Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 1 of x
Chap,3 Climate/Change and Agriculture
3.1 Environment and plant growth
3.2 Inventory of climate resources
3.4 Plant growth and crop growth models
3.5 Impacts of climate changes on
agriculture
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 2 of x
3.1 Environment and plant growth
3.1.1 Ground environment
? CO2
? Radiation
? Heat
? Water
3.1.2 Soil
? Water
? Nutrient matter
? Air/heat
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 3 of x
3.1 Environment and plant growth
3.1.3 Plant canopy and microclimate
? Radiation
? Wind
? Temperature
? Moisture
? CO2
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 4 of x
3.1 Environment and plant growth
3.1.4 Farming system
一个地区或生产单位作物种植制度以及与之相适应
的养地制度的综合技术体系 。
（ 1） Cropping system
一个地区或生产单位作物组成, 配置, 熟制与种植
方式的总称 。
（ 2） Crop composition and distribution
一个地区或生产单位作物组成和配置的总称 。
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 5 of x
Cropping system
? multiple cropping（ 多熟种植 ）
? sequential cropping （ 复种 ）
? fallow （ 休闲 ）
? row intercropping （ 间作 ）
? mixed intercropping （ 混作 ）
? relay cropping （ 套作 ）
? crop rotation （ 轮作 ）
? continuous cropping （ 连作 ）
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 6 of x
Cropping system in China
（ 1） 种植方式
撂荒制 （ shifting cultivation)
全年休闲
一年一熟 （ rotation,continuous）
二年三熟
一年三熟
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 7 of x
Cropping system in China
（ 2） 作物组成与布局
粮食作物
经济作物
其他作物
Homework 3,crop composition and
distribution in China during 1999-2000
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 8 of x
Cropping system in China
（ 3） 种植制度区划
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 9 of x
climate change and its impacts on
agriculture
Focus on,food security
depend on how to use
? climate resources
variations of productivity
? land resources
basic farmland
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 10 of x
3.2 Inventory of climate resources
3.2.1 Radiation and photosynthesis
3.2.2 Heat and temperature
3.2.3 Precipitation and water requirement
3.2.4 Climate resources
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 11 of x
3.2.1 Radiation and photosynthesis
(1) Radiation
Q = D + S
Rg = F? - F? =(1-?)Q - Fo
Fo=Eg - ?Ea
? Measured Data
? Calculation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 12 of x
Measured Radiation
? Solar radiation,Q,D,S,R
? Terrestrial radiation,Fo,Eg,Ea
? Radiation stations (98)
Class one(17),Q,D,S,R,Fo
Class two(33),Q,Fo
Class three(48),Q
? Weather stations,s,c
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 13 of x
Calculation of Radiation
? Solar radiation,Q,D,S
? Terrestrial radiation,Fo,Rg,Eg,Ea
Reference,
翁笃鸣, 中国辐射气候，气象出版社,1997
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 14 of x
Calculation of Radiation
? Radiant flux(J/s,W)
? Radiant flux density(W/m2)
? Radiation amount (W/m2 d or mon)
? Unit conversion
1 cal = 4.187J
1J = 1Nm=2.78*10-7kw h=0.239cal
1cal/s=4.178 w
1ly(Langley)=1cal/cm2
1cal/cm2 min=697.8 W/m2
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 15 of x
Calculation of Radiation
General equation,
J = Jo f(x)
J,average radiation in a condition
Jo,average radiation in an ideal condition
F(x),function for atmosphere
transparency
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 16 of x
Calculation of Radiation
Errors of estimation depends on,
? Start values of Jo
? Function forms of F(x) and involved
influencing factors
? Empirical relative errors,
For Q,5%
For D and S,10%
For Fo,10-15%
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 17 of x
Calculation of Ground Solar Radiation
Q=Qi*F(x)
? Qi--astronomical solar radiation (Qa)
? Qi--clear radiance,possible ground
solar radiation in a clear sky (Qo)
? Qi--ground solar radiation through
ideal (dry) atmosphere (Qm)
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 18 of x
Calculation of Ground Solar Radiation
Qa(W/m2 day)
=(24/?)(Io/?2)(?o·sin? · sin? + cos?· cos?· sin?o)
? ?o=arccos(-tg?tg?)
