2. Annual summaries of the climate system in above normal in Okinawa/Amami because hot and 2009 sunny weather was dominant under the subtropical high in July and August. 2.1 Climate in Japan (d) Autumn (September – November 2009, Fig. 2.1.1 Average surface temperature, precipitation 2.1.4d) amounts and sunshine durations Seasonal mean temperatures were near normal in The annual anomaly of the average surface northern and Eastern Japan, although temperatures temperature over Japan (averaged over 17 observatories swung widely. In Okinawa/Amami, seasonal mean confirmed as being relatively unaffected by temperatures were significantly above normal due to urbanization) in 2009 was 0.56°C above normal (based the hot weather in the first half of autumn. Monthly on the 1971 – 2000 average), and was the seventh precipitation amounts were significantly below normal highest since 1898. On a longer time scale, average nationwide in September due to dominant anticyclones. surface temperatures have been rising at a rate of about In contrast, in November, they were significantly 1.13°C per century since 1898 (Fig. 2.1.1). above normal in Western Japan under the influence of the frequent passage of cyclones and fronts around 2.1.2 Seasonal features Japan. In October, Typhoon Melor (0918) made (a) Winter (December 2008 – February 2009, Fig. landfall on mainland Japan, bringing heavy rainfall and 2.1.4a) strong winds. Since the winter monsoon was much weaker than (e) December 2009 usual, seasonal mean temperatures were above normal In the first half of December, temperatures were nationwide. In particular, they were significantly high above normal nationwide, and heavy precipitation was in Northern Japan, Eastern Japan and Okinawa/Amami. brought to the Pacific side by migratory lows. In Snowfall amounts were also significantly below contrast, in the second half of the month, a strong cold normal on the Sea of Japan side. Cyclones periodically surge brought heavy snowfall to the Sea of Japan side passed near mainland Japan, and consequently, and low temperatures all over Japan. Monthly snowfall precipitation amounts were above normal on the amounts were above normal on the Sea of Japan side Pacific side. Anticyclones tended to cover the area of Eastern Japan for the first time in four years. around Okinawa/Amami, where seasonal sunshine durations and precipitation amounts were significantly 2.2 World climate above and below normal, respectively. 2.2.1 Global average surface temperature (b) Spring (March – May 2009, Fig. 2.1.4b) The annual anomaly of the global average surface Seasonal mean temperatures were above normal in temperature in 2009 (i.e., the average of the Northern, Eastern and Western Japan. In Western Japan, near-surface air temperature over land and the sea seasonal precipitation amounts and sunshine durations surface temperature (SST)) was 0.31°C±0.13 above were significantly below and above normal, normal (based on the 1971 – 2000 average), and was respectively, due to the limited influence of cyclones the third highest since 1891. On a longer time scale, and fronts. In Okinawa/Amami, cloudy or rainy global average surface temperatures have been rising at weather was dominant in March and April, but sunny a rate of about 0.68°C per century since 1891 (Fig. weather was dominant in May. 2.2.1). (c) Summer (June – August 2009, Fig. 2.1.4c) Cloudy or rainy weather were dominant in mainland 2.2.2 Regional climate Japan during the summer. As a result, seasonal Annual mean temperatures were above normal in sunshine durations were below normal over Northern, most areas of the world except in central Siberia and Eastern and Western Japan, and seasonal precipitation from Canada to the USA (Fig. 2.2.3). Extremely high amounts were above normal in Northern Japan and on temperatures were frequently observed around low the Sea of Japan side of Western Japan. In the second half of July and the first half of August, cyclones, fronts and typhoons brought localized heavy rain in many parts of Japan. Seasonal temperatures were 6 +1.5 +1.0 +0.5 （℃） 0.0 Anomaly -0.5 -1.0 CPD/JMA -1.5 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year Fig. 2.1.1 Long-term change in annual anomaly of average surface temperature over Japan The bars indicate the annual anomaly of the average surface temperature for each year. The blue line indicates the five-year running mean, and the red line indicates the long-term linear trend. Fig. 2.1.2 Five-day running mean temperature anomaly for subdivisions (January – December 2009) 7 Table 2.1.1 Regional average and rank of annual mean temperature