Expressions of ENSO and the SAM in Modeled Antarctic Surface Temperatures The Transantarctic...

Expressions of ENSO and the SAM in Modeled Antarctic

Surface Temperatures

Expressions of ENSO and the SAM in Modeled Antarctic

Surface Temperatures

The Transantarctic Mountains, A. Huerta, 2003

David B. ReuschEMS Earth and Environmental Systems Institute and Department of GeosciencesThe Pennsylvania State University

David B. ReuschEMS Earth and Environmental Systems Institute and Department of GeosciencesThe Pennsylvania State University

Funded by the Office of Polar Programs,

National Science Foundation

Special thanks to David Bromwich and Andy Monaghan for sharing their

data

IntroductionIntroduction Questions

Are there robust spatial relationships between surface temperatures and ENSO/SAM?

Does SAM modulate the ENSO fingerprint? Methods

Extract patterns of variability in temperature and circulation data (SOMs)

Stratify data by SAM/ENSO states and hope there’s something to interpret in the patterns

Questions Are there robust spatial relationships between

surface temperatures and ENSO/SAM? Does SAM modulate the ENSO fingerprint?

Methods Extract patterns of variability in temperature

and circulation data (SOMs) Stratify data by SAM/ENSO states and hope

there’s something to interpret in the patterns

Background ● ENSO ● Land-only T-2m ● SAM ● T <= SAM,ENSO

Polar MM5 initialized by ERA-40 Jan 1979 - Aug 2002 60 km grid, 6-hourly

Daily averages, DJF (Jul) T-2m (Z850, Z700, Z500)

See Monaghan et al, 2006

Polar MM5 initialized by ERA-40 Jan 1979 - Aug 2002 60 km grid, 6-hourly

Daily averages, DJF (Jul) T-2m (Z850, Z700, Z500)

See Monaghan et al, 2006

The Model DatasetThe Model Dataset

Grid Domain


Self-organizing Maps (SOMs)Self-organizing Maps (SOMs)

Patterns arranged in a grid Patterns arranged in a grid by their relative similarityby their relative similarity

1) Generalized pattern extractor1) Generalized pattern extractor

Holocene ice core chemistryHolocene ice core chemistry

Each input record matches Each input record matches one pattern most closelyone pattern most closely

Concise summary of data Concise summary of data variability expressed as a variability expressed as a user-defined number of user-defined number of generalized patternsgeneralized patterns


Subset input by time period, Subset input by time period, external index, etc.external index, etc.

Self-organizing Maps (SOMs)Self-organizing Maps (SOMs)

Group input records that Group input records that match the same pattern; use match the same pattern; use pattern insteadpattern instead

2) Data classifier by pattern matching2) Data classifier by pattern matching

Basis for frequency, transition Basis for frequency, transition and trajectory mapsand trajectory maps

Sample Frequency MapSample Frequency Map


125 m

200 m


Seasonal Land-Only Temperatures

Seasonal Land-Only Temperatures

Broadening study period Switch to land-only

Focus on ice sheet Ocean temperatures of less interest

Still daily resolution

Broadening study period Switch to land-only

Focus on ice sheet Ocean temperatures of less interest

Still daily resolution


Land-only Surface Temperature Climatology


SAM and TemperatureSAM and Temperature

Create data subsets using high/low values of the SAM index

Create frequency maps for each year in each subset

Identify which pattern frequencies are statistically unusual

Count how often each pattern is unusual

Create data subsets using high/low values of the SAM index

Create frequency maps for each year in each subset

Identify which pattern frequencies are statistically unusual

Count how often each pattern is unusual


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T = f(ENSO) o g(SAM)?T = f(ENSO) o g(SAM)?

r2 ~ 0


December 1982Low SAM/El Niño

December 1994High SAM/El Niño

Potential Next StepsPotential Next Steps

Work with READER data Not high spatial density like a model grid… But the records are longer Then again, it’s monthly not daily…

Other fields that express the SAM Compare notes with those using other

methodologies!

Work with READER data Not high spatial density like a model grid… But the records are longer Then again, it’s monthly not daily…

Other fields that express the SAM Compare notes with those using other

methodologies!

SummarySummary

Intriguing signatures of both El Niño and the SAM are in the data

Untangling joint effects SAM/ENSO remains a challenging task

Intriguing signatures of both El Niño and the SAM are in the data

Untangling joint effects SAM/ENSO remains a challenging task

[email protected]@psu.eduNSF ANT 06-36618NSF ANT 06-36618

J-M05 Manifestation of anthropogenic forcing and natural variability in the Arctic and Antarctic climate systems

June 28 – July 11, Melbourne, AUS

www.iugg2011.com

Call for Abstracts still TBA

J-M05 Manifestation of anthropogenic forcing and natural variability in the Arctic and Antarctic climate systems

June 28 – July 11, Melbourne, AUS

www.iugg2011.com

Call for Abstracts still TBA

Expressions of ENSO and the SAM in Modeled Antarctic Surface Temperatures The Transantarctic...

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