SPATIAL AND TEMPORAL CHANGES IN PRECIPITATION IN PUERTO RICO FROM 1956-2010 A Thesis Presented to The Graduate Faculty of The University of Akron In Partial Fulfillment of the Requirements for the Degree Master of Science José Javier Hernández Ayala May, 2012 SPATIAL AND TEMPORAL CHANGES IN PRECIPITATION IN PUERTO RICO FROM 1956-2010 José Javier Hernández Ayala Thesis Approved: Accepted: ________________________________ _____________________________ Advisor Dean of the College Dr. Linda Barrett Dr. Chand Midha ________________________________ _____________________________ Co-Advisor Dean of the Graduate School Dr. Thomas Schmidlin Dr. George Newkome ________________________________ _____________________________ Faculty Reader Date Dr. John Szabo ________________________________ Department Chair Dr. John Szabo ii ABSTRACT In this study annual, seasonal and monthly series for total precipitation are analyzed to find increasing or decreasing trends in rainfall over space and time in Puerto Rico from 1956 to 2010. The precipitation series were observed at forty meteorological stations scattered over the island of Puerto Rico. The groups of series were selected for their spatial and temporal representativeness. In order to detect possible trends in precipitation over the island, the Mann-Kendall test was applied to the annual, seasonal and monthly series. This test is non-parametric and thus, has the advantage of being insensitive to the true (unknown) form of the distribution involved. The Mann-Kendall statistical test results of this research have shown that statistically significant increasing and decreasing trends occurred on some locations in the island of Puerto Rico from 1956-2010. The spatial and temporal distribution of the trends vary from increasing trends in the southwest, central and northeast regions for the annual series and dry season months to decreasing trends for the early wet season months mainly in the western area of the island. The results show that increasing trends occurred in the months of January, March, April, September and October mainly in the southwest and northeast and decreasing trends dominated in the months of May, July, August, November and December mainly in the west. iii TABLE OF CONTENTS Page LIST OF FIGURES…………………………………………………..……………….vii CHAPTER I. INTRODUCTION…………………………………………………………………….1 Problem Statement…………………………………………………………….2 Importance of Study……………………………………………………….......3 II. LITERATURE REVIEW………………………………...………………………….4 Global Changes in Precipitation Patterns………………………...…………4 Regions Impacted by Precipitation Change………………... ………………7 Precipitation Changes the Case of the Iberian Peninsula……………….10 Precipitation Changes in the Caribbean and Puerto Rico……………….11 III. DATA AND METHODOLOGY………………………..…………………………15 Area of Study…………………………………………………………………15 Statistical & Spatial Analysis………………………………………………..18 iv IV. RESEARCH RESULTS……………………………………………….…………23 Spatial Distribution of Annual Rainfall Trends…………………………….23 Spatial Distribution of Early Dry Season Rainfall Trends………………...27 December Rainfall Trends…………………………………………..30 January Rainfall Trends……………………………………………..32 February Rainfall Trends……………………………………………36 Spatial Distribution of Late Dry Season Rainfall Trends…………….......38 March Rainfall Trends………………………………………………..42 April Rainfall Trends………………………………………………....45 May Rainfall Trends………………………………………………….47 Spatial Distribution of Early Wet Season Trends…………………………49 June Rainfall Trends…………………………………………………52 July Rainfall Trends…………………………………………………..54 August Rainfall Trends………………………………………………56 Spatial Distribution of Late Wet Season Trends…………………………..58 September Rainfall Trends………………………………………….61 October Rainfall Trends……………………………………………..63 v November Rainfall Trends…………………………………………..64 V. DISCUSSION AND FINDINGS……………………………….…………………66 Annual, Seasonal and Monthly Rainfall Trends……………………….….67 ENSO Effects on Precipitation Trends in Puerto Rico…………….……..70 Cyclonic Precipitation Effects on Rainfall Trends in Puerto Rico……….74 Local Factors Effects on Precipitation Trends in Puerto Rico…………...75 VI. CONCLUSIONS………………………………………………………………….78 BIBLIOGRAPHY……………………………………………………………………...80 vi LIST OF FIGURES Figure Page 1.1 The Island of Puerto Rico and its main cities and elevation…………….16 1.2 Puerto Rico’s climate zones based on Koppen climate classification and selected weather stations…………….....................17 1.3 Average total annual precipitation for Puerto Rico from 1956-2010…...............................................................17 1.4 Monthly average precipitation for all stations in Puerto Rico from 1956- 2010……………………….…………………...18 2.1 Spatial distribution of Mann Kendall trends results for annual rainfall for 1956-2010……………………..