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


Lecture notes


Please indicate this if you want a printed version of the lecture notes

Lecture notes


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 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

zonal mean heating


heating

Total precipitation

Intertropical convergence zone (ITCZ) and “stormtracks”

Total precipitation

Intertropical convergence zone (ITCZ) and “stormtracks”

zonal mean zonal wind, u



What features do you observe???


Subtropical jet; polar night stratospheric jet; Trade winds; What else?


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

Documents

Lecture 1 Atm Dyn 2014