The Impact of Drought on Leaf Area Index (LAI) over Texas

Ling Huang12/04/2012

Background – Why LAI is concerned?Leaf Area Index (LAI): one half the

total leaf area per unit of ground area Importance: critical parameter

controlling many biological and physical processes involving vegetation

LAI is a key variable controlling ozone production!

LAI

Background – Why LAI is concerned?

NO NO2 sunlight

O2

Air O2

O(3P)O3

VOC….RO2

RO

No ozone accumulation!!

Accumulation!

Biogenic Emission

s

Drought?

How LAI is affected by drought?

LAIBiogenic Emission

s

Data and Method2011 (drought) vs. 2010 (wet)MODIS LAI product (Moderate Resolution

Imaging Spectroradiometer) Area: TexasPeriod: May to September

Mosaic

Raw LAI

Apply QC mask

Scaling

Clip

Final LAI

Model Builder in ArcGIS

Temperature

Results – LAI distribution over Texas

Precipitation

Results – Statistical comparison

Results – geographical comparison

>0.75 No impact

LAI_2010LAI_2011ratio LAI

0.5-0.75 Moderate

0.25-0.5 Significant

<0.25 Extreme

Impact of Drought

Results – Texas climate divisionsNCDC: 10 climate divisions in TexasSimilar characteristics: vegetation, temperature,

humidity, rainfall, seasonal weather changes

semi-arid savanna semi-arid savanna

semi-arid brushland and savanna

Sub-humid savannaand woodland

Sub-arid brushland

Transition Zone!

ConclusionsLAI Biogenic

EmissionsOzone

concentrations

1.

2. LAITemperatur

e

Precipitation

3. LAIDrought

In July 2011, nearly 90% of areas saw the impact of

drought and over 50% were significantly affected.

4. Transition zones

5. GIS is an excellent tool to view the

impact of drought geographically.

6. Less Ozone Production,

especially in VOC-limited regions

AcknowledgementsDr. MaidmentGonzalo Espinoza DávalosYosuke KimuraDr. Allen

Thank you!