Executive Summary

Annual Report on Atmospheric and Marine Environment Monitoring

— Executive Summary —


  This report outlines the results of observations and analyses made by JMA up to the end of 2009 with regard to atmospheric and oceanic greenhouse gases, the ozone layer, ultraviolet radiation, aerosols and solar radiation, precipitation and dry deposition, and marine pollution.

Carbon Dioxide

  • The atmospheric concentrations of CO2 observed at Ryori, Minamitorishima and Yonagunijima show seasonal variations, with high values from winter to spring and low values from summer to autumn, and an increasing year-on-year trend. The mean growth rates over the last decade are 1.85 ppm, 1.91 ppm and 1.89 ppm at Ryori, Minamitorishima and Yonagunijima, respectively.

  • The global mean concentration of CO2 in 2009 was 386.8 ppm based on analysis using data reported to the World Data Centre for Greenhouse Gases (WDCGG). This represents an increase of 38% relative to the concentration (280 ppm) seen before the start of the industrial era in about 1750.

  • The CO2 partial pressure in seawater compared to that in air (ΔpCO2) was below normal in many latitudes along the 137°E line in the winter and summer of 2009.

  • The average concentration of CO2 in the air along the 137°E line between 7°N and 33°N was 388.1 ppm in the winter of 2009. This is 0.1 ppm higher than the value of the previous year and represents an average rate of increase of 1.7 ± 0.1 ppm/year over the period of 1984–2009. In the seawater along the same line, the concentration was 342.5 ppm, representing a decrease of 2.7 ppm on the previous year and an average growth rate of 1.5 ± 0.2 ppm over the same period. The difference in CO2 concentration between seawater and air increased.


Summary of atmospheric CO2 observations in 2009.

Annual mean concentration in 2009
(ppm)
Growth from 2008
(ppm)
JapanRyori389.7+1.2
Minamitorishima388.0+1.4
Yonagunijima389.4+1.4
Global386.8+1.6

Time series of monthly atmospheric CO2 concentrations and deseasonalized concentrations at Ryori, Minamitorishima and Yonagunijima.

Time series of monthly atmospheric CO2 concentrations and deseasonalized concentrations at Ryori, Minamitorishima and Yonagunijima.

Temporal development of latitudinal distributions of atmospheric CO2 concentrations

Temporal development of latitudinal distributions of atmospheric CO2 concentrations for the period 1983–2009.

Time series of the ENSO index and estimated monthly CO2 fluxes from land and the oceans estimated using an inversion analysis

Time series of the NINO.3 deviation and estimated monthly CO2 fluxes from land and ocean areas estimated by inversion analysis. The NINO.3 deviation is defined as the difference between the monthly mean SST and the sliding 30-year mean averaged over the El Niño monitoring region (5°N–5°S, 150°W–90°W). Background fluxes (−2 Gt/year for ocean absorption and 4 Gt/year for land and anthropogenic emissions) are subtracted from the estimated fluxes.


Summary of oceanic CO2 observations in 2009.

Value in 2009Difference from 2008
Mean concentration
(ppm)
Area along 137°E in winter
(7–33°N)
atmosphere388.1+0.1
seawater342.5−2.7
Estimated net flux
(PgC/yr)
Subtropical region in the western North Pacific
(130–165°E, 11–30°N)
−0.076−0.015*
Equatorial Pacific
(135°E–95°W, 10°S–5°N)
+0.48−0.15*

* These values differ from differences between values of 2009 here and those of 2008 in Annual Report on Atmospheric and Marine Environment Monitoring No. 10 because of changing datasets used for flux estimation.


Distributions of differences in CO2 partial pressure between seawater and air

Distributions of differences in CO2 partial pressure (ΔpCO2) between seawater and air: (a) 16 January to 8 March 2009, (b) 22 April to 10 May 2009, (c) 9 June to 11 August 2009 and (d) 30 October to 23 November 2009.

Interannual variations in atmospheric and oceanic CO2</sub> in summer and winter averaged between 7°N and 33°N along 137°E

Interannual variations in oceanic and atmospheric CO2 in summer (oceanic only) and winter averaged between 7°N and 33°N along 137°E from 1984 to 2009.

