José J. Hernández Ayala

PhD Student

Department of Geography

University of Florida

INTRODUCTION

• Teleconnection: is a recurring and persistent large scale pattern of

pressure, sea surface temperature or circulation anomalies that spans

vast geographical areas.

• Teleconnections influence:

• Jet stream patterns

• Jet stream location/ intensity

• Temperature

• Rainfall

• Storm development/tracks

TELECONNECTIONS

(Feldstein and Franzke, 2006), (Deser, 2000).

(Gray, 1984).(Poveda, Waylen and Pulwarthy, 2006)

(Hurrell and Van Loon, 1997), (Visbeck, Hurrel and Kushnick, 2001) (Malmgren, Winter and Chen, 1997)

North Atlantic Oscillation

(NAO)

Arctic Oscillation (AO)

El Niño Southern Oscillation (ENSO)

PROBLEM STATEMENT

• This study examines the relationship between rainfall and the (NAO), (AO)

and (ENSO) in the island of Puerto Rico.

Questions:

1. Which teleconnection exhibits the strongest relationship with

rainfall?

2. During what temporal scale (annual, dry season or wet

season) are the correlations statistically significant?

3. Is there a specific region of the island that exhibits stronger

correlations?

HYPOTHESIS NAO AO SOI

• Above average precipitable water values are associated with the negative phase of each of the Teleconnections for the Caribbean region where Puerto Rico is

located.

• Area: 9,104 km.sq

• Population: 3.7 million (Census 2010)

• Pop Density: 418/km.sq

Study Area

RAINFALL OVER SPACE AND TIME

• Most of Puerto Rico precipitation is

orographic in nature.

• Wettest months are September and

October and the driest February and

March.

DATA

• Monthly data for 30 weather stations (1960-2010) from the National Climate

Data Center (NCDC).

• Annual, dry season (Dec-April) and wet season (May-Nov) rain was calculated.

• Teleconnections indexes were obtained from the Climate Prediction Center

(CPC).

NAO Index (daily 500mb height anomalies over the Northern Hemisphere)

AO Index (daily 1000mb height anomalies poleward of 20°N)

SOI Index (Stand Tahiti - Stand Darwin) Sea Level Press Anomaly

• Annual, dry season and wet season means of the indexes were calculated.

METHODS

• The annual, dry season, and wet season rainfall (Log 10) for all stations were regressed with their correspondent NAO, AO and SOI (Z scores) indexes.

• A factor analysis regionalization was employed in order to group and reduce the number of stations to only a few factors in order to capture regional patterns (Carter and Elsner, 1996).

• The annual, dry season and wet season rainfall factors (regions) were regressed with their respective NAO, AO and ENSO indexes.

REGRESSION RESULTS ANNUAL

• AR/NAO - significant correlations (.05 or less) in the northern and central mountain stations.

• AR/AO - the strongest correlations (.05 or less) in almost all regions of the island.

• AR/ENSO – no significant correlations, however positive correlations were present.

REGRESSION RESULTS DRY SEASON

• DSR/NAO - exhibits significant correlations (.05 or less) in two of the northern stations.

• DSR/AO -the strongest correlations (.05 or less) in the northwest region of the island.

• DSR/ENSO - did not show any statistically significant correlations.

REGRESSION RESULTS WET SEASON

• WSR/NAO - only one station in the central mountains with positive correlations.

• WSR/AO - shows two stations in the central mountains with significant negative correlations.

• WSR/ENSO - only one station in the central mountains with positive correlations.

FACTOR ANALYSIS REGIONALIZATION ANNUAL

• F4 (Northwest/Central) significant with NAO (-.336)

• F6 (Northwest) significant with NAO (-.271)

• F4 (Northwest/Central) correlations with AO (-.483)

• F5 (Central West Region) significant with ENSO (.310)

FACTOR REGIONALIZATION DRY SEASON AND WET SEASON

• F3 (Northwest) significant

correlations with NAO (-.333).

• F3(Northwest) significant

correlations with AO (-.396).

• No correlations with wet season rainfall regions and the

teleconnections.

CONCLUSIONS• AR/ teleconnections - negative correlations for both NAO and AO.

• The strongest correlations were found with AO in almost all of Puerto Rico.

• DSR/ teleconnections - strongest correlations in the northwest region of the island.

• Mainly with AO and NAO, again the AO with the strongest correlations.

• WSR/ teleconnections - three stations with significant correlations, 1 positive with NAO, 2 negative with AO and 1 positive with ENSO.

• All three of them in the central mountains region.

• Factor Analysis Regionalization/Regression - northwest and central mountain regions to be negatively correlated with NAO and AO for both the annual and dry season rainfall.

• ENSO only exhibited significant correlations with one factor located in the central mountains for annual rainfall.

RESEARCH LIMITATIONS

• Limited to annual, dry season and wet season rainfall.

• Correlations with the teleconnections, how to separate NAO signal from AO or ENSO?

• Other teleconnections not considered? AMO?

• Local factors?

QUESTIONS?