Surface Wind Speed Simulations in the NARCCAP Models

Rachel Hatteberg and Eugene S. TakleIowa State University

NARCCAP Fourth Users MeetingBoulder,CO

10-11 April 2012

Presented by Bill Gutowski

Outline

• Spectra of winds from NARCCAP models for NCEP-driven runs

• Representation of extreme high winds in NARCCAP models

• Impact of climate change on wind spectra in NARCCAP models

• Representation of extreme low winds in NARCCAP models

• Peculiar behavior of MM5 at low wind speeds

Background on Study• May – September (original objective

was to look at derechoes)• 3 – hourly instantaneous wind speeds• 10 m u, v wind components• Calculated U = (u^2 + v^2)^1/2• Domain = 37°N to 49°N, -82°W to -

101°W• Domain allowed for minimal

orographic affects• Masked out Great Lakes

What Does a Regional Climate Model with 52-km Grid Spacing Consider to be an “Extreme” High Wind?

What Does a Regional Climate Model with 52-km Grid Spacing Consider to be an “Extreme” High Wind?

800,000 - 1,100,000 modeled wind speeds in each distribution

Note. (More on this later)

What Does a Regional Climate Model with 52-km Grid Spacing Consider to be an “Extreme” High Wind?

800,000 - 1,100,000 modeled wind speeds in each distribution

0 10 20 30 40 50 60 70 80 90 1000

2

4

6

8

10

12

14

16

18

NCEP/RCM Percentiles

RCM3MM5IECPCCRCMWRFPHRM3

Percentile

Win

d SP

eed

(m/s

)

How extreme? 95%? 99?

What Does a Regional Climate Model with 52-km Grid Spacing Consider to be an “Extreme” High Wind?

Message: RCMs differ in their representation of surface winds. This has implications for applications to studies of evapotranspiration, air pollution, extreme wind characteristics

What Does a Regional Climate Model with 52-km Grid Spacing Consider to be an “Extreme” High Wind?

Effect of Climate Change on Surface Winds

Result:

CRCM/CGCM3:Overall decrease in

surface winds

0.0-0.5

1.0-1.5

2.0-2.5

3.0-3.5

4.0-4.5

5.0-5.5

6.0-6.5

7.0-7.5

8.0-8.5

9.0-9.5

10.0-10.5

11.0-11.5

12.0-12.5

13.0-13.5

14.0-14.5

15.0-15.5

16.0-16.5

17.0-17.5

18.0-18.5

19.0-19.5

20.0-20.5

21.0-21.5

-0.008-0.006-0.004-0.002

00.0020.0040.0060.008

0.010.012

CRCM/CGCM3 Difference (Future – Current)

Wind Speed (m/s)

Nor

mal

ized

Freq

uenc

y of

Oc-

curr

ence

Result:

RCM3/CGCM3:Overall decrease in

surface winds

Effect of Climate Change on Surface Winds

0.0-0.5

1.0-1.5

2.0-2.5

3.0-3.5

4.0-4.5

5.0-5.5

6.0-6.5

7.0-7.5

8.0-8.5

9.0-9.5

10.0-10.5

11.0-11.5

12.0-12.5

13.0-13.5

14.0-14.5

15.0-15.5

16.0-16.5

17.0-17.5

18.0-18.5

19.0-19.5

20.0-20.5

21.0-21.5

-0.008

-0.006

-0.004

-0.002

0

0.002

0.004

0.006

0.008

0.01

0.012

RCM3/CGCM3 Difference (Future – Current)

Wind Speed (m/s)

Nor

mal

ized

Freq

uenc

y of

Oc-

curr

ence

Effect of Climate Change on Surface WindsResult:

RCM3/GFDL:Yo, what’s this?!

Change at night but not day? More/fewer traveling synoptic systems?

Must be introduced by GCM(see previous slide)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

RCM3/GFDL Difference (Future – Current)

Wind Speed (m/s)

Nor

mal

ized

Freq

uenc

y of

Occ

urre

nce

Effect of Climate Change on Surface Winds

Result:MM5I/CCSM:

Hmm… Not only GFDL creates this peculiar behavior

0.0-0.5

1.0-1.5

2.0-2.5

3.0-3.5

4.0-4.5

5.0-5.5

6.0-6.5

7.0-7.5

8.0-8.5

9.0-9.5

10.0-10.5

11.0-11.5

12.0-12.5

13.0-13.5

14.0-14.5

15.0-15.5

16.0-16.5

17.0-17.5

18.0-18.5

19.0-19.5

20.0-20.5

21.0-21.5

-0.004

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.004

MM5I/CCSM Difference (Future – Current)

Wind Speed (m/s)

Nor

mal

ized

Freq

uenc

y of

Oc-

curr

ence

Summary:Influence of GCM on the RCM?

