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Chap,2 Climate and Its Change
--Background Knowledge
2.1 Climate and climate system
2.2 Climate changes
2.3 Climate models and its applications
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Chap,2 Climate and Its Change
--Background Knowledge
2.1 Climate and climate system
2.1.1 Understanding of climate
2.1.2 Climate system
2.1.3 Processes in climate system
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2.1.1 Understanding of Climate
古典气候学 现代气候学
研究对象 气候因子 气候系统
研究内容 气候状态 气候变化
研究方法 描述、统计 定量、模型
观测手段 地面、高空观测 气象卫星
时间尺度 100-104年 100-109年
空间尺度 局地、全球 局地到全球连续
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2.1.2 Climate System
1,Definition of a system
现代汉语辞典,同类事物 按一定的 关系 组成的
整体 。
物理学,各成分 按某种 方式 合成一个 整体协同
动作 （ 质量 /能量 ） 。
2,Classification of a system
Isolated system
Close system
Open system
Cascade system
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2.1.2 Climate System
3,Definition of climate system
Interactions of 5 major components
? the atmosphere,greenhouse effect
? the hydrosphere,water cycle,heat regulator
? the cryosphere,high reflectivity,low thermal
conductivity and inertia
? the land surface,radiation,thermal,hydrological,
dynamic
? the biosphere, carbon cycle,climate indicator
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2.1.2 Climate System
Examples of interactions/processes
Atmosphere-ocean,heat,water,dynamic
Land use/cover change –atmosphere,radiation,
water,heat
Biosphere-atmosphere, carbon cycle,
indicator
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4,Nature of a climate system
Temporary scale,pp.8-11
? Kinetic energy,5 days
? Latent heat,11 days
? Internal energy,3 months
References,
林本达，黄建平, 动力气候学引论，气象出版社，
1994,pp8-11
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2.1.2 Climate System
4,Nature of a climate system
? Thermal energy budget
? Dynamical movement,boundary
? Hydrological water circulation
? Chemical carbon circle
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Thermal features of components
Mass
(t)
Specific
heat
(J/kg oC)
Heat
capacity
(MJ/oC)
Atmosphere 5.3*1015 103 5.3*1015
Hydrosphere 8.7*1016 4.19*103 36.45*1016
Land
surface
3*1015 0.79*103 2.38*1015
Ratio of mass,1:16.4:0.55
Ratio of heat capacity,1:68.8:0.45
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2.1.3 Processes in climate system
1,Energy budget in climate system
? Radiation budget
? Radiative forcing for climate change
? Observed global radiation budget
? Energy budget
2,Ocean-atmosphere,ENSO
3,Land surface-atmosphere
4,Chemical Processes
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Radiation budget
Ra = F? - F? = qa + a·Fo - F?a
Rg = F? - F? =(1-?)(D+S)-Fo
Rs = F? - F? =(1-?)(D+S)+qa-F?
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Radiative forcing for climate change
? GHGs effects
? Tropospheric Ozone
? Tropospheric Aerosols
? Land-use Change (Albedo Effect)
? Solar Forcing
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Radiation budget
? incoming,100%
? reflected,26%+4%=30%
? absorbed,20% +50% =70%
? outgoing,(38%+26%)+6%=70%
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Observed global radiation budget
Seasonal change
? Comparison of absorbed solar radiation,
observed VS calculated
? Global radiation budget for atmosphere-
earth system(Rs)
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Observed global radiation budget
(2) Spatial distributions
? Atmosphere-earth system
Reflectivity
Absorbed solar radiation (short wave)
Emitted/terrestrial radiation(F?) (long wave)
Radiation budget(Rs),annual average
Dec-Jan
Jun-Aug
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Observed global radiation budget
(2) Spatial distributions
? The earth surface,
radiation budget (Rg)
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Understanding of Greenhouse Effects
Observed,
Global average temperature,14oC
Question,
How does greenhouse effect maintain it?
