer model. This is a BIG computational effort, but we think it is worth the effort as with this correction, the images (visible bands) are much sharper, especially towards the edge of the viewing area. Note also that, for generating the True Colour RGB, the green band (band 2 of AHI at 510nm), which misses the 555nm chlorophyll signal, is corrected to better show vegetated areas. The correction is done by blending the 510nm band (band 2) with the vegetation-sensitive 856nm band (band 4) of AHI to produce a “hybrid green” band. A description of the method can be found in the early online release of a paper from Steve Miller: A Sight for Sore Eyes—The Return of True Color to Geostationary Satellites.
Media report
At Least 11 Dead After Typhoon Lionrock Hits Northern Japan (The Wall Street Journal)
Nepartak
5-8 July, Taiwan
By HansPeter Roesli
Super Typhoon Nepartak reached winds of 270 km/h when it was seen by Himawari-8 on 6 July. When Typhoon Nepartak formed on 3 July, it ended an long-term record storm-free period in the northwest Pacific Ocean. It had been 200 days since a tropical storm or typhoon had formed in that part of the world.
By 6 July it had become a category 5 Super Typhoon, with maximum estimated sustained winds of more than 280km/h; becoming the strongest typhoon since Super Typhoon Souldelor in August 2015.
The Himawari-8 infrared and visible images of Typhoon Nepartak on 6 July (Figure 27), show Nepartak over the Philippine Sea.
Himawari-8 comparison
Figure 27: The Himawari-8 images of Typhoon Nepartak over the Philippine Sea, visible (left) and infrared (right), 6 July 2016 05:00 UTC
The very distinct eye is shown in more detail on Figure 28. The eye shows fine cellular and radial cloud structures at 500m spatial resolution. The right-hand image is the same visible image overlaid with the semi-transparent temperature from band IR11.2 in false colours at 2km resolution.
Visible image comparison
Figure 28: On the Himawari-8 infrared and visible images of Typhoon Nepartak on 6 July 05:00 UTC, a very distinct eye can be seen
On the infrared animation, 6 July 03:15–07:22 UTC Nepartak was tracked on its west-northwest trajectory with images every 2.5 minutes at 2km spatial resolution. During this period a cloud patch showed temperature values were as cold as 180K, indicating the presence of very high cloud tops.
The full progress of Typhoon Nepartak can be seen on this animated sequence of Himawari-8 infrared images from 5 July 00:00 UTC to 8 July 23:30 UTC.
Figure 29 is the VIIRS image of the big eye when Nepartak was a Category 5 storm on 7 July, 04:43 UTC. The image is at 375m resolution from band I1 (VIS0.64) overlaid in semi-transparency by I5 (IR11.45). I5's colour scale goes from white/cold to yellow/warm. The enormous eye wall is well exposed on its western side (Suomi-NPP passed over to the east of the eye).
Warning
Other image sources
CIMSS Tropical Cyclones tracker
Staring into the eye of Nepartak (Dan Lindsey/Twitter)
The Himawari-8 satellite shows Super Typhoon #Nepartak churning through the Pacific Ocean (NOAA Satellites/Twitter)
Media report
Category 5 Super Typhoon Nepartak Prompts Typhoon Warning in Taiwan; Heavy Rain Threat in Eastern China (Weather Channel)
Winston
21 Feb, Fiji
By Mark Higgins
Record-breaking Tropical Cyclone Winston devastated parts of Fiji when it hit the archipelago in February.
Tropical Cyclone Winston was reported to be the strongest storm in recorded history for the Southern Hemisphere, after hitting Fiji with maximum sustained winds of around 297km/h (185mph). It was also the first recorded Category 5 cyclone to make landfall in Fiji.
At least 18 people were reported to have died, hundreds of properties were destroyed and approximately 80% of the nation's 900,000 people lost power.
The Metop-B AVHRR infrared images show Tropical Cyclone Winston after it had passed over Fiji. The storm initially formed northeast of the islands and circled round them before making landfall on 20 February.
Figure 30 is the Metop-B AVHRR IR image with the ASCAT winds overlaid, from 21 February 21:34 UTC. Figure 31 is the comparison between the standard infrared and the enhanced infrared from the same time. The enhanced image shows the cloud top temperatures, with the colder clouds shown in blue to red (the coldest tops were 180K).
