No. 53

Summer 2018
Contents

P a geUpgrade of JM A’s Supercomputer System

1

Primary Factors behind the Heavy Rain Event of July 2018
and the Subsequent Heatwave in Japan from Mid-July Onward

2

Sea Ice in the Sea of Okhotsk in the 2017/2018 Winter Season

3

Kosa (Aeolian dust) Events over Japan in January–June 20184

TCC Experts Visit the Philippines

6

Upgrade of JMA’s Supercomputer System
Using the new system, JMA plans to make various improvements to domestic services and related international
services (see this news release for more details). With regard to TCC services, plans are being made to upgrade theGlobal Ensemble Prediction System (Global EPS) used forone-month forecast products within a year and to upgrade
the Seasonal EPS used for three-month and warm/coldseason forecast products within a couple of years.

The Japan Meteorological Agency (JMA) began operation of its 10th-generation super-computer system on 5
June 2018 with the aim of improving its meteorologicalinformation services. The new system, known as Cray
XC50, has 10 times more capacity in terms of meteorological numerical calculation than its Hitachi SR16000/M1
predecessor and to make more than 1.8 quadrillion floating-point calculations per second in theory (see below forspecifications). The new system allows JMA to run moresophisticated atmospheric and oceanic models than before,
supporting the provision of highly precise very-short- tolong-range forecasts.

(Atsushi Minami, Tokyo Climate Center)

Comparison of Specifications
PreviousNew

HITACHI SR16000/M1

Cray XC50(Vendor: Hitachi)(Vendor: Hitachi)

Theoretical Peak Performance

847 TFlops (*)

18,166 TFlops

Capacity of Main Memory

108 TBytes

528 TBytes

Capacity of Magnetic Disk

348 TBytes

10,608 TBytesModel* TFlops: capability to perform a trillion floating-point calculations per second

The new supercomputer system used for JMA’s weather and climate prediction
Left: main system Right: sub-system

TCC News1No. 53 | Summer 2018

Primary Factors behind the Heavy Rain Event of July 2018 and the Subsequent Heatwave in Japan from Mid-July Onward
TCC issued a press release regarding primary factors behind the Heavy Rain Event of July 2018 and the subsequent
heatwave in japan from mid-July onward. An abstract of thepress release and the download link for the full article are asfollows.

moist air streams over western Japan and persistent upward
flow associated with the activation of a stationary Baiu front(Figure 1). The related heatwave is attributed to the expansion of a persistent North Pacific Subtropical High and Tibetan High to the Japanese mainland (Figure 2). The serial
occurrence of these two extreme climate events was causedby significant and persistent meandering of the subtropicaljet stream in the upper troposphere. The long-term trend ofincreased intensity in observed extreme precipitation eventsin Japan and the clear upward trend in amounts of airbornewater vapor also suggest that the Heavy Rain Event may belinked to global warming. Global warming and ongoinghigher-than-normal zonally averaged tropospheric air temperatures associated with the northward shift of the subtropical jet stream are also considered responsible for theextreme heatwave.
URL:
http://ds.data.jma.go.jp/tcc/tcc/news/press_20180822.pdf

Abstract
Japan experienced significant rainfall particularly fromwestern Japan to the Tokai region mainly in early July (TheHeavy Rain Event of July 2018), which caused widespread
havoc nationwide. Extremely high temperatures subsequently persisted throughout most of Japan from mid-Julyonward.
In this context, the Japan Meteorological Agency (withthe help of the Tokyo Climate Center Advisory Panel onExtreme Climatic Events) investigates atmospheric andoceanic conditions considered to have contributed to suchclimate extremes and summarizes related primary factors.
Based on this work, the Heavy Rain Event of July 2018 is
attributed to an ongoing concentration of two massivelymoist(Yasushi Mochizuki, Tokyo Climate Center)

Figure 1 Primary factors behind the unprecedentedly heavy rain affecting areas from western Japan to thecountry’s Tokai region from 5th to 8th July 2018

Figure 2 Primary factors behind the unprecedentedly hot conditions observed from mid-July 2018 onward