? 1/?2 = 1.00011+0.034221cos?o+0.00128sin?o
+0.000719 cos2?o+0.000077sin2?o
? ? = (0.006918-0.399912cos?o+0.070257sin?o
-0.006758cos2?o+0.000907sin2?o-0.002697cos3?o
+0.000148sin3?o)(180/?)（ degree)
? ?o = 2?(dn-1)/365 (弧度）
? ?=b/a
Chapter 3
Assessment of Climate/Change Impacts 19 of x
Calculation of Ground Solar Radiation
Qa(W/m2 day)
=(24/?)(Io/?2)(?o·sin? · sin? + cos?· cos?· sin?o)
? Io –solar constant,1367 W/m2
? ?o –solar angels of sun raise and sunset
? ?--latitude
? ? sun 赤纬
? dn—the series number of the day
? ?=b/a
Chapter 3
Assessment of Climate/Change Impacts 20 of x
Calculation of Ground Solar Radiation
Qm(W/m2)
? ground solar radiation through dry air
Reference,
王炳忠等，我国太阳能资源及其计算，太阳能
学报,1980,1（ 1）,1-9
Chapter 3
Assessment of Climate/Change Impacts 21 of x
Calculation of Ground Solar Radiation
Qo(W/m2)
? Possible ground solar radiation
? ground solar radiation through clear sky
Reference,
孙治安等，中国可能太阳总辐射的气候计算及其分布
特征，太阳能学报,1988,9（ 1）,12-23
翁笃鸣等，晴天太阳总辐射的一种参数化形式，南京
气象学院学报,1995,18（ 3）,317-323
Chapter 3
Assessment of Climate/Change Impacts 22 of x
Calculation of Ground Solar Radiation
Qo=(Io · sin(ho))/(1+f · m)
For clear sky,
f=a+b · ln(1+e)
a=0.183(p/po); b=0.0542+0.0598(p/po);
e—vapor pressure; p,po—air pressure
For possible radiation,
f=0.5 - a · exp(b · e)
a=0.426,b= -0.0492,Nov.-Apr,
a=0.380,b= -0.0194,May-Oct,
Chapter 3
Assessment of Climate/Change Impacts 23 of x
Calculation of Ground Solar Radiation
F(x) function,
? Q=Qi(a+b·s or n)
? a+b=1 or a+b=0.7
Factors,
? Hours of sunshine (or percent of sunshine),s
? Cloud,n
? s+n>=1
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 24 of x
左大康 （ 1963）,
Q=Qo(0.248+0.752s)
翁笃鸣 （ 1964）,
Q=QA(0.625+0.130s) 华南
Q=QA(0.475+0.205s) 华中
Q=QA(0.708+0.105s) 华北
Q=QA(0.390+0.344s) 西北
王炳忠 （ 1980）, Q=Qm(a+b?s )
陆渝蓉等 （ 1976）, Q= a+b?QA?s
Calculation of Ground Solar Radiation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 25 of x
Summary
? Qi
? s+n=A
? a,b
Reference,
翁笃鸣, 试论总辐射的气候学计算方法，气象学报,1964,34
（ 3）,304-315
祝昌汉, 再论总辐射的气候学计算方法（一），南京气象学院学
报,1982,1,15-24
祝昌汉, 再论总辐射的气候学计算方法（二），南京气象学院学
报,1982,2,196-206
Calculation of Ground Solar Radiation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 26 of x
? Net terrestrial radiation,Fo
Fo = ??[To4-T4(1.035-0.295e-0.166w)]
(1-0.54e0.02z^2n)0.965e0.18z
w= (0.1054+0.1513e)exp(0.06z)
To—earth surface temperature(K)
T—air temperature (K)
e—vapor pressure (hPa)
w—vapor content(g/cm2)
z—elevation (km)
n—cloud,?=0.95
Calculation of Lone Wave Radiation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 27 of x
? Atmosphere counter radiation,Ea
For clear sky,
Ea = ?T4[(0.536+0.128Ln(1+e)]
For cloud sky,
Ea = ?T4[(0.536+0.128Ln(1+e)](1+0.145n2)
T—air temperature (K)
e—vapor pressure (hPa)
n--cloud
Calculation of Lone Wave Radiation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 28 of x
? Definition
Solar radiation with wave band of 0.4 - 0.7?m,
absorbed by plants for their photosynthesis
? Amount
About 50% of insolation
? Unit
Photon flux density(?mol/m2 s)
(2) Photosynthetically Active
Radiation(PAR)
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 29 of x
? Radiation distribution in plant canopies
? Measurement of PAR in canopies
(2) Photosynthetically Active
Radiation(PAR)
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 30 of x
? SUNFLECK(Light Bar)
? SunScan Canopy Analysis System
Measurement of PAR for plant canopies
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 31 of x
? Model SF-80
? 80 light sensors alone a probe at 1cm intervals
? 7 functions
? Unit,
PAR:?mol/m2 s2
SUNFLECK(Light Bar)
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 32 of x
Measurement of PAR
—top of the canopy
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 33 of x
Measurement of PAR
—bottom of the canopy
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 34 of x
Measurement of PAR--Sunscan
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 35 of x
(1) Heat intensity
(2) Length of heating
(3) Accumulation of heat
(4) Plants response to heat/temperature
3.2.2 Heat and temperature
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 36 of x
? Average air temperature