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Understanding of Greenhouse Effects
? Absorbed solar radiation,
342-107(30%)=235 W/m2
? Based on Stefen-Boltzman’s law
T= -19oC
? Balance of incoming/outgoing energy
with altitude,5km(-19oC)
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Understanding of Greenhouse Effects
Explanation,
The decreasing temperature with height
The greenhouse effects
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Energy budget
Ideal surface,
Rg - LeE - P - A - M = 0
Rg– net radiation
LE– latent heat
P– sensible heat
A– heat exchange downwards into soil
M– heat used for snow or ice melt
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Energy budget
Bowen Ratio（ 1926）,
Ｂ ＝ Ｐ／ LeE
LE– latent heat
P– sensible heat
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2,Ocean-atmosphere
Act on the ocean,
? dynamical
Act on the atmosphere
? LE– latent heat
? P– sensible heat
References,
林本达，黄建平, 动力气候学引论，气象出版社,1994
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3,Land surface-atmosphere
Act on the atmosphere
? Dynamical
? LE– latent heat
? P– sensible heat
? Matter
References,
林本达，黄建平, 动力气候学引论，气象出版社,1994
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4,Chemical processes
1,Composition of the atmosphere
2,Greenhouse Gases
3,Climate effects of GHGs
References,
林振山，杨修群, 理论气候学，南京大学出版社,1995
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2.2 Climate changes
2.2.1 Temporary scales
2.2.2 Observed climate changes
2.1.3 Causes of climate changes
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2.2.1 Temporary scales
1,Seasonal,atmosphere
2,Annual,atmosphere
ocean
3,Longer,crysphere
land surface
References,
林本达，黄建平, 动力气候学引论，气象出版社，
1994,28-30
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2.2.1 Temporary scales
1,Pre-instrumental period
? The past Millennium
? Changes across the last 500,000 years
2,Instrumental record period
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2.2.1 Observed climate variability
and change
1,Measured data
? in situ observation
? space-based observation
2,Proxy data
? ice-core
? deep-sea sediment
? speleothem,coral and lake level data,
? tree rings and varved lake records
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Global Climate Observation System
(GCOS)
? Atmosphere (GCOS),variables(upper/surface),
components,radiation
? Ocean (GOOS),variables(air,ocean--
temperature,level,salty,current,carbon
exchange)
? Terrestrial (GTOS),hydrosphere,cryosphere,
biosphere (ecosystem)
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Observed climate variability and
change
? Climate changes
near surface temperature
precipitation
water vapor
? Climate variability
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3,Changes in surface temperature
--from the instrumental record
? Global surface temperatures have increased by
0.6oC since the late 19th century,with 95%
confidence limits of near 0.4 and 0.8oC,
? Most of this increase has occurred in two periods,
about 1910-45 and since 1976,and the largest
recent warming is in the winter extratropical
Northern Hemisphere,
? The rate of temperature increase in 1976-99 is
0.19oC/decade,slightly higher than the rate of
warming between 1910-45,
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2,Changes in surface temperature
--during the past Millennium
? Rate and duration of the warming in the 20th
century is likely to have been the largest in the last
1000 years,
? The 1990’s are likely to have been the warmest
decade of the millennium in the Northern
Hemisphere and 1998 is likely to have been the
warmest year,
? There remains insufficient evidence to show that
the Little Ice Age and Medieval Optimum were truly
global,However,reconstructed average Northern
Hemisphere temperatures do show a broad
minimum during the Little Ice Age,and a relatively
warm period during early medieval times,but still
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2,Changes in surface temperature
--across the last 500,000 years
? It is likely that large and rapid decadal temperature
changes occurred during the last glacial and its
deglaciation (between about 100,000 and 10,000
years ago),particularly in higher latitudes of the
Northern Hemisphere,
? Changes locally may have been as large as 7oC in
a few decades in the last deglaciation,During the
same period there is evidence of less pronounced
changes that are worldwide and nearly
synchronous,except in high southern latitudes,
