Summer 2010

No. 21Contents
Introduction of Seasonal Mean Global Average Temperature Provision by JMA

1Addition of new content: Introduction to the Interactive Tool for Analysis of the Climate System (ITACS)

2

Summary of Kosa (Aeolian(Aeolian dust)dust) events over Japan in 2010

2

Sea Ice in the Sea of Okhotsk for the 2009/2010 Winter Season

4

Introduction of Seasonal Mean Global Average Temperature Provision
by JMAJMA will start to provide information on seasonal average
global temperatures through the TCC website in September
2010.
The Japan Meteorological Agency (JMA) provides information on annual and monthly averages of global temperatures through the TCC website to assist with monitoring for the state of global warming. In addition to this information, seasonal mean temperature data (i.e., for winter,spring, summer and autumn in the Northern Hemisphere)
will also be released in September 2010.
The new information, which is updated every threemonths, includes interannual variability graphs, long-term

trend values and global distribution maps of seasonal temperature anomalies against the normal in the same way as
for annual and monthly temperatures.
Recent seasonal mean temperatures show that this spring
was tied with that of 1998 as the warmest on record since1891 (partly because of the El Niño phenomenon thatstarted last summer), and that last autumn was the second
warmest and this winter was the fourth warmest on record .
The new information can be found together with annual
and monthly temperature data at http://ds.data.jma.go.jp/tcc/tcc/products/gwp/temp/ann_wld.html.
(Hiroshi Ohno, Climate Prediction Division)

Figure 1 Long-term change in seasonally averaged surface temperature anomalies from March to May worldwide

Tokyo Climate Center1No. 21 | Summer 2010

Addition of new content: Introduction to the Interactive Tool for
Analysis of the Climate System (ITACS)
ite, correlation, empirical orthogonal function (EOF) andsingular value decomposition (SVD) analyses, making it
easy for users to study climate systems without the need forcomplicated programming. Data sets available on theITACS include JMA's atmospheric analysis data (JRA/JCDAS), outgoing longwave radiation (OLR) data provided
by NOAA, and JMA's sea surface temperature analysis data(COBE-SST).
Users obtaining useful phenomena analysis results orapplying operational products using ITACS are requested tointroduce them in the interests of sharing usage and knowledge.

JMA/TCC has developed the Interactive Tool for Analysis of the Climate System (ITACS) to assist National Meteorological and Hydrological Services (NMHSs) in analyzing the causes of extreme climate events. The ITACS will
enable users not only to monitor current climate conditions
but also to analyze the characteristics and factors that lie
behind them and extreme climatic events.
TCC has added new content called Introduction to theInteractive Tool for Analysis of the Climate System(ITACS) in order to assist users.
To monitor and analyze the climate system, various
types of charts can be drawn using the ITACS, including
latitude-longitude maps, polar stereographic maps, crosssections and time-series graphs. The system is equippedwith a variety of statistical analysis tools, such as compos-(Shotaro Tanaka, Takashi Yamada, Climate Prediction
Division)

Figure 2
ITACS web page (http://jra.kishou.go.jp/itacs-info/tcc/itacsinfo.html)

Summary of Kosa (Aeolian dust) events over Japan in 2010
recorded observation (referred to below simply as the number of days) was 15 – far higher than the 1971 – 2000 normal of 3.3 and a new record for May (Figure 3). The total
number of days up to the end of June was as high as 30,
which also exceeds the 1971 – 2000 normal of 19.3.

Characteristics of Kosa events in 2010
Looking at significant features of Kosa events in 2010, 63
out of 67 stations in Japan (the highest number ever recorded) observed the phenomenon on 21 March, and thenumber of days when any meteorological station in Japan

Figure 3 Daily numbers of stations observing Kosa from March to May in 2010Tokyo Climate Center

2No. 21 | Summer 2010

Kosa event on 21 March observed by the largest numberof stations everOutline
Kosa originating from around the Gobi Desert from 18to 19 March moved over to the area of Japan and was observed in the country from 20 to 24 March. On 21 March,
it was seen at most Kosa observing stations (63 out of 67).
The daily number of stations reporting the phenomenon
was the highest on record since 1967 when statistics began(the previous record was 53 on 2 April, 2007).
During this event, visibility dropped to less than 2 km atWajima, Omaezaki, Tsu, Nara, Kagoshima and Naha. The
photographs in Figure 4 show the remarkable visibility deterioration experienced in Osaka. The event was also observed by the MTSAT geostationary meteorological satellite, which produced imagery clearly showing Kosa moving
over to Japan (Figure 5).
The low visibility conditions caused by this Kosa event
resulted in a number of flights cancellations in Kagoshimaand Okinawa, and a pleasure boat that became lost was rescued by a patrol boat in Okinawa. It was reported that theKosa event from 19 to 20 March in China affected the largest area since 2003 and reached the vicinity of Hong Kong,and that the concentration of suspended particulate matter
was the highest since 2005 during the Kosa event from 20
to 21 March in the Republic of Korea. The Kosa information on the website of JMA was accessed more than
230,000 times on 21 March, which was a new record for thenumber of daily visits.

