Jessie Sagona SARP Presentation

8/14/2019 Jessie Sagona SARP Presentation

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Estimation ofEvapotranspiration with

Jessie Sagona

Student Airborne Research

Program


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Outline

Introduction

What is ET, why is it important?

Method

How can we estimate ET? Whatassumptions go into it?

Results

Conclusions

Acknowledgements


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How does METRIC calculate


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Solar radiation

Inputs:

Day of year

Time of day

Latitude

Elevation

Transmissivity of atmosphere

Albedo


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Longwave radiation

Inputs:

Surface temperature (from Cassie andJames)

Emissivity (both atmosphere and crop)


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Sensible heat flux

Difficult to measure directly

In METRIC, calculated via iterationswith aerodynamic resistance.


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Latent heat flux


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Inputs to Code

Once code was ready, usedtemperature and SAVI estimates asinputs, with other variables set the

same for every pixel (i.e. latitude).


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Two types of runs

LAI from MASTER bandmath

LAI from Emilys analysis

Temperature always from MASTER data


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~3.3

~0.78


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Almond irrigation

Drip irrigation

Fanjet irrigation


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Almond ET using Emilys LAI

For 2nd field: average LAI = 2.65

For 3rd field: average LAI = 2.28

Resulting ET values: Field 2: 1.064 mm/hr

Field 3: 1.058 mm/hr


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1.110 mm/hr

1.074

1.081

1.053

1.078

1.064

1.056

ET using LAI from

ET using LAI fromground


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ET from CIMIS Penman-

The Penman-Monteith equationcalculates ET based onmeteorological parameters.

The CIMIS version has a slightlydifferent treatment of wind speedcompared to the classic version.

For almond orchard at time of flight:

ET = 1.38 mm hr


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Cotton Fields

~2.56

~3.15


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1.059

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1.024

1.027


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Cotton ET using Emilys LAI

Overall LAI for cotton was 1.49.


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ET from CIMIS Penman-

For cotton fields at time of flight:

ET = 0.572 mm/hr


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Conclusions - Almonds

The fanjet irrigation is more effectivethan drip irrigation, leading to higherET. METRIC underestimates ET

compared to the CIMIS PM equation.


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Conclusions - Cotton

METRIC strongly overestimates ETcompared to the CIMIS PM equation.

However, ground LAI measurements

and LAI from SAVI are very similar,resulting in similar ET values.


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Acknowledgements

Cassie, James, and Emily for directuse of data

Shawn for guiding our project

All of the SARP staff for this greatprogram!


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Questions?

Jessie Sagona SARP Presentation

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