Metop-B image comparison
Figure 31: Comparison of Metop-B images, with the coldest clouds (-180K) shown in red on the enhanced infrared
The composite infrared animation, below, shows the progress of Cyclone Winston, from 10 Feb 00:00 UTC–22 Feb 06:00 UTC, as it circled Fiji before making landfall.
Other image source
Severe Cyclone Winston in the South Pacific Ocean (CIMSS Blog)
Media report
Fiji: images of flattened villages show brutal force of Cyclone Winston (The Guardian)
2015
Infa
20-25 Nov, Northern Pacific
By Jochen Kerkmann
Typhoon In-fa (storm No. 27 of the 2015 typhoon season) developed late in 2015, over the still warm waters of the central Northern Pacific (Figure 32).
According to the typhoon forecast track (source: CIMSS), In-fa quickly strengthened to a category 4 tropical cyclone with a pronounced eye (on 21 November), but then weakened under increasing vertical wind shear each day to tropical storm status on 25 November.
Himawari-8 image comparison
Figure 32: 20 November 2015, 04:00 UTC, IR10.4 (Band 13) versus Airmass RGB. In-fa can be seen in the centre of the image (see red arrow)
Figure 33 shows In-fa on 24 November when it was a category 1 typhoon with a cloud-filled eye surrounded by a large band of thunderstorms wrapping into the low-level centre in the northern quadrant, and stretching north-east.
Forecasters at the Joint Typhoon Warning Center (JTWC) noted that the system continued to be elongated to the northeast along the leading edge of an approaching mid-latitude trough (elongated area of low pressure).
Airmass RGB comparison
Figure 33: Airmass RGB versus 'tropical' Airmass RGB, 24 November 2015 04:00 UTC.
The standard Airmass RGB in Figure 33 shows cold, high-level clouds in a strong white colour, which is a result of selected ranges that over-enhance high, cold clouds, thus not allowing viewers to easily distinguish features like overshooting tops, radial cirrus or gravity waves.
The 'tropical' Airmass RGB (also shown for comparison in Figure 33) alleviates this problem by using ranges more appropriate for cold, high clouds. In particular, for the green range (IR9.6–IR10.4) it uses a range from -25 to +25K (instead of -40 to +5K). This makes this RGB very suitable for detecting overshooting tops (white). Also see the large overshooting 'dome' in the centre of typhoon In-fa.
The detailed development of this 'dome' can be seen in the animation (rapid scans at 2.5 minutes intervals) shown in the animated gif (Figure 34). This animation shows Band 03 of the Advanced Himawari Imager (AHI) (VIS0.64 channel), which is the only band that has a horizontal resolution (sampling distance) of 500m.
At around 03:19 UTC two convective towers (close to each other) can be observed that penetrate the high cloud anvil of typhoon In-fa. A few minutes later, these two towers merge into a quickly expanding convective dome with lots of gravity waves spreading around.
On the 25 November animation (Figure 35) In-fa (then downgraded to tropical storm status) continued to produce huge convective blobs in its centre. The animation shows one of these fascinating systems for a period of one hour (02:32 to 03:32 UTC) seen in the high-resolution band (VIS0.64).
It looks like a giant octopus with arms (radial cirrus) growing in all directions.
It would be very interesting to simulate such a system with a high-resolution cloud model, and try to understand the features seen in the animation.
When Prof. Pao Wang from the Academia Sinica looked at the Himawari-8 loop he replied that "the radial cirrus feature at the top of the clouds has been studied by a few before, my feeling is that it is similar to the radial cirrus, namely, it is associated with interference of gravity waves. But here the motion is more complicated as the whole system is strongly rotating, and hence the waves are rotating with it. Since the waves are originally generated by cumulonimbus clouds (Cbs) in the centre of the tropical storm, they also propagate outward and you can perceive such outward propagation in this loop as well."
Animation, 25 November 02:02–04:02 UTC
Animation, 25 November 02:02–04:02 UTC
Finally, the shear structure of In-fa on 25 November can be well seen on the RGB images shown in Figures 36 and 37. The centre of the deep convection is displaced to the north-east of the LLCC (Low Level Circulation Centre). This displacement is best seen in the animations.
Figure 37 shows the standard Day Natural Colour RGB using the bands NIR1.6 (on red), VIS0.8 (on green) and VIS0.4 (on blue).
Ice clouds are shown in cyan colour and water clouds in pink colours. However, it has often been noted that the separation of ice and water clouds is far from being perfect in this RGB product. In particular, water clouds with large droplets have often been confused with ice clouds — see scatter plot of water and ice clouds in VIIRS bands (source Météo France).