1.8 km
4.6 km

0.6 kmFigure 4 Views of Osaka on 21 (top) and 22 (bottom) March(courtesy of Mr Kenichi Adachi, Osaka District Meteorological Observatory)
The distance to the tall buildings in the center is about 1.8 km.

Figure 5 Kosa moving over to Japan captured in an MTSAT
infrared differential image (00 UTC on 21 March)
The colored areas indicate the estimated Kosa extent, and are highlighted in the grayscale image.

Kosa forecast issued byJMA
JMA issued a Kosa forecast
three days before the event
stating that thick Kosa wasexpected to reach the vicinity of Japan after 20 March.
Observation results provedthat the event’s timing andextent were appropriately
forecasted (Figure 6).

Figure 6 Kosa forecast (left) and observation (right) charts for 00 UTC on 21 March

Tokyo Climate Center

3No. 21 | Summer 2010

Aerosol optical depth andÅngström exponent

Most frequent Kosa observation on record for MayIn May 2010, the monthly total for thedaily number of stations observing Kosareached its highest level ever. The key
factors were that the upper air flow in theatmosphere was favorable for transporting
Kosa to Japan in the first half of May andthat dust reaching the vicinity of the coun-(Yoshihisa Mamiya, Atmospheric Environment Division)
small

1.6
1.4
1.2
10.8
0.6
0.4
0.2
0largelargesmall

1213141516（JST）

amount of aerosols* A sunphotometer is an instrument that observes the amount and size distribution of aerosols in the total column atmosphere above thestation by measuring solar radiation at different
wavelengths.

try remained there for a long time due to a slowly moving
low-pressure area in the second half of the month. In theKosa source regions including the Gobi and Taklamakan
deserts and the Loess Plateau, Kosa was generated in May
with a frequency similar to that seen in the past few years.

size of aerosols

Measurements at RyoriAt Ryori (an atmospheric environmental measurement
station in northern Japan operated as part of international
monitoring networks including the WMO’s Global Atmosphere Watch (GAW)), measurements taken on 21 Marchusing a sunphotometer* indicated a gradual decrease in theamount of aerosols and the proportion of large-sized particles characterizing Kosa from around1.8
13:00 JST (Figure 7).

Figure 7 Aerosol optical depth at a wavelength of 500 nm (in green; highervalues indicate larger aerosol amounts) and the Ångström exponent (in yellow;smaller values indicate larger aerosol sizes) measured using a sunphotometer at
Ryori on 21 March
Data for periods when the sun was hidden by clouds are missing.

Sea Ice in the Sea of Okhotsk for the 2009/2010 Winter Season
The sea ice extent in the Sea of Okhotsk was smaller
than normal from December 2009 to February 2010, andwas near normal or larger than normal from March toMay 2010.
The sea ice extent in the Sea of Okhotsk wassmaller than normal from December 2009 to February
2010, and was near normal or larger than normal fromMarch to May 2010 (Figure 8). It reached its seasonal
maximum of 111.41 x 104 km2 (below the normal) on
10 March (Figures 8, 9 and 10).
Figure 10 shows overall trends for the period from1971 to 2010. Although the sea ice extent in the Seaof Okhotsk shows large interannual variations, there isa slight decreasing trend of 174 [55 – 294] x 104 km2

Figure 8 Seasonal variations of sea ice extent at five-day
intervals in the Sea of Okhotsk from November 2009 toJuly 2010

per decade (the numbers insquare brackets indicate the twosided 95% confidence interval)in the accumulative sea ice extent, and another slight decreasing trend of 5.5 [1.3 – 9.7] x 104
km2 (equivalent to 3.5% of thearea of the Sea of Okhotsk) per
decade in the maximum extent.
(Hiroshi Kunimatsu, Office ofMarine Prediction)
Figure 9 Sea ice conditions for 10 March 2010
The white area shows the observed sea ice extent, and the redline indicates the extent of normal coverage (1971 – 2000).

Figure 10 Interannual variations in the maximum sea ice extent (redlines) and accumulated sea ice extent (green lines) in the Sea of Okhotsk from 1971 to 2010
Accumulated sea ice extent: the sum of all five-day sea ice extent values
from December of the previous year to May.

Any comments or inquiries on this newsletter and/or the Tokyo Climate Center (TCC), Climate Prediction Division, JMA
TCC website would be much appreciated. Please e-mail Address: 1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan
to: tcc@climar.kishou.go.jp
TCC website: http://ds.data.jma.go.jp/tcc/tcc/index.html(Chief Editor: Kumi Hayashi)Tokyo Climate Center4No. 21 | Summer 2010