optical measurements (licor) & k d values
DESCRIPTION
Optical Measurements (LiCor) & K D Values. Briana Rice CHM 576 Fall 2009. Outline. Measurements K D Values Significance Effects Depth vs. PAR Irradiance K D vs. Turbidity K D vs. DOC. Measurements. LiCor sensor used for measurements - PowerPoint PPT PresentationTRANSCRIPT
Optical Measurements
(LiCor) & KD Values
Briana Rice
CHM 576
Fall 2009
OutlineMeasurementsMeasurements
KKDD Values Values
SignificanceSignificanceEffectsEffects
Depth vs. PAR IrradianceDepth vs. PAR Irradiance
KKDD vs. Turbidity vs. Turbidity
KKDD vs. DOC vs. DOC
Measurements
LiCor sensor used for measurementsLiCor sensor used for measurements
Scalar collector- measuring light Scalar collector- measuring light from any directionfrom any direction
Blocked upward irradiance to Blocked upward irradiance to measure in airmeasure in air
Measure irradiance at various Measure irradiance at various depthsdepths
KD Values
Diffuse attenuation coefficient in mDiffuse attenuation coefficient in m-1-1
Determined by inherent optical Determined by inherent optical properties, but are strictly properties of properties, but are strictly properties of the radiation fieldthe radiation field
Light attenuation is exponential with Light attenuation is exponential with depthdepth
€
KD =1
z2 − z1
lnEd z1( )Ed z2( )
KD Value Effects
Larger KLarger KDD value, light attenuated so does not reach as far value, light attenuated so does not reach as far
Varies with different water bodiesVaries with different water bodies
Scattering overcomes difference in beam angle (sunlight), Scattering overcomes difference in beam angle (sunlight), so Kso KDD can be used to compare one water body to another can be used to compare one water body to another
Varies with different water typesVaries with different water types
KKDD increases with increasing turbidity increases with increasing turbidity
KKD D increases with increasing DOC concentrationincreases with increasing DOC concentration
Calculated KD Values (units m-
1) Station
Cruise 1
LCFRP Sept ‘08
Cruise 2
LCFRP Oct ‘08
M18 1.36 1.07 1.55 0.82
M23 1.37 1.01 1.43 1.34
M35 2.05 1.91 1.79 2.27
M42 2.15 2.48 1.95 2.56
M54 2.11 2.07 2.40 3.10
M61 2.59 3.03 2.46 3.68
HB 2.60 4.02 2.46 3.79
ln (E0/Ez) vs. Depth (m)
Cruise 1 (Station M42): Depth Plot for KD
Cruise 2 (Station M42): Depth Plot for KD
Cruise 1: KD Values vs.
Turbidity
Cruise 2: KD Values vs.
Turbidity
KD vs. DOC Concentration
KD vs. DOC Concentration