When we use the NIR2.3 (AHI band 06) instead of the VIS0.8 (AHI band 04) on the green beam, we can devise a new RGB product (let us call it 'Day Cloud Phase RGB') that has similar cloud colours than the Natural Colour RGB, but with improved separation of ice and water clouds. This new RGB product is shown above. Ice clouds are shown in cyan (small ice) or blue colours (large ice) and water clouds in magenta colours.
Looking at the clouds in the Day Natural Colour RGB, some water clouds have a slightly cyan colour (could be ice clouds, see eg the circled area on the enlarged image), but when you look at the new Day Cloud Phase RGB it becomes clear that these clouds are water clouds. This becomes more obvious when you toggle between them (Figure 38).
Natural Colour and Cloud Phase comparison
Figure 38: Annotated imagery, with water clouds showing on the Day Cloud Phase RGB, 24 November 2015 02:15 UTC
Atsani
20-25 Aug, Japan
By NOAA Ocean Prediction Center, Scott Bachmeier (CIMSS ), Jochen Kerkmann and HansPeter Roesli
In mid-August there were two powerful typhoons in the Western Pacific — Goni and Atsani. While Typhoon Goni made landfall on the Japanese island of Kyushu on 25 August, Atsani circulated over the ocean and didn't make landfall.
On 19 August Atsani reached super typhoon status, with 1-minute sustained winds of 260km/h (160mph), and in the following days it started to weaken.
However, on 24–25 August, instead of dying out as it got caught up in the mid-latitude jet stream winds, it transformed into a powerful extra-tropical storm. It went from a storm that had a warm core, with a centre milder than the surrounding air, into a system with a cold core. The resulting storm reportedly produced hurricane-force winds and extremely high waves across the North Pacific (Credit: Mashable).
The Himwari-8 Airmass imagery, Figure 39 and animation produced by NWSOPC (NOAA's Ocean Prediction Center), clearly shows that on 25 August Atsani started to transition into an intense extra-tropical low. On the animation, a graphic is included that highlights the main differences between a tropical and extra-tropical low.
Surface analysis from the Ocean Prediction Center (Figure 40) indicated that the extra-tropical storm deepened to a minimum central pressure of 957hPa at 12:00 UTC on 25 August, and was producing hurricane-force winds until 00:00 UTC on 26 August (Credit: CIMSS Blog).
Figure 41 shows the Night Microphysics RGB product, for the same situation as shown in Figure 39. This RGB product is mainly used to identify clouds at different levels, including low-level clouds, which are not as visible in the Airmass RGB (Figure 39).
In Figure 41 two images are shown: one RGB with the SEVIRI standard tuning (green component (IR11.2-IR3.9) is displayed for a range of 0 to 10K), and the other one with a tuning that is appropriate for the AHI instrument (green component is displayed for a range of –5 to +5K). This shift of the range of the green component is needed as the AHI band 7 (IR3.9) is not affected by CO2 absorption. In the tuned RGB product, low-level clouds can be easily identified by their green colour.
Himawari-8 image comparison
Figure 41: In the tuned RGB product (right), low-level clouds can be easily identified by their green colour, 25 August 12:00 UTC
Figure 42 shows typhoon Atsani at its full strength on 20 August 2015, 00:02 UTC.
On this day, Atsani was close to the Philippines. The image shows Band 3 of the AHI instrument (0.64 µ), which is the only channel that has a high resolution of 0.5km.
Other image source
The transition of Typhoon Atsani to a strong extra-tropical storm (CIMSS Blog)
Media report
How Super Typhoon Atsani transformed from one type of monster storm into another (Mashable)
Linfa, Chan-Hom, Nangka
6-16 July, China, Guam, Japan
By Jochen Kerkmann, Sancha Lancaster, HansPeter Roesli and Ivan Smiljanic
The three tropical cyclones are lined up over the western Pacific. From west to east there were tropical storm Linfa and typhoons Chan-Hom and Nangka. Nangka displayed an eye.
The line of cyclones can be clearly seen on the visible image from the Korean geostationary Communication, Ocean and Meteorological Satellite (COMS), taken on 6 July at 02:15 UTC.
Imagery the Japan Meteorological Agency's Himawari-8 satellite, which only became fully operational on 7 July 2015, also clearly shows the three cyclones in a train across the ocean.
