Climate Modeling: MEA-719 DATE OF EXAM: MAY 05, 2003 TIME OF EXAM: 9-11am REVIEW FOR FINAL EXAM.

Climate Modeling: MEA-719

DATE OF EXAM: MAY 05, 2003TIME OF EXAM: 9-11am

REVIEW FOR FINAL EXAM

Grading scheme

• Homework assignments: 20%

• Mid-term test: 20%

• Final exam: 30%

• Term paper: 30% (10%o/20%w)

Organization of the Course

Course divided into the following components ~

• International climate research organizational structure • Climate models• Climate model predictions (SIP; Paleo climate; CC projections)• Climate modeling (observational)• Climate modeling (prediction)• Climate modeling applications (end-user)

Main Topics Covered

TOPIC 1: International organization of climate research and applications programs

TOPIC 2: SESONAL-TO-INTERANNUAL VARIABILITY & PREDICTABILITY OF THE GLOBAL OCEAN-ATMOSPHERE-LAND SYSTEM (GOALS)~observations-diagnosis-models-applications

• ENSO (G1) • VARIABILITY OF THE ASIAN-AUSTRALIAN MONSOON SYSTEM (G2)• VARIABILITY OF THE AMERICAN MONSOON SYSTEM (VAMOS-G3)• VARIABILITY OF THE AFRICAN CLIMATE SYSTEM (VACS-G4)

TOPIC 3: DECADAL TO CENTENNIAL TIME SCALES (DecCen)

• NORTH ATLANTIC OSCILLATION (D1)• TROPICAL ATLANTIC VARIABILITY(D2)• ATLANTIC THERMOHALINE CIRCULATION (D3)

TOPIC 4: ANTHROPOGENIC CLIMATE CHANGE • CLIMATE CHANGE PREDICTION (A1)• CLIMATE CHANGE DETECTION AND ATTRIBUTION (A2)

Chronology of Lectures for MEA-719

• Lecture Notes for Lecture 1: Introduction• Lecture Notes for Lecture 2: International organization of global climate research

programs• Lecture Notes for Lectures 3 & 4: Climate models (global and regional)• Lecture Notes for Lecture 4: Methods for solving Model Equations• Lecture Notes for Lecture 5: Spectral Method for solving Model Equations• Lecture Notes for Lecture 6: Semi-Lagrangian Method for solving Model Equations• Lecture Notes for Lecture 7: Model Skill in Predicting ENSO• Lecture Notes for Lecture 8: Value and Skill of Climate Prediction Models• Lecture Notes for Lecture 9: African and European Climate Variability• Mid-term exam• Lecture Notes for Lecture 10: EOF Method• Lecture Notes for Lecture 11: Asian Summer Monsoon• Lecture Notes for Lecture 12: Variability of the American Monsoon System (VAMOS)• Lecture Notes for Lecture 12: Variability of the American Monsoon System (VAMOS)-

supplement• Lecture Notes for Lecture 13: Anthropogenic Climate Change (ACC)• Lecture Notes for Lecture 14: Review for MEA-719

Guiding Questions

Should be familiar with all the guiding questions given at the beginning of the class notes for each major course topic

International organization of climate programs

• Basic structure of the CLIVAR- World Climate Research Program - WCRP (see schematic diagram

• Scientific functions of each principal component

Organization

• WCRP – oversees coordination of several key areas of climate variability

• CLIVAR – oversees co-ordination of the physical component of climate variability

• Components (or Panels) – each has an agenda, typically about 12 experts from all around the World, provide guidance to the international climate community in its particular area

Methods of Model and Observational Data Analyses

(i) Time evolution of the anomalies(ii) EOF method(iii) Time series & pattern correlation analysis(iv) Root mean square error analysis(v) Hit/false alarm rates (& ROC)(vi) Decision modeling (added value)

EOF Method

Need to be familiar with the primary steps for implementing the EOF method

Main Steps for Implementing EOF Method

1. Construction of standardized data matrix

2. Construction of covariance or correlation matrix (R)

3. Solve characteristic equation for the covariance/correlation matrix to obtain eigen value/eigen vector pairs

4. Determine cutoff for “noise” & signal E0Fs. A rule of thumb is to retain only those components with variance () greater than one or that explain at least a proportion 1/p of the total variance. This rule doesn’t always work & more sophisticated criteria exist.