TCC News2No. 53 | Summer 2018

Sea Ice in the Sea of Okhotsk in the 2017/2018 Winter Season
The maximum sea ice extent in the Sea of Okhotsk for
winter 2017/2018 corresponded to the normal.
The sea ice extent in the Sea of Okhotsk for winter2017/2018 was lower than the normal from late December
to early March (Figure 3). The seasonal maximum of 1.124
x 106 km2 was reached on 25 March (Figures 3 and 4) andwas near the normal of 1.169 x 106 km2 (based on the30-year average from 1980/1981 to 2009/2010). Figure 5
shows the overall trend of maximum sea ice extent from1971 to 2018. Although values for the Sea of Okhotsk
show large interannual variations, there is a long-term
downward trend of 0.066 [0.035 – 0.098] x 106 km2 per
decade (the numbers in square brackets indicate thetwo-sided 95% confidence interval), which equates to aloss of 4.2 [2.2 – 6.2]% of the total sea area per decade.
(Ryohei Okada, Office of Marine Prediction)

Figure 4 Sea ice situation on 25 March 2018
The white area shows the observed sea ice extent, andthe red line indicates the extent of normal coverage(the 30-year average from 1980/1981 to 2009/2010).

Figure 5 Interannual variation of maximum sea ice
extent in the Sea of Okhotsk from 1971 to 2018
Maximum sea ice extent: the greatest amount of sea
ice extent observed during the year

Figure 3 Seasonal variation of sea ice extent atfive-day intervals in the Sea of Okhotsk from November 2017 to July 2018The normal is the 30-year average from 1980/1981 to2009/2010.

TCC News

3No. 53 | Summer 2018

Kosa (Aeolian Dust) Events over Japan in January–June 2018
Kosa (Aeolian dust) was observed in Japan on 11 days
between January and June 2018, which is close to the average frequency for the last decade.

Kosa was observed at several manned stations in Japan on
28 and 29 March 2018 (Figure 10). TCR imagery provides
vivid images of atmospheric dust in the daytime.

Kosa is an atmospheric phenomenon in which visibility
is reduced when fine sand and dust are blown up from arid
and semi-arid areas of the Asian continent and transported
to Japan. Observation to detect the presence of Kosa isconducted visually at 59 manned JMA meteorological stations. The monthly normal frequency (i.e., the 1981 – 2010average) of Kosa events in Japan peaks from March toApril, and more than 95% of such events are observed
from January to June.
During the first half of 2018, Kosa events were observed
on 11 days at one or more meteorological stations in Japan(Figure 6). This was well below the normal frequency(23.0 days), but closer to the average for the last decade(13.6 days). Identification of any statistically significant
trend in the frequency of Kosa events is hindered by interannual variability (Figure 6).

(Daisaku Uesawa, Atmospheric Environment Division)*True Color Reproduction imagery
True Color Reproduction (TCR) technology enables the display of earth images taken from space in a way that is familiar tothe human eye. The imagery consists of data from three visible
bands (Band 1, 2 and 3), one near-infrared band (Band 4) andone infrared band (Band 13). For color reproduction, the RGB
chromaticity of AHI is converted to sRGB (an international standard for RGB color space). In this process, as an alternative to thebi-spectral hybrid green method outlined by Miller et al. (2016),
the green band is optimally adjusted using Band 2, 3 and 4. To
make the imagery more vivid, atmospheric correction (Rayleighcorrection, Miller et al., 2016) is also applied. Software for thispurpose is provided by the Cooperative Institute for Research in
the Atmosphere (CIRA) established by NOAA/NESDIS and Colorado State University in the United States of America.

Himawari images for a significant Kosa event in MarchImages from JMA’s Himawari satellites provide useful
information for Kosa monitoring. The Dust RGB image
from the Himawari-8 satellite for 12 UTC on 27 March2018 in Figure 7 shows that dust (in magenta) was swept
up into a low-pressure system over northeastern China.
Major dust storms making visibility less than 2 km wereobserved at meteorological stations throughout China andMongolia (Figure 8) in association with the event. Dust
RGB images are composites of three thermal infrared
Himawari observation bands, allowing identification ofdust storms both during the day and at night. Figure 9shows a True Color Reproduction (TCR) image* from
Himawari-8 for 00 UTC on 29 March 2018 (i.e., 36 hours
after observation of significant dust storms in China andMongolia), and illustrates how dust transported to Japan by
the low-pressure system covered a large area of Japan.

