Presented at: A Doctoral Students Conference. Challenges for Earth system science in the Baltic Sea region:
From measurements to models. University of Tartu and Vilsandi Island, Estonia, 10-14 August 2015
UNDERSTANDING THE WATER AND ENERGY
EXCHANGES IN THE COUPLED ATMOSPHERE-LANDOCEAN SYSTEM
ANDERS OMSTEDT, E-MAIL: [email protected]
Main components of the water cycle
• Water storage in oceans
The storehouses for the vast majority of all water on Earth are the oceans. It is estimated that of 1,386,000,000 cubic kilometers (km 3)
of the world's water supply (1,338,000,000 km3) is stored in oceans. That is about 96.5 percent. It is also estimated that the oceans
supply about 90 percent of the evaporated water that goes into the water cycle.
During colder climatic periods more ice caps and glaciers form, and enough of the global water supply accumulates as ice to lessen
the amounts in other parts of the water cycle. The reverse is true during warm periods. During the last ice age glaciers covered almost
one-third of Earth's land mass, with the result being that the oceans were about 122 meters lower than today. During the last global
"warm spell," about 125,000 years ago, the seas were about 5.5. meters higher than they are now.
• Evaporation
Evaporation is the process by which water changes from a liquid to a gas or vapor. Studies have shown that the oceans, seas, lakes,
and rivers provide nearly 90 percent of the moisture in our atmosphere via evaporation, with the remaining 10 percent being
contributed by plant transpiration. Net evaporation occurs when the rate of evaporation exceeds the rate of condensation. Evaporation
removes heat from the environment, which is why water evaporating from your skin cools you.
http://water.usgs.gov/edu/watercyclesummary.html
Main components of the water cycle
• Sublimation
Sublimation describes the process of snow and ice changing into water vapor without first melting into water.
Sublimation is a common way for snow to disappear in certain climates e.g. the south side of Mt. Everest. Low
temperatures, strong winds, intense sunlight, very low air pressure - just what is needed for sublimation to
occur.
• Evapotranspiration
The process by which water vapor is discharged to the atmosphere as a result of evaporation from the soil and
transpiration by plants.
• Water storage in the atmosphere
Water stored in the atmosphere as vapor, such as clouds and humidity. If all of the water in the atmosphere
rained down at once, it would only cover the ground to a depth of 2.5 cm.
http://water.usgs.gov/edu/watercyclesummary.html
Main components of the water cycle
• Condensation
The process by which water is changed from vapor to liquid and thus responsible for the precipitation in clouds
• Precipitation
The discharge of water, in liquid or solid state, out of the atmosphere, generally upon a land or water surface
• Freezing and melting sea ice
During freezing sea ice salt is rejecter from the ice into the surface causing mixing similar as evaporation.
Melting sea ice adds fresh water to the surface water similar as precipitation.
• Water storage in ice and snow
Freshwater stored in frozen form, generally in glaciers, ice fields, and snowfields
What is energy and where does it come from?
Energy is a property of a physical body which can be transformed to other objects or converted into different
forms. A common definition is that it is the ability of a system to perform work and is measured in Joules.
Energy can be convertible to other kinds of energy forms, and obey the conservation of energy. Common
energy forms include: Kinetic energy of moving objects, radiation energy carried by light as short or long
waves, potential energy stored by an object's position in a force field (gravitational, electric or magnetic), elastic
energy stored by stretching solid objects, chemical energy released when a fuel burns, and heat energy due to
an object's temperature.
From: the Sun (direct as heat, wind, precipitation and indirect true storage in oil, cool, gas, peat), nuclear
energy, tidal energy, geothermal energy.
In general we only consider the heat energy in BALTEX or IPCC, which is a great limitation of the energy
cycles.
Main components of the surface heat balance
• Sun radiation
• Longwave radiation from atmosphere and clouds
• Longwave radiation from land and water surfaces
• Latent heat
• Sensible heat
• Heat storage
Global Mean Radiation Budget (IPCC, 2013)
Radiation fluxes and turbulent
fluxes different ways to
change heat.
Radiation, transform energy in the form of photons. Shortwave
radiation (visible light) contains a lot of energy; longwave radiation
(infrared light) contains less energy than shortwave radiation.
Turbulent, transform energy by turbulence.
