1. 2008 Climate Prediction Applications Science Workshop
Jamaica’s Mid-Summer “Dry Spell”
Teddy Allen and Dr. Scott Curtis
Atmospheric Science Program
Department of Geography
East Carolina University
Dr. Douglas Gamble
Department of Geography and Geology
University of North Carolina at Wilmington
March 6, 2008
2008 Climate Prediction Applications Science Workshop

2. OUTLINE Economic Motivation Defining the Mid-Summer “Dry Spell”
MSD variability and patterns
Modified Pressure Index
Vegetation Response
Future Work

3. Dataset grid box nearest Montego Bay

4. MOTIVATION
GDP
per capita
Jamaica is a relatively poor* nation that largely depends on its agricultural yields for both export and domestic consumption. An improved understanding of the mechanisms of the Mid Summer “Dry-Spell” can have significant impacts upon agricultural productivity and economic prosperity.
* Definition of poor neglects significant cultural wealth that Jamaica possesses.
( CIA World FactBook 2007 )

5. Data Sets NASA Global Precipitation Terra MODIS spectral imagery
NCEP NCAR monthly Reanalysis
2.5 degree gridded dataset
NASA Global Precipitation
Climatology Project (GPCP) V2
Terra MODIS spectral imagery

6. Mid Summer “Dry-Spell” Signature
GPCP CLIMATOLOGY
Mid Summer “Dry-Spell” Signature
mm day-1

7. Mid-Summer “Dry Spell” Conceptual Model
MSD timing
July
May
NAM H
divergence
upwelling

8. Mid-Summer “Dry Spell” Pattern
Mean pentad gauge precip. Apr. - Nov

9. Mid-Summer “Dry Spell” Inter-Annual Variability
1998
1999
2000
2001
2002
2003
2004
2005
2006

10. Average Sea Level Pressure (NCEP NCAR Reanalysis)
Apr.–Nov
APRIL
MAY
JUNE
JULY
AUGUST
SEPTEMBER
OCTOBER
NOVEMBER

11. Monthly Caribbean Low Level Jet Averages (925mb) Apr.-Nov. 1979-2007
APRIL
MAY
JUNE
JULY
AUGUST
SEPTEMBER
OCTOBER
NOVEMBER

12. Monthly GPCP Caribbean Precip. Averages
Apr.-Nov
APRIL
MAY
JUNE
JULY
AUGUST
SEPTEMBER
OCTOBER
NOVEMBER

13. Average 925mb Divergence 1979-2007
JULY
JUNE
AUG.
SEPT.

14. Average Differences July minus May
+4mb
increase in NASH
+5 ms-1
increase in CLLJ
-2 mm / day
decrease in precip.

15. Modified Bermuda High Index P Montego Bay – P 30N, 40W
BHI
30N, 40W
MBHI
Montego Bay

16. MBHI Monthly Climatologies
Montego Bay
30N, 40W
MBHI
January
-7.34
February
-6.77
March
-6.86
April
-7.56
May
-9.58
June
1013.5
-10.19
July
-10.30
August
-9.04
September
-8.42
October
-7.65
November
-6.59
December
-6.04

17. Modified BHI 2002 MBHI Jan. -8.21 Feb. -5.8 Mar. -8.78 Apr. -10.14
1983
MBHI
Jan.
-10.89
Feb.
-3.08
Mar.
-7.16
Apr.
-6.67
Modified BHI
2002 GPCP Montego Bay
Early Season MBHI
1983 GPCP Montego Bay

18. Vegetation Response Via Remote Sensing
Terra MODIS (Moderate Resolution Imaging Spectrometer)
36 Spectral Bands covering the Earth every 1-2 days
250m resolution
Jamaican Region Imagery delivered every 16 days
Normalized Difference Vegetation Index (NDVI) Classification through ERDAS Imagine software

19. April 2006
NIR - red
________
NDVI =
NIR + red
October 2006

20. NDVI TIME SERIES CLASSIFICATION For more info: teddyallen@yahoo.com
FUTURE WORK
NDVI TIME SERIES CLASSIFICATION
FARMING PERSPECTIVE
ENSO FORCINGS
For more info:

21. Acknowledgements Dr. Scott Curtis Dr. Douglas Gamble
Dr. Rosana Nieto-Ferreira
ECU Geography Department
Dr. Peter Robinson and the SERCC
National Science Foundation