? Temperature extremes
? Temperature ranges
? Soil temperature
(1) Heat intensity
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 37 of x
For plants,
? Threshold temperature
lower(base)
upper
? Optimum temperature
(1) Heat intensity
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 38 of x
? Frost free days
? Growth days
? Day of daily temperature above,
0oC
5oC
10oC
15oC
20oC
(2) Length of heating
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 39 of x
? Temperature sum
Active temperature sum,
Da=?t
Effective temperature sum,
De=?(t-tb)
(3) Accumulation of heat
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 40 of x
? Active temperature sum (?10oC day-degree) and
crops in China
?8000oC,tropical crops like coffee,rubber tree
4500-8000oC,subtropical crops like tea
3400-4500oC,warm temperate crops like cotton
1600-3400oC,temperate crops like maize,wheat,
soybean
?1600oC,cold temperate crops like spring wheat,potato
(3) Accumulation of heat
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 41 of x
? Threshold temperature
lower(base)
upper
? Optimum temperature
? Effects on plant development
? High/low temperature injury
(4) Plants response to heat/temperature
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 42 of x
(1) Water cycle
(2) Water balance
(3) Precipitation
(4) Evaporation
(5) Soil moisture
(6) Plants response to water
3.2.3 Precipitation and water requirement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 43 of x
? Precipitation
? Evaporation
? Runoff
? Vapor transportation
(1) Water cycle
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 44 of x
dw/dt = P + I + M – ET – D – R
? dw/dt- change of soil moisture
? P- precipitation
? I- irrigation
? M- snowmelt
? ET- evportranspiration
? D- drainage
? R- runoff
(2) Water balance
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 45 of x
? Amount
? Intensity
? Duration
? Return period
? Variation
? Droughts and floods
(3) Precipitation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 46 of x
? Amount(mm)
daily,monthly,annual
? Intensity and duration(mm/min,mm/h)
average intensity
peak intensity
relationship between intensity and duration
(3) Precipitation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 47 of x
? Return period
p=m/n
order of rainfall amount
(3) Precipitation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 48 of x
? Variation,Droughts and floods
>R+1.17 ??R
R+0.33 ??R,R+1.17 ??R
R-0.33 ??R,R+0.33 ??R
R-1.17 ??R,R+0.33 ??R
<R-1.17 ??R
(3) Precipitation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 49 of x
? Storms
>50mm/d
100-200mm/d
>200mm/d
1h,24h,7d,etc,
(3) Precipitation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 50 of x
? Weather stations
1949,101 stations
1960,3240 stations
1982,2352 stations
? Hydrological stations
1960,5684 stations
1970,10154 stations
1980,15732 stations
1990,15602 stations
(3) Precipitation measurement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 51 of x
? Density of rainfall stations
China,21.3 stations/104km2
Eastern China,50-100 stations/104km2
Japan,160 stations/104km2
UK,290 stations/104km2
(3) Precipitation measurement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 52 of x
? Rainfall data availability
Weather stations
Hydrological stations
(3) Precipitation measurement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 53 of x
? The ordinary rain gauges
British,5-inch
Canada,10 square inch
USA,8-inch
China,20-cm
? Recording rain gauges
the automatic siphon gauge
the tipping-bucket gauge
(3) Precipitation measurement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 54 of x
? Definitions
? Influencing factors
? Measurement
? Estimation
(4) Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 55 of x
? Evaporation,process of converting liquid
to water vapor
? Transpiration,evaporation of water that
has passed through the plant
? Evapotranspiration,total process of
water transfer into the atmosphere from
vegetated land surface
Definitions
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 56 of x
? Available water
? Climate factors
radiation/temperature
