slide1
Download
Skip this Video
Download Presentation
Magdalena A. Balmaseda Anthony Weaver

Loading in 2 Seconds...

play fullscreen
1 / 20

Magdalena A. Balmaseda Anthony Weaver - PowerPoint PPT Presentation


  • 110 Views
  • Uploaded on

Temperature, Salinity and Sea Level: climate variability from ocean reanalyses (Intercomparison Items 3 & 4). Magdalena A. Balmaseda Anthony Weaver. Outline. Defining the variability: signal and noise Seasonal cycle removed: Anomalies with respect to the common period (1994-2000)

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Magdalena A. Balmaseda Anthony Weaver' - durin


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
slide1
Temperature, Salinity and Sea Level:climate variability from ocean reanalyses(Intercomparison Items 3 & 4)

Magdalena A. Balmaseda

Anthony Weaver

GSOP Workshop, Reading, 31 Agust-1 September 2006

outline
Outline
  • Defining the variability: signal and noise
    • Seasonal cycle removed: Anomalies with respect to the common period (1994-2000)
    • 12-month/3-month running mean
    • Focus on the upper ocean (upper 300m): Equator, Mid latitudes
  • Temperature and salinity:
    • What can we say about climate variability?
    • Time variation of uncertainty
    • Outliers?
  • Source of uncertainty (forcing, model, assimilation method)?
  • Sea Level variations: volume or mass changes?
  • Summary and conclusions

GSOP Workshop, Reading, 31 Agust-1 September 2006

focus regions for items 3 4
Focus Regions for Items 3 & 4

GSOP Workshop, Reading, 31 Agust-1 September 2006

uncertainty in the mean
Uncertainty in the Mean
  • Ambiguity in the definition
    • closest level, interpolated values…?
  • Real Uncertainty?

We will use anomalies…

GSOP Workshop, Reading, 31 Agust-1 September 2006

t300 equatorial regions

Eq Indian: Uncertainty remains large throughout the record.

  • Signal to noise <1. Outliers
  • This is also the case for the Eq Atlantic
T300: Equatorial regions
  • Eq Pac: Uncertainty decreases with time.
  • Relatively robust interannual variability.
  • Increased uncertainty after 2000. Why?

GSOP Workshop, Reading, 31 Agust-1 September 2006

what can we say about tropical variability
What can we say about Tropical variability?

How should we interpret the outliers?

Need to understand the reasons

An outlier for the good reason is very valuable

An outlier for the wrong reason is damaging

GSOP Workshop, Reading, 31 Agust-1 September 2006

t300 mid latitudes northern

The North Pacific does not show a warming trend, but more of a rapid shift in the early 90’s

  • Large uncertainty after 2000
  • Phase/amplitude of decadal signal is poorly resolved. Outliers.
T300: Mid latitudes (northern)
  • The North Atlantic is dominated by a warming trend, especially post 1997
  • Large uncertainty after 2000.
  • Phase/amplitude of decadal variability is poorly resolved.

GSOP Workshop, Reading, 31 Agust-1 September 2006

global signals

GLOBAL: Upper T-300m

GLOBAL Upper T-750m

GLOBAL Upper T-3000m

GLOBAL SIGNALS

Warming occurs ~ in first 750m

GSOP Workshop, Reading, 31 Agust-1 September 2006

salinity variability
Salinity Variability
  • Salinity variability dominated by spin-up effects in several cases.
  • There is no consistency among reanalyes

GSOP Workshop, Reading, 31 Agust-1 September 2006

signal noise ratio long period

T300-12m-rm

S300-12m-rm

T750-12m-rm

S750-12m-rm

T3000-12m-rm

S3000-12m-rm

Signal/Noise Ratio (long period)

EQPAC

EQATL

EQINDTRPAC

TRATL

NPAC

NATL

GLOBAL

GSOP Workshop, Reading, 31 Agust-1 September 2006

signal noise ratio short period interannual

T300-3m-rm

S300-3m-rm

T750-3m-rm

S750-3m-rm

T3000-3m-rm

S3000-3m-rm

Signal/Noise Ratio (Short period, interannual)

EQPAC

EQATL

EQINDTRPAC

TRATL

NPAC

NATL

GLOBAL

GSOP Workshop, Reading, 31 Agust-1 September 2006

sources of uncertainty
Sources of Uncertainty

All

ERA40

ERA40-No data

ERA40-Assim

GSOP Workshop, Reading, 31 Agust-1 September 2006

equatorial atlantic assimilation increases spread
Equatorial Atlantic: Assimilation increases spread

All

ERA40

ERA40-No data

ERA40-Assim

GSOP Workshop, Reading, 31 Agust-1 September 2006

assimilation and uncertainty t300
Assimilation and Uncertainty T300

1956-2005

EQPAC EQATL EQIND TRPAC

Long period 1956-2005:

Assimilation decreases uncertainty everywhere

1993-2005

EQPAC EQATL EQIND TRPAC

TRATL NPAC NATL GLOBAL

Latest period 1993-2005

Only in EQPAC the assimilation reduces uncertainty

TRATL NPAC NATL GLOBAL

GSOP Workshop, Reading, 31 Agust-1 September 2006

assimilation and uncertainty s300
Assimilation and Uncertainty S300

1956-2005

EQPAC EQATL EQIND TRPAC

Long period 1956-2005:

Assimilation increases uncertainty everywhere

1993-2005

EQPAC EQATL EQIND TRPAC

TRATL NPAC NATL GLOBAL

Latest period 1993-2005

Assimilation increases uncertainty

TRATL NPAC NATL GLOBAL

GSOP Workshop, Reading, 31 Agust-1 September 2006

global sea level variations i
GLOBAL SEA LEVEL VARIATIONS I
  • Prior to 2002, changes in sea level and steric height are correlated:
  • Volume rather than mass
  • Changes in bottom pressure are not consistent amont analyses?

GSOP Workshop, Reading, 31 Agust-1 September 2006

global sea level variations ii
GLOBAL SEA LEVEL VARIATIONS II

Temperature contribution to dynamic height dominates the trend

GSOP Workshop, Reading, 31 Agust-1 September 2006

sea level variations seasonal cycle
Sea level variations: Seasonal cycle

Seasonal variations in global sea level are attributed to mass variations that affect the bottom pressure.

GSOP Workshop, Reading, 31 Agust-1 September 2006

summary and conclusions
Summary and Conclusions
  • There is large uncertainty in climate signals
    • Signal to noise ratio > 1 in the Eastern Pacific for Temperature
    • Signal to noise ratio <1 for salinity in most regions
    • Warming trend in the 90’s is consistently reproduced
    • What is happening now? There is not consistent picture
  • Forcing fluxes and analysis methods are largest source of uncertainty
    • Data Assimilation does not always collapse the spread: We need to pay more attention to the assimilation methods.
  • Global Sea level trends
    • 1993-2002: Consistently attributed to temperature rise.
    • 2002-present: It is not clear. Mass increase?
    • Seasonal variations related to mass variations.

GSOP Workshop, Reading, 31 Agust-1 September 2006

slide20
NEXT
  • Web page to collect. WHERE? GSOP web page?
  • Maps of signal to noise ratio, and so on
  • Need to define the variables so there are not “so” dependent on the vertical model grid.
  • There are currently 20 analysis… are there more there?
  • Agreement on colour coding and naming convention?
  • Other?

GSOP Workshop, Reading, 31 Agust-1 September 2006

ad