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Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models Renguang Wu Institute of Space and Earth Information Science The Chinese University of Hong Kong Conference on the East Asia and Western Pacific Meteorology and Climate cum Hong Kong Meteorological Society 25th Anniversary 2-4 November 2013, Hong Kong, China Co-authors: Jiepeng Chen, Zhiping Wen

Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

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Page 1: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Evaluation of Precipitation-Surface Temperature

Relationship in IPCC CMIP5 Models

Renguang Wu

Institute of Space and Earth Information Science

The Chinese University of Hong Kong

Conference on the East Asia and Western Pacific Meteorology and

Climate cum Hong Kong Meteorological Society 25th Anniversary

2-4 November 2013, Hong Kong, China

Co-authors: Jiepeng Chen, Zhiping Wen

Page 2: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Why talk about the precipitation-

surface temperature relationship?

• Precipitation (P) and temperature (T) are two

basic quantities directly related to our lives.

• The P-T relationship can help to understand the

physical processes connecting the atmosphere

with ocean and land.

2

Page 3: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Types of P-T correlation

• Positive P-T correlation (ocean): ocean forcing the atmosphere

The P and T variations are related in different ways that

indicate different physical connections between them:

SST warmer

Ta higher

Ps lower

Lower-level convergence

Ascending motion

More precipitation

3

Page 4: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Types of P-T correlation

• Negative P-T correlation (land): atmosphere influencing land

The P and T variations are related in different ways that

indicate different physical connections between them:

More precipitation

(more clouds)

atmosphere

absorbs/reflects more

shortwave radiationless shortwave radiation reaching the surface

lower surface temperature 4

Page 5: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Types of P-T correlation

• Positive P-T correlation (land/winter):

temperature controlling precipitation

The P and T variations are related in different ways that

indicate different physical connections between them:

less moisture in the atmosphere

Lower surface temperature

less precipitation

5

lower air temperature

Page 6: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Why talk about the precipitation-

surface temperature relationship?

• The P-T relationship can help to understand

the physical processes connecting the

atmosphere with ocean and land.

• The performance of the climate models in

the P-T relationship provides information

about whether the physical processes in the

models are realistic, which may be of great

help for understanding the biases that may

appear in P and T variations.

6

Page 7: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Seasonality of P-SST relationship

P-SST correlation P-∂SST/∂t correlationDJF

JJA

Wu & Kirtman 2007

Page 8: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Datasets

• Precipitation (ocean): GPCP V2, 2.5°x2.5° grid,

1979-2010.

• Precipitation and surface air temperature (land):

University of Delaware, 0.5°×0.5°, 1901-2008.

• Sea surface temperature (SST): NOAA Extended

Reconstruction SST V3, 2.0°x2.0°, 1854 to present.

• Precipitation, surface air temperature, and

surface skin temperature: IPCC CMIP5, 17 models.

Page 9: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Focus on year-to-year variations

• P’ = P – Pm

• T’ = T – Tm

• Pm and Tm are multiple-year mean climatology.

• The correlation between P’ and T’ is calculated

for summer months (MJJAS) and winter

months (NDJFM) separately.

Page 10: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Positive P-T correlationNegative P-T correlation

10

Page 11: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Positive P-T correlationNegative P-T correlation

11

Page 12: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Figure 1 Point-wise correlation between observed monthly mean anomalies of

precipitation and surface temperature (surface air temperature over the land and SST

over the ocean) for groups of months of MJJAS (a) and NDJFM (b) during 1979-2005.

• A positive P-T correlation

in the equatorial central-

eastern Pacific Ocean

through the year.

• The P-T correlation in the

tropical western Pacific

warm pool depends on the

season: positive in boreal

winter and negative in

boreal summer.

• Negative P-T correlation

prevails over the

continental land in

summer, whereas positive

P-T correlation is observed

in high-latitude land

regions in winter.