saturation
wind
Factors of Influencing Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 57 of x
? Evaporation power(capacity)
? Potential evaporation
? Evporativity
? Potential evapotranspiration
? Reference crop evapotranspiration
? Actual evapotranspiration
Some Concepts on Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 58 of x
Evaporation,
? Large evaporation tanks
? Small evaporation pans
Evapotranspiration,
? Lysimeters
? Evaporimeters
Measurement of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 59 of x
In irrigation management,
? Crop water requirements
? Consumptive water use of a plant
? Irrigation water need
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 60 of x
? Hydrologic/water balance method
? Climatological methods
? Micrometeorological methods
Mass transport
Aerodynamic
Bowen ratio
Resistance
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 61 of x
? Climatological methods
Thornthwaite (1948)
Penman (1948)
Penman method modified by Monteith (1963,
1964)
Priestley-Taylor (1972)
Hargreaves (1974)
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 62 of x
Thornthwaite method,
ETp＝ 1.6（ 10Ti/I） a
? Ti,monthly temperature
? I,heat index derived from the sum of 12
monthly index values of Ii
? Ii ＝ （ Ti/5） 1.514
? a＝ 6.75?10-7?I3 - 7.71?10-5?I2 + 1.79?10-2?I + 0.49
Variable needed,t
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 63 of x
Hargreaves method,
ETp＝ MF(1.8Ta + 32)CH
? Ta,monthly temperature
? MF,monthly latitude-dependent factor (given
in table)
? CH ＝ 0.166(100-RH) 0.5,correction factor for
relative humidity RH,only used when daily
RH exceed 64%
Variable needed,t,RH,latitude
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 64 of x
Priesley-Taylor,
ETp=α× （ Rn+G） /(1+γ/Δ)
? α:modified coefficient,1.2
? Rn,net radiation
? G,soil heat flux density
? γ,psychrometric constant
? Δ,slope vapor pressure curve
Variable needed,R(S),t
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 65 of x
Blaney-Criddle method,
reference evaportransipiration
ETo = p (0.46 T mean +8)
? T mean:mean daily temperature (° C)
? p,mean daily percentage of annual daytime
hours
Variable needed,R(S),t
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 66 of x
Penman method,
ETp＝ (?R+?Ea)/(?+?)
? ?,the sope of the saturation vapor pressure curve
? ?, psychromeric PCp/L?; ?=Mw/Ma (mole
weight)
? R,net radiation
? Ea=f(U)(es-ea)
Variable needed,R(S),t,ea (RH),U
Estimation of Evaporation
Chapter 3
67 of x
Penman-Monteith method,
reference potential evaportanspiration
ETp＝ (?(R-G)+?(900/T)Ea)/(?+?(1+0.34U2))
? ?,slope vapor pressure curve
? ?, psychromeric PCp/L?; ?=Mw/Ma (mole weight)
? R,net radiation
? G,soil heat flux density
? Ea=f(U2)(es-ea)
Variable needed,R(S),t,ea(RH),U
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 68 of x
? Some related terms
? Measurement
? Soil available water
(5) Soil moisture
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 69 of x
? Soil bulk density (dry,g/cm3),?b=ms/vt
? Soil bulk density (wet,g/cm3),?t=ms +mw/vt
? Soil porosity,vt -vs /vt
? Soil moisture(%),
Volume(?v)—vw/vt(used widely)
Weight(?m)—mw/ms
?v = ?b ?m
Some related terms
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 70 of x
soil water content,
? Depth,Dw=h ?v
? Water content
available soil water,
?v –Wp
?v/Fc
Some related terms
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 71 of x
土壤水分常数
? field capacity,Fc,-0.1bar/-0.3bar
? wilting point,Wp,-15bar
Some related terms
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 72 of x
? Some related terms
? Measurement
? Soil available water
Some related terms
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 73 of x
? Oven-dry method,?m,100-110oC
? Neutron-scattering,?v
? TDR (time domain reflectometry),?v
Measurement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 74 of x
? Water use
? Water stress
(6) Plants response to water
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 75 of x
Combinations of variables,
? Amount
? Temporary distributions
? Spatial distributions
3.2.4 Climate resources
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 76 of x
