Teddy Allen and Dr. Scott CurtisTeddy Allen and Dr. Scott Curtis

Atmospheric Science Program Atmospheric Science Program

Department of GeographyDepartment of Geography

East Carolina UniversityEast Carolina University

Dr. Douglas Gamble Dr. Douglas Gamble

Department of Geography and GeologyDepartment of Geography and Geology

University of North Carolina at University of North Carolina at WilmingtonWilmington

Jamaica’s Mid-Summer “Dry Jamaica’s Mid-Summer “Dry Spell”Spell”

March 6, 2008March 6, 20082008 Climate Prediction Applications Science Workshop

OUTLINEOUTLINE

• Economic MotivationEconomic Motivation

• Defining the Mid-Summer “Dry Spell”Defining the Mid-Summer “Dry Spell”

• MSD variability and patternsMSD variability and patterns

• Modified Pressure IndexModified Pressure Index

• Vegetation ResponseVegetation Response

• Future WorkFuture Work

Dataset grid box nearest Montego Bay

$0

$10,000

$20,000

$30,000

$40,000

$50,000

GDP per capita

MOTIVATIONMOTIVATION

0

25

50

75

100

% GDPAgriculture% Labor inAgriculture

Jamaica is a relatively Jamaica is a relatively poor* nation that poor* nation that largely depends on its largely depends on its agricultural yields for agricultural yields for both export and both export and domestic consumption. domestic consumption. An improved An improved understanding of the understanding of the mechanisms of the Mid mechanisms of the Mid Summer “Dry-Spell” Summer “Dry-Spell” can have significant can have significant impacts upon impacts upon agricultural agricultural productivity and productivity and economic prosperity.economic prosperity.* Definition of poor neglects significant cultural

wealth that Jamaica possesses.

( CIA World FactBook 2007 )

Data SetsData Sets

• NCEP NCAR monthly ReanalysisNCEP NCAR monthly Reanalysis 2.5 degree gridded dataset2.5 degree gridded dataset

• NASA Global Precipitation NASA Global Precipitation

Climatology Project (GPCP) V2Climatology Project (GPCP) V2

• Terra MODIS spectral Terra MODIS spectral imageryimagery

0

1

2

3

4

5

6

JAN

FEB

MAR AP

RMAY JU

NJU

LAU

GSE

POCT

NOVDEC

Montego Bay18N, 80W

mm

day

-1GPCP CLIMATOLOGY 1979 - GPCP CLIMATOLOGY 1979 - 20072007 Mid Summer “Dry-Spell” Mid Summer “Dry-Spell”

SignatureSignature

Mid-Summer “Dry Spell” Mid-Summer “Dry Spell” Conceptual ModelConceptual Model

divergence

upwelling

NAM

H

MSD timing

MayJuly

Mid-Summer “Dry Spell” Mid-Summer “Dry Spell” PatternPattern

Mean pentad gauge precip. Apr. - Nov. 1979-2007

Mid-Summer “Dry Spell” Mid-Summer “Dry Spell” Inter-Annual VariabilityInter-Annual Variability

1998 1999 2000

2001 2002 2003

2004 2005 2006

Average Sea Level Pressure (NCEP NCAR Average Sea Level Pressure (NCEP NCAR Reanalysis)Reanalysis)

Apr.–Nov. 1979 - 2007Apr.–Nov. 1979 - 2007APRIL MAY JUNE

JULY AUGUST SEPTEMBER

OCTOBER NOVEMBER

Monthly Caribbean Low Level Jet Averages Monthly Caribbean Low Level Jet Averages (925mb) Apr.-Nov. 1979-2007(925mb) Apr.-Nov. 1979-2007

APRIL MAY JUNE

JULY AUGUST SEPTEMBER

OCTOBER NOVEMBER

Monthly GPCP Caribbean Precip. Averages Monthly GPCP Caribbean Precip. Averages Apr.-Nov. 1979 - 2007Apr.-Nov. 1979 - 2007

APRIL MAY JUNE

JULY AUGUST SEPTEMBER

OCTOBER NOVEMBER

Average 925mb Divergence Average 925mb Divergence 1979-20071979-2007

JUNE JULY

AUG. SEPT.

Average DifferencesAverage DifferencesJuly minus MayJuly minus May

increase in NASH

increase in CLLJ

decrease in precip.

+4mb

-2 mm / day

+5 ms-1

Modified Bermuda High IndexModified Bermuda High IndexP P Montego BayMontego Bay – P – P 30N, 40W30N, 40W

Montego Bay

30N, 40W

MBHI

BHI

MBHI Monthly ClimatologiesMBHI Monthly Climatologies

Montego Montego BayBay

30N, 40W30N, 40W MBHIMBHI

JanuaryJanuary 1015.261015.26 1022.601022.60 -7.34-7.34

FebruaryFebruary 1015.121015.12 1021.891021.89 -6.77-6.77

MarchMarch 1014.291014.29 1021.151021.15 -6.86-6.86

AprilApril 1013.521013.52 1021.081021.08 -7.56-7.56

MayMay 1012.831012.83 1022.411022.41 -9.58-9.58

JuneJune 1013.51013.5 1023.691023.69 -10.19-10.19

JulyJuly 1014.511014.51 1024.811024.81 -10.30-10.30

AugustAugust 1013.691013.69 1022.731022.73 -9.04-9.04

SeptembeSeptemberr

1012.261012.26 1020.681020.68 -8.42-8.42

OctoberOctober 1011.771011.77 1019.421019.42 -7.65-7.65

NovembeNovemberr

1012.621012.62 1019.211019.21 -6.59-6.59

DecembeDecemberr

1014.421014.42 1020.461020.46 -6.04-6.04

0

2

4

6

8

10

12

Modified BHIModified BHI 20020022

MBHIMBHI

Jan.Jan. -8.21-8.21

Feb.Feb. -5.8-5.8

Mar.Mar. -8.78-8.78

Apr.Apr. --10.1410.14

19819833

MBHIMBHI

Jan.Jan. --10.8910.89

Feb.Feb. -3.08-3.08

Mar.Mar. -7.16-7.16

Apr.Apr. -6.67-6.67

2002 GPCP Montego Bay

1983 GPCP Montego Bay

0

2

4

6

8

10

JAN FEB MAR APR

20021983AVG

Early Season MBHI

Vegetation Response Via Vegetation Response Via Remote SensingRemote 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

April 2006April 2006

OctoberOctober 2006

NDVI = NIR - red

NIR + red

________

FUTURE WORKFUTURE WORK

NDVI TIME SERIES CLASSIFICATION ENSO

FORCINGS

FARMING PERSPECTIVE

For more info: teddyallen@yahoo.com

AcknowledgementsAcknowledgements

• Dr. Scott Curtis Dr. Scott Curtis

• Dr. Douglas GambleDr. Douglas Gamble

• Dr. Rosana Nieto-FerreiraDr. Rosana Nieto-Ferreira

• ECU Geography DepartmentECU Geography Department

• Dr. Peter Robinson and the SERCCDr. Peter Robinson and the SERCC

• National Science FoundationNational Science Foundation