No. 41

Summer 2015
ContentsPage

Sea Ice in the Sea of Okhotsk in the 2014/2015 Winter Season

1

Summary of Kosa (Aeolian dust) Events over Japan in 2015

2

TCC contributions to Regional Climate Outlook Forums in Asia

4

TCC Experts Visit Sri Lanka

5

Sea Ice in the Sea of Okhotsk in the 2014/2015 Winter Season
The maximum sea ice extent in the Sea of Okhotsk for thewinter 2014/2015 was the smallest since 1970/1971.
The maximum sea ice extent in the Sea of Okhotsk fromFebruary to March 2015 was the smallest since winter1970/1971 (Figure 1). The seasonal maximum of 0.67 x
106 km2 (less than the normal of 1.17 x 106 km2 based on
the 30-year average from 1980/1981 to 2009/2010) was
reached on 28 February (Figures 1 and 2). This was thesmallest extent since 1970/1971, and was much smaller
than the same period’s second-smallest value of 0.86 x 106
km2 recorded in 1983/1984. Figure 3 shows the overall
trend of maximum sea ice extent from 1971 to 2015. Although values for the Sea of Okhotsk show large interannual variations, there is a long-term downward trend of 0.071[0.036 – 0.107] x 106 km2 per decade (the numbers insquare brackets indicate the two-sided 95% confidenceinterval), which equates to a loss of 4.5 [2.3 – 6.8]% perdecade.

Figure 1 Seasonal variation of sea ice extent at five-day intervals in the Sea of Okhotsk from November 2014 to July 2015.
The normal is the 30-year average from 1980/1981 to 2009/2010)(Keiji Hamada, Office of Marine Prediction)

Figure 2 Sea ice situation
on 28 February 2015.
The white area shows theobserved sea ice extent, andthe red line indicates theextent of normal coverage(the 30-year average from1980/1981 to 2009/2010).

TCC News

1Figure 3 Interannual variation of maximum sea ice extent
in the Sea of Okhotsk from 1971 to 2015.
Maximum sea ice extent: the greatest amount of sea ice extent
observed during the year

No. 41 | Summer 2015

Summary of Kosa (Aeolian dust) Events over Japan in 2015
Characteristics of Kosa events in 2015
Kosa (Aeolian dust) is a meteorological phenomenon inwhich fine dust is blown up to an altitude of several thousand meters by cyclonic or other wind systems from deserts
or cropland in semi-arid areas of the Asian continent, and istransported over long distances by westerly winds, resulting
in haze or dustfall in downstream areas. It is often observed
between March and May in Japan and makes the sky yellowand hazy. Heavy Kosa can affect transportation by obstructing visibility. A total of 60 JMA meteorological stations (as of 1 August 2015) perform Kosa monitoring. From
January to June 2015, the number of days on which meteorological stations in Japan observed the presence of Kosa(referred to here simply as “the number of days”) was 18,
which was below the 1981 – 2010 normal of 23.1. The

number of days in May was almost the same as the normal, but was lower in January, March and April andhigher in February and June (Figure 4, left).
The total number of stations observing the presence ofKosa (referred to here simply as “the total number ofstations”) over the same period was 144, which was also
below the normal of 208.3. The total number of stations
was lower than the normal in January, March, April andMay and higher in February and June (Figure 4, right).
Kosa was observed in western Japan from 12 to 13 June2015. As the phenomenon is rarely observed over thecountry in mid-June, this occurrence prompted media
reports.

12010

Number of Days

Total Number of Stations

Normal82015

642100Normal802015

60
40
2000JanFebMar

AprMayJan

JunFebMar

AprMayJun

Figure 4 Monthly number of days when meteorological stations in Japan observed Kosa (left), and the monthly total numberof stations observing Kosa (right) from January to June 2015
The red and yellow bars show the values for 2015 and the 1981 – 2010 normals, respectively.

Significant Kosa event in late March
Kosa was extensively observed at stations inwestern Japan and elsewhere from 22 to 23 March
2015 (Figure 5). Due to a large dust storm in an areaof the Gobi Desert around 19 March, massive volumes of dust were blown up into the atmosphereand carried over to Japan by upper-air westerlywinds.

Figure 5 Meteorological stations observing Kosa and minimum
visibility on 22 MarchTCC News2

No. 41 | Summer 2015

Low-pressure systems were located in the areafrom Primorskii (a federal subject of Russia aroundVladivostok) to Hokkaido (the northernmost ofJapan's prefectures, its capital is Sapporo) on March
22 as shown by the surface weather chart in Figure
6, and westerly winds around these systems carried
the dust to over Japan. Based on results from JMA’s
Kosa prediction model, the phenomenon was expected to prevail over western Japan on 22 March(Figure 7). In consideration of forecast results andsurface observation reports from meteorologicalstations, JMA released information on the Kosaevent to the public on 22 March in order to call attention to potential traffic hazards due to visibility
degradation.

Figure 6
Surface weather analysis
chart at 09 JST (00UTC) 22 March

Figure 7 Forecasts of surface dust concentration by JMA’s Kosa prediction model at 09 JST (00 UTC) on 20, 21 and 22 March(initial time: 21 JST (12 UTC) on 19 March) The Kosa was expected to reach Japan on 22 March.