? Regionalization of climate resources
temperature sum
precipitation
? Agro-ecological zone
? Plant/crop productivity
3.2.4 Climate resources
2012-3-21 Assessment of Climate/Change Impacts 1 of x
Chap,3 Climate/Change and Agriculture
3.1 Environment and plant growth
3.2 Inventory of climate resources
3.4 Plant growth and crop growth models
3.5 Impacts of climate changes on
agriculture
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 2 of x
3.1 Environment and plant growth
3.1.1 Ground environment
? CO2
? Radiation
? Heat
? Water
3.1.2 Soil
? Water
? Nutrient matter
? Air/heat
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 3 of x
3.1 Environment and plant growth
3.1.3 Plant canopy and microclimate
? Radiation
? Wind
? Temperature
? Moisture
? CO2
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 4 of x
3.1 Environment and plant growth
3.1.4 Farming system
一个地区或生产单位作物种植制度以及与之相适应
的养地制度的综合技术体系 。
（ 1） Cropping system
一个地区或生产单位作物组成, 配置, 熟制与种植
方式的总称 。
（ 2） Crop composition and distribution
一个地区或生产单位作物组成和配置的总称 。
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 5 of x
Cropping system
? multiple cropping（ 多熟种植 ）
? sequential cropping （ 复种 ）
? fallow （ 休闲 ）
? row intercropping （ 间作 ）
? mixed intercropping （ 混作 ）
? relay cropping （ 套作 ）
? crop rotation （ 轮作 ）
? continuous cropping （ 连作 ）
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 6 of x
Cropping system in China
（ 1） 种植方式
撂荒制 （ shifting cultivation)
全年休闲
一年一熟 （ rotation,continuous）
二年三熟
一年三熟
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 7 of x
Cropping system in China
（ 2） 作物组成与布局
粮食作物
经济作物
其他作物
Homework 3,crop composition and
distribution in China during 1999-2000
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 8 of x
Cropping system in China
（ 3） 种植制度区划
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 9 of x
climate change and its impacts on
agriculture
Focus on,food security
depend on how to use
? climate resources
variations of productivity
? land resources
basic farmland
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 10 of x
3.2 Inventory of climate resources
3.2.1 Radiation and photosynthesis
3.2.2 Heat and temperature
3.2.3 Precipitation and water requirement
3.2.4 Climate resources
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 11 of x
3.2.1 Radiation and photosynthesis
(1) Radiation
Q = D + S
Rg = F? - F? =(1-?)Q - Fo
Fo=Eg - ?Ea
? Measured Data
? Calculation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 12 of x
Measured Radiation
? Solar radiation,Q,D,S,R
? Terrestrial radiation,Fo,Eg,Ea
? Radiation stations (98)
Class one(17),Q,D,S,R,Fo
Class two(33),Q,Fo
Class three(48),Q
? Weather stations,s,c
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 13 of x
Calculation of Radiation
? Solar radiation,Q,D,S
? Terrestrial radiation,Fo,Rg,Eg,Ea
Reference,
翁笃鸣, 中国辐射气候，气象出版社,1997
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 14 of x
Calculation of Radiation
? Radiant flux(J/s,W)
? Radiant flux density(W/m2)
? Radiation amount (W/m2 d or mon)
? Unit conversion
1 cal = 4.187J
1J = 1Nm=2.78*10-7kw h=0.239cal
1cal/s=4.178 w
1ly(Langley)=1cal/cm2
1cal/cm2 min=697.8 W/m2
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 15 of x
Calculation of Radiation
General equation,
J = Jo f(x)
J,average radiation in a condition
Jo,average radiation in an ideal condition
F(x),function for atmosphere
transparency
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 16 of x
Calculation of Radiation
Errors of estimation depends on,
? Start values of Jo
? Function forms of F(x) and involved
influencing factors
? Empirical relative errors,
For Q,5%
For D and S,10%
For Fo,10-15%
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 17 of x
Calculation of Ground Solar Radiation
Q=Qi*F(x)
? Qi--astronomical solar radiation (Qa)
? Qi--clear radiance,possible ground
solar radiation in a clear sky (Qo)
? Qi--ground solar radiation through
ideal (dry) atmosphere (Qm)
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 18 of x
Calculation of Ground Solar Radiation
Qa(W/m2 day)
=(24/?)(Io/?2)(?o·sin? · sin? + cos?· cos?· sin?o)
? ?o=arccos(-tg?tg?)