Monthly (a), annual (b) and monthly in 2009 (c) net CO<sub>2</sub> exchange between the atmosphere and the ocean in the equatorial Pacific (10°S–5°N, 135°E–95°W)

Monthly (a), annual (b) and monthly in 2009 (c) net CO2 exchange between the atmosphere and the ocean in the equatorial Pacific (10°S–5°N, 135°E–95°W). The dotted line in (b) indicates the average from 1992 to 2009. The white solid line and blue shaded area in (c) indicate the average and standard deviation (±1σ), respectively. Positive values indicate CO2 emission from the ocean into the atmosphere. Periods of El Niño and La Niña events are indicated in red and blue respectively in (a).


Methane

  • The atmospheric concentrations of CH4 observed at Ryori, Minamitorishima and Yonagunijima show an overall increasing trend with seasonal variation. The increasing trend seen up to 2003 was not clear in 2004–2006, but the concentrations have increased again since 2007. Levels of CH4 should be watched carefully.

  • The global mean concentration of CH4 in 2009 was 1803 ppb based on analysis using data archived at the WDCGG, exceeding the value of the previous year by 5 ppb. The CH4 concentration in 2009 was about 2.5 times as high as those seen before the industrial era (typically about 715 ppb). The concentration increased largely in three consecutive years, but it is uncertain if such a trend will continue.

  • The equatorial, subtropical and subarctic regions of the western North Pacific were proven to be the major sources of CH4 as seen before, based on analysis of CH4 observations in seawater and air.


Summary of CH4 observations in 2009.

Annual mean concentration in 2009
(ppb)
Growth from 2008
(ppb)
JapanRyori1879 +3
Minamitorishima1822 +8
Yonagunijima1852+11
Global1803 +5

Time series of monthly mean atmospheric CH4 concentrations and deseasonalized concentrations at Ryori, Minamitorishima, and Yonagunijima

Time series of monthly mean atmospheric CH4 concentrations and deseasonalized concentrations at Ryori, Minamitorishima and Yonagunijima.


Temporal development of the latitudinal distributions of atmospheric CH4 concentrations

Temporal development of latitudinal distributions of atmospheric CH4 concentrations for the period 1984–2009.


Halocarbons

  • The concentrations of CFC-11, CFC-12 and CFC-113 observed at Ryori have decreased since peaking in 1993–1994, 2005 and 2004, respectively.

  • Based on analysis using data up to 2009 reported to the WDCGG, concentrations of CFC-11 have shown a slightly decreasing trend since 1992–1993 in the Northern Hemisphere and 1993–1994 in the Southern Hemisphere. The growth rates of CFC-12 have declined since the 1990s, while concentrations have recently remained almost constant. Concentrations of CFC-113 have decreased slightly since 1993–1994 in the Northern Hemisphere and about 1997 in the Southern Hemisphere.


Summary of halocarbon observations in 2009.

Annual mean concentration in 2009
(ppt)
Growth from 2008
(ppt)
RyoriCFC-11244−2
CFC-12537−2
CFC-113 78+1
CH3CCl3 11−1
CCl4 98−5

Time series of monthly mean atmospheric CFC-11 concentrations at Ryori
Time series of monthly mean atmospheric CFC-12 concentrations at Ryori
Time series of monthly mean atmospheric CFC-113 concentrations at Ryori

Time series of monthly mean atmospheric CFC-11, CFC-12 and CFC-113 concentrations at Ryori.


Nitrous Oxide

  • The annual mean concentration of N2O observed at Ryori in 2009 was 322.7 ppb, and the average growth rate over the last decade was 0.7 ppb/year.

  • The global mean concentration of N2O in 2009 was 322.5 ppb based on analysis using data archived at the WDCGG. This represents an increase of 19% relative to the concentration seen before the industrial era. The average growth rate over the last decade was 0.77 ppb/year.


Summary of N2O observations in 2009.

Annual mean concentration in 2009
(ppb)
Growth from 2008
(ppb)
Ryori322.7−0.5
Global322.5+0.6

Time series of monthly mean atmospheric N2O concentrations at Ryori

Time series of monthly mean atmospheric N2O concentrations at Ryori.


Carbon Monoxide

  • Concentrations of CO have shown a slightly decreasing trend over the long term at all stations in Japan, but the trend is not significant due to large interannual variations.

