Autumn 2023

Table of Contents: TCC News No. 74
El Niño Outlook (November 2023 - May 2024) .............................................................................................. 1
JMA's Seasonal Numerical Ensemble Prediction for Boreal Winter 2023/2024 .......................................... 3
Summary of the 2023 Asian Summer Monsoon ............................................................................................. 6
Status of the Antarctic Ozone Hole in 2023 .................................................................................................. 12
Status of the Arctic Sea Ice in 2023................................................................................................................ 14
Eleventh session of the East Asia Winter Climate Outlook Forum .............................................................. 16
TCC and WMC Tokyo co-contributions to Regional Climate Outlook Forums .......................................... 17

El Niño Outlook (November 2023 - May 2024)
Atmospheric and oceanic indicators suggest that El Niño conditions have persisted in the equatorial Pacific sinceboreal spring this year. It is likely that these conditions will continue through boreal spring next year (80%) (article
based on the El Niño outlook issued on 10 November 2023).
1. El Niño/La Niña
In October 2023, the sea surface temperature (SST) for the NINO.3 region was above normal with a deviation of+2.2°C, which was the same as August and September. SSTs were above normal in and around central and easternparts of the equatorial Pacific. (Figures 1-1 and 1-3 (a)). Subsurface temperatures were also above normal in andaround the central and eastern equatorial Pacific (Figures 1-2 and 1-3 (b)). In the atmosphere, convective activity
over the same area was above normal, and easterly winds in the lower troposphere (i.e., trade winds) over thecentral equatorial Pacific were weaker than normal. These oceanic and atmospheric conditions indicate that El Niño
conditions had persisted in this area since boreal spring.
A warm subsurface water volume in central and eastern parts of the equatorial Pacific (Figure 1-2) has caused
ongoing elevated SSTs in the NINO.3 region. JMA’s seasonal ensemble prediction system forecasts that this volume
in central and eastern parts will move eastward and the NINO.3 SST will be above normal during the prediction
period (Figure 1-4). In conclusion, it is likely that El Niño conditions will continue through boreal spring next year(80%) (Figure 1-5).
(https://www.data.jma.go.jp/tcc/tcc/products/elnino/outlook.html)
2. Western Pacific and Indian Ocean
The area-averaged SST in the tropical western Pacific (NINO.WEST) region was near normal in October, and is

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likely to be near or below normal in boreal spring.
The area-averaged SST in the tropical Indian Ocean (IOBW) region was near normal in October, and is likely to be
above normal until boreal winter and above normal in boreal spring.
(ITO Akira, Tokyo Climate Center)* The SST normal for the NINO.3 region (5°S – 5°N, 150°W – 90°W) is defined as a monthly average over the latest sliding
30-year period (1993-2022 for this year).
* The SST normals for the NINO.WEST region (Eq. – 15°N, 130°E – 150°E) and the IOBW region (20°S – 20°N, 40°E –100°E) are defined as linear extrapolations with respect to the latest sliding 30-year period, in order to remove theeffects of significant long-term warming trends observed in these regions.
(a)

(b)

Figure 1-1 Monthly mean (a) sea surface temperatures (SSTs) and (b) SST anomalies in the Indian and Pacific Ocean areas for October 2023
The contour intervals are 1°C in (a) and 0.5°C in (b). The base period for the normal is 1991 – 2020.

(a)

(b)

Figure 1-2 Monthly mean depth-longitude cross sections of (a) temperatures and (b) temperature anomalies in the equatorial Indian andPacific Ocean areas for October 2023
The contour intervals are 1°C in (a) and 0.5°C in (b). The base period for the normal is 1991 – 2020.

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(a)

(b)

Figure 1-3 Time-longitude cross sections of (a) SST and (b) ocean heat content (OHC) anomalies along the equator in the Indian and Pacific
Ocean areas
OHCs are defined here as vertically averaged temperatures in the top 300 m. The base period for the normal is 1991 – 2020.

