Lecture 1 Atm Dyn 2014
description
Transcript of Lecture 1 Atm Dyn 2014
Dynamic Meteorology (Atmospheric Dynamics)
Lecturer: Aarnout van Delden Assistant: Michiel Baatsen (weather discussions) Office: BBG, room 615 [email protected] http://www.staff.science.uu.nl/~delde102/
Lecture 1 - 2014
Introduction What do you expect of this course? Grading Lecture notes and literature
Grade Grade Exams (2x) on 7/11/2014 (week 45) (24%) and week 5 of 2015 (30/1/2015) (26%) (minimum average grade for 2 exams together should be 5/10) Project 1 (Problem 1.11) (written report1) 12%) (3 October; deadline: Friday 14 November 2014) Project 2 (Problem 1.19) (oral*) (14%) (10 October; (hand in hypothesis on/before 7 November) (oral2) Project 3 Problems 1.21-1.24 and 1.26 (written report1) (12%) (17 October; deadline: Friday 28 November 2014) Problem 3.2 (12%) (second period) Projects 1, 2 and 3 can be performed in couples
1<1000 words 2 15 minutes
*in December 2014 or January 2015
Lecture notes
http://www.staff.science.uu.nl/~delde102/AtmosphericDynamics.htm
Lecture notes On blackboard You can also download them from:
Lecture notes
http://www.staff.science.uu.nl/~delde102/AtmosphericDynamics.htm
Lecture notes
http://www.staff.science.uu.nl/~delde102/AtmosphericDynamics.htm
Please indicate this if you want a printed version of the lecture notes
Lecture notes
http://www.staff.science.uu.nl/~delde102/AtmosphericDynamics.htm
Lecture notes include a list contents, an abstract, a reference list, but not an index…
A good learning method is to make your own index
Schedule Lectures First period Friday 1100-1245 in weeks 37, 38, 39, 40, 41, 42, 43. Second period Friday 1100-1245 in weeks 46, 47, 48, 49, 50, 51, 2, 3, 4
Practical sessions First period Friday 1330-1630 in weeks 37, 38, 39, 40, 41, 42, 43. Second period Friday 1330-1630 in weeks 46, 47, 48, 49, 50, 51, 2, 3, 4
Exams First period week 45 (Friday, November 7, 2014) (retake: December 2014) Second period week 5 (Friday, January 30, 2014) (retake: March 2015)
No lectures on October 31 (week 44) (“BBOS-days”)
Excursion KNMI Not yet set
Fill in the information and answer two questions
2014-2015
Prior knowledge I assume that the student is familiar with the thermodynamic concepts of temperature and pressure of a fluid or gas, and with the conservation laws governing the fluid in a rotating frame of reference.
Prior knowledge I assume that the reader is familiar with the thermodynamic concepts of temperature and pressure of a fluid or gas, and with the conservation laws governing the fluid in a rotating frame of reference.
The first part of course consists of sections 1.1-1.11 and 1.13-1.39. If you have passed the bachelors course Geophysical Fluid Dynamics, you will be familiar with the subject matter of sections 1.1-1.8.
Book
Holton, J.R., 2004: An Introduction to Dynamic Meteorology, fourth edition. Academic Press, 535pp. The first (1972), second (1979) and third (1992) edition are also very useful.
A fifth edition of Holton’s book has appeared in 2012 with Gregory Hakim as co-author.
Central Question
John Dutton has phrased it in the following way.
“The basic problems of atmospheric dynamics revolve around the question of why the observed responses are those that are chosen”
The atmosphere responds to the inhomogeneous distribution of insolation by adjusting to some kind of balance of forces.
insolation [W m-2] La
titud
e[°N
]
>500 W m-2
Radiative energy fluxes and water cycle (2000-2004)
Figure 2.25
Global, annual mean energy fluxes in W m-2
Back to the central Question
John Dutton has phrased it in the following way.
“The basic problems of atmospheric dynamics revolve around the question of why the observed responses are those that are chosen”
The atmosphere responds to the inhomogeneous distribution of insolation by adjusting to some kind of balance of forces.
zonal mean heating
Heating due to absorption of Solar radiation, absorption and emission of long-wave radiation, latent heat release
heating
zonal mean temperature
Cold: why?
zonal mean heating
Heating due to absorption of Solar radiation, absorption and emission of long-wave radiation, latent heat release
heating
zonal mean heating
Heating due to absorption of Solar radiation, absorption and emission of long-wave radiation, latent heat release
heating
Total precipitation
Intertropical convergence zone (ITCZ) and “stormtracks”
Total precipitation
Intertropical convergence zone (ITCZ) and “stormtracks”
zonal mean zonal wind, u
“The basic problems of atmospheric dynamics revolve around the question of why the observed responses are those that are chosen”
zonal mean zonal wind, u
What features do you observe???
zonal mean zonal wind, u
Subtropical jet; polar night stratospheric jet; Trade winds; What else?
zonal mean zonal wind, u
Why does the atmosphere respond to heating in this way?
Polar vortex at 250 hPa
General Circulation
A general circulation model of the northern hemisphere showing the zonal flow dominant in middle and high latitudes (from Climatology (third edition), by J.Hidore, J.Oliver, M.Snow and R.Snow,2010, Prentice Hall).
Weather Map Weather Map
12 Feb.’96, 12 UTC
Analysis of sea-level pressure in hPa shows a depression or cyclone.
Satellite Image
NOAA, channel 4 (infra-red). 12 feb 1996, 1313 UTC
Questions Why does de air rotate anticlockwise? Why does the wind direction change with height? Why does the wind speed change with height? What determines the cloud pattern?
Layered clouds
Puffy clouds
July 25, 2010, 5:24 PM
Conceptual Model Typical flow pattern between two isobaric surfaces (1000 hPa is near the Earth’s surface; 500 hPa is at about 5 km above sea level) in a mid-latitude baroclinically unstable disturbance in the northern hemisphere. The warm air rises along very slanted trajectories, giving rise to layered clouds as shown on the next slide…
What do we want to know about the atmosphere?
Density, ρ (mass) Speed, Pressure, p Temperature, T
Four unknowns
€
v
What do you know about fluid dynamics?
The equations expressing conservation of momentum, mass and energy
The equation of state
Closed system of four equations with four unknowns:
The coordinate system
The equations*
€
d v dt
= −α ∇ p − g ˆ k − 2
Ω × v + Fr
€
dρdt
= −ρ ∇ ⋅ v
€
Jdt = cvdT + pdα
€
pα = RT
momentum
mass
energy
state
*see geophysical fluid dynamics and sections 1.7 and 1.8 of lecture notes
Pressure gradient (1.5) Gravity (1.4) Coriolis (1.6&1.7) Friction (1.3)
Unknowns are:
€
v ,ρ,T , p
€
α ≡1ρ
eqs. 1.4a,b,c
Next week
Reduce these 4 equations to system of 3 equations in terms of:
Potential temperature, θ Exner function, Π
Wind speed
Assignment for next week
Study sections 1.1-1.8
Try the following problems: 1.1, 1.2 and 1.6