Upper atmosphere: 340-100-239=1
Earth surface:161-84-20-398+342=1
The global water cycle-hydrological view
The global water cycle following
Baumgartner and Reichel (1975), see
Bengtsson (2010)
The global water cycle a better perspective
A look at the volumes associated with the components of the
water cycle leads to a better perspective on the relative roles
of ocean atmosphere and land. To focus only upon terrestrial
fluxes, ignoring the oceanic component, would overlook the
ocean-atmosphere interface that plays a critical role in
maintaining the terrestrial moisture balance. Storing 23 times
the water on land and a million times the water in the
atmosphere, the ocean’s air-sea fluxes are many times larger
than the terrestrial equivalents.
http://www.whoi.edu/sbl/liteSite.do?litesiteid=18912&articleId=28408
The global water cycle-oceanographer’s view
Since most of the water cycle is between
atmosphere and ocean, we expect that the
oceanic salinity field will be an excellent
indicator of a changing water cycle. We
thus view it as an especially important
climate variable to monitor.
http://www.whoi.edu/sbl/liteSite.do?litesiteid=18912&articleId=28408
The global water cycle-oceanographer’s view
Our estimates of the flux of water into and out of the
ocean can be integrated over its surface all around the
globe. This provides a view of the strength of the
oceanic return flows. Similarly, measurements of the
strength of north-south winds and their moisture content
allow estimates of the meridional transport of water by
the atmosphere. The two curves are largely
complementary, showing that it is primarily the oceans
that maintain the water balance. One can also see from
the curve labeled “Mississippi” that north-south
transports of water by rivers are quite small by
comparison. Thus, in discussing the “Global Water
Cycle”, it is truly misleading to neglect the dominant
oceanic component.
http://www.whoi.edu/sbl/liteSite.do?litesiteid=18912&articleId=28408
Wijffels et al (1992)
The global water cycle-oceanographer’s view
Wijffels et al (1992)
IPCC (2013, p 43)
What do the trend in salinity
indicate and is this what we
should expect?
What controls surface water and heat balances?
• It is primarily the oceans that maintain the water balance (air-sea interaction, precipitation,
evaporation, sea ice growth/melting)
• Atmosphere properties (cloudiness, humidity, radiation, turbulence, stability, surface layer
structure)
• Land geodiversity (the variety of rocks, fossils, minerals, soils, landforms, natural processes)
• Land biodiversity (the variety of organisms found within a specified geographic region)
• Storage in land and glaciers
Land surfaces and landscape heterogeneity
Recent advances in Earth observation (EO) satellites have made
improved global observations of several key parameters
governing the global water cycle possible. In the coming years
an increasing number of EO missions (e.g., SMOS, AQUARIUS,
SMAP, SWOT, GPM, Sentinel 1, 2 and 3 series, EarthCare) will
provide an unprecedented capacity to observe the land surface,
the oceans and the atmosphere, opening a new era in EO and
water cycle science.
Text from: The ESA and GEWEX conference October 2015
http://www.eo4water2015.info/
See also https://youtu.be/Vjg5REQb-Bc
Land surfaces and the drainage basin concept: Measurements in the drainage
basin outflow give us a strong control on the hydrology cycle
Land surfaces and the drainage basin concept in the
Baltic Sea
The water and heat cycles in the Baltic Sea region,
BALTEX box
Modelling the water cycle in the Baltic Sea region
Omstedt et al (2004)
Bengtsson (2010)
The water and heat cycles in the Baltic Sea region
From Omstedt et al., (2014). Climate model scenarios
display a tendency towards reduced salinities (Meier et
al., 2012), but the large bias in the water balance
means that it is still uncertain how much salinity will
actually change (BACC II, 2015).
…..
Water cycle modelling in the Baltic Sea area could
clearly benefit from additional research efforts.
Land cover and
population density
Baltic Sea water balances and salinity
dV0 S
 dh
 SinQin  SQout  S  ( P  E  As (1  Ai )  i i (Si  S ) As Ai  Qr )  ....
dt
0 dt
Net precipitation
open water
Freezing/melting
Sea ice
Omstedt and Nohr (2004), steady state and present climate
Qin  42 x103
Qout  59 x103
Qr  15 x103
As  P  E   2 x103
S  Sin
Qout
Qin
 Qr  As ( P  E )
 Sin 0.55  14 x0.55  7.7
Omstedt and Nohr, (2004)
Baltic Sea mean salinity
S
1
V
 SdzdA
But to better understand
the freshwater storage we
Introduce freshwater height
Winsor et al., (2001, 2003)
Freshwater height
The fresh water storage can be estimated from the fresh water height F
1
F
S ref
surface

( S ref  S )dz , where Sref is a reference salinity and S salinity.