Figure 1-4 Outlook of NINO.3 SST deviation produced by theseasonal ensemble prediction system
This figure shows a time series of monthly NINO.3 SST deviations.
The thick line with closed circles shows observed SST deviations,and the boxes show the values produced for up to six months
ahead by the seasonal ensemble prediction system. Each box
denotes the range into which the SST deviation is expected to fallwith a probability of 70%.

Figure 1-5 ENSO forecast probabilities based on the seasonal ensemble
prediction system
Red, yellow and blue bars indicate probabilities that the five-monthrunning mean of the NINO.3 SST deviation from the latest sliding
30-year mean will be +0.5°C or above (El Niño), between +0.4 and-0.4°C (ENSO-neutral) and -0.5°C or below (La Niña), respectively.
Regular text indicates past months, and bold text indicates current
and future months.

<<Table of contents <Top of this article

JMA's Seasonal Numerical Ensemble Prediction for Boreal Winter 2023/2024
This report outlines JMA’s dynamical seasonal ensemble prediction for boreal winter 2023/2024 (December –February, referred to as DJF), which was used as a basis for JMA’s operational three-month outlook issued on 21
November 2023. The outlook is based on the seasonal ensemble prediction system of the Coupled
Atmosphere-ocean General Circulation Model (CGCM).
Summary: El Niño conditions have persisted in the equatorial Pacific since boreal spring this year, and are likely to

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continue (80%) through boreal spring next year. In association, active convection is expected over central to easternparts of the equatorial Pacific. Conversely, inactive convection is expected over eastern parts of the equatorial
Indian Ocean to most of the Maritime Continent. In the lower troposphere, anti-cyclonic and cyclonic circulation
anomalies straddling the equator are expected from the Indian Ocean to the Maritime Continent and the tropical
Pacific, respectively, in association with tropical convection.
1. Sea surface temperatures
Figure 2-1 shows predicted SSTs (contours) and related anomalies (shading) for DJF. Positive anomalies are
expected in central-to-eastern parts of the equatorial Pacific and in western parts of the Indian Ocean. Near-normal
conditions are expected in eastern parts of the Indian Ocean and around the Maritime Continent. In conclusion, it islikely that El Niño conditions will continue (80%) through boreal spring next year.

Figure 2-1 Predicted SSTs (contours) and SST anomalies (shading) for December–
February 2023/2024 (ensemble mean of 51 members)

2. Prediction for the tropics and sub-tropics
Figure 2-2 (a) shows predicted precipitation (contours) and related anomalies (shading) for DJF. In association
with ongoing El Niño conditions, precipitation is expected to be above normal over central-to-eastern parts of theequatorial Pacific and western parts of the equatorial Indian Ocean. Conversely, values are expected to be below
normal over eastern parts of the equatorial Indian Ocean to most of the Maritime Continent.
Figure 2-2 (b) shows predicted velocity potential (contours) and related anomalies (shading) in the upper
troposphere for DJF. In association with the precipitation anomalies described above, large-scale divergenceanomalies are expected over the western Indian Ocean and the central tropical Pacific, and convergence anomalies
are expected from the eastern Indian Ocean to the Maritime Continent.
Figure 2-2 (c) shows predicted stream functions (contours) and related anomalies (shading) in the upper
troposphere for DJF. A stationary wave pattern with anti-cyclonic circulation anomalies near the Arabian Sea andcyclonic circulation anomalies over southern Eurasia are expected in association with anomalous convection over
and around the Indian Ocean. Anti-cyclonic circulation anomalies straddling the equator are expected over thecentral-to-eastern tropical Pacific.
Figure 2-2 (d) shows predicted stream functions (contours) and related anomalies (shading) in the lower

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troposphere for DJF. Anti-cyclonic and cyclonic circulation anomalies straddling the equator are expected from theIndian Ocean to the Maritime Continent and the tropical Pacific, respectively.