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2,Changes in surface temperature
--across the last 500,000 years
? New evidence has been found from the Antarctic
ice cores of almost in phase changes of
temperature,carbon dioxide and methane through
the ice age cycles further into history (420,000 BP),
? During the last 10,000 years smaller,but locally
quite large climate changes occurred and such
changes are also likely to have occurred in the last
interglacial,It is likely that rapid changes of
atmospheric and ocean circulation can occur
during interglacial periods,affecting regional
climate,without human interference,
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2,Changes in precipitation
-- from the instrumental record
? Instrumental records of land surface
precipitation continue to show an increase in
much of the Northern Hemisphere mid and high
latitudes,but over much of the tropical land
areas conditions have become drier,However,
other indicators suggest that large parts of the
tropical oceans have become wetter in recent
decades,
? Where available,changes in annual streamflow
usually relate well to changes in total
precipitation,
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2,Changes in water vapor
-- from the instrumental record
? A pattern of overall surface and lower
tropospheric water vapour increases over
the past few decades is emerging,although
there are likely to be some time-dependent
biases in these data and regional variations
in trends,The more reliable data sets show
that it is likely that total atmospheric water
vapour has increased several percent per
decade over many regions of the Northern
Hemisphere since the early 1970’s,
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2.3 Causes of climate changes
2.3.1 Driving forces
2.3.2 Radiative forcing
2.3.3 General circulation variations
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2.3.1 Driving forces
1,External forcing
2,Internal forcing
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2.3.2 Radiative forcing
1,Greenhouse gases
? CO2(30%),CH4(150%),N2O
(16%),
? Anthropogenic aerosols
? O3
2,Solar radiation
3,Volcanic action
4,Land use/cover change
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Definition of radiative forcing
The term,radiative forcing” has been
employed in the IPCC Assessments to
denote an externally imposed perturbation
in the radiative energy budget of the Earth’s
climate system,
?=?Ts/?F
0.5 K/(Wm-2)
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Results of radiative forcing
? GHGs,positive radiative forcing
? Anthropogenic aerosols,negative
radiative forcing,but many aspects
uncertain
? Total net radiative forcing is positive
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2.3.3 General circulation variations
Changes in Atmospheric / Oceanic
Circulation
ENSO
? The behaviour of the El Ni.o-Southern
Oscillation (ENSO),which causes
droughts or floods in many parts of the
world,has been unusual since the mid-
1970s,Warm (El Ni.o) episodes have
been relatively more frequent or
persistent than the opposite (La Ni.a)
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2.3.3 General circulation variations
??This recent behaviour of ENSO is related
to variations of precipitation over the
tropical Pacific and surrounding land
areas (e.g.,the relatively low rainfall over
many subtropical land areas in the last
two decades),as well as to warmth in the
tropics and subtropics and to a mixture of
coolness and warmth in some other
regions,The overall effect is likely to have
been a small contribution to global
warmth,
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2.3.3 General circulation variations
2.NAO/AO/AAO
? The winter North Atlantic Oscillation (NAO)
and the associated Arctic Oscillation (AO),
show decadal to multidecadal variability,
Since the 1970s the NAO/AO has been in
a phase that gives stronger westerly winds
over much of extratropical Eurasia in the
winter half year,This is associated with
cold-season warming over Eurasia,
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2.3.3 General circulation variations
? The Antarctic Oscillation (AAO) has
been in an enhanced positive phase in
the last 15 years,with stronger
westerly winds over the Southern
Ocean,
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2.4 Climate models and its
applications
2.4.1 Introduction
2.4.2 Projections of future climate change
