slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Douglas Speirs PowerPoint Presentation
Download Presentation
Douglas Speirs

Loading in 2 Seconds...

play fullscreen
1 / 30

Douglas Speirs - PowerPoint PPT Presentation


  • 106 Views
  • Uploaded on

Jo King:. Mechanisms relating the ocean-scale distribution of Calanus finmarchicus to environmental heterogeneity. Douglas Speirs. Acknowledgments: Bill Gurney (Strathclyde) Mike Heath (FRS Aberdeen)

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Douglas Speirs' - brandy


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Jo King:

Mechanisms relating the ocean-scale distribution of Calanus finmarchicus to environmental heterogeneity

Douglas Speirs

Acknowledgments: Bill Gurney (Strathclyde)

Mike Heath (FRS Aberdeen)

Simon Wood (Glasgow University)

SOC, PML, SAHFOS

why calanus finmarchicus
Why Calanus finmarchicus ?
  • Widespread & Abundant
  • Links to Fish Stocks
  • Extensively studied

2 mm

the life cycle of calanus finmarchicus
The life-cycle of Calanus finmarchicus
  • Omnivorous, but feeds mainly on phytoplankton.
  • x1000 difference in body weight between eggs and adults.
  • Stage duration strongly dependent on temperature
  • Naupliar survival strongly dependent on food.
  • Reproduction & growth in upper layers (<200m).
  • Overwinters in a resting state at depths of 500-2000m.
the modelling challenge
The modelling challenge
  • The Challenge
  • Physiologically and spatially explicit demographic model
  • Ocean-basin scale – advection plus diffusion
  • Hypothesis tests require wide parameter exploration
  • Need exceptional computational efficiency
  • The Solution
  • Focus on Calanus (physical and biotic environment as given)
  • Separate computation of physical and biological components
  • Discrete-time approach ( 104 speed-up relative to Lagrangian ensemble)
representing physical transport
Representing Physical Transport

Update at regularly spaced times: Ti

Class abundance just before update

Class abundance just after update

Transfer matrix element from y to x for period to Ti. Determine by particle tracking in flow fields from GCM plus random (diffusive) component.

the biological model
The Biological Model
  • Uniform ‘physiological age’ for each group of stages
  • Development rate a function of temp. and food
  • Diapause entry from start of C5 stage – cued by low food
updating the biological model
Updating the Biological Model

Update all classes in given group at given location at times {Ux,i} such that

according to

where

Survival of individual in q at x over increment up to u

updating the system state
Updating the system state

For each cell, in turn:

  • Collect all un-processedupdates from the adult, surface developer and diapauser groups
  • Form the union of the subsets of each sequence which fall before the next transport update
  • Process the new sequence in time order, updating all classes in that group at that location at each operation.

Do next transport update, Output state variables.

Produces model realisations in good agreement with PDE and Lagrangian ensemble solutions, but MUCH faster.

prototype environment
Prototype - Environment

Winter

(day 42)

Spring

(day 133)

Summer

(day 217)

Autumn

(day 308)

Flow

(HAMSOM)

Temp.

(HAMSOM)

Food

(SeaWiFS)

n e atlantic test data
N.E. Atlantic - test data
  • Overall plausibility test
  • Continuous Plankton Recorder surveys (SAHFOS)
  • Winter surveys of resting stages

Ocean Weathership M

Westmann Islands

Saltenfjorden

Murchison

Faroe shelf

Foinaven

Stonehaven

hypothesis testing ows mike
Hypothesis Testing - OWS Mike

Surface Copepodites

Diapausers

H1

H1

H3

H3

Newly surfaced overwinterers

Sharp drop at awakening

No diapausers in spring

plausibility test diapausers
Plausibility test – Diapausers

Winter

(day 28)

Spring

(day 154)

Summer

(day 224)

Autumn

(day 336)

H1:

H3:

plausibility test surface copepodites
Plausibility test – Surface Copepodites

Winter

(day 28)

Spring

(day 154)

Summer

(day 224)

Autumn

(day 336)

H1:

H3:

prototype conclusions
Prototype - Conclusions
  • Spatially and physiologically resolved model on an ocean
  • basin scale can be made fast enough for wide-ranging
  • parameter exploration
  • Current data on C. finmarchicus abundance in the N.E.
  • Atlantic is best fitted by a model which assumes diapause is
  • initiated by low food conditions.
  • Models which assume diapause duration is determined by
  • development are invariably falsified
  • Awakening must be conditioned on a highly spatially
  • correlated cue – such as photoperiod.
prototype model time series test
Prototype Model - Time Series Test

Gulf of Maine

OWS Mike

surface

C5-C6

diapause

C5

prototype model cpr test
Prototype Model – CPR Test

observed

predicted

observed

Jan./Feb.

May/Jun.

Jul./Aug.

c5 s phytoplankton carbon at owsm
C5’s & phytoplankton carbon at OWSM
  • Diapause occurs at end of C5 stage
  • Fixed fraction of each generation
annual mean temperature food
Annual Mean Temperature & Food

=> temperature-dependent background mortality

Labrador Sea is cold

revised model time series test
Revised Model - Time Series Test

Gulf of Maine

OWS Mike

surface

C5-C6

diapause

C5

revised model cpr test
Revised Model – CPR Test

observed

predicted

Jan./Feb.

May/Jun.

Jul./Aug.

domain connectivity
Domain Connectivity

Year 1

Year 3

Year 6

conclusions
Conclusions

Matching Calanus demography =>

  • Fractional diapause entry
  • Diapause entry late in C5
  • Photoperiod-cued diapause exit
  • Temperature-dependent mortality
  • Limited impact of transport
  • High domain connectivity

Fitted model =>

  • Ocean-scale population model feasible
  • Numerical efficiency is key