? 1/?2 = 1.00011+0.034221cos?o+0.00128sin?o
+0.000719 cos2?o+0.000077sin2?o
? ? = (0.006918-0.399912cos?o+0.070257sin?o
-0.006758cos2?o+0.000907sin2?o-0.002697cos3?o
+0.000148sin3?o)(180/?)（ degree)
? ?o = 2?(dn-1)/365 (弧度）
? ?=b/a
Chapter 3
Assessment of Climate/Change Impacts 19 of x
Calculation of Ground Solar Radiation
Qa(W/m2 day)
=(24/?)(Io/?2)(?o·sin? · sin? + cos?· cos?· sin?o)
? Io –solar constant,1367 W/m2
? ?o –solar angels of sun raise and sunset
? ?--latitude
? ? sun 赤纬
? dn—the series number of the day
? ?=b/a
Chapter 3
Assessment of Climate/Change Impacts 20 of x
Calculation of Ground Solar Radiation
Qm(W/m2)
? ground solar radiation through dry air
Reference,
王炳忠等，我国太阳能资源及其计算，太阳能
学报,1980,1（ 1）,1-9
Chapter 3
Assessment of Climate/Change Impacts 21 of x
Calculation of Ground Solar Radiation
Qo(W/m2)
? Possible ground solar radiation
? ground solar radiation through clear sky
Reference,
孙治安等，中国可能太阳总辐射的气候计算及其分布
特征，太阳能学报,1988,9（ 1）,12-23
翁笃鸣等，晴天太阳总辐射的一种参数化形式，南京
气象学院学报,1995,18（ 3）,317-323
Chapter 3
Assessment of Climate/Change Impacts 22 of x
Calculation of Ground Solar Radiation
Qo=(Io · sin(ho))/(1+f · m)
For clear sky,
f=a+b · ln(1+e)
a=0.183(p/po); b=0.0542+0.0598(p/po);
e—vapor pressure; p,po—air pressure
For possible radiation,
f=0.5 - a · exp(b · e)
a=0.426,b= -0.0492,Nov.-Apr,
a=0.380,b= -0.0194,May-Oct,
Chapter 3
Assessment of Climate/Change Impacts 23 of x
Calculation of Ground Solar Radiation
F(x) function,
? Q=Qi(a+b·s or n)
? a+b=1 or a+b=0.7
Factors,
? Hours of sunshine (or percent of sunshine),s
? Cloud,n
? s+n>=1
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 24 of x
左大康 （ 1963）,
Q=Qo(0.248+0.752s)
翁笃鸣 （ 1964）,
Q=QA(0.625+0.130s) 华南
Q=QA(0.475+0.205s) 华中
Q=QA(0.708+0.105s) 华北
Q=QA(0.390+0.344s) 西北
王炳忠 （ 1980）, Q=Qm(a+b?s )
陆渝蓉等 （ 1976）, Q= a+b?QA?s
Calculation of Ground Solar Radiation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 25 of x
Summary
? Qi
? s+n=A
? a,b
Reference,
翁笃鸣, 试论总辐射的气候学计算方法，气象学报,1964,34
（ 3）,304-315
祝昌汉, 再论总辐射的气候学计算方法（一），南京气象学院学
报,1982,1,15-24
祝昌汉, 再论总辐射的气候学计算方法（二），南京气象学院学
报,1982,2,196-206
Calculation of Ground Solar Radiation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 26 of x
? Net terrestrial radiation,Fo
Fo = ??[To4-T4(1.035-0.295e-0.166w)]
(1-0.54e0.02z^2n)0.965e0.18z
w= (0.1054+0.1513e)exp(0.06z)
To—earth surface temperature(K)
T—air temperature (K)
e—vapor pressure (hPa)
w—vapor content(g/cm2)
z—elevation (km)
n—cloud,?=0.95
Calculation of Lone Wave Radiation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 27 of x
? Atmosphere counter radiation,Ea
For clear sky,
Ea = ?T4[(0.536+0.128Ln(1+e)]
For cloud sky,
Ea = ?T4[(0.536+0.128Ln(1+e)](1+0.145n2)
T—air temperature (K)
e—vapor pressure (hPa)
n--cloud
Calculation of Lone Wave Radiation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 28 of x
? Definition
Solar radiation with wave band of 0.4 - 0.7?m,
absorbed by plants for their photosynthesis
? Amount
About 50% of insolation
? Unit
Photon flux density(?mol/m2 s)
(2) Photosynthetically Active
Radiation(PAR)
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 29 of x
? Radiation distribution in plant canopies
? Measurement of PAR in canopies
(2) Photosynthetically Active
Radiation(PAR)
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 30 of x
? SUNFLECK(Light Bar)
? SunScan Canopy Analysis System
Measurement of PAR for plant canopies
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 31 of x
? Model SF-80
? 80 light sensors alone a probe at 1cm intervals
? 7 functions
? Unit,
PAR:?mol/m2 s2
SUNFLECK(Light Bar)
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 32 of x
Measurement of PAR
—top of the canopy
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 33 of x
Measurement of PAR
—bottom of the canopy
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 34 of x
Measurement of PAR--Sunscan
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 35 of x
(1) Heat intensity
(2) Length of heating
(3) Accumulation of heat
(4) Plants response to heat/temperature
3.2.2 Heat and temperature
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 36 of x
? Average air temperature
? Temperature extremes
? Temperature ranges