2.4.3 Climate scenario development
2.4.4 Use of output of GCMs
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2.4.1 Introduction
1,Energy balance model (EBM)
2,Radiation-convection model (RCM)
3,Zonal average dynamical model
(ZADM)
4,General circulation model (GCM)
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2.4.2 Projections of future climate change
? The mean and standard deviation of this
quantity from 17 mixed layer models used
in the SAR is 3.8° C and 0.78° C,
respectively,
? The same quantities from 10 more recent
models is 3.3° C and 0.82° C,
? These quantites are model dependent to a
certain extent and we see no reason to
change the previous estimated range for
this quantity widely cited as 1.5 to 4.5° C,
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2.4.3 Climate scenario development
? Processes for scenario projections
? Climate scenario and climate
change scenario
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Processes for scenario projections,
? Social/economic development
population,growth rate,GDP (SAR)
7 fields
? Land use/cover change,policy
? Environment,6 fields
? Climate
? Sea-level rise
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Climate scenario and climate change
scenario
? Methods,
Incremental for sensitivity analysis
Analogue (temporal and spatial)
Use of GCMs output
? Baseline,30-year normal (1961-1990)
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2.4.4 Use of output of GCMs
? Some popular used GCMS
Max Plankck Institute fur
Meteorologie(MPIfM),ECHAM4/OPYC3
Hadley Centre for Climate Prediction and
Research(HCCPR),HADCM3
Australia’s Commonwealth Scientific and
Industrial Research Organisation(CSIRO),
CSIRO-Mk2
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2.4.4 Use of output of GCMs
National Centre for Atmospheric
Research(NCAR),NCAR-CSM,NCAR-
PCM
Geophysical Fluid Dynamics
Laboratory(GFDL),R30
Canadian Center for climate Modelling and
Analysis(CCCma),CGCM2
Center for climate System Research( CCSR)
National Institute for Environmental
Studies (NIES),CCSR/NIES
AGCM+CCSR OGCM
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2.4.4 Use of output of GCMs
? Data availability
http://www.nrcs.usda.gov
http://www.ncdc.noaa.gov
http://ipcc-ddc.cru.uea.ac.uk
http://www.cru.uea.ac.uk
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Homework 2,GCMs
? Self study
1,HadCM3--Coupled atmosphere - Ocean general
circulation model
2,CCSM (Coupled Model) Releases
3,Models--The Second Generation Coupled
Global Climate Model (CGCM2)
4,CSIRO Climate change output
5,Parallel Climate Model Effort (Version 1)
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Thanks!
Chapter 2
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Cl
im
ate
Sys
tem
Back
Chapter 2
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Global Radiation Process
back
Chapter 2
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Comparison of absorbed solar radiation,
observed and calculated
back
Chapter 2
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Seasonal radiation budget for the
atmosphere-earth system(Rs)
back
Chapter 2
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Global Reflectivity
back
Chapter 2
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Absorbed solar radiation for the
atmosphere-earth system
back
Chapter 2
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Emitted/terrestrial radiation from
the atmosphere-earth (F?)
back
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Annual average radiation budget for the
atmosphere-earth system (Rs)
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Radiation budget for the atmosphere-
earth system (Rs) during Dec-Feb
Chapter 2
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Radiation budget for the atmosphere-
earth system (Rs) during Jun-Aug
back
Chapter 2
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Radiation budget for the earth surface (Rg)
back
Chapter 2
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Back
Chapter 2
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Back
Chapter 2
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Changes of greenhouse gas concentrations in the
atmosphere since 1750 by human activities
Back
Chapter 2
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The radiative forcing of the climate system since 1750
by gases,aerosol articles,and solar variation Back
Chapter 2
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Climate scenario development Back