Acknowledgement
The imagery was developed on the basis of collaboration between the JMA Meteorological Satellite Center andthe NOAA/NESDIS/STAR GOES-R Algorithm Working
Group imagery team. We would like to acknowledge themfor the collaboration and their permission to use the software.
Reference
Miller, S., T. Schmit, C. Seaman, D. Lindsey, M. Gunshor, R. Kohrs, Y. Sumida, and D. Hillger, 2016: A Sight
for Sore Eyes - The Return of True Color to Geostationary
Satellites.
Bull.
Amer.
Meteor.
Soc.
doi:
10.1175/BAMS-D-15-00154.1

Figure 6 Annual numbers of days on which Kosa was observed at one or more meteorological stations in Japan from January to June
For more on the remarkably low frequency recorded in 2017, see TCC News No. 49.

TCC News

4No. 53 | Summer 2018

Figure 7 (Left) Dust RGB image from the Himawari-8 satellite, and (right) a synoptic chart for 12 UTC on 27
March 2018
Dust is shown in magenta.

Figure 8 Meteorological stations reporting dust orsand for present weather and visibility for 27
March 2018
Visibility is denoted by color plots.

Figure 9 (Left) True Color Reproduction image* from the Himawari-8 satellite, and (right) synopticchart for 00 UTC on 29 March 2018

Figure 10 Meteorological stations reporting dust or sand for present weather and visibility for 28 – 29
March 2018
Visibility is denoted by color plots.

TCC News

5No. 53 | Summer 2018

TCC Experts Visit the Philippines
TCC arranges expert visits to National Meteorologicaland Hydrological Services (NMHSs) to support capacity
building for climate services and facilitate the effective
transfer of technical expertise on TCC products and tools.
As part of such efforts, two TCC experts visited the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) from 10 to 12 July 2018 toprovide training regarding the generation of seasonal forecast. The training was also intended to promote the effective
use of TCC's Interactive Tool for Analysis of the Climate
System (iTacs, a web-based application). The visit wasconducted as follow-up to the 2017 TCC Training Seminar(see TCC News No. 51 and the TCC website for details).
With the attendance of 8 staff from regional branches ofPAGASA and a dozen from its headquarters, the TCC
trainers began with a practice session for basic iTacs operation. On the second day, presentations were given on expertise and techniques necessary to generate seasonal probabilistic forecast products using a statistical downscaling
method.

method. The trainers also outlined verification of probabilistic forecasts and related interpretation in terms of climatological and meteorological dynamics. Using this background expertise and the TCC’s handy guidance tool, attendees produced seasonal forecasts for their own regions in
the Philippines and gave presentations on their achievements. Another significant outcome of the seminar was theadvanced iTacs operation expertise gained by the attendees.
The visit also provided valuable opportunities for TCC interms of awareness regarding the latest status of PAGASA’sclimate services, and TCC staff engaged in fruitful discussions on future collaboration with PAGASA. TCC will continue to arrange expert visits to NMHSs in Southeast Asiaand elsewhere as necessary to assist with operational climate services.
(Hiroshi Ohno and Yasushi Mochizuki, Tokyo Climate Center)

You can also find the latest newsletter from Japan International Cooperation Agency (JICA).
JICA’s World (July 2018)https://www.jica.go.jp/english/publications/j-world/1807.html
JICA’s World is the quarterly magazine published by JICA. It introduces various cooperation projects and partners alongwith the featured theme. The latest issue features “The Gender Issues in Conflict and Disaster Supporting the weak andvulnerable in our society”.
Tokyo Climate Center (TCC), Japan Meteorological Agency
Address: 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan
TCC Website: http://ds.data.jma.go.jp/tcc/tcc/index.html

Any comments or inquiry on this newsletter and/or the TCC
website would be much appreciated. Please e-mail to
tcc@met.kishou.go.jp.
(Editors: Yasushi Takatsuki, Yasushi Mochizuki
and Atsushi Minami)

TCC News

6No. 53 | Summer 2018