Everything you wanted to knowEverything you wanted to know

but was too afraid to askabout “oceanoligists”

Alena MalyarenkoNABOS Summer School 2013

but was too afraid to askabout “oceanoligists”

Alena MalyarenkoNABOS Summer School 2013

OutlineOutline

Oceano.. wait for it.. logy ideas

Water masses

Definition

Classification

Formation

World WM

Arctic Ocean WM

My background special featuresMy background special features

Oceanology (we try to “study” rather than “observe”, or so they say)

Zubov, 1953: Department of Oceanology

We don’t use complicated math & physics (except for ready models)

Department specialization - water masses (you definitely need your imagination)

IMAGINE!IMAGINE!

Water Masses Water Masses

Classic DefinitionClassic DefinitionBodies of water that have a particular combination of properties that makes identifiable are referred to as WATER MASSES.

Defant (1929), analog of air masses in troposphere: “homogeneous limited or unlimited water object that can be characterized with certain physical and chemical properties”

Dobrovolskiy (1961): “some comparatively large water volume formed in a certain region of the World Ocean (the center, the source of the mass) that has over a long period of time almost constant and continuous distribution of physical, chemical and biological characteristics that form a unite complex and propagate as an integrated whole”

One more time!One more time!“some comparatively large water volume

formed in a certain region of the World Ocean (the center, the source of the mass)

that has over a long period of time almost constant and

continuous distribution of physical, chemical and biological characteristics

that form a unite complex

and propagate as an integrated whole”

Traditionally: 1929 - Defant, then Defant and Wust

“Wasswekorpers” - water bodies, homogeneous objects

Dynamic interaction between water bodies

First MentionFirst Mention

Real First MentionReal First MentionNansen, «THE NORWEGIAN SEA / ITS PHYSICAL OCEANOGRAPHY /BASED UPON THE NORWEGIAN RESEARCHES 1900-1904», 1909.

Introduction: By the two last expeditions the existence of the Wyville Thomson Ridge, was finally settled, and its configuration and physical conditions traced out. Thus it was finally proved that Europe (Scotland) is connected with Greenland by a continuous suboceanic ridge extending from Scotland to the Faeroe Bank (see fig. 8), from the Faeroes to Iceland, thence across Denmark Strait to Greenland. The saddle-depths of the ridge hardly exceed 550 metres (300 fathoms). By this ridge, the deeper parts of the Norwegian Sea Basin are entirely shut off from those of the Atlantic, and the cold bottom-water of the former is prevented from running

into the latter. The existence of this ridge is a feature of vital importance for the entire circulation of the Norwegian Sea. It forms a barrier to the movements of the water-masses, even those of the surface, as will be mentioned later; and its depths regulate the depths of the few currents coming in and running out from this basin.

Chapter V. General Description of the Water-Masses of the Norwegian Sea.

Genetic (convection, subduction, advection, subsurface mixing)

Structural (troposphere/intermediate/abyssal or surface/subsurface/intermediate/deep/bottom)

Geographical (center of formation)

Characteristic (high/low salinity/temperature)

Water Masses ClassificationWater Masses Classification

Antarctic Intermediate Low Salinity WM

WM Life Cycle (Genetic classification)

WM Life Cycle (Genetic classification)

3 basic phases:

1) formation,

2) transformation (evolution)

3)disappearance

3 basic phases:

1) formation,

2) transformation (evolution)

3)disappearance

FormationFormation

• 1) convective mixing - vertically unstable because of heat loss (autumn-winter cooling) or salinity increase (evaporation or ice formation)

5 types of thermohaline convection (Zubov, 1947):

1. polar (ice formation)

2. arctic (ice formation and winter cooling)

3. subarctic (winter cooling)

4. subtropic (winter cooling and evaporation)

5. tropical (evaporation)

Convection goes down until stratification is stable (100-4000 m) in several stages

low vertical gradient

modal water mass (McCartney and Talley, 1982)

Formation: SubductionFormation: Subduction

• 2) subduction (diving under) – sinkage cause by both wind and cooling

negative vorticity of wind field

Ekman pumping

slow sinkage of water

underlayers are more dense so sinking water has to move along isopycnic lines

SubductionSubduction1 winter:

•-convection goes down to a dense layer

•-creates a uniform layer

Summer heating:

•insulate water from atmosphere, creates stratification

2 winter:

•winter convection can’t reach this water

Subduction and obductionSubduction and obduction

SubductionSubduction

• Stommel, 1979

• formation of central WM in the main thermocline

• Wind convergence is typical for wide ocean areas with lost of T,S indexes (i.e., subtropical cycles).

• Sinking water has a wide variety of T,S indexes

surface

central

deep

bottom

intermediate

salinity

tem

pera

ture

Formation: mixingFormation: mixing

3) mixing of 2 or more WM under the surface

You get a new WM!

Formation: 4th type?Formation: 4th type?

Advection from the other place

Here: it’s not formed with any of 3 types!

