Theoretical Tropical...
Transcript of Theoretical Tropical...
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Theoretical Tropical Meteorology
1. Introduction: Earth’s tropical atmosphere and ocean (Nov. 21)2. Conservation laws and basic equations (Nov. 22)3. Atmospheric vertical structure: Radiative convection equilibrium (Nov. 22)4. Mean zonal and meridional circulations (Nov. 23-24)5. Equatorial waves (Nov. 28-29) 6. Convection: Why can’t we predict rainfall? (Nov. 30-Dec. 1) Open seminar: Tropical coastlines controlling global climate (Dec. 2)
Manabu D. YamanakaSenior Staff, DCOP, JAMSTEC / Professor Emeritus, Kobe University
[email protected], [email protected]]
Short-term Expert Training Course on Weather Forecasting I, JICA–Sri Lanka Department of Meteorology Improving of Meteorological Observation, Weather Forecasting & Dissemination
Project, 21 November – 1 December 2016http://aoe.scitec.kobe-u.ac.jp/~mdy/srilanka1611/
Additional reading:- Physical climatology of Indonesian maritime continent: An outline to comprehend observational studies, Atmos. Res., Invited Review Section, 178-179, 231-259. http://www.sciencedirect.com/science/article/pii/S0169809516300679
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http://www.sciencedirect.com/science/article/pii/S0169809516300679
}→ Chapters 1‐3, 6 → Chapters 3‐5
}→ Chapters 5‐6 → Seminar
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Yangon
Bangkok HanoiManila
Kuala Lumpur Singapore JakartaJayapura
Dec‐Jan‐Feb monsoon
Monsoons and rainy seasons
Jun‐Jul‐Aug monsoon
Colombo
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From large-scale viewpoint
From physical/dynamical viewpoint
Similarity, applicability
Difference from mid/high latitudes
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Contents1. Introduction: Earth’s tropical atmosphere and ocean (Nov. 21)2. Conservation laws and basic equations (Nov. 22)3. Atmospheric vertical structure: Radiative-convective equilibrium (Nov. 22)
3.1. Radiative equilibrium3.2. Radiative-convective equilibrium3.3. Moisture effect3.4. Log-pressure coordinate
4. Mean zonal and meridional circulations (Nov. 23-24)4.1. Trade wind (Equatorial easterly)4.2. Potential vorticity conservation and inertial instability4.3. Hadley circulation4.4. Monsoon circulation4.5. Brewer-Dobson circulation
5. Equatorial waves (Nov. 28-29)5.1. Classification of waves in geophysical fluids5.2. Zonal-vertical (Walker) circulation5.3. Atmosphere-ocean interaction: El Nino-southern oscillation (ENSO) and Indian-Ocean dipole mode (IOD) 5.4. Wave-mean flow interaction: Quasi-biennial oscillation (QBO) and semi-annual oscillation (SAO)
6. Convection: Why can't we predict rainfall? (Nov. 30-Dec. 1) 6.1. Sea-land breeze circulation (Horizontal convection)6.2. Conditional instability and clouds (Vertical convection)6.3. Conditional instability of second kind (CISK) and tropical cyclones 6.4. Multiple-scale cloud clusters and intraseasonal variations: Madden-Julian oscillation
Open seminar: Tropical coastlines controlling global climate (Dec. 2)
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http://aoe.scitec.kobe-u.ac.jp/~mdy/srilanka1611/
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1. Introduction: The earth ’s equatorial region
Two aspects of atmospheric-hydrospheric-oceanic science: 1. “Geography”: locality, descriptive → “Tropical meteorology/hydrology/oceanography”2. “Physics”: Generality, theoretical
Recent development- Technical innovation: Network computers and observational instruments- Sustainability (continuous development without environmental damages) - Other planets (including extra-solar planets) ⇒ General consideration
Change of scientific interests Geography by observation scientists; Physics by theoreticians
⇒ Geography by modelers; Observations by physicists
Common (a few) physical principles for atmospheric/hydrospheric/oceanic phenomena atmosphere+hydrosphere+ocean ⇒ climate
Quantitative description and prediction.by mathematics & computers (as tools)⇒ More efficient assessment/operations for environment, disaster , … .
