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Atmospheric Physics @ TU Delft Stephan de Roode, Harm Jonker clouds, climate and weather air quality...
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Transcript of Atmospheric Physics @ TU Delft Stephan de Roode, Harm Jonker clouds, climate and weather air quality...
Atmospheric Physics @ TU Delft
Stephan de Roode, Harm Jonker
clouds, climate and weather air quality in the urban environment energy
Conservation equations
€
dρdt
+ρ∂u j
∂x j
= 0Mass
€
du i
dt= −δ i3g −
1ρ
∂p∂x i
+ ν∂2u i
∂x j2
+Sother forcesMomentum"Navier Stokes"
€
dq
dt= ν q
∂2q
∂x j2
+Sevap/cond rainWater
Heat
€
dθdt
= ν θ∂2θ
∂x j2
+Sradiation +Sevap/cond
Clouds & ClimateLandsat satellite 65 km
10 kmLarge Eddy Model
~mm ~100m~1mm-100mm
Earth ~13000 km
Cloud dynamics
10 m 100 m 1 km 10 km 100 km 1000 km 10000 km
turbulence Cumulus
clouds
Cumulonimbus
clouds
Mesoscale
Convective systems
Extratropical
Cyclones
Planetary
waves
Large Eddy Simulation (LES) Model
Limited Area Weather Model (LAM)
Numerical Weather Prediction (NWP) Model
Global Climate Model
The Zoo of Atmospheric Models
DNS
mm
Cloud microphysics
Fundamental Engineering
Cloud dynamics
10 m 100 m 1 km 10 km 100 km 1000 km 10000 km
turbulence Cumulus
clouds
Cumulonimbus
clouds
Mesoscale
Convective systems
Extratropical
Cyclones
Planetary
waves
Large Eddy Simulation (LES) Model
Current developments
DNS
mm
Cloud microphysics
Limited Area Weather Model (LAM)
Global Climate Model
Numerical Weather Prediction (NWP) Model
Fundamental Engineering
Cloud dynamics
10 m 100 m 1 km 10 km 100 km 1000 km 10000 km
turbulence Cumulus
clouds
Cumulonimbus
clouds
Mesoscale
Convective systems
Extratropical
Cyclones
Planetary
waves
Large Eddy Simulation (LES) Model
The Zoo of Atmospheric Models
DNS
mm
Cloud microphysics
Limited Area Weather Model (LAM)
Global Climate Model
Numerical Weather Prediction (NWP) Model
Harm Jonker
Stephan de Roode
Pier Siebesma (KNMI/TUD)
Computing the weather
Wien’s law:
)(I
Stefan-Boltzmann
4
0
Td)(I
4T
1e
1ch2)(I
kT/hc5
2
Km10898.2T 3max
Planck:
K/J1038.1k
Js10625.6h
s/m103c
23
34
8
€
=5.67⋅10−8 Wm-2K -4
Solar radiation
UV image of the sun source: SOHO EIT
The sun
Surface temperature Tsun = 5778 KRadius Rsun = 6.96342×105 km
Total energy production:
Q = sTsun4 x 4pRsun
2 = 3.85×1026 W
energy emitted (W/m2)
total surface area (m2)
Solar constant S0 : flux of solar energy at the top of the Earth's atmosphere
Distance RE-S= 1.496×1011 m
Energy conservation: Flux integrated over the imaginairy surface area of a sphere centered around the sun is constant
=>
Q = sTsun4 x 4pRsun
2 = S0 x 4pRE-S2
€
S0 = σTsun4 Rsun
RE−S
⎛
⎝ ⎜
⎞
⎠ ⎟
2
= 1367 W/m2
Radiative equilibrium for an Earth without an atmosphere
Radiative equilibrium temperature
€
a2 1−α p( ) S0 = 4πa2 σTe4
ap = Earth surface albedo
€
Te =1−α p( ) S0
4σ
⎡
⎣ ⎢
⎤
⎦ ⎥
1/4
Fraction of solar radiation absorbed by the Earth = Radiation emitted by the Earth
Radiative Earth equilibrium temperature (no atmosphere)
sea
land
ice
snow
mea
n al
bed