Figure 44 shows Himawari-8 6.2µm (top), 6.1µm (middle) and 7.3µm (bottom) water vapor infrared imagery, 7 July 02:00 UTC (Credit: CIMSS Blog). Himawari-8 samples a full disc image every 10 minutes, with nominal 2km resolution in the infrared channels.
Further analysis and more imagery (including an animation of the water vapour imagery) can be found on the CIMSS Satellite Blog, written by Scott Bachmeier.
The structure of Chan-Hom can be clearly seen in the MODIS True Color RGB image from 7 July 01:30 UTC (Figure 45).
8 July
The further development of the storms can be seen in these three four-hour animations from Himawari-8, 8 July 00:00–04:00 UTC. The WV6.2 also shows a feature that looks like a fourth cyclone, a whirl squeezed between Chan-Hom and Nangka. Note that Himawari has full disc 10-minute scanning.
Download Airmass and infrared animation
Download True Color animation
Download water vapour animation
9 July
Tropical Storm Linfa was tracking westward parallel to the coast of China and was losing power as it crossed over land. Typhoon Chan-hom was over the Ryukyu Trench south of Okinawa on a track heading northwest toward the China coast north of Wenzhou. With wind speeds around 250km/h Nangka was declared a Super Typhoon, positioned north of Guam.
13 July
In the three days prior to making landfall in Japan, Nangka became a Category 3-equivalent typhoon, maximum sustained winds speeds above 178km/h (110mph). But it made landfall as a Category 1-equivalent typhoon, with lower wind speeds. During that time the typhoon's progress could be seen by the Japanese Meteorological Agency's new Himawari-8 satellite, which became operational on 8 July.
Figure 46 is the visible image of Nangka taken on 13 July at 00:00 UTC.
Nangka was upgraded from a depression to a tropical storm by the Joint Typhoon Warning Center early on 4 July. It then intensified into a severe tropical storm at noon on 5 July, with a partially exposed low-level circulation centre under moderate vertical wind shear and slightly improving outflow (Credit: JTWC).
On 6 July, as vertical wind shear weakened with improved outflow, Nangka began to rapidly deepen, formed an eye, and was upgraded to a typhoon.
The typhoon tracked west-northwestward along the southwestern edge of a subtropical ridge. It reached its first peak intensity on 7 July, with 10-minute maximum sustained winds at 185km/h (115mph). After that, Nangka slightly weakened due to vertical wind shear, before intensifying again on 9 July, when it was upgraded to a super typhoon, with maximum winds speeds above 240km/h (150mph).
Nangka maintained super typhoon strength for 24 hours before weakening to a typhoon on 10 July, due to northerly wind shear eroding convection on the north side of the circulation.
Nangka weakened to a Category 1-equivalent typhoon on 11 July, but began strengthening again late 12 July reaching a secondary peak as a Category 3-equivalent typhoon.
On all the imagery (Figure 46/47/48) it can be seen that typhoon was large, more than 1000km in diameter, with a nice multi-spiral structure but relatively small eye.
Looking at Figure 47 the ice particle size is better seen in the Day Microphysics RGB than in the Natural Colour RGB. The Day Microphysics RGB gives a good colour contrast between large ice particles (dark red to magenta) and small ice particles (bright red to orange).
Himawari-8 comparison
Figure 47: Comparison of Himawari-8 images showing ice particle size
The rapid scan, visible animated gif (Figure 48) shows Nangka as it closed in on Japan, as a Category-1 equivalent typhoon.
On July 16, Nangka made the first landfall over Muroto, Kōchi at around 14:00 UTC and the second landfall over Kurashiki, Okayama at 21:00 UTC.
More than 500mm of rain was reported in parts of Kōchi, Wakayama, Nara and Mie prefectures in the central part of the country.
It was reported that the typhoon caused flooding in Greater Tokyo area, hundreds of miles from what was then the eye of Typhoon Nangka.
According to Japan's Fire and Disaster Management Agency one person died in Saitama prefecture after falling into a swollen canal during the flooding.
Typhoon Nangka had dissipated by 18 July, but, as can be seen on the infrared imagery from 13 July 00:00 UTC (Figure 49) another tropical cyclone (Typhoon Halola) was already over the Pacific.