Chapter 2
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2.1 Climate System
An example,
Processes of climate/change impact
Land
Water
Ecosystem
Disasters
Agriculture
Desertification
Degradation
Quantity
Quality
Diversity
Biomass
Wetland
Floods/droughts
Frost,etc,
Productivity
Soil erosion
Climate
2012-3-21 Assessment of climate/change impacts 1 of 71
Chap,2 Climate and Its Change
--Background Knowledge
2.1 Climate and climate system
2.2 Climate changes
2.3 Climate models and its applications
Chapter 2
2012-3-21 Assessment of climate/change impacts 2 of 71
Chap,2 Climate and Its Change
--Background Knowledge
2.1 Climate and climate system
2.1.1 Understanding of climate
2.1.2 Climate system
2.1.3 Processes in climate system
Chapter 2
2012-3-21 Assessment of climate/change impacts 3 of 71
2.1.1 Understanding of Climate
古典气候学 现代气候学
研究对象 气候因子 气候系统
研究内容 气候状态 气候变化
研究方法 描述、统计 定量、模型
观测手段 地面、高空观测 气象卫星
时间尺度 100-104年 100-109年
空间尺度 局地、全球 局地到全球连续
Chapter 2
2012-3-21 Assessment of climate/change impacts 4 of 71
2.1.2 Climate System
1,Definition of a system
现代汉语辞典,同类事物 按一定的 关系 组成的
整体 。
物理学,各成分 按某种 方式 合成一个 整体协同
动作 （ 质量 /能量 ） 。
2,Classification of a system
Isolated system
Close system
Open system
Cascade system
Chapter 2
2012-3-21 Assessment of climate/change impacts 5 of 71
2.1.2 Climate System
3,Definition of climate system
Interactions of 5 major components
? the atmosphere,greenhouse effect
? the hydrosphere,water cycle,heat regulator
? the cryosphere,high reflectivity,low thermal
conductivity and inertia
? the land surface,radiation,thermal,hydrological,
dynamic
? the biosphere, carbon cycle,climate indicator
Chapter 2
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2.1.2 Climate System
Examples of interactions/processes
Atmosphere-ocean,heat,water,dynamic
Land use/cover change –atmosphere,radiation,
water,heat
Biosphere-atmosphere, carbon cycle,
indicator
Chapter 2
2012-3-21 Assessment of climate/change impacts 7 of 71
4,Nature of a climate system
Temporary scale,pp.8-11
? Kinetic energy,5 days
? Latent heat,11 days
? Internal energy,3 months
References,
林本达，黄建平, 动力气候学引论，气象出版社，
1994,pp8-11
Chapter 2
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2.1.2 Climate System
4,Nature of a climate system
? Thermal energy budget
? Dynamical movement,boundary
? Hydrological water circulation
? Chemical carbon circle
Chapter 2
2012-3-21 Assessment of climate/change impacts 9 of 71
Thermal features of components
Mass
(t)
Specific
heat
(J/kg oC)
Heat
capacity
(MJ/oC)
Atmosphere 5.3*1015 103 5.3*1015
Hydrosphere 8.7*1016 4.19*103 36.45*1016
Land
surface
3*1015 0.79*103 2.38*1015
Ratio of mass,1:16.4:0.55
Ratio of heat capacity,1:68.8:0.45
Chapter 2
2012-3-21 Assessment of climate/change impacts 10 of 71
2.1.3 Processes in climate system
1,Energy budget in climate system
? Radiation budget
? Radiative forcing for climate change
? Observed global radiation budget
? Energy budget
2,Ocean-atmosphere,ENSO
3,Land surface-atmosphere
4,Chemical Processes
Chapter 2
2012-3-21 Assessment of climate/change impacts 11 of 71
Radiation budget
Ra = F? - F? = qa + a·Fo - F?a
Rg = F? - F? =(1-?)(D+S)-Fo
Rs = F? - F? =(1-?)(D+S)+qa-F?
Chapter 2
2012-3-21 Assessment of climate/change impacts 12 of 71
Radiative forcing for climate change
? GHGs effects
? Tropospheric Ozone
? Tropospheric Aerosols
? Land-use Change (Albedo Effect)
? Solar Forcing
Chapter 2
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Radiation budget
? incoming,100%
? reflected,26%+4%=30%
? absorbed,20% +50% =70%
? outgoing,(38%+26%)+6%=70%
Chapter 2
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Observed global radiation budget
Seasonal change
? Comparison of absorbed solar radiation,
observed VS calculated
? Global radiation budget for atmosphere-
earth system(Rs)
Chapter 2
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Observed global radiation budget
(2) Spatial distributions
? Atmosphere-earth system
Reflectivity
Absorbed solar radiation (short wave)
Emitted/terrestrial radiation(F?) (long wave)
Radiation budget(Rs),annual average
Dec-Jan
Jun-Aug
Chapter 2
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Observed global radiation budget
(2) Spatial distributions
? The earth surface,
radiation budget (Rg)
Chapter 2
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Understanding of Greenhouse Effects
Observed,
Global average temperature,14oC
Question,
How does greenhouse effect maintain it?