12

Page 13: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Schematic summary of CMIP 5 long-term experiments with tier 1 and tier 2 experiments

organized around a central core. Green font indicates simulations to be performed only by

models with carbon cycle representations. Experiments in the upper hemisphere are

suitable either for comparison with observations or provide projections, whereas those in

the lower hemisphere are either idealized or diagnostic in nature and aim to provide better

understanding of the climate system and model behavior. (Taylor et al. 2012)

This talk

Page 14: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Table 1 Information of the 17 climate models used in the present analysis.

Institute Model Version Resolution

Grid numbers: lon*lat

BCC BCC-CSM1.1 1 128*64

BNU BNU-ESM 20120504 128*64

CCCMA CanCM4 20120207 128*64

NCAR CCSM4 20120213 288*192

CNRM-

CERFACS

CNRM-CM5 20110701 256*128

CSIRO-QCCCE CSIRO-Mk3.6.0 20120318 192*96

LASG-IAP FGOALS-S2.0 1 128*108

NOAA-GFDL GFDL-CM3 20120227 144*90

NASA-GISS GISS-E2-R 20120205 144*90

NIMR-KMA HadGEM2-AO 20120503 192*145

MOHC HadGEM2-CC 20110927 192*145

INM INM-CM4 20111201 180*120

IPSL IPSL-CM5A-LR 20110406 96*96

MIROC MIROC4h 20110729 640*320

MPI-M MPI-ESM-P 20120315 192*96

MRI MRI-CGCM3 20110831 320*160

NCC NorESM1-ME 20120402 144*96

Institute Acronyms

T85(~1.40625°×1.40625°)

C48(2°×2.5°)

1.875°×1.25°

2°×1.5°

T63(~1.875°×1.875°)

T42(~2.8125°×2.8125°)

Page 15: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

NCC NorESM1-ME 20120402 144*96

Institute Acronyms

BCC: Beijing Climate Center, China Meteorological Administration

BNU: College of Global Change and Earth System Science, Beijing Normal

University

CCCMA: Canadian Centre for Climate Modeling and Analysis

NCAR: National Center for Atmospheric Research

CNRM-CERFACS: Centre National de Recherches Meteorologiques/Centre

Europeen de Recherche et Formation Avancees en Calcul Scientifique

CSIRO-QCCCE: Commonwealth Scientific and Industrial Research Organization in

collaboration with Queensland Climate Change Centre of Excellence

LASG-IAP: LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences

NOAA-GFDL: NOAA Geophysical Fluid Dynamics Laboratory

NASA-GISS: NASA Goddard Institute for Space Studies

NIMR-KMA: National Institute of Meteorological Research/Korea Meteorological

Administration

MOHC: Met Office Hadley Centre

INM: Institute for Numerical Mathematics

IPSL: Institut Pierre-Simon Laplace

MIROC: Atmosphere and Ocean Research Institute (The University of Tokyo),

National Institute for Environmental Studies, and Japan Agency for Marine-Earth

Science and Technology

MPI-M: Max Planck Institute for Meteorology

MRI: Meteorological Research Institute

NCC: Norwegian Climate Centre

Page 16: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Taylor diagramTaylor diagram (Taylor 2001) provides a way of quantifying

how well model simulated fields match an observed climate field based on three non-dimensional statistics:

• the ratio of the variances of the two fields: r2 = σ2mod/σ 2obs

(the relative amplitude)

• the correlation between the two fields (R) (the pattern similarity)

• the root-mean-square difference between the two fields (E, which is normalized by the standard deviation of the observed field).

These three statistical quantities are related as follows:

E'2 = E2 - E02 = 1 + r2-2rR (already normalized)

where E0 is the difference in mean, which is often considered separately.

Page 17: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Taylor diagram

The observed field is represented by a point at unit distance from the origin along the

abscissa. All other points, which represent simulated fields, are positioned such that r is the

radial distance from the origin, R is the cosine of the azimuthal angle, and E' is the distance

to the observed point. When the distance to the point representing the observed field is

relatively short, good agreement is found between the simulated and observed fields. In the

limit of perfect agreement, E' would approach zero, and r and R would approach unity.