Main Steps (continued)

5. Plot (i) Histogram for eigen values & separation between ‘noise’ & ‘signal’ modes may show

(ii) E0F patterns for dominant modes(iii) E0F time series for dominant modes

6. If needed reconstruct data matrix by combining contribution of a subset of eigen modes. This is one way of filtering the original data set by ignoring the ‘noise’ modes

Construction of E0F Time series

1 rp1

rp1 1

Correlation =Matrix =Data

iH eigen vector of R Matrix

ei1,ei2 ,...,eip Z1k

Zpk

= amp(E0Fi t k)

e i1Z1k e i 2Z2k ei 3Z3k eip Zpk

data map at t=k(k Column)k ie

Z11 Z1k Z1n

Zp1 Zpk Zpn

t:=1

t:=1

t:=n

t:=n

t:=nt:=k

amp (E0Fi , t=k)

E0Fi , amp 1Var=1

E0Fi , ampi

Var=i

E0Fi , ampp

Var=p

.

Patterns

Decision Models

(i) Derivation of simple decision model

(ii) Main assumptions (concept of ensemble forecasting)

(iii) Interpretation extreme conditions

Palmer’s Decision ModelUSER SECTOR MODEL HINDCAST MET. OBS

Define (E)Identity C & L

Forecast (E)Specify (Pt)

Obs (E)Compute

o (E)

OCCURANCE

Fst No Yes No Yes

Region 1

Region 2

Region 9ROC

Hit rate H / False alarm F

Perfect

Mper o CL

oL

CoHo

L

CFM

11

Climatology

MCli minCL

,o

HF

V pt MCli M

MCli Mper

Vopt max V

Savings$ MCli Mopt NL

DECISION IF $ ISIMPORTANT TO SECTOR

See fig.

See fig.

Models

- AGCMs/OGCMS/AOGCMS

- Vorticity equation model

(i) Basic assumptions, (ii) terms in governing equations, and (iii) simple numerical schemes (in class reviewed centered differencing scheme)

…difference between Spectral & Finite Difference Methods…

Finite Difference Method

• Local such that represents the value of

at a particular point in space

• Finite difference equations determine the evolution

Spectral

Method• Based on global functions

• Basis functions determine the amplitudes and phases such that when summed up determine spatial distribution of dependant variables

nm,

,

Mathematical forms and main properties of basic numerical schemes

- eulerial- semi-Lagrangian- explicit- semi-implicit

Building blocks of simple spectral barotropic model and main components of typical

prediction cycle

kj

kj

,

,

2

2

,A

tt

tt

ddAYA

2

0

1

1

* ,4

1

1

2

3

4

,,, Ytt

Anntitt

11 A

kjA ,

Interannual & Decadal Variability

• Climatology - Global annual cycle (e.g., rainfall)

• Variability (& mechanism where known) for all primary regions - location of dominant signal

• Model capabilities and deficiencies based on model vs observations) with emphasis on the following:

: ENSO: AA-Monsoon: VAMOS (North America): Europe: Africa

Current performance of models for ENSO

• (i) Both statistical and dynamical models produce useful tropical SSTA forecasts for the peak phase of ENSO up to two seasons in advance.

• (ii) A consensus forecast (i.e. an ensemble across prediction systems) is remarkably skillful, whereas an ensemble of realizations of a single prediction system improves the skill only marginally.

• (iii) The periods of retrospective forecasting are too short in terms of distinguishing between the skill scores of the various prediction systems.

• (iv) Models predict the sign of extreme events well, but sometimes predict warm or cold events when the observations call for normal conditions.

