TCC home About TCC Site Map Contact us

Seasonal Highlights on the Climate System

'Seasonal Highlights on the Climate System' has been issued since March 2007 as a seasonal bulletin focusing on the seasonal highlights of the monitoring results. For monthly information, please refer to 'Monthly Highlights on the Climate System.'

Notice: Products have been upgraded from PDF to HTML format starting from the issue of spring 2025 for improved accessibility.

Highlights in Spring (March 2025 - May 2025)

- The condition of equatorial Pacific remained neutral with no El Niño or La Niña phenomena occurring. Significant positive sea surface temperature (SST) anomalies were observed in the western tropical Pacific and positive anomalies were seen off the west coast of South America. In the central to eastern equatorial Pacific, negative anomalies were observed from the equator to the tropical North Pacific, and positive anomalies were observed in the tropical South Pacific. The Indian Ocean also showed significant positive anomalies (Fig. S3).
- Convective activity (Fig. S4) and circulation anomalies (Fig. S5) (Fig. S6) in the tropic were resembled with the patterns often seen during La Niña events such as active convection around the Maritime Continent and pairs of same circulation anomalies in the northern and the southern hemisphere over the Indian Ocean and the Pacific.
- No tropical depression has been generated over the northwest Pacific in the boreal spring accompanied with suppressed convection over the Micronesia forced by active convection around the Maritime Continent and over the western tropical South Pacific.
- A global tropospheric thickness temperature recorded the second high succeeded the last year.
- In the 500-hPa height field of the Northern Hemisphere (Fig. S7), significantly positive anomalies were observed from West Asia to Central Asia and over the mid-latitudes of North Pacific. In the Far East, polar front jet streams (Fig. S8) often split and positive and negative anomalies were seen over Eastern Siberia and around the Yellow Sea with periodically southward movement of cold air mass, respectively.
- As the subtropical jet stream (Fig. S8) meandered over East Asia resulting the southward shift over China and northward shift over the east of Japan, a trough was located west of Japan.
- In spring, temperatures largely fluctuated nationwide in Japan and seasonal mean temperatures were significantly above normal in northern Japan and above normal in eastern and western Japan (Fig. S1). On northern and eastern Japan, seasonal sunshine durations and seasonal precipitation amounts were below and above normal respectively, while seasonal sunshine durations were above normal on Okinawa/Amami.

Supplemental information

- Climate Anomaly Table over Japan

Fig.S1 Seasonal climate anomaly/ratio over Japan (March 2025 - May 2025) Top: temperature anomalies (degree C) Middle: precipitation ratio (%) Bottom: sunshine duration ratio (%) The base period for the normal is 1991-2020.

Fig.S7 Three-month mean 500-hPa height and anomaly in the Northern Hemisphere (March 2025 - May 2025) The contours show 500-hPa height at intervals of 60 m. The shading indicates its anomalies. The base period for the normal is 1991-2020.	Fig.S8 Three-month mean 200-hPa wind speed and vectors in the Northern Hemisphere (March 2025 - May 2025) The black lines show wind speed at intervals of 10 m/s. The brown lines show its normal at intervals of 20 m/s. The base period for the normal is 1991-2020.
Fig.S9 Three-month mean sea level pressure and anomaly in the Northern Hemisphere (March 2025 - May 2025) The contours show sea level pressure at intervals of 4 hPa. The shading indicates its anomalies. The base period for the normal is 1991-2020.	Fig.S10 Three-month mean 850-hPa temperature and anomaly in the Northern Hemisphere (March 2025 - May 2025) The contours show 850-hPa temperature at intervals of 3 degree C. The shading indicates its anomalies. The base period for the normal is 1991-2020.

Back Number

The descriptions from May-2011 to April-2021 issue are based on the former climatological normal (1981-2010 average).
In the descriptions until April-2011 issue, 1979-2004 average is used as climatological normal unless otherwise stated.
The descriptions until January-2014 issue are based on the JRA-25/JCDAS datasets.
The descriptions from February-2014 to April-2023 issue are based on the JRA-55 reanalysis.

Figures and Tables

Notice: Products based on JRA-3Q were updated to those with improved quality in terms of tropical cyclone analysis. OLR-related products from January 1991 are based on NOAA CPC Blended OLR (CBO).

Notice: Figures of 'Atmospheric Circulation', 'Time Cross Section', and 'Indices' have been revised with improved quality data regarding tropical cyclone analysis. (18 June 2024)

Notice: Depending on the availability of NOAA CPC Blended OLR (CBO) data, updates may be delayed or figures may be filled with gray indicating data missing.

• Explanation on the Products for Climate System Monitoring
• 3-month Mean Figures
• Time Cross Sections
• Indices
• Oceanic Figures and Tables