(a)

(b)

(c)

(d)

Figure 2-2 Predicted atmospheric fields over 60°N-60°S for December–February 2023/2024 (ensemble mean of 51 members)(a) Precipitation (contours) and anomaly (shading). The contour interval is 2 mm/day. (b) Velocity potential at 200-hPa(contours) and anomaly (shading). The contour interval is 2 × 10 6 m2/s. (c) Stream function at 200-hPa (contours) andanomaly (shading). The contour interval is 16 × 106 m2/s. (d) Stream function at 850-hPa (contours) and anomaly (shading).
The contour interval is 5 × 106 m2/s.

3. Prediction for mid/high latitudes of the Northern Hemisphere
Figure 2-3 (a) shows predicted 500-hPa geopotential heights (contours) and related anomalies (shading) for DJF.
Positive anomalies are expected over a wide area of East Asia and areas near Central Siberia, and negative
anomalies are expected near the Aleutian Islands.
Figure 2-3 (b) shows predicted sea level pressure (contours) and related anomalies (shading) for DJF. The Aleutian
Low is expected to be intensified over its normal position. Positive anomalies are expected over the eastern part of
East Asia, corresponding to positive height anomalies at 500 hPa.

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(a)

(b)

Figure 2-3 Predicted atmospheric fields over 20°N-90°N for December–February 2023/2024 (ensemble mean of 51 members)(a) Geopotential height at 500-hPa (contours) and anomaly (shading). The contour interval is 60 m. (b) Sea level pressure(contours) and anomaly (shading). The contour interval is 4 hPa.

Note: JMA operates a seasonal Ensemble Prediction System (EPS) using the Coupled atmosphere-ocean General
Circulation Model (CGCM) to make seasonal predictions beyond a one-month time range. The EPS produces
perturbed initial conditions by means of a combination of the initial perturbation method and the lagged average
forecasting (LAF) method. Prediction is made using 51 members from the latest 17 initial dates (3 members areused every day). Details of the prediction system and verification maps based on 30-year hindcast experiments(1991–2020) are available at https://www.data.jma.go.jp/tcc/tcc/products/model/.
(ITO Akira, Tokyo Climate Center)<<Table of contents <Top of this article

Summary of the 2023 Asian Summer Monsoon
This report summarizes the characteristics of the surface climate and atmospheric/oceanographic considerations
related to the Asian summer monsoon for 2023.
Note: The Japanese Reanalysis for Three Quarters of a Century (JRA-3Q) dataset (Kosaka et al. 2024) and MGDSST(Kurihara et al. 2006) were used to analyze atmospheric circulation and sea surface temperature (SST) in the research
reported here. NOAA Climate Prediction Center (CPC) blended Outgoing Longwave Radiation (OLR) data from the NOAA
website (https://ftp.cpc.ncep.noaa.gov/precip/CBO_V1/) were used to infer tropical convective activity. The base period
for the normal is 1991 to 2020. The term “anomaly” as used in this report refers to deviation from the normal.

1. Precipitation and temperature
CLIMAT data on total precipitation for the monsoon season (June – September) showed more than 140% of thenormal over Pakistan, northwestern India, northern Mongolia, parts of southeastern and northeastern China andsouthern Korea, while less than 60% of the normal was seen over southern Central Asia, in and around southern
India, and in northern China and southern Indonesia (Figure 3-1 (a)). Notably, values exceeding 200% of the normal

