Iprc symposium on ocean salinity and global water cycle
This presentation is the property of its rightful owner.
Sponsored Links
1 / 14

IPRC Symposium on Ocean Salinity and Global Water Cycle PowerPoint PPT Presentation


  • 77 Views
  • Uploaded on
  • Presentation posted in: General

IPRC Symposium on Ocean Salinity and Global Water Cycle. Recent Trends and Future Rainfall Changes in Hawaii. Honolulu, Hawaii, 2010-08-02 Presentation by Oliver Elison Timm Acknowledgements: Tom Giambelluca Mami Takahashi Henry Diaz. Latent Heat Flux from NCEP reanalysis climatology.

Download Presentation

IPRC Symposium on Ocean Salinity and Global Water Cycle

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Iprc symposium on ocean salinity and global water cycle

IPRC Symposium onOcean Salinity and Global Water Cycle

Recent Trends and Future Rainfall Changes in Hawaii

Honolulu, Hawaii, 2010-08-02

Presentation by

Oliver Elison Timm

Acknowledgements:

Tom Giambelluca

Mami Takahashi

Henry Diaz


Iprc symposium on ocean salinity and global water cycle

Latent Heat Flux from NCEP reanalysis climatology

World Ocean Atlas Sea Surface Salinity climatology (WOA9)


Spurious trends in globally averaged monthly mean rainfall

Spurious trends in globally averaged monthly mean rainfall

NCEP reanalysis

ERA-40

CMAP

mm/day


Globally averaged monthly precipitation minus evaporation

Globally averaged monthly precipitation minus evaporation

NCEP reanalysis

ERA-40

mm/day


Imprints of hawaiian islands on the hydrological cycle

Imprints of Hawaiian Islands on thehydrological cycle

NCEP reanalysis latent heat flux climatology


Imprints of hawaiian islands on the hydrological cycle1

Imprints of Hawaiian Islands on thehydrological cycle

NCEP reanalysis latent heat flux climatology

WOA sea surface salinity


Rain gauge observation 1920 2005 recent negative trend

Hawaii Rainfall Index

Rain-gauge observation1920-2005: recent negative trend?

Chu et al. (2005):

PDO and ENSO have a significant influence on the rainfall amounts in Hawaii.

Recent negative trend part of

Natural variability or first sign anthropogenic forcing?

We applied statistical downscaling for the wet and dry season average rainfall:

Only very weak changes

Figures from Diaz et al. (2008)


Synoptic statistical downscaling for rainfall stations in hawaii

Synoptic-Statistical Downscaling for rainfall stations in Hawaii

Above average rainfall

Below average rainfall

(Timm and Diaz J. Clim., 2009)

134 stations

Wet and dry season average rainfall.

Selected 6 of the 23 IPCC AR4 models

Use surface meridional winds as predictors

High-low composite


Statistical downscaling sd for rainfall stations in hawaii

Statistical downscaling (SD) for rainfall stations in Hawaii

(Timm and Diaz J. Clim., 2009)

134 stations and analyzed the

Wet and dry season average rainfall.

Selected 6 of the 23 IPCC AR4 models

Use surface meridional winds as predictors

SD model: Explained Variance

Wet Season

Dry Season


Iprc symposium on ocean salinity and global water cycle

Statistical downscaling for the wet and dry season average rainfall:Only very weak changes projected in the ensemble mean.

dry season wet season


Changes in the frequency of heavy rain events

Changes in the frequency of heavy rain events?

Daily rainfall data

Heavy rain events:

Daily precipitation > 95% quantile in the daily rainfall distribution (wet season, 1958-1976 base period)

count the number of events in each wet season

Examine the relationship between ENSO, PNA and numbers of events

Apply Multiple Linear Regression (MLR)

Number of events ~ SOI & PNAI

Analyzed 12 selected stations with daily rainfall data

MLR: Number of events

SOI

PNA index


Iprc symposium on ocean salinity and global water cycle

Mid 1970th climate shift

Associated regression pattern

(SOI) and PNAI

Observed changes

in number of events

MLR estimated changes

in number of events


Iprc symposium on ocean salinity and global water cycle

How will future climate change

project onto SOI and PNA

Observed mid-1970th shift

Associated regression pattern

(SOI) and PNAI

6 model ensemble

projected changes (SRESA1B)

1958-1976 and 1977-2005


Iprc symposium on ocean salinity and global water cycle1

IPRC Symposium onOcean Salinity and Global Water Cycle

  • Summary

    • Observations show decreasing trend in mean precipitation and heavy rain events

    • Attribution to anthropogenic forcing not possible yet

    • ENSO and PNA explain about 20-40% of the variability in number of heavy rain events

    • Future changes in ENSO-PNA:

      SRESA1B scenarios show no robust shifts in mean, covariance=> no significant changes is the frequency of heavy rain events

Honolulu, Hawaii, 2010-08-02

Presentation by

Oliver Elison Timm

Acknowledgements:

Tom Giambelluca

Mami Takahashi

Henry Diaz

BUT: we do not know yet how other factors will change the frequency of heavy rain events (i.e. the unexplained part of the the variance)


  • Login