  • The global mean concentration of CO in 2009 was about 89 ppb based on analysis using data archived at the WDCGG. Deseasonalized concentrations are the highest in the mid-latitudes of the Northern Hemisphere and lower in the Southern Hemisphere. The concentrations decreased temporally in 1992–1993 and increased temporally in 1997–1998 and 2002–2003, mainly in the Northern Hemisphere.


Summary of CO observations in 2009.

Annual mean concentration in 2009
(ppb)
Growth from 2008
(ppb)
JapanRyori146*
Minamitorishima105−1
Yonagunijima144*
Globalabout 89−2


* The observation system at Ryori and Yonagunijima were replaced in January 2009 and January 2008 respectively. The difference between the old and new systems is now under investigation.


Time series of monthly mean atmospheric CO concentrations and deseasonalized concentrations at Ryori, Minamitorishima and Yonagunijima

Time series of monthly mean atmospheric CO concentrations and deseasonalized concentrations at Ryori, Minamitorishima and Yonagunijima. Observation data at Ryori and Yonagunijima have been indicated by open circles since January 2009 and January 2008 respectively when the observation system was replaced. The difference between the old and new systems is now under investigation.


Tropospheric Ozone

  • The concentration of surface ozone at Ryori increased slightly in general after the 1990s, but the increase has been insignificant since 2007.

  • The concentrations of surface ozone at the three stations in Japan show a seasonal variation with low values in summer. This is due to the fact that an oceanic air mass with a low ozone concentration dominates Japan in summer. A similar seasonal variation is also seen in tropospheric observations from ozonesondes, but high ozone levels are observed around the surface at Tsukuba occasionally from spring to summer, which accounts for photochemical generation of ozone.


Summary of surface O3 observations in 2009.

Annual mean concentration in 2009
(ppb)
Growth from 2008
(ppb)
Ryori41+2
Minamitorishima24−2
Yonagunijima39+1

Time series of monthly mean surface O3 concentrations and deseasonalized concentrations at Ryori, Minamitorishima and Yonagunijima

Time series of monthly mean surface O3 concentrations and deseasonalized concentrations at Ryori, Minamitorishima and Yonagunijima.


Ozone Layer

  • In 2009, higher total ozone values continued at all four stations in Japan. Meanwhile, spells of lower total ozone values were observed in January and February at some stations.

  • Observed total ozone decreased from the 1980s to the mid-1990s, but has remained unchanged or increased slightly since then at Sapporo and Tsukuba. At Naha, it has shown a slow increase since the mid-1990s.

  • In 2009, the ozone hole appeared in mid-August and developed to its largest size for the year at 2.4 million km2 on 17 September. It was its third smallest extent in the previous ten years since 2000. The ozone hole disappeared on 1 December.

  • Decreasing trends in total ozone values are significant from north Europe to west Siberia in the Northern Hemisphere and from southern South America to southern Africa in the Southern Hemisphere. Decreasing trends are less significant from southern Australia to the Southern Pacific.


Time series of annual mean total ozone from the beginning of observation at four stations in Japan

Time series of annual mean total ozone from the start of observations at four stations in Japan (Sapporo, Tsukuba, Naha and Minamitorishima).

Daily changes of the ozone hole area

Daily changes in the area of ozone hole for 2009 (top) and annual changes in its maximum area since 1979 (bottom). The area of ozone hole is defined as the area of the region where total ozone ≤ 220 m atm-cm, based on TOMS data and OMI data supplied by NASA.

Global distribution of trends in total ozone

Global distribution of trends in total ozone in 2009 relative to 1979 (% per decade). The trends are estimated from TOMS and OMI data supplied by NASA using regression to an EESC (Equivalent Effective Stratospheric Chlorine) curve.


Ultraviolet Radiation

  • In 2009, the lowest daily accumulation of erythemal UV radiation for the month was recorded in July at Sapporo, while the highest values were recorded for the month in April at Tsukuba and in January, February and May at Naha.

  • The annual accumulation of erythemal UV radiation at Sapporo, Tsukuba and Naha shows an increasing trend in the long term, although it is not statistically significant (95% confidence interval) except for Sapporo.


Time series of annual accumulation of erythemal UV from the start of observations at three stations in Japan

Time series of annual accumulation of erythemal UV from the start of observations at three stations in Japan (Sapporo, Tsukuba and Naha). The straight lines are regression lines for the whole observation period.