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were seen over Pakistan, and it was reported that heavy rain from June to August caused at least 1,380 fatalities
from India to Afghanistan (sources: governments of India and Pakistan, EM-DAT). Monthly precipitation in India was
the lowest on record for August since 1901 (India Meteorological Department).
Four-month mean temperatures for the same period were above normal in many parts of the area from Central
Asia to East Asia, while values were below normal in and around Pakistan and over northwestern India (Figure 3-1(b)). Monthly mean temperatures in Japan were at record highs since 1891 from May to September. The seasonalmean temperature in China from June to August was the second highest on record since 1961 (China
Meteorological Administration). The monthly mean temperature in Korea was also the highest on record for
September since 1973 (Korea Meteorological Administration). Intense heat is reported to have caused 94 fatalities
in Japan (Fire and Disaster Management Agency of Japan, as of 29 September) and more than 50 in northeastern
India in June (European Commission).
(a)

(b)

Figure 3-1 Four-month (a) precipitation ratios [%] and (b) mean temperature anomalies [°C] from June to September 2023
The base period for normal is 1991 – 2020. The red (a) and green (b) dots show stations providing map data, which are interpolated due toa lack of CLIMAT reporting and climatological normal values in some areas.

2. Tropical cyclones
There was a total of 14 named tropical cyclones (TCs) over the western North Pacific and the South China Sea
by the end of September 2023, compared with the normal of 18.6 (Table 3-1). From June to September, there was a
total of 12 named TCs (climatological normal: 16.1), with 11 approaches or landfalls on Southeast and East Asia and8 (climatological normal: 9.5) on Japan. The series of TCs that formed over or around the Philippines in late July was
associated with northward migration of enhanced convection from the equatorial western Pacific to the Philippines.
This coincided with a phase-shift of intra-seasonal oscillation and intrusion of upper-level high-potential-vorticity(PV) air as described in Section 3.

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Table 3-1 Named Tropical cyclones over the western North Pacific and the South China Sea by the end of
September 2023

Note: Based on information from the RSMC Tokyo-Typhoon Center.
1) Intensity classification for tropical cyclones.
TS: tropical storm (34 – 47 kt), STS: severe tropical storm (48 – 63 kt), TY: typhoon (≥64 kt)
2) Estimated maximum 10-minute mean wind.
3) Based on early analysis data (rather than best track data) for tropical cyclones from Lan (2307) toKoinu (2314).
4) Dora (2308) entered the western North Pacific cross the International Date Line from the central
North Pacific. The data are shown for the period when Dora existed over the western North Pacific.

3. Monsoon activity and atmospheric circulation
Convective activity inferred from OLR averaged for June – September 2023 (Figure 3-2) was enhanced from theequatorial Pacific to the seas east of the Philippines, while convective activity was suppressed from the central
Indian Ocean to Southeast Asia. The anomalous convection observed from the central Indian Ocean to theequatorial Pacific is associated with a positive phase of the Indian Ocean Dipole (IOD) mode, which is characterized
by negative SST anomalies in the southeastern tropical Indian Ocean, positive SST anomalies in the western tropicalIndian Ocean, and the El Niño event (Figure 3-3). OLR index values (Table 3-2) indicate that the overall activity of
the Asian summer monsoon (represented by the SAMOI (A) index) was below normal from May through August.
The active convection area was shifted eastward of its normal position in the same period (see SAMOI (W) index).
Although the average activity of the Asian monsoon was weaker than normal during summer, convective activity
in the Asian monsoon region exhibited remarkable intra-seasonal oscillation. Convection over India and the Bay of
Bengal was suppressed in June and from late July to August, and was near normal from late June to mid-July (Figure
3-4 (a)). Convection over the Philippines showed variability with a period of approximately 30 – 60 days (Figure 3-4(b)), possibly in association with boreal summer intra-seasonal oscillation (BSISO; Lee et al. 2013; Kikuchi 2021).