? Soil temperature
(1) Heat intensity
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 37 of x
For plants,
? Threshold temperature
lower(base)
upper
? Optimum temperature
(1) Heat intensity
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 38 of x
? Frost free days
? Growth days
? Day of daily temperature above,
0oC
5oC
10oC
15oC
20oC
(2) Length of heating
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 39 of x
? Temperature sum
Active temperature sum,
Da=?t
Effective temperature sum,
De=?(t-tb)
(3) Accumulation of heat
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 40 of x
? Active temperature sum (?10oC day-degree) and
crops in China
?8000oC,tropical crops like coffee,rubber tree
4500-8000oC,subtropical crops like tea
3400-4500oC,warm temperate crops like cotton
1600-3400oC,temperate crops like maize,wheat,
soybean
?1600oC,cold temperate crops like spring wheat,potato
(3) Accumulation of heat
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 41 of x
? Threshold temperature
lower(base)
upper
? Optimum temperature
? Effects on plant development
? High/low temperature injury
(4) Plants response to heat/temperature
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 42 of x
(1) Water cycle
(2) Water balance
(3) Precipitation
(4) Evaporation
(5) Soil moisture
(6) Plants response to water
3.2.3 Precipitation and water requirement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 43 of x
? Precipitation
? Evaporation
? Runoff
? Vapor transportation
(1) Water cycle
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 44 of x
dw/dt = P + I + M – ET – D – R
? dw/dt- change of soil moisture
? P- precipitation
? I- irrigation
? M- snowmelt
? ET- evportranspiration
? D- drainage
? R- runoff
(2) Water balance
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 45 of x
? Amount
? Intensity
? Duration
? Return period
? Variation
? Droughts and floods
(3) Precipitation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 46 of x
? Amount(mm)
daily,monthly,annual
? Intensity and duration(mm/min,mm/h)
average intensity
peak intensity
relationship between intensity and duration
(3) Precipitation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 47 of x
? Return period
p=m/n
order of rainfall amount
(3) Precipitation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 48 of x
? Variation,Droughts and floods
>R+1.17 ??R
R+0.33 ??R,R+1.17 ??R
R-0.33 ??R,R+0.33 ??R
R-1.17 ??R,R+0.33 ??R
<R-1.17 ??R
(3) Precipitation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 49 of x
? Storms
>50mm/d
100-200mm/d
>200mm/d
1h,24h,7d,etc,
(3) Precipitation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 50 of x
? Weather stations
1949,101 stations
1960,3240 stations
1982,2352 stations
? Hydrological stations
1960,5684 stations
1970,10154 stations
1980,15732 stations
1990,15602 stations
(3) Precipitation measurement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 51 of x
? Density of rainfall stations
China,21.3 stations/104km2
Eastern China,50-100 stations/104km2
Japan,160 stations/104km2
UK,290 stations/104km2
(3) Precipitation measurement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 52 of x
? Rainfall data availability
Weather stations
Hydrological stations
(3) Precipitation measurement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 53 of x
? The ordinary rain gauges
British,5-inch
Canada,10 square inch
USA,8-inch
China,20-cm
? Recording rain gauges
the automatic siphon gauge
the tipping-bucket gauge
(3) Precipitation measurement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 54 of x
? Definitions
? Influencing factors
? Measurement
? Estimation
(4) Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 55 of x
? Evaporation,process of converting liquid
to water vapor
? Transpiration,evaporation of water that
has passed through the plant
? Evapotranspiration,total process of
water transfer into the atmosphere from
vegetated land surface
Definitions
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 56 of x
? Available water
? Climate factors
radiation/temperature
saturation
wind
Factors of Influencing Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 57 of x
? Evaporation power(capacity)