Characteristics of “Equatorial” atmosphere, hydrosphere and oceans- Earth’s rotation axis becomes horizontal → small Coriolis force- Stronger solar heating and weaker annual cycle → hotness and diurnal cycles - Broad ocean → active evaporation, convective cloud generation and latent heating- Wind (around cyclones) makes clouds in extratropics, but clouds make wind in tropics
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Universe: 13.7 billion years
Solar System (Planets):4.5 billion years
Earth with continents, oceans & lives
Sufficient Oxigen and Landing of lives 400 million years
Human beings 5 million years
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Both ∝ (distance)-2, but planetary response is different Gravitation
Radiation
(star)
Two major forcings of star on planet
Balanced with planetary IR cooling・Time scale ≫ rotation
⇒Meridional differential heating・Time scale ~ rotation
⇒Zonal diffrential heatingAtmospheric tides
Balanced with revolutional centrifugal force
Revolutional orbit (Kepler’s laws)⇒ Stellar distance ⇒ Stellar radiation,
annual lengthOceanic tides, planetary tides
(star)
planet
planet
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Sir Isaac Newton (1642 – 1726/27)
(http://www.newton.ac.uk/about/art-artefacts/newton-portrait)
(Gredenberg, 1995)
1298
Principles of Natural Philosophy(1687, 1713, 1726)
Opticks: Or, a Treatise of the Reflexions, Refractions, Inflexions and Colours of Light
(1704)
Geometrical opticsLight wave
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α → 1/sin α = 1/cos Zenith
→ sin α = cos Zenith
n → n2
→ 1/ n2
Geometry of solar radiationRadiation intensity = Energy flux/area
? 倍
? 倍
?
?
(Zenith)
Zenithangle
The distance-2 lawRadiation intensity at a ground with a solar zenith angle α
distance- times times
times
times
times
area
Radiation
zenith area
Radiation
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(Integration (area) → Energy flux intensity)Stefan-Boltzmann’s law
≡
( =5.67 10−8 J s − 1 m − 2 K − 4)
(Differentiation (peak) → Maximum mode wavelength)Wien’s law
μm2897 K
(→ Exercise 1-2)
“Energy(-density) flux” (energy per unit time and unit area) for electromagnetic waves radiated (with unit solid angle and unit wavelength interval) from a “black body” with temperature T:
2exp / 1
( : wavelength, : light speed, : Boltzmann constant, : Planck constant).
(Andrews, 2000, Chapter 3
http://www.gahetna.nl/collectie/afbeeldingen/fotocollectie/zoeken/weergave/detail/start/2/tstart/0/q/zoekterm/Planck
Max Planck (1858-1947) Black Body Radiation Law (1900)
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Electromagnetic waves
EHF SHF UHF VHF HF MF LF VLF
μm 1mm 1cm 10cm 1m 10m 100m 1km 10km 100km1Å 1nm
vacu
um u
ltrav
iole
t
X-r
ay
γ-ra
y
radi
o w
ave
1THz 100 10 1GHz 100 10 1MHz 100 10 1kHz
Frequency
W Ka KuXCS L
30000 3000 300 30 KTemperature
Sun Earth Radars Profilers Radios
Wavelength Frequency = Light Speed = 300,000 km/s
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1 2 5 10 20 50
0
-100
-200
200
Solar Distance (108 km)
100
Earth Mars
Mercury
Venus
Surf
ace
Tem
pera
ture
(ºC
)
Habitable zone with liquid water
UranusSaturn NeptuneJupiter
Titan
· σ · 4 → 4σ ∝ 1
Distance l
radius r
( is the solar constantat the earth at =1 AU)
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Parasol effect(Cooling)
Greenhouse effect
(Warming)
(a)(Trenberth et al., 2009)
(b)
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Lord RayleighJohn William Strutt
(1842-1919)
Lord KelvinWilliam Thomson
(1824- 1907)
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Why sky is blue?Shorter wavelength (violet)
=> Particle (Mie) refraction
Blue color light => Molecule (Rayleigh) refraction
Longer wavelength (green, yellow, red) => Moving straight (sunrise/sunset)
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Rainbow by liquid droplets
(Wallace & Hobbs) (Wallace & Hobbs)
(Gedzelman)
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(Wallace & Hobbs)
(Gedzelman)
Haloby ice crystals
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Lunine (1999)
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1904: Doctorate in civil engineering 1909: Professor of applied math at U. Belgrade (Beogradu) 1912: Noted insolation change by earth’s astronomical motion 1920, 30, & 41: Publication on glacial/interglacial cycles 1924: Evaluation (exceptional) by Kӧppen & Wegener 1958 (aged 79): Died of stroke in Belgrade
Milutin Milanković (1879 –1958)
(http://b.static.trunity.net/files/120401_120500/120456/Milankovitch.jpg)
(Milanković, 1941: Kanon der Erdbestrahlung und Seine Anwendung auf das Eiszeitenproblem; Japanese translation by Kshiwaya et al., 1992)
ඉහළ බැමුම්ஒரு சிறந்த ஸ்பின்
spin a top
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http://xenon.colorado.edu/spotlight/
Climate-Glacier interaction
(Wallace & Hobbs, 2006)
Glacial isostatic adjustment
Almost linear response at ~20 and ~40 ky cycles.