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Convection variability also superimposes further variability with a quasi-biweekly period (Zhu et al. 2020, 2023). In
July, enhanced convection migrated northwestward from the western equatorial Pacific to the Philippines,
contributing to a series of TC occurrences and an intensified Pacific-Japan (PJ) pattern (Nitta 1987, Kosaka andNakamura 2006) as presented later.
Figure 3-5 shows four-month mean 200- and 850-hPa stream function fields for June – September. In the upper
troposphere (Figure 3-5 (a)), cyclonic circulation anomalies were seen over a wide area of Eurasia in association
with suppressed convection from the central Indian Ocean to Southeast Asia, implying that extension of the
Tibetan High was weaker than normal. The high was zonally split and remarkably deformed, with detached
upper-level low PV air masses migrating toward northern Japan (Figure 3-6). Meanwhile, high PV air masses
detached from the intensified mid-Pacific trough (Figure 3-5 (a)) and migrated toward the south of Japan (Figure3-6), possibly contributing to enhanced convection and several related TC occurrences via dynamical ascent overareas south of Japan and east of the Philippines (Figure 3-2).
In the lower troposphere (Figure 3-5 (b)), anti-cyclonic circulation anomalies were seen from the Arabian Sea tothe Bay of Bengal in association with suppressed convection from the central Indian Ocean to Southeast Asia
(Figure 3-2). Meridional dipole anomalies along with cyclonic circulation anomalies from the area south of Japan tosoutheastern China and anti-cyclonic circulation anomalies to the east of Japan were seen in association with theintensified PJ pattern, contributing to intense heat in Japan from late July onward.

Figure 3-2 Four-month mean OLR [W/m2] for June–
September 2023
Contours indicate OLR lower than 240 W/m2 at intervalsof 10 W/m2, and color shading denotes OLR anomalies
from the normal (i.e., the 1991–2020 average).
Negative (cold color) and positive (warm color) OLR
anomalies show enhanced and suppressed convection
compared to the normal, respectively.

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Figure 3-3 Four-month mean SST anomalies [°C] for
June–September 2023
The base period for the normal is 1991 – 2020.

Table 3-2 Summer Asian Monsoon OLR Index (SAMOI) values observed from May to September 2023
Asian summer monsoon OLR indices (SAMOI) are derived from OLR anomalies. SAMOI (A), (N) and (W) indicate the overall activity of the
Asian summer monsoon, its northward shift and its westward shift, respectively. SAMOI definitions are as follows: SAMOI (A) = (-1) × (W +E); SAMOI (N) = S – N; SAMOI (W) = E – W. W, E, N and S indicate area-averaged OLR anomalies for the respective regions shown in the
figure on the right normalized by their standard deviations.

Summer Asian Monsoon OLR Index (SAMOI)
SAMOI
(A):
Activity

SAMOI (N):SAMOI (W):

Northward-shift

Westward-shift

May 2023

-1.0

-0.2

-1.8

Jun 2023

-1.3

-0.2

-1.3

Jul 2023

-0.6

-0.3

-1.6

Aug 2023

-3.2

+0.9

-0.7

Sep 2023

+0.4

-0.3

+1.4

(a)

(b)

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Figure 3-4 Time-series representation of OLR [W/m2] averaged over (a) India and the Bay of Bengal (shown by the rectangle on the bottom:
10°N - 25°N, 70°E - 100°E) and (b) the Philippines (shown by the rectangle on the bottom: 10°N - 20°N, 115°E - 140°E)
The OLR indices are calculated after Wang and Fan (1999). The thick and thin blue lines indicate seven-day running mean and daily meanvalues, respectively. The black line denotes the normal (i.e., the 1991 - 2020 average), and the gray shading shows the range of thestandard deviation calculated for the time period of the normal.

(a)

(b)

Figure 3-5 Four-month mean (a) 200-hPa and (b) 850-hPa stream function [106 m2/s] for June–September 2023
Contours indicate stream function at intervals of (a) 10 × 106 m2/s and (b) 3 × 106 m2/s, and shading shows stream function anomalies. Red(blue) shading denotes anti-cyclonic (cyclonic) circulation anomalies in the Northern Hemisphere, and vice-versa in the Southern
Hemisphere. The base period for the normal is 1991 – 2020.

