(Upload on September 25 2016) [ 日本語 | English ]

Climate (気候)

Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily



The patterns of variations of meteorological variables, such as temperature, humidity, atmospheric pressure, wind, precipitation in a given region (area) over long periods → weather (= short term)

klima (Gr.) = inclination

Climatic factor (気候因子), y
y = f(s, t, a, m, p)

s: solar radiation 日射
t: temperature 温度
a: air pressure 気圧
m: air mass 気団
p: precipitation 降水量

[electromagnetic spectrum, temperature, cloud, acid rain ]
[Hokkaido, global warming]

climate factors

Temperature (温度), T

Seasonal change
ΔTt = advection (移流量) - sink + source

= vertical and horiozontal advection - terrestrial radiation + solar radiation

latitudinal and daily fluctuations, in the same way

Annual temperature
annual mean temerature (T) and its related variables

monthly mean maximum temperature (月平均最高気温), Tmax
monthly mean minimum temperature (月平均最低気温), Tmin
temperature difference (温度格差), DT = Tmax - Tmin
accumulated temperature (積算温度): the sum of monthly mean temperature in a year

Warmth index (温量指数)
WI = Σ12i=1 (ti > 5), ti = mean monthly temperature > +5°C

WI is roughly consistent with the distribution of ecosystems in Japan

[cherry blossom front (桜前線)]

Climate classification (気候区分)

Temperature, T

(Kawakita & Kira 1945)

Aridity-humidity index (乾湿度指数, K)
= P/(WI + 20) (W < 100)
= P/(WI + 140) (W > 100)

WI: warmth index

< 3.0__3-5____5-7_____7-10__> 10
Desert Steppe Savanna Forest Rain forest

(Thornthwaite 1948)

Thornthwaite climate classification
TE percent (temperature-evaporation percent) = (T - 32)/4

mean annual temperature, T (Fahrenheit, °F): adjusted 0 °C by -32 (un-frozen temperature)

TE index = Σn=112(10 × TE percent)

(Hamät-ahti et al. 1974)

Mean annual biotemperature, MABT
= Σi=112Pi/12 (case Pi > 0)

→ matched well with Japanese vegetation classification
↔ WI is used for investigating maritime and/or continental patterns of precipitation

  • Arctic (A): MABT < 3.0
  • Hemiarctic (HA), Noshery boreal (NB), Middle boreal (MB), Southern boreal (SB), Hemiboreal (HB): 3.0-7.5 (northern zone, cold zone)
  • Temperate (T), Hemitemperate (HT): 7.5-12.0
  • Meridional (M): 12.0-18.0
  • Subtropical (STR): 18.0-25.0
  • Tropical (TR): > 25.0

Precipitation, P


Pecipitation effectiveness index (降水効果指数, Ep)
Ep = Σi=1120.17{Pi/(ti + 12.1)} = 11.5P(T – 10)10/9

< 128__127-64__63-32__31-16__< 16
_______Forest_________Steppe Desert

T-P relationships

A climatic graph showing relationships between temperature and humidity or temperature and precipitation
hythergraph T: temperature
P: precipitation

Walter's climate diagram
(max) mean daily max. temperature of the warmest month
(min) mean daily min. temperature of the coldest month

Macroclimate classification (大気候区分)

Köppen climate classification (ケッペンの気候区分)

= Köppen-Geiger climate classification system
A: Tropical/megathermal climates
B: Dry (arid and semiarid) climates
C: Temperate/mesothermal climates
D: Continental/microthermal climates
E: Polar and alpine climates

Climate change (気候変動)

Acid rain (酸性雨)

A rain (including fog, snow and other precipitation, s.l.) that is unusually acidic, i.e., pH < 5.6 (or 5.7)
Most acid rain is now derived from human activities, in particular, consuming fossil fuels, such as coal and oil

SO3 + H2O → H2SO4

NOX (nitrogen oxides)
= thermal NOX + fuel NOX

NO2 + OH+ → HNO3

SOX (sulfur oxides)

acid rain
Fig. 1. Schematic representation of the main components of the atmospheric sulfur budget from synthetic crude oil plants in a northern environment (Hammer 1980)