? Potential evaporation
? Evporativity
? Potential evapotranspiration
? Reference crop evapotranspiration
? Actual evapotranspiration
Some Concepts on Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 58 of x
Evaporation,
? Large evaporation tanks
? Small evaporation pans
Evapotranspiration,
? Lysimeters
? Evaporimeters
Measurement of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 59 of x
In irrigation management,
? Crop water requirements
? Consumptive water use of a plant
? Irrigation water need
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 60 of x
? Hydrologic/water balance method
? Climatological methods
? Micrometeorological methods
Mass transport
Aerodynamic
Bowen ratio
Resistance
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 61 of x
? Climatological methods
Thornthwaite (1948)
Penman (1948)
Penman method modified by Monteith (1963,
1964)
Priestley-Taylor (1972)
Hargreaves (1974)
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 62 of x
Thornthwaite method,
ETp＝ 1.6（ 10Ti/I） a
? Ti,monthly temperature
? I,heat index derived from the sum of 12
monthly index values of Ii
? Ii ＝ （ Ti/5） 1.514
? a＝ 6.75?10-7?I3 - 7.71?10-5?I2 + 1.79?10-2?I + 0.49
Variable needed,t
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 63 of x
Hargreaves method,
ETp＝ MF(1.8Ta + 32)CH
? Ta,monthly temperature
? MF,monthly latitude-dependent factor (given
in table)
? CH ＝ 0.166(100-RH) 0.5,correction factor for
relative humidity RH,only used when daily
RH exceed 64%
Variable needed,t,RH,latitude
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 64 of x
Priesley-Taylor,
ETp=α× （ Rn+G） /(1+γ/Δ)
? α:modified coefficient,1.2
? Rn,net radiation
? G,soil heat flux density
? γ,psychrometric constant
? Δ,slope vapor pressure curve
Variable needed,R(S),t
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 65 of x
Blaney-Criddle method,
reference evaportransipiration
ETo = p (0.46 T mean +8)
? T mean:mean daily temperature (° C)
? p,mean daily percentage of annual daytime
hours
Variable needed,R(S),t
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 66 of x
Penman method,
ETp＝ (?R+?Ea)/(?+?)
? ?,the sope of the saturation vapor pressure curve
? ?, psychromeric PCp/L?; ?=Mw/Ma (mole
weight)
? R,net radiation
? Ea=f(U)(es-ea)
Variable needed,R(S),t,ea (RH),U
Estimation of Evaporation
Chapter 3
67 of x
Penman-Monteith method,
reference potential evaportanspiration
ETp＝ (?(R-G)+?(900/T)Ea)/(?+?(1+0.34U2))
? ?,slope vapor pressure curve
? ?, psychromeric PCp/L?; ?=Mw/Ma (mole weight)
? R,net radiation
? G,soil heat flux density
? Ea=f(U2)(es-ea)
Variable needed,R(S),t,ea(RH),U
Estimation of Evaporation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 68 of x
? Some related terms
? Measurement
? Soil available water
(5) Soil moisture
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 69 of x
? Soil bulk density (dry,g/cm3),?b=ms/vt
? Soil bulk density (wet,g/cm3),?t=ms +mw/vt
? Soil porosity,vt -vs /vt
? Soil moisture(%),
Volume(?v)—vw/vt(used widely)
Weight(?m)—mw/ms
?v = ?b ?m
Some related terms
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 70 of x
soil water content,
? Depth,Dw=h ?v
? Water content
available soil water,
?v –Wp
?v/Fc
Some related terms
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 71 of x
土壤水分常数
? field capacity,Fc,-0.1bar/-0.3bar
? wilting point,Wp,-15bar
Some related terms
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 72 of x
? Some related terms
? Measurement
? Soil available water
Some related terms
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 73 of x
? Oven-dry method,?m,100-110oC
? Neutron-scattering,?v
? TDR (time domain reflectometry),?v
Measurement
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 74 of x
? Water use
? Water stress
(6) Plants response to water
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 75 of x
Combinations of variables,
? Amount
? Temporary distributions
? Spatial distributions
3.2.4 Climate resources
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 76 of x
? Regionalization of climate resources
temperature sum
precipitation
? Agro-ecological zone
? Plant/crop productivity
3.2.4 Climate resources
