Assessment of Future Change in Temperature and Precipitation over Pakistan (Simulated by PRECIS RCM for A2 Scenario)

Siraj Ul Islam, Nadia Rehman

Motivation and Objectives

Introduction to Downscaling and PRECIS System

Experiment Design

Data and methods

Results

1. Validation

2. Future Change

Conclusion

Future work

Out Lines

To investigate and Validate PRECIS behaviors over South Asia particularly over Pakistan in a long simulation using nested RCM in GCM

Based on this validation, predictability of future climate change over selected domains is calculated

High resolution information is to be used in different crop and water models specially focusing over Pakistan

Motivations and Objectives

Motivations and Objectives

Overall assessment of PRECIS performance

Future Change and its impacts on Sub Regions

11

22

Output to be used in Impact Studies33

Introduction to Dynamical Downscaling

RCM Model

(Resolution ~ 50 Km)

GCM

Resolution ~ 500km

Downscaling

Adding Local Details

Lateral Boundary

Initial Conditions

Other Forcing

A Regional Climate Model is a tool to add small-scale detailed information of future climate change to the large-scale projections of a GCM. It is a comprehensive physical model, usually of the atmosphere and land surface, containing representations of the important processes in the climate system (e.g. clouds, radiation, rainfall, soil hydrology) as are found in a GCM.

HadAM3P GCM150km

PRECIS Regional Climate Model (RCM)

50km

HADCM3 Coupled GCM (300km atmosphere)

SST/sea-ice change from coupled GCM

At its boundaries, an PRECIS is mainly driven by atmospheric winds, temperatures and humidity output from a GCM.

Introduction to PRECIS System of Downscaling

HadAM3P

PRECIS

The third-generation Hadley Centre RCM (PRECIS) is based on the latest GCM, HadCM3. It has a horizontal resolution of 50 km with 19 levels in the atmosphere (from the surface to 30 km in the stratosphere) and four levels in the soil.

Surface and lateral boundary conditions

1. Surface boundary conditions are only required over water, where the model needs time series of

surface temperatures and ice extents.

2. Lateral boundary conditions provide dynamical atmospheric information at the latitudinal and longitudinal edges of the model domain. There is no prescribed constraint at the upper boundary of the model. The lateral boundary conditions comprise the standard atmospheric variables of surface

pressure, horizontal wind components and measures of atmospheric temperature and humidity.

3. These lateral boundary conditions are updated every 6 hours, surface boundary conditions are updated every day.

Sulphur cycle

1. A certain configuration of the PRECIS RCM contain a full representation of the sulphur cycle then a set of boundary conditions (including sulphur dioxide, sulphate aerosols and associated chemical

species) are also required for this.

The model step forward every five minutes of model time (about four seconds of real time), calculating the new state of the climate system at each step.

Experiment Design

Model Used PRECIS (A Regional Climate Model of Hadley Center UK)

Driving Data HadAM3P (A High Resolution (150 Km) GCM Derived from HadCM3 AOGCM )

Resolution 50 Km (0.44°)

Model Domain South Asia (Lat 5N to 50N, Lon 55E to 100E)

Time Slices 1961-90 (Base), 2071-2100 (Future)

Scenario A2

Analysis Domain Pakistan (Divided into three Sub-regions)

Output Data Monthly and Daily

A measure of the confidence to be placed on projections of climate change from a particular climate model (global or regional) comes in part from its

ability to simulate recent climate.

Needless to say, no model will give a perfect validation against climatology or observations. It is best to validate two or more climate models (GCM or RCM) as it will then enable a choice to be made of the most appropriate model to be used in

scenario generation for that region.

Validation Results

(a)

(b)

(a) South Asia domain topography showing values of altitude in meters (m).

(b) The standard deviation (S.D) of elevation showing RCM elevations are averaged values for each grid box's area (so peaks will indeed be smoothed out), S.D. is calculated from the original 10 minute resolution global data and then averaged to the grid of the regional model (In meters).

