overview

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•Overview of Dataflow data processing method• Chlorophyll-a correction method•Dataflow processing output• Thoughts on supplementary data analysis methods

Overview

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Processing the 2005 – 2013 DATAFLOW Data

Pair YSI chlorophyll-a

with extracted chlorophyll-a

data

Correct/calibrate YSI data using extracted

chlorophyll-a

InterpolationPost-process interpolation

results

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• Purpose: To correct/calibrate YSI chl-a based on extracted chl-a• Different methods used in past by DEQ, VIMS,

HRSD• Variants:• How to lump data (by season, segment, year, etc.)• Whether or not to ln-transform• Whether to include additional explanatory variables

(turbidity, temperature)

• Magnitude of correction is small compared to normal variation (over space and time)

Chlorophyll-a Correction Method

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• Recently recommended method was a compromise between monthly and multi-year lumping• Lump by season-segment-year• Use ln transform• Exclude turbidity and temperature

• However, it results in some unreasonable corrections; e.g.:• 192 ug/L 808 ug/L• 333 ug/L 954 ug/L

• Cause: Outliers and fewer number of high chl-a values (limited dynamic range) in some combinations

Recent developments

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Appears that seasons can be lumped

0 50 100 150 200 250 300 350 4000

100

200

300

400

500

600

700

R² = 0.815755152261404

R² = 0

SpringLinear (Spring)Summer

YSI Chla (ug/L)

Extr

acte

d C

hla

(u

g/L

)

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TF different, but little evidence that other segments are fundamentally different

0 50 100 150 200 2500

20

40

60

80

100

120

140

160

180

R² = 0.486964803348307

R² = 0.747940161656906R² = 0R² = 0

ELIMH

Linear (ELIMH)

JMSMH

YSI Chla (ug/L)

Extr

acte

d C

hla

(u

g/L

)

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Some years are different

0 50 100 150 200 250 3000

50

100

150

200

250

300

350

2005Linear (2005)2006

YSI Chla (ug/L)

Extr

acte

d C

hla

(u

g/L

)

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Log transform improves some regression properties but can contribute to unreasonable corrections

-2 -1 0 1 2 3 4 5 60

1

2

3

4

5

6

7

2005

Lin-ear (2005)

2006

Ln YSI Chla

Ln

Extr

acte

d C

hla

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• Use consistent correction method• Remove outliers• Lump non-TF segments by year• Simple linear regression• These regressions have already been

developed by HRSD.

Recommendation: Annual Correction Method

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Dataflow Processing Output:Maps

Mesohaline

Polyhaline

…can be made “prettier” using GIS

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• By segment, individual cruise• Spatial exceedance, no temporal averaging

• By segment-season• Averaged spatially and temporally

• Can perform CFD calculations

Dataflow Processing Output:Tables of Threshold Exceedance Rates

Cruise Date Segment Season YearArithmetic Mean Chla

Geometric Mean Chla

% Area Exceed 10

ug/L

% Area Exceed 20

ug/L

% Area Exceed 30

ug/L

% Area Exceed 40

ug/L

% Area Exceed 50

ug/L

% Area Exceed 60

ug/L

% Area Exceed 70

ug/L

% Area Exceed 80

ug/L

% Area Exceed 90

ug/L

% Area Exceed

100 ug/L03/02/2010 JMSMH Spring 2010 6.99 6.30 9.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.003/05/2013 JMSMH Spring 2013 18.57 6.99 38.3 25.4 20.3 15.1 12.0 10.4 9.1 8.8 7.6 5.903/06/2006 JMSMH Spring 2006 74.76 42.60 96.5 67.5 57.4 50.8 47.4 43.3 39.2 35.2 32.2 29.203/06/2008 JMSMH Spring 2008 5.42 4.40 14.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.003/07/2012 JMSMH Spring 2012 27.11 14.86 63.3 39.2 25.6 19.3 17.3 16.5 11.6 11.6 8.5 6.303/08/2006 JMSMH Spring 2006 36.40 8.12 36.9 22.1 19.0 16.6 14.8 14.0 13.2 13.2 13.2 12.803/08/2007 JMSMH Spring 2007 3.79 3.60 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.003/08/2010 JMSMH Spring 2010 5.09 4.74 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.003/08/2011 JMSMH Spring 2011 3.57 2.92 1.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.003/10/2009 JMSMH Spring 2009 18.49 9.60 36.7 19.2 16.8 14.9 10.0 8.2 7.6 6.4 6.4 4.1

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Dataflow Processing Output:Charts of %Area by Chl-a Bin

2005 2006 2007 2008 2009 2010 2011 2012 20130%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

JMSMHSummer

Mean % Area > 100 ug/LMean % Area 90 - 100 ug/LMean % Area 80 - 90 ug/LMean % Area 70 - 80 ug/LMean % Area 60 - 70 ug/LMean % Area 50 - 60 ug/LMean % Area 40 - 50 ug/LMean % Area 30 - 40 ug/LMean % Area 20 - 30 ug/LMean % Area 10 - 20 ug/LMean % Area 0 - 10 ug/L

14.5 7.1 8.2 19.9 9.17 17.3 6.1 10.3 9.3 Seasonal mean

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Dataflow Processing Output:Graphics of Mean vs. Threshold Exceedance Rates

0 5 10 15 20 25 300.0

5.0

10.0

15.0

20.0

25.0

% Area Exceeding 80 ug/LJMSMH Summer - 2005-2013 - Individual Cruises

Geometric Mean Chl-a (ug/L)

% A

rea

Exce

ed

ing

80

ug

/L

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• Conditional probability• Chl-a bin charts are a version of this• Some bins are data limited• Inter-bin thresholds?

• Potential supplementary analyses• Simple graphical (e.g., scatterplots)• Locally-weighted averaging (LOWESS)• Continuous conditional probability methods• Changepoint analysis

Other Potential Graphical/Statistical Analysis Methods

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Scatterplot/LOWESS Example: Cocholodinium density vs. chlorophyll-a

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Scatterplot/LOWESS Example: C. polykrikoides density (transformed) vs. chlorophyll-a

10,000 cells/mL

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Locally-weighted conditional probability example: Probability that C. polykrikoides exceeds 10k cells/mL vs. chlorophyll-a

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Changepoint analysis example: Probability of C. polykrikoides > 10k cells/mL split by chlorophyll-a

Significantly higher probability when chla > 100 ug/L

Brown and Caldwell 19

Extra Slides


2005 2006 2007 2008 2009 2010 2011 2012 20130%

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2005 2006 2007 2008 2009 2010 2011 2012 20130%

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JMSPHSpring



2005 2006 2007 2008 2009 2010 2011 2012 20130%

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