bottom
The freshwater height is now put in relation to some reference salinity
unaffected by regional freshwater supplies e.g. 35.0, with a 10 meter layer
of salinity 20 (typical Kattegat):
1
F
S ref
surface

bottom
( S ref  S )dz 
 35  20  x10  4.3 m
35
Freshwater volume or storage
Now we also include the area depth distribution:
1
F
S ref
surface

( S ref  S ) dA dz
bottom
The average fresh water volume in
The Baltic Sea is 1.7x104 km3
corresponding to 80% of the total
volume of the Baltic Sea. The freshwater residence time:
Tres 
Vstorage
Qf

1.7 x104  km3 
500  km / year 
3
 34( year )
Winsor et al., (2001, 2003)
Baltic Sea heat balances,
water temperature and ice
dH
 ( Fi  Fo  Floss  Fr ) As
dt
H    c pTdzdA
Floss  (1  Ai )( Fn  Fsw )  Ai ( Fwi  Fsi )
Fn  Fh  Fe  Fl  Fprec
Heat balances and water temperature
and ice
Omstedt and Nohr(2004) assume steady state present climate
Floss  Fin  Fr  Fout
Floss Asur  0 c pTinQin  0c pTr Qr  0c pTQout
 0 c p Tr Qr  T  Qout  Qin  
 0 c p Qr Tr  T   0?
Omstedt and Nohr, (2004)
Baltic Sea mean temperature and variability
dH
 ( Fi  Fo  Floss  Fr ) As
dt
H    c pTdzdA
Sea ice heterogeneities
Baltic Sea ice many
different types with and
without leads and snow and
in general more “grey” than
Arctic Sea ice
Baltic Sea heat balances, ice and variability
Omstedt and Hansson (2006)
BACC II Author Group (2015)
Baltic Sea water balances, niver run-off and variability
Hansson et al., (2011)
Baltic Sea water balances, salinity and variability
Model calculations indicating how salinity
in the central Baltic Sea can vary with
variations in freshwater inflow from rivers
and precipitation. The hatched field
represents observed variation over the last
hundred years (redrawn from Omstedt and
Hansson, 2006a).
The Swedish oceanographic expedition 1877 in relation to today
Fredrik Laurentz Ekman
Available in Swedish at:
http://www.havsmiljoinstitutet.se/publikationer/havet1888
Observed temperatures summer 1877 and two standard deviations of summer
temperatures during present climate
Observed salinities summer 1877 and two standard deviations of summer
salinities during present climate
BACC I (2008) results – in short
→ Presently a warming is going on in the Baltic Sea region, and will continue
throughout the 21st century.
→ BACC considers it plausible that this warming is at least partly related to
anthropogenic factors.
→ So far, and in the next few decades, the signal
is limited to temperature and directly related variables, such as ice
conditions.
→ Later, changes in the water cycle are expected to become obvious.
→ This regional warming will have a variety of effects on terrestrial and
marine ecosystems – some predictable such as the changes in the
phenology others so far hardly predictable.
BACC II results – in short
•
•
•
•
•
•
•
New assessment finds results of BACC I valid
Significant detail and additional material has been found and assessed.
Some contested issues have been reconciled (e.g. sea surface
temperature trends)
Ability to run multi-model ensembles seems a major addition; first signs of
detection studies, but attribution still weak
Regional climate models still suffer from partly severe biases related to the
heat and water balances and the effect of certain drivers (aerosols, land
use change) on regional climate statistics cannot be described by these
models.
Data homogeneity is still a problem and sometimes not taken seriously
enough
The issue of multiple drivers on ecosystems and socio-economy is
recognized, but more efforts to deal with are needed
In many cases, the relative importance of different drivers, not only climate
change, needs to be evaluated.
http://www.springer.com/gp/book/9783319160054
BACC II results – continue
•
•
•
•
•
Estimates of future deposition and concentration of substances like sulphur and nitrogen
oxides, ammonia/ammonium, ozone, carbon dioxide depend on future emissions and
climate conditions. Atmospheric factors seem relatively less important than emission
changes. The specification of future emissions is plausibly the biggest source of uncertainty
when attempting to envisage future deposition or marine acidification.
In the narrow coastal zone, where climate change and land uplift act together plant and
animal communities had to adapt to changing environment conditions.
Climate change is a compounding factor to major drivers of freshwater biogeochemistry, but
evidence is still often based on small scale studies in both time and space. The effect of
climate change cannot be quantified yet on a Baltic Basin wide-scale.
From climate model scenarios there is tendency towards reduced salinities but due to the
large bias in the water balance it is still uncertain whether Baltic Sea will become less or
more saline.