JMA launched its Himawari-8 next-generation
geostationary meteorological satellite in October
2014. The unit is equipped with a new sensor called
the Advanced Himawari Imager (AHI), which canmonitor the Earth’s surface using 16 visible to infrared bands with finer spatial resolution than everbefore, and provides superior capability for Kosaobservation. The Kosa in this event showed up
clearly in color composite imagery fromHimawari-8 during the commissioning phase (Figure 8).
(Nozomu Ohkawara,Atmospheric Environment Division)

Figure 8 Color composite imagery from Himawari-8 taken at 10JST (01 UTC) on 22 March during the satellite’s commissioning
phase
Kosa is clearly visible over the Yellow Sea and near Japan.

TCC News3No. 41 | Summer 2015

TCC contributions to Regional Climate Outlook Forums in Asia
WMO Regional Climate Outlook Forums (RCOFs)
bring together national, regional and international climate experts on an operational basis to produce regional
climate outlooks based on input from participating
NMHSs, regional institutions, Regional Climate Centersand global producers of climate predictions. By providing a platform for countries with similar climatologicalcharacteristics to discuss related matters, these forums
ensure consistency in terms of access to and interpretation of climate information. In spring 2015, TCC experts
participated in two RCOFs and provided information on
Southeast Asian summer monsoon prediction to another.
SASCOF-6
The first RCOF was the sixth session of the South
Asian Climate Outlook Forum (SASCOF-6) held in
Dhaka, Bangladesh, from 21 to 22 April. This forum has
been held every year since 2010 to provide a consensus
outlook of South Asian monsoon season. The member
countries are Afghanistan, Bangladesh, Bhutan, India,Maldives, Myanmar, Nepal, Pakistan and Sri Lanka. The
consensus outlook made by global experts is important
for these countries to mitigate disasters caused by extreme climates such as heavy rainfall and drought. For
this purpose, TCC sends an expert every year to providea latest South Asian monsoon prediction based on
JMA’s seasonal ensemble prediction system (EPS) andto contribute to discussions on the consensus outlook. At
the 2015 session, a TCC expert gave a presentation on
the El Niño conditions and below-normal monsoon
rainfall tendency predicted by JMA’s seasonal EPS. Thisprediction was consistent with other model predictions
and played an important role to decide the outlook.

ASEANCOF
In Addition, although TCC expert didn’t participate, TCC
contributed to a consensus outlook at the fourth session of
the ASEAN Climate Outlook Forum (ASEANCOF-4) heldin Jakarta, Indonesia from 21 to 22 May by providing information on Southeast Asian summer monsoon prediction
based on JMA’s seasonal EPS.
(Takashi Yamada, Motoaki Takekawaand Yasushi Mochizuki)

FOCRAII Participants from Japan (left to right) Yasushi
MOCHIZUKI, Motoaki TAKEKAWA

FOCRA II
The second RCOF was the 11th session of the Forumon Regional Climate Monitoring, Assessment and Prediction for Regional Association II (FOCRAII) held inBeijing, China, from 11 to 13 May. The event was participated by 90 experts from 25 countries/territories(China, China Hong Kong, China Macao, Comoros,
DPR of Korea, Egypt, France, Ghana, Hungarian, Indonesia, Japan, Kazakhstan, Lao PRD, Malaysia, Maldives,Mauritius, Mongolia, Niger, Pakistan, Republic of Korea, Russia, Thailand, Turkey, United Kingdom andUnited States), took place over six sessions featuring
talks by invited lecturers and oral presentations. TheTCC participants gave four presentations on seasonal
predictions based on JMA’s seasonal EPS, external factors influencing atmospheric circulation, climate diagnosis in relation to the previous unseasonable summer, andnew TCC products. JMA’s latest seasonal predictions
thus contributed to discussions on the consensus outlook
for the coming summer.

TCC News

Motoaki TAKEKAWA as a session chair at FOCRAII

4No. 41 | Summer 2015

TCC Experts Visit Sri Lanka
TCC arranges expert visits to NMHSs to support climate services and the effective transfer of technology.
As part of such efforts, TCC experts paid a visit to Sri
Lanka’s Department of Meteorology (DOM) from 23 to26 June 2015 to conduct a follow-up seminar regarding
the generation of global warming projection information
covered at the TCC Training Seminar in 2014 (refer toTCC News No.39 for details of the seminar) and to discuss climate services in Sri Lanka as well as future collaboration between DOM and TCC.
In the presence of around 12 DOM experts, the TCCvisitors outlined the generation of global warming projection information using JMA’s JRA-55 reanalysis data and20-km-resolution MRI-AGCM data produced by JMA’s
Meteorological Research Institute (MRI) under Theme Cof the Program for Risk Information on Climate Change(also known as SOUSEI) – an initiative supported by Ja-pan’s Ministry of Education, Culture, Sports, Science andTechnology (MEXT). Using the same projection data, theattendees then estimated future changes in precipitationand other climate variables relating to the Southwestern
monsoon season in Sri Lanka. The TCC visitors also
highlighted the basic operation of TCC’s Interactive Tool
for Analysis of Climate System (iTacs) via practical exercises.
The visit provided outstanding opportunities for attendees to deepen their understanding of global warming
projection and to discuss future collaborative work withTCC. TCC will continue to arrange expert visits toNMHSs in Southeast Asia and elsewhere as necessary toassist with operational climate services.

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: Kazutoshi Onogi, Atsushi Gotoand Yasushi Mochizuki)

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

TCC News(Atsushi Goto, Tokyo Climate Center)5No. 41 | Summer 2015