1. José J. Hernández Ayala
PhD Student
Department of Geography
University of Florida
2. 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
3. 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)
4. 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?
5. 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.
6. • Area: 9,104 km.sq
• Population: 3.7 million (Census 2010)
• Pop Density: 418/km.sq
Study Area
7. 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.
8. 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.
9. 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.
10. 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.
11. 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.
12. 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.
13. 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)
14. 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.
15. 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.
16. 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?