o E
arth
real mean Tearth = 288 K
€
Te =1−α p( ) S0
4σ
⎡
⎣ ⎢
⎤
⎦ ⎥
1/4
Scattering and absorption
absorption cross section sa:
effective area of the molecule for removing energy from the incident beam
shortwave longwave
scattering cross section ssca
absorption cross section sa
Apply energy balance
4eT
€
S0 / 4
€
asS0 /4
€
Te
€
1−ε( ) σTe4
€
Ta
€
1−α( )σTe4
4aT
4aT
Energy conservation of the system4aT
€
S0 1−as( )/4 = εσTa4 + 1−ε( ) σTe
4
Apply energy balance
4eT
€
S0 / 4
€
asS0 /4
€
Te
€
1−ε( ) σTe4
€
Ta
€
1−α( )σTe4
4aT
4aT
Energy conservation of the system4aT
€
S0 1−as( )/4 = εσTa4 + 1−ε( ) σTe
4
Radiative energy balance of the atmosphere
4e
4a T T 2
Apply energy balance
4eT
€
S0 / 4
€
asS0 /4
€
Te
€
1−ε( ) σTe4
€
Ta
€
1−α( )σTe4
4aT
4aT
Energy conservation of the system4aT
€
S0 1−as( )/4 = εσTa4 + 1−ε( ) σTe
4
Radiative energy balance of the atmosphere
4e
4a T T 2
Radiative equilibrium temperature of the Earth surface
€
Te4 =
S0 1− as( )
4σ 1− ε /2( )
Radiative equilibrium temperature for an Earth with an atmosphere
€
Te =1−as( ) S0
4σ 1−ε /2( )
⎡
⎣ ⎢
⎤
⎦ ⎥
1/4
mea
n em
issi
vity
atm
osph
ere
16°C
enhanced greenhouse effect
Stephens et al., 2012
Clouds in a future climate
Dufresne & Bony, Journal of Climate 2008
Radiative effects only
Water vapor feedback
Surface albedo feedback
Cloud feedback
The playground for cloud physicists: Hadley circulation
deep convection shallow cumulus stratocumulus
Study the evolution of a low cloud deck during its
advection towards the tropics
deep convection shallow cumulus stratocumulus
Study the effects of clouds on the radiation budget with a
high-resolution turbulence model
Clouds are strong reflectors of solar radiation
0
0. 2
0. 4
0. 6
0. 8
1
0 10 20 30 40 50 60
clo
ud
alb
ed
o
c l o u d o p ti c a l d e p th
100 200 300 400 500 c lo u d la y e r th i c k n e s scloud layer geometric thickness [m]
A total amount of about 0.1 mm of liquid water in an atmospheric column is sufficient to reflect 50% of the downward solar radiation
courtesy Kees Floor
stratocumulus
The Eddington (E) Index
Arthur Eddington
(Einstein and Eddington, HBO-BBC co-production, 2008 )
Chandrasekhar (Nobel prize for physics 1983)
(E-Index 84!)
Navier Stokes in DWDD
http://dewerelddraaitdoor.vara.nl/media/308806
Journal papers
writing a paper, how to deal with citations, co-authors?
H-index
peer review
journal impact factor
open access journals
Exercises
22 October: Paper discussions
Stephens et al., 2012: An update on Earth's energy balance in light of the latest global observations, Nature
Geosciences. (group 1 presents, group 2 asks questions)
Stevens and Bony, 2013: Water in the atmosphere, Physics Today. (group 3 presents, group 4 asks questions)
29 October?: One paper, one exercise
Dufresne and Bony, 2008: An assessment of the primary sources of spread of global warming estimates from
coupled atmosphere-ocean models, J. Climate. (group 2 presents, group 1 asks questions)
Exercise on equilibrium state solutions of low clouds. (group 3 presents, group 4 asks questions)