Figure 3-6 Four-month mean 360-K isentropic potential vorticity [PVU; 10-6m2s-1K kg-1] for
June–September 2023
Shading indicates anomalies, and contours show potential vorticity at intervals of 1 PVU. Thebase period for the normal is 1991 – 2020.

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References
Kikuchi, K., 2021: The boreal summer intraseasonal oscillation (BSISO): A review. J. Meteor. Soc. Japan, 99, 933-972.
Kosaka Y., S. Kobayashi, Y. Harada, C. Kobayashi, H. Naoe, K. Yoshimoto, M. Harada, N. Goto, J. Chiba, K. Miyaoka, R.
Sekiguchi, M. Deushi, H. Kamahori, T. Nakaegawa; T. Y. Tanaka, T. Tokuhiro, Y. Sato, Y. Matsushita, K. Onogi, 2024: The
JRA-3Q Reanalysis. J. Meteor. Soc. Japan, 102, Early Online Released.
Kosaka, Y., and H. Nakamura, 2006: Structure and dynamics of the summertime Pacific-Japan teleconnection pattern.
Quart. J. Roy. Meteor. Soc., 132, 2009-2030.
Kurihara, Y., T. Sakurai, and T. Kuragano, 2006: Global daily sea surface temperature analysis using data from satellite
microwave radiometer, satellite infrared radiometer and in-situ observations. Weather Service Bulletin, 73, Special issue,
s1-s18 (in Japanese).
Lee, J.-Y., B. Wang, M. C. Wheeler, X. Fu, D. E. Waliser, and I.-S. Kang, 2013: Real-time multivariate indices for the boreal
summer intraseasonal oscillation over the Asian summer monsoon region. Clim. Dyn., 40, 493-509.
Nitta, T., 1987: Convective activities in the tropical western Pacific and their impact on the Northern Hemisphere summer
circulation. J. Meteor. Soc. Japan, 65, 373-390.
Wang, B. and Z. Fan, 1999: Choice of South Asian summer monsoon indices. Bull. Amer. Meteor. Soc., 80, 629–638.
Zhu, Y., Z. Wen, Y. Guo, R. Chen, X. Li, and Y. Qiao, 2020: The characteristics and possible growth mechanisms of thequasi-biweekly Pacific-Japan teleconnection in boreal summer. Climate Dyn., 55, 3363-3380.
Zhu, Y., R. Chen, Q. Song, X. Li, Y. Guo, Z. Wen, 2023: An investigation of the maintenance mechanisms of thequasi-biweekly Pacific-Japan teleconnection. Climate Dyn., https://doi.org/10.1007/s00382-023-06908-2.

(TAKEMURA Kazuto, Tokyo Climate Center)<<Table of contents <Top of this article

Status of the Antarctic Ozone Hole in 2023
The annual maximum size of the Antarctic ozone hole in 2023 exceeded the most recent decadal average due to alarge low-temperature area in the stratosphere.
Since the early 1980s, the Antarctic stratospheric ozone level has fallen every year in austral spring with a peakin September or early October. This area of depletion is referred to as the Antarctic ozone hole.
JMA analysis based on data from the Ozone Mapper Profiler Suite (OMPS) on board the Suomi National
Polar-orbiting Partnership (NPP) satellite indicates that the 2023 Antarctic ozone hole appeared in early August andexpanded rapidly from late August onward, exceeding the scale of the most recent decadal average (Figure 4-1,
upper left). Its annual maximum size (observed on 21 September) was 25.9 million square kilometers (Figure 4-1,
upper right), which is larger than the average over the most recent decade but slightly smaller than that observedin 2022 and around 1.9 times as large as Antarctica itself. In 2023 the polar vortex over Antarctica was stable until
mid-September, and the low-temperature area in the stratosphere was larger than the most recent decadal averagein September. These conditions had contributed to an expanded Antarctic ozone hole by mid-September due to