The topography of the domain

Bias over South AsiaBase (1961-1990)

Correlation Maps

Temperature Precipitation

Base (1961-1990)

Model Bias over Pakistan Prec %change=[(base-cru)/cru]*100

Temp Diff =(base-cru)

Base (1961-1990)

RMSE Maps

Temperature Precipitation

Base (1961-1990)

BOX A

BOX B

BOX C

Base (1961-1990)

Scatter Plot of Precipitation (mm/d) BOX-A

y = 0.4047x + 0.2518R2 = 0.8301

0

1

2

3

4

5

6

0 1 2 3 4 5 6

PRECIS

CR

U

Scatter Plot of Temperature (°C) BOX-A

y = 0.7047x + 3.3452R2 = 0.961

-20

-15

-10

-5

0

5

10

15

-20 -15 -10 -5 0 5 10 15

PRECIS

CR

U

Scatter Plot of Precipitation (mm/d) BOX-B

y = 0.5473x + 0.695R2 = 0.6591

0

1

2

3

4

5

6

0 1 2 3 4 5 6

PRECIS

CR

U

Scatter Plot of Temperature (°C) BOX-B

y = 0.7058x + 6.4329R2 = 0.8868

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35

PRECIS

CR

U

Scatter Plot of Precipitation (mm/d) BOX-C

y = 0.2826x + 0.2033R2 = 0.7075

0

1

2

3

4

0 1 2 3 4

PRECIS

CR

U

Scatter Plot of Temperature (°C) BOX-C

y = 0.7955x + 4.2002R2 = 0.933

10

15

20

25

30

35

40

10 15 20 25 30 35 40

PRECISC

RU

Base (1961-1990)Annual Cycle profile for scatter plots

BOX A (PREC)

y = 0.2109x + 0.716

R2 = 0.1455

0

2

4

6

8

10

12

0 2 4 6 8 10 12

Model

Obs

erve

d

BOX A (TEMP)

y = 0.6961x + 3.3218

R2 = 0.9336

-25

-20

-15

-10

-5

0

5

10

15

20

25

-25 -15 -5 5 15 25

Model

Obs

erve

d

BOX B (PREC)

y = 0.4843x + 0.7898

R2 = 0.393

0

2

4

6

8

10

0 2 4 6 8 10

ModelO

bser

ved

BOX B (TEMP)

y = 0.6922x + 6.709

R2 = 0.8559

0

10

20

30

40

0 10 20 30 40

Model

Obs

erve

d

BOX C (PREC)

y = 0.2496x + 0.2322

R2 = 0.3168

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 7

Model

Obs

erve

d

BOX C (TEMP)

y = 0.7771x + 4.6491

R2 = 0.8957

0

10

20

30

40

0 10 20 30 40

Model

Obs

erve

d

Base (1961-1990)Monthly profile of Scatter plot for all three boxes (12 x 30 = 360 months)

PR

EC

IPIT

AT

ION

TE

ME

RA

TU

RE

Monthly profile of Scatter plot for all three boxes (12 x 30 = 360 months)

Base (1961-1990)

Annual Cycle of Precipitation (BOX A)

0

1

2

3

4

5

6

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Pre

cip

itat

ion

(m

m/d

)

PRECIS CRU

Annual Cycle of Temperature (BOX A)

-25

-20

-15

-10

-5

0

5

10

15

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Tem

per

atu

re (

°C)

PRECIS CRUAnnual Cycle of Precipitation (BOX B)

0

1

2

3

4

5

6

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Pre

cip

itat

ion

(m

m/d

)

PRECIS CRU

Annual Cycle of Temperature (BOX B)

0

5

10

15

20

25

30

35

40

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Tem

per

atu

re (

°C)

PRECIS CRU

Annual Cycle of Precipitation (BOX C)

0

0.5

1

1.5

2

2.5

3

3.5

4

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Pre

cip

itat

ion

(m

m/d

)