Aerosols

  • In 2009, the largest aerosol optical depth observed using sun photometers was observed in June at Ryori and in March at Minamitorishima and Yonagunijima. The Ångström exponent (α) representing the distribution of radius of aerosols was normal in these cases.

  • The vertical distribution of aerosols observed using lidar at Ryori showed large scattering ratios from July 2009 in the troposphere with a peak from August to September at a height of 12–19 km. The scattering ratios and peak height decreased gradually until this event diminished in December. It has been suggested that the large scattering ratios may relate to aerosols originating from the eruption of the Sarychev volcano in the Kuril Islands in June 2009.


Monthly means of aerosol optical depth at 500 nm and Angstrom exponent at Ryori, Minamitorishima, and Yonagunijima

Observation data for aerosol optical depth at 500 nm (AOD (500nm)) and the Ångström exponent (α) at Ryori, Minamitorishima and Yonagunijima in 2009. Data at Yonagunijima were missing from August to December 2009 due to failure in the sunphotometer.


Kosa (Aeolian Dust)

  • In 2009, Kosa was observed on a total of seven days in February, five days in March and two days each in April and May. It was also observed on four days in October and two days in December, for the first time in 17 and 16 years respectively for the month.

  • The annual cumulative number of stations of Kosa observation was 251 in 2009. This number has often exceeded 300 since 2000, but no significant long-term trend is seen due to large interannual variations.


Annual cumulative number of stations of Kosa observation

Annual cumulative number of stations of Kosa observation (from 1967 to 2009), targeting the 67 stations that were active for the whole period..


Solar Radiation

  • In 2009, monthly cumulative direct solar radiation observed at Sapporo, Tsukuba, Fukuoka and Ishigakijima was significantly above the normal respectively at three stations in April, May and September. Otherwise it was generally normal. There was an increasing long-term trend in annual average at a rate of about 1.5 MJ/m2 per decade in about 1990–2002, but it has been slightly decreasing thereafter.

  • The monthly mean atmospheric turbidity coefficient observed at Sapporo, Tsukuba, Fukuoka and Ishigakijima was generally normal in 2009 in spite of some exceptions at different stations for a short while. Since the eruption of Mt. Pinatubo in 1991, there have been no significant volcanic events and atmospheric turbidity has been as low as the level seen before the eruption of Mt. Agung in 1963.


Time series of Feussner-Dubois' turbidity coefficient monthly-minimum averages in Japan

Time series of Feussner-Dubois' turbidity coefficient (1960–2009) monthly-minimum averages in Japan.


Precipitation and Dry Deposition

  • In 2009, the annual mean acidity was pH 4.7 at Ryori and pH 5.2 at Minamitorishima. At Ryori, it exceeded pH 5.0 shortly after the start of observations in 1976, but has since been in the range of pH 4.4–5.0. At Minamitorishima, it remained in the range of pH 5.5–5.8 from 1996 to 2002, but has recently declined.


Histograms of pH in precipitation of daily sampling obtained at Ryori and at Minamitorishima

Histograms of pH in precipitation of daily sampling at Ryori (a) and Minamitorishima (b) in 2009.

Time series of annual mean pH weighted by precipitation amounts at Ryori and Minamitorishima

Time series of annual mean pH weighted by precipitation amounts at Ryori and Minamitorishima.


Marine Pollution

  • In 2009, the concentration of floating pollutants observed in the seas adjacent to Japan was 7.6 pieces per 100 km. This figure has been on an increasing trend since the beginning of the 2000s, and the level in 2009 was about the same as observed between 2004 and 2007.

  • In 2009, the concentrations of cadmium in surface waters were 76–112 ng/kg along the 165°E line north of 45°N in summer and were also high from winter to spring and in autumn to the southeast of Hokkaido. The mean concentration of cadmium in surface waters south of 30°N was 1.8 ng/kg, and has remained almost the same since 1997. The concentrations of mercury averaged for all observations were 4.2 ng/kg in surface waters and 4.8 ng/kg at a depth of 1000 m, and have remained almost the same since 1986.


Time series of the number of floating pollutants

Time series of the number of floating pollutants in the seas adjacent to Japan and along 137E from 1977 to 2009.

Cadmium concentration in surface sea water

Distributions of cadmium concentration in surface sea water: (a) winter, (b) spring, (c) summer and (d) autumn of 2009. Values in parentheses indicate cadmium concentration at a depth of 1000 m.


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