Chapter 2
2012-3-21 Assessment of climate/change impacts 18 of 71
Understanding of Greenhouse Effects
? Absorbed solar radiation,
342-107(30%)=235 W/m2
? Based on Stefen-Boltzman’s law
T= -19oC
? Balance of incoming/outgoing energy
with altitude,5km(-19oC)
Chapter 2
2012-3-21 Assessment of climate/change impacts 19 of 71
Understanding of Greenhouse Effects
Explanation,
The decreasing temperature with height
The greenhouse effects
Chapter 2
2012-3-21 Assessment of climate/change impacts 20 of 71
Energy budget
Ideal surface,
Rg - LeE - P - A - M = 0
Rg– net radiation
LE– latent heat
P– sensible heat
A– heat exchange downwards into soil
M– heat used for snow or ice melt
Chapter 2
2012-3-21 Assessment of climate/change impacts 21 of 71
Energy budget
Bowen Ratio（ 1926）,
Ｂ ＝ Ｐ／ LeE
LE– latent heat
P– sensible heat
Chapter 2
2012-3-21 Assessment of climate/change impacts 22 of 71
2,Ocean-atmosphere
Act on the ocean,
? dynamical
Act on the atmosphere
? LE– latent heat
? P– sensible heat
References,
林本达，黄建平, 动力气候学引论，气象出版社,1994
Chapter 2
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3,Land surface-atmosphere
Act on the atmosphere
? Dynamical
? LE– latent heat
? P– sensible heat
? Matter
References,
林本达，黄建平, 动力气候学引论，气象出版社,1994
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4,Chemical processes
1,Composition of the atmosphere
2,Greenhouse Gases
3,Climate effects of GHGs
References,
林振山，杨修群, 理论气候学，南京大学出版社,1995
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2.2 Climate changes
2.2.1 Temporary scales
2.2.2 Observed climate changes
2.1.3 Causes of climate changes
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2.2.1 Temporary scales
1,Seasonal,atmosphere
2,Annual,atmosphere
ocean
3,Longer,crysphere
land surface
References,
林本达，黄建平, 动力气候学引论，气象出版社，
1994,28-30
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2.2.1 Temporary scales
1,Pre-instrumental period
? The past Millennium
? Changes across the last 500,000 years
2,Instrumental record period
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2.2.1 Observed climate variability
and change
1,Measured data
? in situ observation
? space-based observation
2,Proxy data
? ice-core
? deep-sea sediment
? speleothem,coral and lake level data,
? tree rings and varved lake records
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Global Climate Observation System
(GCOS)
? Atmosphere (GCOS),variables(upper/surface),
components,radiation
? Ocean (GOOS),variables(air,ocean--
temperature,level,salty,current,carbon
exchange)
? Terrestrial (GTOS),hydrosphere,cryosphere,
biosphere (ecosystem)
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Observed climate variability and
change
? Climate changes
near surface temperature
precipitation
water vapor
? Climate variability
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3,Changes in surface temperature
--from the instrumental record
? Global surface temperatures have increased by
0.6oC since the late 19th century,with 95%
confidence limits of near 0.4 and 0.8oC,
? Most of this increase has occurred in two periods,
about 1910-45 and since 1976,and the largest
recent warming is in the winter extratropical
Northern Hemisphere,
? The rate of temperature increase in 1976-99 is
0.19oC/decade,slightly higher than the rate of
warming between 1910-45,
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2,Changes in surface temperature
--during the past Millennium
? Rate and duration of the warming in the 20th
century is likely to have been the largest in the last
1000 years,
? The 1990’s are likely to have been the warmest
decade of the millennium in the Northern
Hemisphere and 1998 is likely to have been the
warmest year,
? There remains insufficient evidence to show that
the Little Ice Age and Medieval Optimum were truly
global,However,reconstructed average Northern
Hemisphere temperatures do show a broad
minimum during the Little Ice Age,and a relatively
warm period during early medieval times,but still
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2,Changes in surface temperature
--across the last 500,000 years
? It is likely that large and rapid decadal temperature
changes occurred during the last glacial and its
deglaciation (between about 100,000 and 10,000
years ago),particularly in higher latitudes of the
Northern Hemisphere,
? Changes locally may have been as large as 7oC in
a few decades in the last deglaciation,During the
same period there is evidence of less pronounced
changes that are worldwide and nearly
synchronous,except in high southern latitudes,