PRECIS CRU

Annual Cycle of Temperature (BOX C)

0

5

10

15

20

25

30

35

40

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Tem

per

atu

re (

°C)

PRECIS CRU

Bas

e (1

961-

1990

)

Co-efficient of Variation (CV) for Temperature(BOX C)

0

2

4

6

8

10

12

14

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

CV

(%

)

CRU PRECIS

Co-efficient of Variation (CV) for Precipitation(BOX C)

0

50

100

150

200

250

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

CV

(%

)

CRU PRECIS

Co-efficient of Variation (CV) for Precipitation(BOX B)

0

20

40

60

80

100

120

140

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

CV

(%

)

CRU PRECIS

Co-efficient of Variation (CV) for Temperature(BOX B)

0

5

10

15

20

25

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

CV

(%

)

CRU PRECIS

Co-efficient of Variation (CV) for Precipitation(BOX A)

0

20

40

60

80

100

120

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

CV

(%

)

CRU PRECIS

Co-efficient of Variation (CV) for Temperature(BOX A)

-150

-100

-50

0

50

100

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

CV

(%

)

CRU PRECIS

Bas

e (1

961-

1990

)

Annual Cycle of Precipitation (PAK)

0

0.5

1

1.5

2

2.5

3

3.5

4

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Pre

cipi

tatio

n (m

m/d

)

PRECIS CRU

Annual Cycle of Temperature (PAK)

0

5

10

15

20

25

30

35

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Tem

pera

ture

(°C

)

PRECIS CRU

Co-efficient of Variation (CV) for Temperature(PAK)

0

5

10

15

20

25

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

CV

(%)

CRU PRECIS

Co-efficient of Variation (CV) for Precipitation(PAK)

0

20

40

60

80

100

120

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

CV

(%)

CRU PRECIS

Base (1961-1990)

Annual

Summer

Winter

Annual Average Precipitation

0

0.5

1

1.5

2

2.5

BOX - A BOX - B BOX - C PAK

Boxes

Pre

cip

itati

on

(m

m/d

)

CRU PRECISSummer Average Precipitation

0

0.5

1

1.5

2

2.5

3

3.5

4

BOX - A BOX - B BOX - C PAK

Boxes

Pre

cip

itati

on

(m

m/d

)

CRU PRECISWinter Average Precipitation

0

0.5

1

1.5

2

2.5

3

3.5

BOX - A BOX - B BOX - C PAK

Boxes

Pre

cip

itati

on

(m

m/d

)

CRU PRECIS

Annual Average Temperature

-5

0

5

10

15

20

25

30

BOX - A BOX - B BOX - C PAK

Boxes

Tem

pera

ture

(°C

)

CRU PRECISSummer Average Temperature

5

10

15

20

25

30

35

BOX - A BOX - B BOX - C PAK

Boxes

Tem

pera

ture

(°C

)

CRU PRECISWinter Average Temperature

-20

-15

-10

-5

0

5

10

15

20

BOX - A BOX - B BOX - C PAK

Boxes

Tem

pera

ture

(°C

)

CRU PRECIS

Base (1961-1990)

PRECIPITATION

CORR RMSE (mm/d)% diff (mm/d)

(model-cru)/cru *100

BOX A 0.381472 1.95056 96.1434

BOX B 0.62688 1.38729 -0.8917

BOX C 0.562821 1.09698 94.0005

PAK 0.6148 1.0203 49.8928

TEMPERATURE

CORR RMSE (mm/d)Diff (°C)

(model-cru)

BOX A 0.966213 5.74479 -4.1514

BOX B 0.925165 4.26976 -0.4439

BOX C 0.946407 3.10695 0.7832

PAK 0.9502 3.3034 -0.3163

Base (1961-1990)

FUTURE CHANGE

Future Change over South AsiaFuture (2071-2100)