BUT it was formed somewhere else

Transformation Transformation Start: 1) consolidation (Tomczak, 1999) – mixing inside the formed water volume

2) part mixing

If you know T1,S1 and T2,S2 you can calculate Tout and Sout (Mamaev, 1970)

TransformationTransformation• 3) modification and aging - changes non-conservative variables

because of biochemical processes ( decrease of O2, increase of nitrates and phosphates under the surface), decay (decrease 14C, tritium, 3He)

Aging of bottom Indian water

WM Age (Classic)WM Age (Classic)14C decay

O2 decrease

increase of nitrates and phosphates under the surface

GOC:GlobalOcean

Conveyer

WM Age (New)WM Age (New)Freons: unstable, biologically inactive, sea-atmosphere interaction (since 1975)

Sen Gupta, 2006

¼ degree model of freon distribution

1980

Net freon concentration <2km

2000

2020

2040

Transformation Transformation

4) different forming

intensive inter annual variability (heat and freshwater flux, bioproduction)

OUTSIDE OF FORMATION REGION, STAYING IN ONE POINT(YOU HAVE TO STOP MOVING WITH THE SAME WATER)

Elimination (disappearance) Elimination (disappearance)

1.WM is a part of creation of the new one, so that the new WM is “re-birthed”

2. WM is a part of mixing, you can’t identify it anymore, so it was “adsorbed”

WM Life circleWM Life circle

FormingTransformatio

nElimination

(disappearing)

Convection

Subduction

Mixing

Part-mixing

Aging (modification)

Different forming

Поглощение

Перерождение (Слияние)

Absorption

Re-birth(merging)

WM Formation WM Formation

Structural WMStructural WMtroposphere/intermediate/abyssal

or surface/subsurface/intermediate/deep/

bottom

troposphere/intermediate/abyssal or

surface/subsurface/intermediate/deep/bottom

Troposphere WMTroposphere WM

Surface (zonal)

Modal (subtropical modal waters, subpolar, modal high salinity waters)

Central

Very relative

z: max mixed layer

Latitude zoning:

•polar - subpolar: summer ice extension

•subpolar – mid latitudes : polar front

•mid latitudes - subtropical : subtropical front

•subtropical-tropical - change in wind direction in anticyclonic gyres

• tropical-equatorial - countercurrent between trade winds and

Surface WaterSurface Water

Surface WM (Lebedev, 1998)Surface WM (Lebedev, 1998)

• Minimum vertical gradient (T,S, density, O2) between seasonal and permanent thermocline

• Forming of modal WM is due to convection near permanent hydrological fronts from the side where density is less

• From subduction and advection from the center of forming modal WM spread on extensive territories

Modal WMModal WM

•Subtropical modal WM: on the sides of subtropical gyres

•Subpolar (subarctic, subantarctic): convection to the south from North Atlantic and North Pacific current and to the north from Antarctic Сircumpolar current

•High Salinity WM: subduction during higher evaporation from regions with salinity maximums inside subtropical gyres

3 types of modal WM

3 types of modal WM

Subpolar and Subtropical Modal WMSubpolar and Subtropical Modal WM

• Strait line on TS-diagram

• Subduction in subtropical gyres

Central Modal WMCentral Modal WM

Antarctic Intermediate WM

Antarctic Intermediate WM1/8 World Ocean volume

more that 50% of water area

low salinity + high biogenic elements

main freshwater flux from south polar front to the North

Formation: trans frontal change (the Pacific), convection (the Atlantic), advection (the Indian)

November 2004

World OceanWorld Ocean

Pacific Atlantic

North NorthSouth South

Т Т

S S

O2 O2

Pacific Atlantic

Silicate, mmole /kg

Phosphate, mmole/kg

NorthSouth NorthSouth

How much WM do we need?

How much WM do we need?

Mamaev, 1987: 23 WM

Emery, Meinke, 1986: 36 WM

Google: “Do you want more?”

Van Aken: “There is a real danger of transition from a very useful method of water mass analysis to a somewhat like a collection of post stamps”

Arctic OceanArctic Ocean

The Barents SeaThe Barents SeaAtlantic water , Arctic water (low S, T below 0, surface water), Coastal water (river run-off and Norway coastal current, low S and different T during the year)

Barents water (mixed all above: low T, high S)

Winter: no arctic water, North: Barents waters, South: Atlantic water

Summer (very stable, little amount of mixing):

North: Arctic on the surface, then Barents

Center: Atlantic water

South: Coastal, then Atlantic

The Cara SeaThe Cara SeaSurface Arctic water (up to 200 m, freezing T, 29-33,5‰)

3 layers:

upper layer is mixed during winter circulation (up to 50 m)

50-100 m: steep rise of S up to 34‰

100-200 m: intermediate characteristic between subsurface and deep waters

+ extra stratification in spring-summer because of heating and freshening

Warm Atlantic water in a trough (0 - +1°C, 35‰)

The Laptev SeaThe Laptev Sea

Surface Arctic water (5-7m)

Warm Atlantic water in a trough

Cold bottom waters (-0,4 - -0,9°C; 34,9‰)

The East-Siberian Sea

The East-Siberian Sea

Shallow

There’s no deep troughs

Low river run-off

Surface Arctic water, Coastal water (small areas near river mouths, less saline, warmer)

General PictureGeneral Picture

Nikiforov, Shpayher 1980

-1 to -1.8°C, 29‰

0 to +2°C, 33‰

-1 to -1.8°C, 29‰

-1.5 to 0°C, 34‰