Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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SST Analysis By Temperature Class

Kenneth S. CaseyUCAR-NOAA/NESDIS/NODC

Peter CornillonURI/GSO

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Introduction

Interests in annual-decadal SST trendsand climatology development

New method of binning anomalies

Temperature classes based on mean SST

Comparisons to traditional binningschemes

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Key Results

SST analysis by temperature class…

Provides new perspective for climatologytesting and trend estimation

Finds similar trends in recent years

Extends trends further back in time

Lowers error in data-sparse years

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Technique

Develop satellite-only climatology fromAVHRR Pathfinder

9 km resolution

Twice-dailyfields from 1985

Erosion filter

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

5

Technique

Erosion Filter:

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Technique

Compute individual SST anomalies:• COADS (~ 88 million, 1942-)• WOA94 (~ 4 million, 1900-)• Use Reynolds, GOSTA, GISST, WOA94,

and Pathfinder climatologies

Average into temperature class bins and5-degree latitude-longitude binsApply to climatology testing and trends

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Temperature Classes

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Climatology Testing

Create WOA94 and COADS anomaliesfrom several different climatologiesBin by latitude band or temperatureclassFind climatology with lowest standarddeviation of anomalies…

(Casey and Cornillon, 1999)

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Climatology Testing: COADS

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Climatology Testing: WOA94

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Climatology Testing: Latitude

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Climatology Testing: Latitude

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Trend Estimation

Create WOA94 and COADS anomaliesfrom AVHRR Pathfinder climatology

Average into 5° bins or temperature class

Calculate global and regional SSTtrends…

(Casey and Cornillon, 2001)

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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COADS Global Trend Results

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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WOA94 Global Trend Results

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Measure relative ability of two averagingmethodsCompare mean variances and number ofobservations in monthly bins to achievesmallest standard error, _2/NEfficiency parameter = _2

5/ _2T

Determine needed NT to achieve lower_2

T/NT than _25/N5

Statistical Efficiency

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Statistical Efficiency

2.221.920.52WOA94

clustered

2.472.040.49WOA94

4.731.490.67COADS

NT/ N5observed

NT/N5needed

_25/ _2

TDataset

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Regional SST Trends

Determine annual anomalies in eachtemperature class or 5° bin

Average within regions

Calculate linear trends from 1960-1990

Plot and compare…

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Regional SST Trends

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Regional SST Trends

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Subregional Trends

Bin anomalies by temperature class andplot 1960-1990 linear trends

Compare with trends calculated from 5°bins averaged latitudinally

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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COADS Regional Trends

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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WOA94 Regional Trends

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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COADS Regional Trends

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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WOA94 Regional Trends

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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Temperature Class Summary

AVHRR Pathfinder SST climatology

New perspective for climatology testingand trend estimation

Similar results in well-sampled years

Trends extended further back in time

Smaller error in data-sparse years

Jan 29-Feb 1, 2002Kenneth.Casey@noaa.gov

Workshop on Advances in the Use ofHistorical Marine Climate Data

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For More Info…

Casey, K.S. and P. Cornillon (1999). Acomparison of satellite and in situ based seasurface temperature climatologies, Journal ofClimate, vol 12, no 6, pp. 1848-1863Casey, K.S. and P. Cornillon (2001). Globaland regional sea surface temperature trends,Journal of Climate, vol 14, no 18, pp. 3801-3818.PPT presentation and PDF and PS versions at:http://intra.nodc.noaa.gov/Information/kcasey