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CHAPTER 1 LAND AND CLIMATE
This chapter covers land and climate.
The section of land contains statistics on the area of the national land as well as those on major islands, lakes, mountains and rivers. Data are obtained mainly from "Abstract of National Land Statistics" by the Ministry of Land, Infrastructure, Transport and Tourism, "Land Survey of Prefectures, Shi, Ku, Machi and Mura" by the Geospatial Information Authority of Japan, Ministry of Land, Infrastructure, Transport and Tourism, "Summary Report on Prices, etc. of Fixed Assets (Land)" by the Ministry of Internal Affairs and Communications. As for the area of cultivated land and forest area, see "8 Agriculture, Forestry and Fisheries"; for the area of state-owned land, "5 Public Finance"; for the area of housing land, "21 Housing and Estate"; for the area of parks, "26 Culture"; and for land prices, "20 Prices".
The section of climate contains statistics on main meteorological elements such as temperature, humidity, duration of sunshine, precipitation, etc. Data are obtained from "Meteorological data of the past" and "2010 normal annual values" by the Japan Meteorological Agency. For natural disasters, see "29 Disasters and Accidents".
Area
Areas are obtained from "Land Survey of Prefectures, Shi, Ku, Machi and Mura" which has been compiled annually, as of 1 October, since 1955 by the Geospatial Information Authority of Japan, Ministry of Land, Infrastructure, Transport and Tourism.
Land Survey for 2014 was conducted changing the methods of area measurement employed in surveys for 2013 and before.
Land area measurements were done for districts surrounded by coastlines and administrative boundary lines on the Digital Japan Basic Maps (map information), and the land area figures were published using the results obtained through those measurements as bases.
Coastlines on the Digital Japan Basic Maps represent shorelines at flood tide, and rivers, lakes and marshes are included in land. Boundaries of land and sea of estuaries are made by connecting the tips of both banks according to natural coastline forms.
For the places where coastline forms have changed due to temporarily submerged areas by the Great East Japan Earthquake in 2011, areas are to be calculated, for the meantime, using coastlines before the Earthquake adjusted to coordinates after the diastrophism by the Earthquake.
Islands and Length of coastline
Number of islands and length of coastline are based on the survey conducted by the Maritime Safety Agency (now, Japan Coast Guard) in 1986, for the islands with coastline over 0.1 kilometre on the marine charts of the scale of 1:25,000 (for Habomai Islands, Shikotan Island, Kunashiri Island and Etorofu Island, the data are taken from the 1969 survey).
Areas by configuration and gradient
Data are tabulated from the National Land Numerical Information by the Geospatial Information Authority of Japan, Ministry of Land, Infrastructure, Transport and Tourism.
The National Land Numerical Information is composed of a variety of digitised geographical information on the state of development and utilisation of national land, and is provided for the computer use. A standard areal mesh system is employed for this purpose.
The standard areal mesh system, also called "grid square system" or "longitude and latitude system", is a system in which the whole area of the country is divided into areal meshes of equal size with the aid of the specified longitude and latitude lines. The standard areal meshes consist of the primary areal division, the secondary areal division and the tertiary areal division and are given appropriate code numbers which are based on longitude and latitude and constitute locational information in the National Land Numerical Information. In general, this tertiary division (a square with about 1 kilometre on a side) is called a basic areal mesh. For details, see "Guide to the Application of National Land Numerical Information" by the Geospatial Information Authority of Japan, Ministry of Land, Infrastructure, Transport and Tourism and "A Guide to the Grid Square Statistics" by the Statistics Bureau, Ministry of Internal Affairs and Communications.
Configuration
The configuration of each basic areal mesh is represented by the configuration of the largest area in the section.
Gradient
Gradients are calculated from the altitude of central points of 250 metre meshes. The maximum and minimum gradients are obtained from the gradients between the reference point and neighbouring points in eight directions. The gradient shown in this Yearbook represents the maximum gradient.
Private land area
Data are derived from "Summary Report on Prices, etc. of Fixed Assets (Land)" compiled by the Ministry of Internal Affairs and Communications based on the reports from the prefectural offices on fixed assets as of 1 January of each year.
Private land refers to taxable land (paddy fields, farm fields, forests, residential lands, pastures, grasslands, spas, ponds and marshes, and miscellaneous land) registered in the basic ledgers (i.e., the land ledgers and the supplemental land ledgers), which are kept in shi (cities), machi (towns) and mura (villages) for the purpose of imposition of the fixed asset taxes. Accordingly, private lands under the statutory tax exemption are included, but excluded are following lands, which are exempted from the fixed asset tax, such as lands owned by the government or the local public bodies, lands for official or public use, graveyards, roads, irrigation channels, sewerage, reservoirs, reserved forests, private school sites, compounds of religious bodies, etc.
Climate
Data are obtained from "Meteorological data of the past" compiled by the Japan Meteorological Agency from the surface observations at observation stations throughout the country during the year.
Observations of air temperature, relative humidity, etc. are made at the scheduled times of a day, but the frequency of observation varies depending on the observation station and the object. The average of a day is the average of all observations during the day; average of a month is the averages of days in the month; and average of a year is the averages of months in the year. Arithmetic average is used for the calculation. Normal values are taken from "2010 normal annual values" published decennially by the Japan Meteorological Agency. The normal annual values are calculated according to the widely used international practice by taking average of 30 years consisting of three decades on the Gregorian calendar. The average normal values now in use are the average of the 30-year period from 1981 to 2010.
Meteorological statistics were not compiled when the observations were not considered comparable or the number of observations is not enough. In January 2005, however, the method was improved to compile statistics as far as possible by making maximum use of the observations. Annual data of the past are compiled again by the new method.
Duration of sunshine
Data are based on rotational sunshine recorder, sun-tracking sunshine recorder, or electric pyrheliometer, indicating total hours of sunshine on the ground.
Maximum precipitation
Data refer to the maximum value of daily precipitation.
Wind speed
Data are measured by an anemograph with recording wind vane of pinwheel type. Maximum wind speed relates to the average of ten minutes.
Maximum snowfall
Data refer to the maximum depth of snow during the cold-season-centered year (from August of the preceding year to July of the reference year).
Days by weather
"Clear day" is defined as the average cloud cover is less than 1.5. The cloud cover is expressed by the proportion of cloudy space in the sky, with 10 as the total. "No-sunshine day" is a day with less than 0.1 hour of sunshine. "Rainy day" is a day with 1 millimetre or more of precipitation, and "snowy day" is a day with any snowfall (excluding snow hail, ice hail, sleet and hailstones) irrespective of quantity.