anomaly, annual precipitation ratio and annual sunshine duration ratio for subdivisions (2009) Table 2.1.2 Onset/end of Baiu (Japan’s rainy season) for each region and total precipitation during the period for major observatories in each region (2009) Average Average Area Average of total Total precipi- Onset of date of date of averaged preciptation End of rainy precipitation Major city in tation during Regions rainy rainy season rainy season during rainy season* ratio during each region rainy season season* onset end season (mm) rainy in 2009(mm) (1971- 2000) (1971- 2000) season (%) (1971-2000) Okinawa 18 May 8 May 6 July 23 June 94 Naha 629.0 356.8 Amami Amami 18 May 10 May 5 July 28 June 93 446.5 564.6 (Naze) Southern Kagoshim 2 June 29 May 12 July 13 July 52 311.5 558.7 Kyushu a Northern 3 June 5 June 4 August 18 July 120 Fukuoka 844.5 538.4 Kyushu Takamats Shikoku 3 June 4 June 30 July 17 July 87 254.0 281.7 u Chugoku 3 June 6 June Not specified 20 July 125 Hiroshima - - Kinki 3 June 6 June 3 August 19 July 93 Osaka 295.5 357.5 Toukai 3 June 8 June 3 August 20 July 104 Nagoya 564.0 417.0 Kantou- 3 June 8 June 14 July 20 July 95 Tokyo 257.0 244.1 Koushin Hokuriku 3 June 10 June Not specified 22 July 115 Niigata - - Southern 4 June 10 June Not specified 23 July 96 Sendai - - Touhoku Northern 4 June 12 June Not specified 27 July 155 Aomori - - Touhoku * The onset/end of the rainy season normally has a transitional period of about five-days. The dates shown in the table denote the middle day of the transitional period. 8 Table 2.1.3 Number of observatories reporting record monthly mean temperatures, precipitation amounts and sunshine duration (2009) Temperature Precipitation amount Sunshine duration Highest Lowest Heaviest Lightest Longest Shortest January 1 4 February 12 1 March April 1 7 May 1 10 4 June 1 July 10 11 August September 7 19 October 1 November 8 1 December 2 Fig. 2.1.3 Annual climate anomaly/ratio over Japan in 2009 9 (a) Winter (b) Spring (c) Summer (d) Autumn Fig. 2.1.4 Seasonal anomalies/ratios over Japan in 2009 (a) Winter (December 2008 to February 2009), (b) Spring (March to May), (c) Summer (June to August), (d) Autumn (September to November) 10 +1.0 +0.5 （℃） 0.0 Anomaly -0.5 CPD/JMA -1.0 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Fig. 2.2.1 Long-term change in annual anomaly of global average surface temperature The bars indicate the annual anomalies of the global average surface temperature for each year. The error bars indicate the 90% confidence intervals. The blue line indicates the five-year running mean, and the red line indicates the long-term linear trend. Fig. 2.2.2 Extreme events and weather-related disasters of 2009 Major extreme climatic events and weather-related disasters that occurred during the year are indicated schematically. 11 Fig. 2.2.3 Annual mean temperatures in 2009 Categories are defined by the annual mean temperature anomaly against the normal divided by its standard deviation and averaged in 5° × 5° grid boxes. The thresholds of each category are -1.28σ, -0.44σ, 0, +0.44σ and +1.28σ. The normal values and standard deviations are calculated from 1971 – 2000 statistics. Areas over land without graphical marks are those where observation data are insufficient or where normal data are unavailable. Fig. 2.2.4 Annual total precipitation in 2009 Categories are defined by the annual precipitation ratio to the normal averaged in 5° × 5° grid boxes. The thresholds of each category are 70%, 100% and 120%. Areas over land without graphical marks are those where observation data are insufficient or where normal data are unavailable. 12 Fig. 2.2.5 Frequencies of extreme high/low temperature in 2009 shown as upper/lower red/blue semicircles The size of each semicircle illustrates the ratios of extremely high/low temperature based on monthly observation for the year in each 5° × 5° grid box. Since the frequency of extreme high/low temperature is expected to be about 3% on average, occurrence is considered to be above normal in cases of 10 – 20% or more. Fig. 2.2.6 Frequencies of extreme heavy/light precipitation in 2009 The details are the same as those for Figure 2.2.5, but for monthly values of extremely heavy/light precipitation. 13 latitudes from 30°S to 30°N, while extremely low (10) Torrential rains in southern Africa (March) temperatures were observed around the central USA in (11) High temperatures around Madagascar (January – October and December, around China in November February, May – December) and from western Siberia to eastern China in (12) Low temperatures around the central USA December (Fig.