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2,Changes in surface temperature
--across the last 500,000 years
? New evidence has been found from the Antarctic
ice cores of almost in phase changes of
temperature,carbon dioxide and methane through
the ice age cycles further into history (420,000 BP),
? During the last 10,000 years smaller,but locally
quite large climate changes occurred and such
changes are also likely to have occurred in the last
interglacial,It is likely that rapid changes of
atmospheric and ocean circulation can occur
during interglacial periods,affecting regional
climate,without human interference,
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2,Changes in precipitation
-- from the instrumental record
? Instrumental records of land surface
precipitation continue to show an increase in
much of the Northern Hemisphere mid and high
latitudes,but over much of the tropical land
areas conditions have become drier,However,
other indicators suggest that large parts of the
tropical oceans have become wetter in recent
decades,
? Where available,changes in annual streamflow
usually relate well to changes in total
precipitation,
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2,Changes in water vapor
-- from the instrumental record
? A pattern of overall surface and lower
tropospheric water vapour increases over
the past few decades is emerging,although
there are likely to be some time-dependent
biases in these data and regional variations
in trends,The more reliable data sets show
that it is likely that total atmospheric water
vapour has increased several percent per
decade over many regions of the Northern
Hemisphere since the early 1970’s,
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2.3 Causes of climate changes
2.3.1 Driving forces
2.3.2 Radiative forcing
2.3.3 General circulation variations
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2.3.1 Driving forces
1,External forcing
2,Internal forcing
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2.3.2 Radiative forcing
1,Greenhouse gases
? CO2(30%),CH4(150%),N2O
(16%),
? Anthropogenic aerosols
? O3
2,Solar radiation
3,Volcanic action
4,Land use/cover change
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Definition of radiative forcing
The term,radiative forcing” has been
employed in the IPCC Assessments to
denote an externally imposed perturbation
in the radiative energy budget of the Earth’s
climate system,
?=?Ts/?F
0.5 K/(Wm-2)
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Results of radiative forcing
? GHGs,positive radiative forcing
? Anthropogenic aerosols,negative
radiative forcing,but many aspects
uncertain
? Total net radiative forcing is positive
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2.3.3 General circulation variations
Changes in Atmospheric / Oceanic
Circulation
ENSO
? The behaviour of the El Ni.o-Southern
Oscillation (ENSO),which causes
droughts or floods in many parts of the
world,has been unusual since the mid-
1970s,Warm (El Ni.o) episodes have
been relatively more frequent or
persistent than the opposite (La Ni.a)
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2.3.3 General circulation variations
??This recent behaviour of ENSO is related
to variations of precipitation over the
tropical Pacific and surrounding land
areas (e.g.,the relatively low rainfall over
many subtropical land areas in the last
two decades),as well as to warmth in the
tropics and subtropics and to a mixture of
coolness and warmth in some other
regions,The overall effect is likely to have
been a small contribution to global
warmth,
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2.3.3 General circulation variations
2.NAO/AO/AAO
? The winter North Atlantic Oscillation (NAO)
and the associated Arctic Oscillation (AO),
show decadal to multidecadal variability,
Since the 1970s the NAO/AO has been in
a phase that gives stronger westerly winds
over much of extratropical Eurasia in the
winter half year,This is associated with
cold-season warming over Eurasia,
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2.3.3 General circulation variations
? The Antarctic Oscillation (AAO) has
been in an enhanced positive phase in
the last 15 years,with stronger
westerly winds over the Southern
Ocean,
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2.4 Climate models and its
applications
2.4.1 Introduction
2.4.2 Projections of future climate change
2.4.3 Climate scenario development
2.4.4 Use of output of GCMs
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2.4.1 Introduction
