sebs for ilwis open 3 - siti personali | libero...

INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION

SEBS for ILWIS OPEN 3.4

An interface for Surface Energy Balance in ILWIS Open Source (Jul 2007)

Gabriel ParodiWRS - ITC

S. E. B. Models of Agricultural Areas from Earth Observation Data”, Lima, Perú, 13 March 2008

Environment for a SEB operation

Work area and sensor/s definition.

(frequency defines volume of operation)

Requires ground and satellite pre- and post-processing near-real time.

pre-processing:

Satellite : download, calibration, geo-location, atm. Correction + extras

Ground data: meteorological and land properties (depending on adopted SEB)

processing:

Calibration, validation?

Running the selected SEB model and archiving (simplified).

Post-processing

Linking outputs to routines for information distribution in PLEIADeS.

Assisting in reports and eventual performance

From the operational point of view the algorithm itself is a “minor”problem.


What we have and can offer to PLEIADeS

Today: SEBS (Beta vesion) Interface in ILWIS Open

source.

When required: Software algorithms adaptations,

interface customization and complementary software

requirements.

Educational and transfer efforts if required.


ILWIS 3.4 open

1 July 2007, ILWIS is free of charge ('as-it-is‘) as open source software (binaries and source code) under the 52°North initiative (GPL license). This software version is called ILWIS 3.4 Open.Since then, independent work is carried out to add methods and models in ILWIS.

New release with updates (SEBS included): End March 2008.

http://52north.org/index.php?option=com_content&task=view&id=131&Itemid=155


ILWIS 3.4 Open

ILWIS is a remote sensing and GIS software.

Integrates image, vector and thematic data in one unique and powerful package.

ILWIS delivers a wide range of features including:import/export, digitizing, editing, analysis and display of data

production of quality maps.

functional, user-friendly

has established a wide user community over the years of its development.

It remains active after the open source release, both within and outside ITC.


What is SEBS4ILWIS now?

Adapted from SEBS in BEAM.

Interface done for educational purposes.

Limited volume of data and no customization.

SEBS module is documented in many articles

Additional methods are selected from simplicity but they can be customized

according to needs.

Preprocess only MODIS

This version was recently developed and testing was limited to WRS

testing cases. It is in the final debugging state. Deadline (End of March)


Pre-processing (optional) – 1 -



CharacteristicsInterface and models fully customizable (methods + Sensors)Today is customized for teaching and research purposes:

MODIS pre-processing:Raw – radiances – reflectance.Raw – radiances – brightness temperature.Atmospheric correction visible (several sensors SMAC algorithm implemented in ILWIS)Land surface albedoLand surface emissivityLand surface temperature


Summary: pre-processing for MODIS

Calibration: It works fine but requires 3 softwares: RAW image - HEG: conversion to GEO TIFF of all necessary bands + angles - Importing to ILWIS - Resampling the files - Get calibration coefficients with HDF explorer - to finally convert raw into radiance or reflectance. It was programmed for teaching purposes. For daily routinely tasks requires adaptation.

Brightness temperature: Inversion of Planck equation (standard).

SMAC: very convenient, easy, many sensors supported (thanks to authors). Only 2 atmospheric types. Actual limitation: it is band by band.

Land Surface albedo: weight method based on Liang, 2000.

Land surface emissivity: based on PV-NDVI following Sobrino, et. al (2003) and Carlson and Ripley (1997).

Land surface temperature: based on previous emissivity and Sobrino and Raissouni, 2000.

Improvements, more methods/sensors can be customized.


wetdry

wetr HH

HH−−

−=Λ 1

GRE

GRE

n

wetr

n −⋅Λ

=−

=Λλλ

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛ ∆+⎟⎟

⎠

⎞⎜⎜⎝

⎛ −⋅−−=

γγρ

10ee

rC

GRH s

ew

pnwet

0

0 ,0

GRH

orHGRE

ndry

dryndry

−=

≡−−=λ

wetnwet

wetnwet

EGRHorHGRE

λλ

−−=−−=

0

0 ,

wet

wet

wetr E

EEEE

λλλ

λλ −

−==Λ 1

EHGRn λ++= 0

( ) ( )( )GRE

GRH

n

n

−⋅Λ=−⋅Λ−=

λ1

SEBS Basic Equations Su, 2002, HESS, 6(1),85-99


Adopted/distinctive SEBS concepts

1. To evaluate evaporative fraction the energy balance is calculated at limiting wet & dry cases (used in SEBI).

H, u*, L calculated using set of non-linear equations F(u_ref, Ta_ref, To)

H is constrained between Hwet and HdryHdry= Rn-G

Hwet=Rn-G-λEwet and λEwet obtained from Penman Monteith (meteorology!!)

No user interaction or decision affecting the results (Fc required!!).