…………….23 2.2 Annual rainfall totals for the weather stations in Paraiso, Juncos,AibonitoandVillalbafrom19562010………………………………..24 2.3 Annual rainfall totals for the weather stations in Ponce, Adjuntas, Corral Viejo and Yauco from 1956-2010………………………25 2.4 Annual rainfall totals for the weather stations in Ensenada, Lajas, Mayaguez City and Mayaguez AP…………………………………26 2.5 Spatial distribution of Mann Kendall trends results for early dry season rainfall for 1956-2010……………………………….…..27 2.6 Early dry season rainfall totals for the weather stations in Paraiso, Canovanas, San Juan and Aibonito…………………………….28 2.7 Early dry season rainfall totals for the weather stations in Ponce, Cerro Maravilla, Villalba and Isabela……………………….……..29 2.8 Spatial distribution of Mann Kendall trends results for December rainfall for 1956-2010………...…………………………………30 2.9 December rainfall totals for the weather stations in Aibonito, Villalba, Cerro Maravilla and Mayaguez City………………..….31 vii 2.10 Spatial distribution of Mann Kendall trends results for January rainfall for 1956-2010……………………………………………....32 2.11 January rainfall totals for the weather stations in Paraiso, Canovanas, Juncos and Trujillo Alto…………………………….33 2.12 January rainfall totals for the weather stations in San Juan, Rio Piedras, San Lorenzo and Aibonito……………………….34 2.13 January rainfall totals for the weather stations in Juana Diaz, Isabela, Maricao and Mayaguez City……………………….35 2.14 Spatial distribution of Mann Kendall trends results for February rainfall for 1956-2010………………………………………...36 2.15 February rainfall totals for the weather stations in Costanza and Lajas…………………………………………………………37 2.16 Spatial distribution of Mann Kendall trends results for late dry season rainfall for 1956-2010…………………………………38 2.17 Late dry season rainfall totals for the weather stations in Villalba, Cerro Maravilla, Ponce and Corral Viejo………………………..39 2.18 Late dry season rainfall totals for the weather stations in Adjuntas Sub, Yauco, Ensenada and Magueyes………………………...40 2.19 Late dry season rainfall totals for the weather stations in Lajas and Mayaguez AP…………………………………………………….41 2.20 Spatial distribution of Mann Kendall trends results for March rainfall for 1956-2010……………………………………………42 2.21 March rainfall trends for the weather stations in Paraiso, Aibonito, Guayama and Cerro Maravilla…………………………………..43 2.22 March rainfall trends for the weather stations in Ponce, Isabela, Yauco and Hacienda Constanza………………………………...44 2.23 Spatial distribution of Mann Kendall trends results for April rainfall for 1956-2010……………………………………………...45 2.24 April rainfall trends for the weather stations in Villalba, Yauco, Corral Viejo and Magueyes………………………………………..46 viii 2.25 Spatial distribution of Mann Kendall trends results for May rainfall for 1956-2010………………………………………………47 2.26 May rainfall trends for the weather stations in Jajome Alto, Maricao, Villalba and Mayaguez City……………………………………...48 2.27 Spatial distribution of Mann Kendall trends results for early rainfall season for 1956-2010…………………………………….49 2.28 Early wet season trends for the weather stations in Trujillo Alto, Villalba and Corral Viejo……………………………………...50 2.29 Early wet season trends for the weather stations in Maricao Fish, Coloso and Mayaguez City………………………………...51 2.30 Spatial distribution of Mann Kendall trends results for June rainfall for 1956-2010…………………………………………………52 2.31 June rainfall trends for the weather stations in Mayaguez City and Mayaguez AP…………………………………………53 2.32 Spatial distribution of Mann Kendall trends results for July rainfall for 1956-2010………………………………………………54 2.33 July rainfall trends for the weather stations in Villalba, Coloso, Mayaguez City and Mayaguez AP……………………………….55 2.34 Spatial distribution of Mann Kendall trends results for August rainfall for 1956-2010…………………………………………...56 2.35 August rainfall trends for the weather stations in Juncos, Guayabal, Jajome Alto, Corral Viejo and Mayaguez City……………….57 2.36 Spatial distribution of Mann Kendall trends results for late wet season rainfall for 1956-2010………………………………...58 2.37 Late wet season rainfall trends for the weather stations in Paraiso, Juncos, Gurabo and Aibonito…………………………………59 2.38 Late wet season rainfall trends for the weather stations in Villalba, Ponce, Mayaguez City and Mayaguez AP…………………..60 2.39 Spatial distribution of Mann Kendall trends results for September rainfall for 1956-2010………………………………………….61 ix 2.40 September rainfall trends for the weather stations in Rio Piedras, Mayaguez City, Mayaguez AP, Aibonito and Corozal…………………...62 2.41 Spatial distribution of Mann Kendall trends results for October rainfall for 1956-2010………………………………………….63 2.42 October rainfall trends for the weather stations in Gurabo, Cerro Maravilla and Mayaguez City……………………………..64 2.43 Spatial distribution of Mann Kendall trends