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sustained formation of polar stratospheric clouds (PSCs), which play an important role in ozone depletion.
The WMO/UNEP Scientific Assessment of Ozone Depletion: 2022 reports that total column ozone in the Antarctic
continues to recover, notwithstanding substantial interannual variability in the size, strength and longevity of theozone hole, and is expected to return to 1980 values around 2066.
The ozone layer acts as a shield against ultraviolet radiation, which can cause skin cancer. The Antarctic ozone
hole was first recognized in the early 1980s, and large-scale events have been observed since the 1990s. Its
maximum area on record was 29.8 million square kilometers (2000). Antarctic ozone depletion caused an expansionof the tropics and a poleward shift of the jet stream and storm tracks in the Southern Hemisphere that led topronounced changes in summertime surface climate conditions according to recent assessment.

Figure 4-1 Antarctic ozone hole observation
Upper left: Time-series representation of the daily ozone hole area for 2023 (red line), 2022 (orange line) and the 2013
– 2022 average (black line). Blue shading represents the range of daily maxima and minima over the previous 10 years.
JMA defines the extent of Antarctic ozone hole expansion area expanding as the area in which the total ozone column
value is less than or equal to 220 m atm-cm.
Upper right: Inter-annual variability of the annual maximum ozone hole area. The green dotted line shows the area of
the Antarctic Continent (13.9 million square kilometers).
Bottom: Snapshots of total column ozone distribution on the day of the annual maximum ozone hole area for theprevious three years; the Antarctic ozone hole is shown in grey. Images are based on NASA satellite data.
(UEMURA Keiko, Atmospheric Environment and Ocean Division)<<Table of contents <Top of this article

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Status of the Arctic Sea Ice in 2023
It is virtually certain that there has been a long-term decreasing trend of sea ice extent in the Arctic Ocean since
1979, when the current method of monitoring using satellite sensors began. The trend is statistically significant at aconfidence level of 99%. The reduction in the annual minimum extent is particularly notable at 0.086 × 10 6 km2 peryear up to 2023 (Figure 5-1).

Figure 5-1Time-series representations of annual maximum and annual minimum sea ice extent in the Arctic
Ocean (including the Sea of Okhotsk and the Bering Sea) from 1979 to 2023
Blue and red lines indicate annual maximum and annual minimum sea ice extents, respectively, with dashedlines indicating linear trends. Sea ice extents are calculated from brightness temperature data provided byNASA (the National Aeronautics and Space Administration) and NSIDC (the National Snow and Ice Data
Center).

Based on preliminary analysis, the annual maximum Arctic sea ice extent was 14.72 × 10 6 km2 on 2 March
2023, marking the 4th-lowest value since 1979. The value subsequently decreased during spring and summer in the
Northern Hemisphere and reached its annual minimum of 4.21 × 10 6 km2 on 16 September, marking the 5th-lowest
level since 1979 (Figure 5-2, 5-3).
(HAMADA Keiji, Office of Marine Prediction)

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Figure 5-2 Annual variations in the Arctic sea ice extent
The black line represents the normal, and shading represents the normal range. The base period for thenormal is 1991 – 2020.
Figure 5-3 Annual minimum Arctic
sea ice distribution
As of 16 September 2023. The
red lines represent the normal
extent. The base period for thenormal is 1991 – 2020.