2. Roughness for heat transfer is calculated instead of being a “fixed”value with respect to roughness for momentum

kB-1= F(weighted with fc of a canopy, a soil and an interaction function)

3. Algorithms for upscaling ASL -> PBL and downscaling PBL-> ASLUses Monin-Obukhov Similarity (MOS) for ASL

Uses Bulk atmospheric Boundary Layer (ABL) Similarity (BAS) for PBL scaling

Criteria for using MOS or BAS follows (Brutsaert, 1999). Valid for unstable conditions.

Stable and unstable situations MOS & BAS considered.

wetdry

wetr HH

HH−−

−=Λ 1GR

EGR

E

n

wetr

n −⋅Λ

=−

=Λλλ


Relative evaporation

The relative evaporation is given as


Surface air potentials


Normalized temperature difference versus albedo


The scalar roughness height for heat transfer

The within-canopy wind speed profile extinction coefficient,

( )22*2 huu

LAICn dec

⋅=

( ) ( )( ) 21

*2

2*

10*

214

sst

hz

huu

sccn

t

d fkBC

kfff

ehu

uC

kCkBm

ec

−

−

− +⋅⋅

+−

=

( ) [ ]4.7lnRe46.2 41*

1 −=−skB

( )100 exp/ −= kBzz mh


Wind, air temperature, humidity(aerodynamic roughness,

thermal dynamic roughness)H

G0

LERn

⎥⎦

⎤⎢⎣

⎡⎟⎠⎞

⎜⎝⎛Ψ+⎟

⎠⎞

⎜⎝⎛ −

Ψ−⎟⎟⎠

⎞⎜⎜⎝

⎛ −=

Lz

Ldz

zdz

kuu m

mmm

00

0

0* ln

( )1

00

0

00* ln

−

⎥⎦

⎤⎢⎣

⎡⎟⎠⎞

⎜⎝⎛Ψ+⎟

⎠⎞

⎜⎝⎛ −

Ψ−⎟⎟⎠

⎞⎜⎜⎝

⎛ −−=

Lz

Ldz

zdzCkuH h

hhh

ap θθρ

kgHuC

L vp θρ 3*−=

[ ]?,, 000 hm zdz

Energy Balance Residual Method - Turbulent Heat Fluxes

[ ]?,, quTa


SEBS Interface

Originally developed in Beam and converted to ILWIS

last year.

Require both maps and ground data. All input is

delivered in one interface.

There are mandatory inputs, optional inputs and

alternative or subrogate inputs to compensate

mandatory's.

No interaction after the process is initiated, calculation

time depends on number of pixels in the map and, of

course, processor speed.

Mandatory map

Mandatory Map or Modeled map

Mandatory value: manual or modeled

Mandatory value

Mandatory map or mandatory value

Surrogate value


SEBS sequence

SW↓, To, ro, Ta, εa → Rn

Pv, Rn → G

Rn, G → Hdry

Based on PBL height and Reference height: MOS or BAS

U, To, Ta, LAI, Zom, PV →u*, L, H, kB-1, Zoh

RH, Rn, G, u*, Zoh → Lwet, Hwet

Hdry, Hwet, H → Λr

Hwet, Rn, G → λEwet

λEwet, Λr , Rn, G → Λ

Λ, Rn, G → λEwet

Λ, Rn24, G24 → Edaily


SEBS Input: Mandatory maps

± 0.01± 0.01± 0.01± 0.1Precision:

FcG

RnRnRnGH, L, u*

Used for:

Units [-]AC

Units [-]AC, broadband

Units [-]broadband

Units [K]AC

Pre-processing:

NDVIAlbedoSurf. EmissivitySurface Temp.

AC: atmospherically correctedRn: net radiationFc: fractional canopy coverage

G: soil heat fluxRn: net radiationFc: fractional canopy coverage


SEBS Input: Mandatory or modeled maps

± 0.01± 0.01± 0.1Precision:

Zom (attribute table)GkB-1

kB-1Used for:

Equations!

Land UsePvLAI

( )2minmax

min

NDVINDVINDVINDVI−

−NDVI

NDVINDVI−

+⋅1

)1(


Mandatory value when modeled

τ⋅−⋅⋅⋅↓= )cos(

1

)cos(1367 SZAo eSZAeSW

)5.51/exp(042.0

)5.5(105.05.5)0(10

)5.5(/)0(ln(5.51

0030765.0)5.5(0116.0)0(

)0()50log()0(

aHHDEMaHaHaH

aHaHaaH

ar

rVis

a

ββτ

ββββ

ββ

ββ

ββ

+⋅=

⋅−=⋅=

=

==

−=


OTHER equations in the program

( )26 15.273102.9 +⋅⋅= −aatm Tε

( )28 15.27310678.5 +⋅⋅⋅↓= −aatm TLW ε


Outputs from SEBS as Maps in ILWIS

Instantaneous actual evaporationDaily evaporationSoil heat fluxSensible heat flux at dry limitSensible heat flux at wet limitSensible heat fluxNet radiationLatent heat fluxUpdates are possible after feedback.

sebs for ilwis open 3 - siti personali | libero...

Documents