0.0-0.5

1.0-1.5

2.0-2.5

3.0-3.5

4.0-4.5

5.0-5.5

6.0-6.5

7.0-7.5

8.0-8.5

9.0-9.5

10.0-10.5

11.0-11.5

12.0-12.5

13.0-13.5

14.0-14.5

15.0-15.5

16.0-16.5

17.0-17.5

18.0-18.5

19.0-19.5

20.0-20.5

21.0-21.5

-0.008

-0.006

-0.004

-0.002

0

0.002

0.004

0.006

0.008

0.01

0.012

RCM3/CGCM3

Wind Speed (m/s)

Nor

mal

ized

Freq

uenc

y of

Occ

urre

nce

0.0-0.5

1.0-1.5

2.0-2.5

3.0-3.5

4.0-4.5

5.0-5.5

6.0-6.5

7.0-7.5

8.0-8.5

9.0-9.5

10.0-10.5

11.0-11.5

12.0-12.5

13.0-13.5

14.0-14.5

15.0-15.5

16.0-16.5

17.0-17.5

18.0-18.5

19.0-19.5

20.0-20.5

21.0-21.5

-0.008

-0.006

-0.004

-0.002

0

0.002

0.004

0.006

0.008

0.01

0.012

CRCM/CGCM3

Wind Speed (m/s)

Nor

mal

ized

Freq

uenc

y of

Occ

urre

nce

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

RCM3/GFDL

Wind Speed (m/s)

Nor

mal

ized

Freq

uenc

y of

Occ

urre

nce

0.0-0.5

1.0-1.5

2.0-2.5

3.0-3.5

4.0-4.5

5.0-5.5

6.0-6.5

7.0-7.5

8.0-8.5

9.0-9.5

10.0-10.5

11.0-11.5

12.0-12.5

13.0-13.5

14.0-14.5

15.0-15.5

16.0-16.5

17.0-17.5

18.0-18.5

19.0-19.5

20.0-20.5

21.0-21.5

-0.004

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.004

MM5I/CCSM Difference (Future – Current)

Wind Speed (m/s)Nor

mal

ized

Freq

uenc

y of

Occ

urre

nce

Summary of Influence of Climate Change on RCM/GCM Percentiles

RCM/GCM Scenario Mode 10% 50% 90% 95% 99% 99.90%

m/s m/s m/s m/s m/s m/s m/s

CRCM/CGCM3 Current 3.75 1.75 5.45 9.75 11.25 14.25 17.25

Future 3.75 1.75 4.94 8.75 10.25 13.25 16.25

RCM3/CGCM3 Current 3.75 2.25 5.06 8.75 9.75 12.25 16.25

Future 3.75 2.25 4.73 7.75 8.75 10.75 13.75

RCM3/GFDL Current 3.75 1.75 4.46 7.25 8.25 11.25 14.25

Future 3.75 1.75 4.43 7.25 8.25 10.75 14.75

MM5I/CCSM Current 2.75 1.25 3.95 7.25 8.25 10.75 13.25

Future 3.25 1.25 3.93 7.25 8.25 10.25 12.75

Result: Large decrease in extreme high end; less change to mode or low end

What about the peculiar behavior of low wind speeds in MM5?

MM5 WRF

Calm happens! – especially in flat terrain mid-continent areas.

If model winds are extrapolated from lowest model level to zero at the surface, the wind at 10 m should almost never be zero.

BUT, MM5 spectra looks more realistic than others compared to observed winds in Midwest – for some wrong reason?

What about the peculiar behavior of low wind speeds in MM5?

What about the peculiar behavior of low wind speeds in MM5?

Choice of model could have high impact for studying air pollution stagnation events, heat waves, and agricultural applications (e.g., irrigation, evapotranspiration, pollen spread).

This MM5 behavior is present in future scenario simulations and in simulated values over the entire year (not just May-August)

MM5I/CCSM Current and Future ScenariosLow-End Wind Speeds

MM5I/CCSM (Full Year)

Summary• For the Upper Midwest domain and time period

studied, NARCCAP models show some differences in wind speed spectra, particularly at extreme high values

• Wind speeds decline with climate change, although peculiar behavior is shown for some RCM/GCM combinations

• MM5 has a unique representation of extreme low wind speeds for reasons yet unknown

Sooo, for those of you who may have thought RCMs were orderly and systematic….

Think Again!!

THANKS, BILL !!