Scenario simulations suggest that most probably the Baltic Sea will become more acid in the
future. Increased oxygen deficiency, increased temperature, changed salinity and increased
acidification will impact the marine ecosystem in several ways and may erode the resilience
of the ecosystem.
http://www.springer.com/gp/book/9783319160054
Literature;
•
BACC II Author Team (2015). Second Assessment of Climate Change for the Baltic Sea basin. Springer Regional Climate Studies. ISSN 1862-0248 ISSN 1865505X (electronic). ISBN 978-3-319-16005-4 ISBN 978-3-319-16006-1 (eBook). DOI 10.1007/978-3-319-16006-1. Springer Cham Heidelberg New York
Dordrecht London.
•
Bengtsson, L., (2010). The global atmospheric water cycle. Environ. Res. Lett., 5.
•
Hansson, D. and A., Omstedt, (2008). Modelling the Baltic Sea ocean climate on centennial time scale; temperature and sea ice. Climate Dynamics 30, 763-778.
DOI 10.1007/s00382-007-0321-2
•
Hansson, D., Eriksson, C., Omstedt, A., and D., Chen (2011). Reconstruction of river runoff to the Baltic Sea. Int. J. Climatol., DOI: 10.1002/joc.2097
•
HAVET 1888 , utgiven av Havsmiljöinstitutet 2015. ISBN: 978-91-982291-0-3.
•
IPCC (2013). Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental
Panel on Climate Change. (Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley ,eds.).
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.
•
Jutterström, S., Andersson, H.C., Omstedt, A. and J.M., Malmaeus (2014). Multiple stressors threatening the future of the Baltic Sea-Kattegat marine ecosystem:
Implications for policy and management actions. Marine Pollution Bulletin 86, 468-480.
•
Meier, H.E.M., R. Hordoir, H.C. Andersson, C. Dieterich, K. Eilola, B.G. Gustafsson, A. Höglund, and S. Schimanke (2012). Modeling the combined impact of
changing climate and changing nutrient loads on the Baltic Sea environment in an ensemble of transient simulations for 1961-2099. Clim. Dyn. , 39, 2421-2441,
doi: 10.1007/s00382-012-1339-y.
Literature continue;
•
Omstedt, A., (2011). Guide to process based modelling of lakes and coastal seas. Springer-Praxis books in Geophysical Sciences, DOI 10.1007/978-3-642-17728-6. Springer-Verlag
Berlin Heidelberg. Second edition in 2015.
•
Omstedt, A. and C., Nohr (2004). Calculating the water and heat balances of the Baltic Sea using ocean modelling and available meteorological, hydrological and ocean data. Tellus
56A, 400-414. DOI 10.1111/j.1600-0870.2004.00070.x
•
Omstedt, A. and D., Hansson, (2006). The Baltic Sea ocean climate system memory and response to changes in the water and heat balance components. Continental Shelf Research
26, 236-251. DOI 10.1016/j.csr.2005.11.003
•
Omstedt, A. and D., Hansson, (2006). Erratum to: 'The Baltic Sea ocean climate system memory and response to changes in the water and heat balance components'. Continental
Shelf Research 26, 1685-1687. DOI 10.1016/j.csr.2006.05.011
•
Omstedt, A., Elken, J., Lehmann, A., and J., Piechura (2004). Knowledge of the Baltic Sea Physics gained during the BALTEX and related programmes. Progress in Oceanography 63,
1-28. DOI 10.1016/j.pocean.2004.09.001
•
Omstedt, A., Elken, J., Lehmann, A., Leppäranta, M., Meier, H.E.M., Myrberg, K.,Rutgersson, A., Progress in physical oceanography of the Baltic Sea during the 2003–2014 period,
Progress in Oceanography (2014), doi: http://dx.doi.org/10.1016/j.pocean.2014.08.010
•
Wijffels, A. E., et al., (1992).Transport of Freshwater the Oceans. J. Phys. Oceanogr., Febr., pp. 155-162.
•
Winsor, P., J. Rodhe, and A. Omstedt (2001). Baltic Sea ocean climate: an analysis of 100 yr of hydrographic data with focus on the freshwater budget, Clim. Res., 18, 5-15, 2001.
•
Winsor, P., J. Rodhe, and A. Omstedt (2003). Erratum: Baltic Sea ocean climate: an analysis of 100 yr of hydrographical data with focus on the freshwater budget. Climate Research,
18:5-15, 2001. Climate Research, 25, 183.
Presented at: A Doctoral Students Conference. Challenges for Earth system science in the Baltic Sea region:
From measurements to models. University of Tartu and Vilsandi Island, Estonia, 10-14 August 2015
The Baltic Earth Science Grand Challenges 2015• Salinity dynamics in the Baltic Sea
• Land-Sea biogeochemical feedbacks in the Baltic Sea region
• Natural hazards and extreme events in the Baltic Sea region
• Understanding sea level dynamics in the Baltic Sea
• Understanding regional variability of water and energy exchanges