Other image sources
Chan-Hom in the western Pacific Ocean (CIMSS Blog)
Loop of Typhoons Chanhom and Nangka via Himawari-8 (Credit: JMA/Dan Lindsey)
Himawari visible satellite imagery of Typhoon Chan-Hom (NWSOPC/YouTube)
Real-time storm coverage (SSEC, University of Wisconsin-Madison)
Typhoon Nangka Approaches Japan (NASA Earth Observatory)
Unusual Double Eyewall structure in Himawari-8 Infrared Imagery of Typhoon Nangka (CIMSS Blog)
Real-time storm coverage (CIMSS)
Warnings
Typhoon warnings from Joint Typhoon Warning Center (JTWC)
Media reports
Japan’s New Satellite Captures an Image of Earth Every 10 Minutes (New York Times)
Typhoon Nangka Recap: 29 Inches of Rain Reported (The Weather Channel)
2014
Hagupit
4-5 Dec, Philippines
By Jose Prieto and HansPeter Roesli
Typhoon Hagupit was building strength over the Pacific, with gusts of up to 170km/h (105mph), when it was seen by Metop-B on 4 December.
The Natural Colour RGB and infrared images, from 4 November, show Typhoon Hagupit, know locally at Ruby, in the Western Pacific as it was forming into a category 5 Super Typhoon.
Hagupit struck the far eastern island of Samar on 6 December with winds of 210km/h (130mph) — just over a year after the country was devastated by Super Typhoon Haiyun. Twenty-seven people died and there was widespread damage.
5 December activity
On 5 December the storm was downgraded from Super Typhoon, but remained a danger to the Philippines.
Quick tracking of Typhoon Hagupit with IASI
The very high spectral resolution of IASI provided a huge amount of information on the atmospheric conditions that intensified Hagupit from a tropical storm on 1 December into a category 5 super typhoon on 4 December.
This allowed the Japan Meteorological Agency (JMA) to determine that Hagupit had reached peak intensity at 06:00 UTC on 4 December, with winds of 215km/h and central pressure of 905hPa.
Having two IASI instruments currently mapping the radiances emitted over a given region — without the gaps which would result from having only one instrument — allowed EUMETSAT to track the displacement of the typhoon by monitoring its radiance using one channel at 11 microns, of the more than 8,461 channels available.
The resulting quick tracking of Typhoon Hagupit helped give the Philippine authorities enough warning to evacuate the threatened areas, keeping the death toll in the low double digits, compared to the 7,000 dead and missing caused by Super Typhoon Haiyan in November 2013.
On 6 December, the IASI instruments on Metop-A and -B showed Hagupit weaken to a category 3 typhoon, which made landfall over Dolores, Eastern Samar (Figure 54) .
Other image sources
Typhoon Hagupit on Flickr
Real-time storm coverage (SSEC, University of Wisconsin-Madison)
Media reports
Typhoon Hagupit makes landfall in Philippines (Met Office News Blog)
A year after Haiyan’s devastation, new typhoon threatens Philippines (CNN)
Hotter Ocean Waters Give Typhoons a Boost (Scientific American)
Super Typhoon Vongfong
8 Oct, Japan
By Jochen Kerkmann and HansPeter Roesli
Vongfong became the strongest Pacific cyclone of 2014 after rapidly intensifying on 6/7 October.
The image from Metop-B clearly shows a distinct eye on 8 October 00:30 UTC, as Super Typhoon Vongfong was travelling across the Pacific towards Japan.
The typhoon was reported to have maximum sustained wind speeds of 287km/h (155kt), with gusts of 352km/h (190kt). It is the fifth Super Typhoon of the 2014 season.
Other image sources
MTSAT-2 visible image, 7 October 21:32 UTC (CIMSS)
NASA Eyes Super typhoon Vongfong (NASA)
Real-time storm coverage (SSEC, University of Wisconsin-Madison)
Warning
Warning from the Joint Typhoon Warning Center
Media report
Super Typhoon Vongfong Now World's Strongest Cyclone of 2014 (Weather Channel)
Halong
3 Aug, Japan, Philippines
By HansPeter Roesli
In early August Typhoon Halong became the third super typhoon of 2014 in the Western Pacific basin.
The wide-open eye can be seen in the Metop-A image from 3 August, 00:50 UTC. The image is a combination of the visible (VIS0.86) channel (in black and white) and infrared (IR12.0) channel. The infrared shows the cold temperatures. The coldest and most intense areas of the storm are shown as bright pink/magenta, around 200K (-73°C).
The typhoon rapidly intensified on 1–2 August. In just 24 hours Halong went from a typhoon with sustained winds of 120km/h to a super typhoon with winds in excess of 240km/h.
