Annual mean pH of precipitation
The table below shows annual mean pH values for precipitation as observed at Ryori (Ofunato, Iwate) and Minamitorishima (Ogasawara, Tokyo). The annual mean pH is weighted by the amount of precipitation.
The monitoring ended in the end of 2011 at Ryori and in the end of 2020 at Minamitorishima.
| Year | Ryori | Minamitorishima |
|---|---|---|
| 2020 | - | 5.17 |
| 2019 | - | 5.24 |
| 2018 | - | 5.23 |
| 2017 | - | 5.33 |
| 2016 | - | 5.35 |
| 2015 | - | 5.36 |
| 2014 | - | 5.31 |
| 2013 | - | 5.23 |
| 2012 | - | 5.31 |
| 2011 | 4.76 | 5.37 |
| 2010 | 4.71 | 5.14 |
| 2009 | 4.71 | 5.20 |
| 2008 | 4.53 | 5.18 |
| 2007 | 4.63 | 5.44 |
| 2006 | 4.78 | 5.47 |
| 2005 | 4.52 | 4.99 |
| 2004 | 4.76 | 5.45 |
| 2003 | 4.76 | 5.16 |
| 2002 | 4.73 | 5.77 |
| 2001 | 4.61 | 5.65 |
| 2000 | 4.71 | 5.57 |
| 1999 | 4.96 | 5.68 |
| 1998 | 4.94 | 5.56 |
| 1997 | 4.87 | 5.72 |
| 1996 | 4.72 | 5.63 |
| 1995 | 4.65 | - |
| 1994 | 4.80 | - |
| 1993 | 4.65 | - |
| 1992 | 4.48 | - |
| 1991 | 4.70 | - |
| 1990 | 4.68 | - |
| 1989 | 4.60 | - |
| 1988 | 4.64 | - |
| 1987 | 4.83 | - |
| 1986 | 4.72 | - |
| 1985 | 4.82 | - |
| 1984 | 4.47 | - |
| 1983 | 4.59 | - |
| 1982 | 4.68 | - |
| 1981 | 4.81 | - |
| 1980 | 4.93 | - |
| 1979 | 4.92 | - |
| 1978 | 4.69 | - |
| 1977 | 5.00 | - |
| 1976 | 5.25 | - |