1,Energy balance model (EBM)
2,Radiation-convection model (RCM)
3,Zonal average dynamical model
(ZADM)
4,General circulation model (GCM)
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2.4.2 Projections of future climate change
? The mean and standard deviation of this
quantity from 17 mixed layer models used
in the SAR is 3.8° C and 0.78° C,
respectively,
? The same quantities from 10 more recent
models is 3.3° C and 0.82° C,
? These quantites are model dependent to a
certain extent and we see no reason to
change the previous estimated range for
this quantity widely cited as 1.5 to 4.5° C,
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2.4.3 Climate scenario development
? Processes for scenario projections
? Climate scenario and climate
change scenario
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Processes for scenario projections,
? Social/economic development
population,growth rate,GDP (SAR)
7 fields
? Land use/cover change,policy
? Environment,6 fields
? Climate
? Sea-level rise
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Climate scenario and climate change
scenario
? Methods,
Incremental for sensitivity analysis
Analogue (temporal and spatial)
Use of GCMs output
? Baseline,30-year normal (1961-1990)
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2.4.4 Use of output of GCMs
? Some popular used GCMS
Max Plankck Institute fur
Meteorologie(MPIfM),ECHAM4/OPYC3
Hadley Centre for Climate Prediction and
Research(HCCPR),HADCM3
Australia’s Commonwealth Scientific and
Industrial Research Organisation(CSIRO),
CSIRO-Mk2
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2.4.4 Use of output of GCMs
National Centre for Atmospheric
Research(NCAR),NCAR-CSM,NCAR-
PCM
Geophysical Fluid Dynamics
Laboratory(GFDL),R30
Canadian Center for climate Modelling and
Analysis(CCCma),CGCM2
Center for climate System Research( CCSR)
National Institute for Environmental
Studies (NIES),CCSR/NIES
AGCM+CCSR OGCM
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2.4.4 Use of output of GCMs
? Data availability
http://www.nrcs.usda.gov
http://www.ncdc.noaa.gov
http://ipcc-ddc.cru.uea.ac.uk
http://www.cru.uea.ac.uk
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Homework 2,GCMs
? Self study
1,HadCM3--Coupled atmosphere - Ocean general
circulation model
2,CCSM (Coupled Model) Releases
3,Models--The Second Generation Coupled
Global Climate Model (CGCM2)
4,CSIRO Climate change output
5,Parallel Climate Model Effort (Version 1)
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Thanks!
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Cl
im
ate
Sys
tem
Back
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Global Radiation Process
back
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Comparison of absorbed solar radiation,
observed and calculated
back
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Seasonal radiation budget for the
atmosphere-earth system(Rs)
back
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Global Reflectivity
back
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Absorbed solar radiation for the
atmosphere-earth system
back
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Emitted/terrestrial radiation from
the atmosphere-earth (F?)
back
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Annual average radiation budget for the
atmosphere-earth system (Rs)
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Radiation budget for the atmosphere-
earth system (Rs) during Dec-Feb
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Radiation budget for the atmosphere-
earth system (Rs) during Jun-Aug
back
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Radiation budget for the earth surface (Rg)
back
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Back
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Back
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Changes of greenhouse gas concentrations in the
atmosphere since 1750 by human activities
Back
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The radiative forcing of the climate system since 1750
by gases,aerosol articles,and solar variation Back
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Climate scenario development Back
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2.1 Climate System
An example,
Processes of climate/change impact
Land
Water
Ecosystem
Disasters
Agriculture
Desertification
Degradation
Quantity
Quality
Diversity
Biomass
Wetland
Floods/droughts
Frost,etc,
Productivity
Soil erosion
Climate