Halong made landfall in Japan on the evening of 9 August. A rare emergency weather warning for all-time record rainfall was issued in Mie Prefecture. 528mm of rain was recorded at Funato, Wakayama Prefecture, during 9 August. At least nine people were killed and thousands evacuated.
Other image source
Enhanced Metop Natural Colour RGB as Typhoon Halong headed for Japan, 8 August, 00:43 UTC (Flickr)
Typhoon Halong with 12.5 km ASCAT winds, 4 August 00:30 UTC (OSI SAF/KNMI)
Typhoon Halong, MODIS 6 August 04:30 UTC (NASA Earth Observatory)
Warning
Typhoon Halong warning from the Joint Typhoon Warning Center (JTWC)
Media reports
Violent Typhoon Halong Turns North Towards Japan (Western Pacific Weather)
Tropical Storm Halong Update: Several Reported Dead in Japan After Storm (The Weather Channel)
Typhoon Halong triggers evacuation orders in Japan (BBC news)
Amanda
25 May, Mexico
By Mark Higgins
When Hurricane Amanda reached category 4 strength on 25 May 2014 it was the strongest hurricane on record for the Pacific during the month of May.
The storm, which formed off the coast of Mexico, quickly turned from a tropical storm, which has winds of less than 120 km/h (74mph), to the top end of a category 4 hurricane.
On Sunday 25 May Amanda's maximum sustained winds increased to near 249km/h (155mph/134kt) and its central pressure dropped to 932 millibars making it a very powerful Category 4 hurricane.
The image shows Metop-B infrared with ASCAT overlaid, from 25 May 04:41 UTC, winds of 101km/h (63mph/55kt) can be clearly seen around the cyclone's centre. The ASCAT wind is the mean wind over around one hour and doesn't take into account gusts, so this would be the minimum sustained wind at the surface.
Amanda was also the earliest Category 4 hurricane in the eastern Pacific, ahead of Hurricane Adolph in 2001, and the second earliest major eastern Pacific hurricane on record, behind Hurricane Bud in 2012.
Other image source
Warning
National Hurricane Center advisory
Media report
Eastern Pacific Season Off with a Bang: Amanda is First Major Hurricane, NASA
2013
Haiyan
8 Nov, Philippines, China, Vietnam
By Mark Higgins and Vesa Nietosvaara
The equivalent of a category-5 hurricane Typhoon Haiyan, possibly the strongest typhoon ever recorded, struck the Philippines causing major loss of life, flooding and extensive damage to buildings.
The Meteosat-7 Enhanced Infrared animation shows the path of Typhoon Haiyan as it tore its way through the Philippines. After following the coast of Vietnam the storm started to break up over southern China.
The full resolution image shows the typhoon on 8 November 04:00 UTC, as the centre was half way across the Philippines.
Other image sources
Photo of Haiyan from the ISS (Astronaut Karen Nyberg's Twitter feed)
NASA’s Terra satellite captures image of Typhoon Haiyan (NASA Earth Observatory)
Super Typhoon Haiyan (CIMSS Satellite Blog)
View on our flickr channel as Typhoon Haiyan approached the Philippines
Media report
Typhoon Haiyan: Thousands feared dead in Philippines (BBC)
Usagi
20 Sept, China, Philippines, Vietnam
By Jochen Kerkmann
Super Typhoon Usagi, the strongest storm of 2013, so far, is seen by Metop-B as it moves towards China, Vietnam and Hong Kong.
Typhoon Usagi is, reportedly, the Pacific's strongest storm on record this year, with wind speeds estimated to be up to 250 km/h, making it a Category 5 storm. It is the second super typhoon of the year in the Pacific, in August Utor hit the Philippines, causing devastating damage.
According to the Joint Typhoon Warning Center (JTWC) Usagi is expected to:"...weaken as it begins to interact with Taiwan. The system is unlikely to re-intensify over the South China sea due to land interaction and decreasing ocean heat content.".
Forecast track of Tropical Cyclone (Credit: CIMSS )
Article update on 23/09/13
On Sunday 22 September Usagi landed near the city of Shanwei, in the Chinese province of Guangdong, in southern China. The 180km/h winds which were recorded have caused loss of life, cancelled 100s of flights and shut down shipping. Travel in neighbouring Hong Kong was also greatly affected despite Hong Kong missing the worst of the typhoon.
Download full resolution RGB image from 21/09/13 02:14 UTC
Download full resolution RGB image from 22/09/13 01:54 UTC
Download full resolution RGB image from 23/09/13 02:20 UTC
Other image source
Warning