Taylor diagram displaying

statistical comparisons of

12 model runs’ estimates

with observation of the

West African mean

precipitation pattern for

May to October 2003–

2006. (Xue et al. 2010)

E’

1

r

cos-1R

E'2 = 1 + r2-2rR

The law of cosine

cor lineratio arc

dif arc

Page 18: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Figure 2 The Taylor diagram over the global domain for 17 climate model simulations

compared to the observations during 1979-2005.

• The pattern correlation is better in NDJFM than in MJJAS.

• In both MJJAS & NDJFM, the P-T correlation shows a larger spatial

variability in models than in observations by about 50-60%.

• The BNU has the largest pattern correlation in NDJFM

• The INM has the lowest pattern correlation in both MJJAS & NDJFM.

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Page 19: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Figure 3 The same as Fig. 2 except for the land.

• The pattern correlation is higher in NDJFM than in MJJAS.

• The pattern correlation tends to be larger when the STD is higher

in MJJAS.

• The INM has the lowest pattern correlation, deviating largely

from the other models.

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Page 20: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Figure 4 The same as Fig. 2 except for the ocean.

• Compared to the land, the pattern correlation is smaller and has a larger spread

among the models, and the spatial variability of the correlation is smaller.

• The seasonal dependence of the model performance is not as obvious as over

the land.

• Similar to the land in MJJAS, there is a tendency that a larger pattern correlation

corresponds to a higher STD in both MJJAS and NDJFM.

• The BNU performs the best and the MRI model is the worst in both MJJAS and

NDJFM based on the pattern correlation.

20

Page 21: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Figure 5 The same as Fig. 2 except for the tropics (30°S-30°N).

• Most models have a better performance in NDJFM than in

MJJAS.

• There is a notable spread among the models.

• The INM has a relatively low pattern correlation in NDJFM and

MJJAS; the BNU model has somewhat higher pattern correlation

than the other models in both MJJAS and NDJFM.

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Page 22: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Figure 6 The same as Fig. 2 except for the mid-latitudes of the Northern Hemisphere

(30°-60°N) (a, b) and the mid-latitudes of the Southern Hemisphere (30°-60°S) (c, d).

NH: MJJAS > NDJFM

SH: NDJFM > MJJAS

winter&summer: NH > SH

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Page 23: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Figure 7 The same as Fig. 2 except for the high-latitudes of the Northern Hemisphere

(60°-90°N) (a, b) and the high-latitudes of the Southern Hemisphere (60°-90°S) (c, d).

NH: NDJFM > MJJAS

SH: NDJFM > MJJAS

summer: SH >> NH

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Page 24: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

The BNU model captures the pattern well, but overestimates the

magnitude of the correlation.

A single simulation of the BNU model

Signal/noise ratio?

Page 25: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

a single simulation of the INM model.

The INM model displays inconsistency from observations over the land.

Problem in Iand surface

component?

Page 26: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

a single simulation of the MRI model.

The MRI model shows notable differences from observations in some oceanic regions.

Problem in oceanic processes

and/or atmosphere-ocean

coupling processes?

Page 27: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Summary• The P-T correlation is mostly positive over the tropical oceans and

negative over the mid-latitude lands (observations and models).

• The P-T correlation shows obvious seasonal change over the land:

large negative in summer and weak in winter, positive over the

high-latitude regions of the Northern Hemisphere in boreal winter.

• The model performance is better in NDJFM than in MJJAS except

for the mid-latitude lands of the Northern Hemisphere. The model

performance is generally better over the land than over the ocean.

• The seasonal dependence of the model performance is more

obvious over the land than over the ocean and more pronounced

over the mid- and high-latitudes than over the tropics.

• The INM model has difficulty to capture the P-T correlation over

the land. The MRI model has improper P-T correlation over the

equatorial oceanic regions.27

Page 28: Evaluation of Precipitation-Surface Temperature ... · Evaluation of Precipitation-Surface Temperature Relationship in IPCC CMIP5 Models RenguangWu Institute of Space and Earth Information

Thanks!