<<Table of contents <Top of this article

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Eleventh session of the East Asia Winter Climate Outlook Forum
The World Meteorological Organization (WMO) actively supports the activities of the Regional Climate Outlook
Forum (RCOF), which brings together experts from climatologically homogeneous regions and provides
consensus-based seasonal predictions and information. As one of the RCOFs, the East Asia Winter Climate Outlook
Forum (EASCOF) was jointly established by the China Meteorological Administration (CMA), the Japan
Meteorological Agency (JMA), the Korea Meteorological Administration (KMA), and Mongolia's National Agency for
Meteorology and Environment Monitoring (NAMEM) in 2012.
The eleventh session of EASCOF (EASCOF-11) was held at JMA's headquarters in Tokyo, Japan, from 6 to 8
November 2023 with a face-to face format for the first time in four years after restrictions related to COVID-19 werelifted. More than 30 experts from China, Japan, Mongolia and the Republic of Korea attended, sharing informationon the status of and future plans for seasonal forecasting services in individual National Meteorological andHydrological Services (NMHSs). The Forum also welcomed Dr. Wilfran Moufouma Okia as the first-ever direct
attendee from WMO, which contributed highly to the interactions.
The attendees discussed recent understandings of phenomena related to the East Asian Winter Monsoon(EAWM) and seasonal outlooks for the coming winter. A very informative session on the latest forecast systems ofindividual NMHSs highlighted recent developments in each area, and another on good practices toward user
involvement in climate services underlined the status of recent research activities from outside experts in theutilization of climate information.
The first session for Objective Seasonal Forecasts (OSF) as a follow-up to the RAII Operating Plan (OP) was led by
Mr. Hirotaka Sato (JMA; Leader of the RAII Expert Team on Climate Services), with the Forum agreeing to continue
discussions toward an optimal style of OSF for EASCOF.
The discussions held are expected to help develop attendees’ understanding of phenomena related to EAWM
and support improvement of their climate services. Forum materials are available on the EASCOF portal.
(TAKAHASHI Kiyotoshi, Tokyo Climate Center)

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<<Table of contents <Top of this article

TCC and WMC Tokyo co-contributions to Regional Climate Outlook Forums
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 Centres (RCCs) and global producers of climate predictions. By providing aplatform for countries with similar climatological characteristics to discuss related matters, these forums ensure
consistency in terms of access to and interpretation of climate information.
In autumn 2023, representatives from TCC and the World Meteorological Centre (WMC) Tokyo attended two
online RCOFs. WMC Tokyo gave presentations about outlooks based on their model predictions.
 The 26th winter session of the South Asian Climate Outlook Forum (SASCOF-26), 26 – 27 September and 3
October The 21st session of the ASEAN Climate Outlook Forum (ASEANCOF-21), 17, 20 – 21 and 23 November
The WMC Tokyo representatives provided winter outlooks based on climate monitoring and forecast products
from the TCC website, highlighting Copernicus Climate Change Service (C3S) multi-model ensemble prediction
incorporating JMA’s seasonal prediction system.
These activities are intended to support the output of country-scale outlooks by National Meteorological andHydrological Services (NMHSs), and to contribute to the summarization of consensus outlooks as well as the
reduction of climate disaster risk in the water, agriculture and health sectors for each target area. TCC and WMCTokyo are committed to ongoing collaboration with operational climate communities to enhance progress inforecast skill and application of climate information toward the resolution of common issues and the realization of aworld resilient to adverse climate conditions.

TCC News

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No. 74 | Autumn 2023

(NEMOTO Noboru and TAKAHASHI Kiyotoshi, Tokyo Climate Center)<<Table of contents <Top of this article

You can also find the latest newsletter from Japan International Cooperation Agency (JICA).
JICA Magazine
https://jicamagazine.jica.go.jp/en/"JICA Magazine" is a public relations magazine published by JICA. It introduces the current situation ofdeveloping countries around the world, the people who are active in the field, and the content of their activities.
Any comments or inquiry on this newsletterTokyo Climate Center, Japan Meteorological Agency

and/or the TCC website would be much

3-6-9 Toranomon, Minato City, Tokyo 105-8431, Japanappreciated.
Please e-mail to tcc@met.kishou.go.jp.

TCC Website:(Editors: NEMOTO Noboru, TAKAHASHI Kiyotoshi)

https://www.data.jma.go.jp/tcc/tcc/index.html<Top of this article

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No. 74 | Autumn 2023