Internal tidal waves effects on near-surface

chlorophyll concentration and primary production

around Nazaré Canyon (western Portugal) and in

the central region of the Bay of Biscay

Muacho , S. (1) , da Silva, J.C.B., Brotas, V., Oliveira, P. (1) IPMA - Portuguese Institute for Ocean and Atmosphere

1. Can Internal Tidal (IT) waves influence (sub)surface chlorophyll

distribution?

2. Can IT increase ocean productivity?

ROI:

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

- Nazaré Canyon (western Portugal)

- Central Bay of Biscay

Questions:

What are IT waves?

tidal period*courtesy of Da Silva (in Robinson, 2010)

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Dept

h (m

)

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Dept

h (m

)

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

courtesy of Quaresma, L. (2006)

Internal Solitary Waves

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Internal Solitary Waves:

usually phase-locked to the interfacial ITs, and appear close to the IT troughs (see e.g. Jeans and Sherwin, 2001)

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Nazaré Canyon (western Portugal)

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Nazaré Canyon (western Portugal)

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

“Canyons” (R/V PELAGIA – NIOZ Institute) Nazaré Canyon (western Portugal)

Internal Solitary wavefronts

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

CHLSAT=f(CHL,K)

CHL

sigma-theta

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

v ~ 0.7 m.s-1 Synergy SAR / log(CHL(mg.m-3)) MODIS 14:15 UTC 10.09.2006

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

coherent with non-linear IT

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Ecological effect?

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Primary production: PP (z) = CHL (z). Pb

max [1 – exp (-α.E(z)/ Pbmax ]

Platt et al. (1980) formulation, without photoinhibition

Sathyendranath et al. (1995) climatological data

Platt T, Gallecos CL, Harrison WG (1980). Photoinhibition on photosynthesis in natural assemblages of marine phytoplankton, Journal of Marine Research, 38, 687-701.

Sathyendranath S, Longhurst I, Caverhill CM, Platt T (1995). Regionally and seasonally differentiated primary production in the North Atlantic, Deep Sea Research I, Vol. 42, No. 10, 1773-1802.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Primary production: PP (z) = CHL (z). Pb

max [1 – exp (-α.E(z)/ Pbmax ]

Platt et al. (1980) formulation, without photoinhibition

Sathyendranath et al. (1995) climatological data

Platt T, Gallecos CL, Harrison WG (1980). Photoinhibition on photosynthesis in natural assemblages of marine phytoplankton, Journal of Marine Research, 38, 687-701.

Sathyendranath S, Longhurst I, Caverhill CM, Platt T (1995). Regionally and seasonally differentiated primary production in the North Atlantic, Deep Sea Research I, Vol. 42, No. 10, 1773-1802.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Primary production: PP (z) = CHL (z). Pb

max [1 – exp (-α.E(z)/ Pbmax ]

Platt et al. (1980) formulation, without photoinhibition

Sathyendranath et al. (1995) climatological data

Platt T, Gallecos CL, Harrison WG (1980). Photoinhibition on photosynthesis in natural assemblages of marine phytoplankton, Journal of Marine Research, 38, 687-701.

Sathyendranath S, Longhurst I, Caverhill CM, Platt T (1995). Regionally and seasonally differentiated primary production in the North Atlantic, Deep Sea Research I, Vol. 42, No. 10, 1773-1802.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

1497 mgC.m-2.d-11627 mgC.m-2.d-1

Muacho, S., da Silva, J.C.B., and Brotas, V. (submitted). Internal waves effect on near surface chlorophyll concentration and primary production in the Nazaré canyon. Deep-Sea Research Part I

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Bay of Biscay

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

da Silva JCB, New AL, Srokosz M, Smyth T (2002) On the observability of internal tidal waves in remotely-sensed ocean color data. Geophys. Res. Lett. 29 (12), 1569-1572.

Bay of Biscay

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

ENVISAT-ASAR 12.08.2005

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

ENVISAT-ASAR 12.08.2005

I

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Azevedo A, da Silva JCB, New AL (2006). On the generation and propagation of internal waves in the southern Bay of Biscay. Deep-Sea Res. I 53

da Silva JCB, New AL, Azevedo A (2007). On the role of SAR for observing “Local Generation” of internal solitary waves off the Iberian Peninsula. Can. J. Remote Sens. 33, 388-403

“local generation” of ISW

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

“local generation” of ISW

Azevedo A, da Silva JCB, New AL (2006). On the generation and propagation of internal waves in the southern Bay of Biscay. Deep-Sea Res. I 53

da Silva JCB, New AL, Azevedo A (2007). On the role of SAR for observing “Local Generation” of internal solitary waves off the Iberian Peninsula. Can. J. Remote Sens. 33, 388-403

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

SAR / CHL (mg.m-3) MODIS 11.08.2005

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

SAR / CHL (mg.m-3) MODIS 11.08.2005 SAR / CHL (mg.m-3) MODIS 14.09.2003

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

This strong internal wave activity in the region of the central Bay (particularly intense in late summer) has any effect on ocean colour data on a larger timescale?

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

This strong internal wave activity in this region of the central Bay (particularly intense in late summer) has any effect on ocean colour data on a larger timescale?

Monthly climatology from ocean colour data from late summer (September) has been used. September was chosen for two primary reasons: 1. It coincides with stronger thermocline stratification conditions (e.g. Pingree

and New, 1995)2. Has one of the two highest spring tides of the year (the other is in March),

wherein internal waves are more frequent and stronger.

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

September chlorophyll (log(CHL(mg.m-3))) climatology (2002-11) from MODIS

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

September chlorophyll (log(CHL(mg.m-3))) climatology (2002-11) from MODIS

Muacho, S., da Silva, J.C.B., and Brotas, V. (in prep.). Chlorophyll enhancement in the central region of the Bay of Biscay as a result of internal (tidal) wave interaction.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay

Conclusions

The results show that: a) PP can increase up to 8% due to the presence of IT crests;b) strong IT activity also presents ocean colour signatures on climatology satellite data.

In summary, IT waves can play an important role in the regional ecology in some coastal or oceanic regions, such as the Nazaré Canyon and the central of the Bay of Biscay.

Internal tidal waves effects on near-surface chlorophyll concentration and primary production around Nazaré Canyon (western Portugal) and in the central region of the Bay of Biscay