ANNUALPrec %change=[(future-base)/base]*100

Temp Diff =(Future-base)Future (2071-2100)

Future (2071-2100)

Annual Cycle of Precipitation (BOX A)

0

1

2

3

4

5

6

7

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Pre

cip

itat

ion

(m

m/d

)

BASE FUTURE

Annual Cycle of Temperature (BOX A)

-25

-20

-15

-10

-5

0

5

10

15

20

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Tem

per

atu

re (

°C)

BASE FUTURE

Annual Cycle of Precipitation (BOX B)

0

1

2

3

4

5

6

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Pre

cip

itat

ion

(m

m/d

)

BASE FUTURE

Annual Cycle of Temperature (BOX B)

0

5

10

15

20

25

30

35

40

45

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Tem

per

atu

re (

°C)

BASE FUTURE

Annual Cycle of Precipitation (BOX C)

0

0.5

1

1.5

2

2.5

3

3.5

4

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Pre

cip

itat

ion

(m

m/d

)

BASE FUTURE

Annual Cycle of Temperature (BOX C)

5

10

15

20

25

30

35

40

45

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Tem

per

atu

re (

°C)

BASE FUTURE

Fu

ture

(20

71-2

100)

Annual Cycle of Precipitation (PAK)

0

0.5

1

1.5

2

2.5

3

3.5

4

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Pre

cip

itat

ion

(m

m/d

)

BASE FUTURE

Annual Cycle of Temperature (PAK)

0

5

10

15

20

25

30

35

40

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Tem

per

atu

re (

°C)

BASE FUTURE

Future (2071-2100)

Annual Average Precipitation

0

0.5

1

1.5

2

2.5

3

BOX - A BOX - B BOX - C PAK

Boxes

Pre

cip

itati

on

(m

m/d

)

FUTURE BASESummer Average Precipitation

0

0.5

1

1.5

2

2.5

3

3.5

4

BOX - A BOX - B BOX - C PAK

Boxes

Pre

cip

itati

on

(m

m/d

)

FUTURE BASEWinter Average Precipitation

0

0.5

1

1.5

2

2.5

3

3.5

BOX - A BOX - B BOX - C PAK

Boxes

Pre

cip

itati

on

(m

m/d

)

FUTURE BASE

Annual Average Temperature

-5

0

5

10

15

20

25

30

BOX - A BOX - B BOX - C PAK

Boxes

Tem

pera

ture

(°C

)

FUTURE BASESummer Average Temperature

5

10

15

20

25

30

35

40

BOX - A BOX - B BOX - C PAK

Boxes

Tem

pera

ture

(°C

)

FUTURE BASEWinter Average Temperature

-20

-15

-10

-5

0

5

10

15

20

BOX - A BOX - B BOX - C PAK

Boxes

Tem

pera

ture

(°C

)

FUTURE BASE

Annual

Summer

Winter

Future (2071-2100)

PRECIPITATIONΔP %(mm/d)

Annual Summer (JJAS) Winter (DJFM)

BOX A 11.35 -0.88 20.43

BOX B 0.78 0.97 -7.74

BOX C -0.51 -3.37 -24.53

PAK 3.38 -1.45 9.39

TEMPERATUREΔT(°C)

Annual Summer (JJAS) Winter (DJFM)

BOX A 4.76 4.81 4.97

BOX B 4.98 4.86 5.20

BOX C 4.68 4.56 4.71

PAK 4.77 4.68 4.88

Future (2071-2100)

Work in Progress

Daily data analysis of minimum, maximum and mean temperatures for finding climate indices in future. (Paper to be presented in Young Scientist Conference in November)

Future Work

1. Analysis of more downscaled variables like SLP, Solar Radiation flux etc for impact studies (on Monthly bases only)

2. Compassion of HadAM3P simulation with ERA40 downscaled data set. (instead of CRU)

3. Using these outputs in crop and hydrological models.

4. Comparison of PRECIS with RegCM3 output.