• (v) Consistency among forecasts initialized one month apart is not a good a priori measure of forecast skill.

Current performance of models for the AA-Monsoon

- Models have smaller pattern correlations and larger rmsd relative to the observational uncertainty

- The errors among the models are larger than the uncertanity in the observations

EOF-1: associated with the northward shift of the Tropical Convergence Zone (TCZ)

EOF-2: associated with the southward shift of the Tropical Convergence Zone (TCZ)

• Models are realistic in their representation of EOF-2• Discrepancies east of 100E• Models fail to capture extension of enhanced rainfall to the

South China Sea where the EOF-2 mode is deficient

Different strategies of using models to understand climate variability

• Africa

• South America

• Asia

• Should be familiar with the main steps involved in the assessment of the understanding of climate change, including how scenarios of human activities can cause such changes, future projections

•Current state of understanding for @ step

Climate Change

Summary of IPCC Assessment

Activities

Familiarity with Sequence of

activities

KEY FINDINGS

Palaeoclimatic reconstructions for the last 1,000 years indicate that the 20th century warming is highly unusual, even taking into account the large uncertainties in these reconstructions

Observations vs Observations

KEY FINDINGS

The observed warming is inconsistent with model estimates of natural internal climate variability. It is therefore unlikely (bordering on very unlikely) that natural internal variability alone can explain the changes in global climate over the 20th century

Observations vs Models (natural variability)

KEY FINDINGS

The observed warming in the latter half of the 20th century appears to be inconsistent with natural external (solar and volcanic) forcing of the climate system.

Observations vs Models (with external forcing)

KEY FINDINGS

Anthropogenic factors do provide an explanation of 20th century temperature change.

Observations vs. Models (with external forcing)

KEY RESULTS

• SAR-1995: Concluded that, “… The balance of evidence suggests that there is discernable human influence on global climate…”

• TAR-2001: Concluded that, “… There is new & stronger evidence that most of the warming observed over the last 50 years is attributable to human activities …”

MEA-719 Term Paper Assignment May/01/2003

Write a report on the following climate aspects for the country assigned to you.

• Geographical location and features of the country• National meteorological observational network• Main characteristics of the mean climatic conditions• Dominant modes and sources of climate variability• Performance of current dynamical models in simulating and predicting the climate?• Deficiencies of dynamical models that account for inadequacies in the simulation of climate?• How well the climatic impacts of the 2002/2003 ENSO were predicted for your country• National climate research programs• Involvement in international climate programs

The report should not exceed 6 pages of text and 2 pages of diagrams. The report should have a one paragraph summary, an introduction, main body of the text, conclusions, and references. The deadline for submitting the reports is May/01/2003. You will be expected to give a power point presentation on May/01/2003. The countries will be assigned in a ballot.

Give all references and sources of your information (not part of page limit)

Your search for information may include (i) the CLIVAR WebPages for country summaries [http://www.clivar.org/publications/other_pubs/clivar_conf/clivar_conf.htm#NAT], (ii) publications and websites referenced in the course, and (iii) other sources.

Find 2 examples of previous years power point presentations generated by graduate students, at the course webpage. Note that the specific of the example assignments were different. These examples are meant only to give you some appreciation of the scope and quality of power point presentation that is expected.

Country Assignments

• (1) Chenjie Huang: Tanzania

• (2) Ryan Boyles: India

• (3) Katie Robertson: Canada

• (4) Shu-Yun Chen: Argentina

Schedule for Term Paper Oral Presentation

15 minutes @ presentation May 01, 2003, 11.20-12.35

(1) Chenjie Huang: 11.20-11.35Break: 5 minutes

(2) Ryan Boyles: 11.40-11.55Break: 5 minutes

(3) Katie Robertson: 12.00-12.15Break: 5 minutes

(4) Shu-Yun Chen: 12.20-12.35

Note: The deadline for submitting the term paper write-up reports is May/01/2003