Tropical Cyclones and Climate Change

Results from HiGEM

Ray BellSupervisors – Prof. Pier Luigi Vidale, Dr. Kevin

Hodges and Dr. Jane Strachan

Trop goup – 10th Oct

• Will there be a change in TC activity (location, intensity, frequency, lifetime, structure) with climate change?

• How does this change depend on resolution?

• How well are the governing mechanisms represented in climate models and how does resolution affect their representation?

• What is the role of teleconnections - Possible ENSO changes on NAtl TC activity?

• [What is the role of coupling with the ocean?]

PhD questions

• Explaining the change of TC activity– Change in parameters relevant to TCs: SST, vws, RH, -ω

• Investigating the ENSO teleconnections on TCs (and possible ENSO change)

- Change in NINO3.4 SSTs - El Niño composites vs. La Niña composites

Current work

Tighter filter on storms.

• Warm core testing between individual levels (still applying dec. Vor. With height)

• Test for cold core at lower levels and warm core aloft• Removes monsoon type depressions

New warm core level TRACKing

Change in track densities with increased CO2

Change in TC frequency (%)

TC/yr NH ATL WPAC EPAC NIND% changeFor ctrl

att att att att att

30yr 2xCO2

-5.6 -0.7 -24.8 -22 -8.7 -6.6 -3.2 7.7 14.6 38.630yr4xCO2 -22.2 -13.6 -47.5 -41.7 -22.0 -19.25 -40.73 -25.39 -2.76 15.92

CPAC

-1.67 -8.57

38.46 40.79

Regional change of 850hPa wspeed

Large scale tropical change

regional scale tropical change

Change in SST

Zhao et al (2009)

Change in vws

Vecchi et al (2007)

Change in RH700

Vecchi et al (2007)

Change in –ω500

Change in ppt

ENSO telleconnections on HiGEM TCs

Bengtsson et al (2006)

NINO3.4 SST DJF > 1 or <1, year containing D

Future work• More analysis explaining the TC change – change in Walker

and Hadley plots

• TCs in different resolutions and climate change simulations

• Changes in SH

• ENSO influence on NATL activity - compare IBTrACS and re-analysis to HiGEM present day simulation.

2 types of ENSO in HiGEM

Kug and Ham (2011)• Investigate change in TC activity with the 2 types of El Nino.

• Investigate the change in types of ENSO in HiGEM inc. CO2 and the TC relation

HiGEM CTRL TC frequency

CPAC5x30 years ctrl

4.3(1-4.4)

3(0-4.2)

TC/yr NH ATL WPAC EPAC NINDatt att att att att

5x30 years ctrl

67.3(63.9-71)

49.8(47.1-51.3)

4(5.1-2)

3(1-4.1)

32.6(28.9-41)

28.6(26.4-34)

19.4(17.3-22)

10.4(9.5-10.6)

4.6(3-5.6)

3.1(2.3-3.7)

Obs (83-07)

63 12.3 28.3 16.6 5.8

9.010.811.412.114.8

Atl Additional obs are 1851-2010, 1944-2010, 1966-2010, 1981-2010, 1995-2010From Blake (2010)

Change in structure100 most intense TCs at most intense

4xCO2

Earth relative windsBelow 35oNNH

2xCO2

10o radius850hPa

Avg 30 yr ctrl