Too week for the major ~100 ky glacier cycles.
Nonlinear climatic response(ice amount) (subsidence)
(subsidence) (ice amount)
⇓(ice amount) (ice amount) 0⇓
(ice amount) cos
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(NASA, 1992)Climate change for recent 1 Myears
Pitecantropes
Toba eruptionLittl
e G
laci
al
Ocean/Continent ~ 7:3 has been conserved for recent 400 Myears
http://www.scotese.com
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(Wegener, 1911: Thermodynamik der Atmosphäre; 松野, 1982より孫引き)
1905: Doctorate in astronomy. Work for aeronomy. . 1910: Conceiving of an idea of “continent drift” 1915: Publication of a book on the idea. Marriage. 1919-23: Paleoclimatology with father-in-law Kӧppen 1924: Professor at University of Glaz 1930 (aged 50): Died during Greenland expedition.
(http://www.bildindex.de/bilder/fm426294a.jpg)
Alfred Lothar Wegener (1880 –1930)
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Volcano ashes transported by stratospheric zonal flow
(Toba 75,000 year ago; … ; Tambora 1816; Krakatau 1883; …. ; Agung 1964; ……)
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Exercise 1 ‐ 1Knowing the solar constant (solar radiation intensity at the top of the atmosphere) as
1370W/m (where 1 W = 1 J/s) and the sun‐earth distance as 1.5 10 m (called 1 AU, or astronomical unit), calculate the following. (1) Earth’s temperature in the simplest radiative equilibrium as considered in the
previous slide. Use the Stefan‐Boltzmann constant: 5.67 10 W m K .(2) Actually about 30% of should be returned to the space (called albedo). Then how
large the equilibrium temperature? What about the difference from actual earth’s temperature?
(3) Estimate equivalent temperature on Venus at 0.728 AU and on Mars at 1.524 AU, and compare it with observational evidence in the previous slide.
(4) Estimate the surface temperature of the sun with the radius 7.0 10 m. (a little lower than the actual value)
ANSWERS: (1) 4σ⁄ ≒ 278K (Note that is taken by AU. F or earth, 1.(2) 1 0.3 ≒ 0.915. 278K 0.915 254K 19ºC (too cold! Green house effect must be considered. → Chap.3)(3) Venus: 1 0.728⁄ ≒ 1.172. 278K 1.172 325K (lower than actual! Due to greenhouse effect)
Mars: 1 1.524⁄ ≒ 0.729. 278K 0.729 202K (4) 7.0 10 m/ 1.5 10 m =4.7 10 AU. 1 4.7 10⁄ ≒ 10.45278K 10.45 2905K (lower than actual; due to neglect of radiation from below the solar surface)
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Exercise 1 ‐ 2Integrating and differentiating Planck’s law (for electromagnetic‐wave energy‐density flux per unit solid angle and unit wavelength interval):
2exp / 1 ,
derive the Stefan‐Boltzmann law (for the total forward radiative energy flux):
≡
and Wien’s law (for the wavelength with maximum intensity): 2897 [μm K]
ANSWER: Assuming isotropy, the upward component is obtained by multiplying cos ϛ, where ϛ, is the zenith angle, and thesold‐angle integral with the upward hemisphere is rewritten as small‐circle integral with 2 sin ϛ ϛ.
2 cos ϛ sin ϛ ϛ/
2 cos ϛ sin ϛ ϛ/
·
In the first integral we put ≡ sin ϛ, and in the second ≡ / . Then ≡ cos ϛ ϛ, and ≡ ⁄ .
2 ·2
1 ≡
The second integral may be obtained by a complex integral as 1⁄ 15⁄ , and the constant becomes
2 ·2
1215 5.67 10 Wm K ,
using the Boltzmann (absolute gas) constant =1.38 10 23 J/K, the Planck constant =6.63 10 34 J s, and the light speed =3.00 108 m/s. Finally, the differentiation of the Planck function is solved numerically as
0 ∴ 5 / 5 ∴ 2857[μm K]