Some aspects on the arctic energy budget and climatology
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Some aspects on the Arctic energy budget and climatology. Nils Gunnar Kvamstø ( [email protected] ) Input from Asgeir Sorteberg, Igor Ezau, Vladimir Alexeev and Øyvind Byrkjedal. OUTLINE OF THIS WEEKS LECTURES. Arctic Climatology 1 Arctic Climatology 2

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Some aspects on the arctic energy budget and climatology

Some aspects on the Arctic energy budget and climatology

Nils Gunnar Kvamstø ([email protected]) Input from Asgeir Sorteberg, Igor Ezau, Vladimir Alexeev and Øyvind Byrkjedal


Outline of this weeks lectures

OUTLINE OF THIS WEEKS LECTURES

  • Arctic Climatology 1

  • Arctic Climatology 2

  • Sea Ice – role, variability, mechanisms

  • Arctic climate variability and climate change


Some aspects on the arctic energy budget and climatology

FRAMEWORKENERGY CONTENT IN AN ATMOSPHERIC COLUMN

0

ztop

Hartmann (1994) Ch 6

ps

0


Some aspects on the arctic energy budget and climatology

CHANGE OF ENERGY WITH TIME

RTOA

[uAE]

[uAE+d(uAE)]

RS, QH+QS


Some aspects on the arctic energy budget and climatology

OCEANIC ENERGY BUDGET

Li +Si

so

L – Latent heat; S – sensible heat

TERRESTRIAL ENERGY BUDGET


Some aspects on the arctic energy budget and climatology

The Arctic energy budget

  • Atmosphere:

  • Net radiation at top of atmosphere

  • Lateral transport

  • Surface fluxes (radiation, turbulence)

  • Ocean:

  • Surface fluxes (radiation, turbulence)

  • Lateral transport (water)

  • Latent heat (freezing/melting)

  • Ice transport

  • Land Surface:

  • Surface fluxes

  • Fresh water run off

70˚N


Some aspects on the arctic energy budget and climatology

ANNUAL CYCLE

ERA-40: Grided re-analysisUppala et al (2005)

Annual means:

dAE/dt =0,

Fsfc = 11 Wm-2

Rtop=-110Wm-2

∆F = 100Wm-2

Residual 1Wm-2

Serreze et al (2007)

∂AE/∂t <0 in autumn  Rtoa decreases (SW decr) Fsfc + ∆F increases. Damp rad effect

∂AE/∂t < 0 in spring  Rtoa increases (SW incr) Fsfc + ∆F decreases. Damp rad effect

When Rtoa ≈ 0 Fsfc ≈ -∆F

Both late spring and early autumn ∆F partly compensates sfc and toa fluxes


Some aspects on the arctic energy budget and climatology

Annual cycle contd

0

Residuals’ space and time dependency

0

Serreze et al (2007)


Some aspects on the arctic energy budget and climatology

∆F – cosists mostly of dry static energy!

∆Fq ≈ Pr

Fsfc = Rs + QE + QH, Rs dominates

Often QH <0 due to inversion (small)

QEalways positive

Serreze et al (2007)


Assessment of era40 comparison with sat and obs data

Assessment of ERA40 – comparison with sat.- and obs Data

  • ∆F well constrained (similar to NCEP)

  • Fsfc is in the upper range (2.5 – 11) (1Wm-2 = 0.1m sea ice in 1 yr!!)

  • Fsfc too high. Inaccurate cloud properties in ERA40

  • Excessive Rtop – too high content of sensible heat

  • Remember satellite data are inaccurate as well

Serreze et al (2007)


Some aspects on the arctic energy budget and climatology

  • Energy flux from surface to atmosphere during winter

  • Largest fluxes from open ocean QH QE

  • Nearly 0 over land (QE into sfc [inversion] LW out)

  • Energy flux from atmosphere to surface during summer.

  • Largest over open ocean (SW and low albedo)

  • QE downward (melting ice & permafrost deepening active soil layer)

Fsfc in ERA40 are higher than in other datasets. Indication of systematic error.But, the active soil layer may have increased(tawing) over the last decades => more heat stored larger fluxes.

Serreze et al (2007)


Some aspects on the arctic energy budget and climatology

Mean transport

Serreze et al (2007)


Some aspects on the arctic energy budget and climatology

Time series of total transport

Pronounced annual cycle

Weaker interannual cycle

and low frequency variability.

Trends?

Serreze et al (2007)


Some aspects on the arctic energy budget and climatology

ANNUAL ATMOSPHERIC ENERGY TRANSPORT

Andresen and Sorteberg (2009)


Some aspects on the arctic energy budget and climatology

Zonally averaged long term circulation – mean meridional circulation

Polar cell

Ferrel cell

Deviations from mean matters as well –eddies

v

u

Wallace and Hobbs (2006)

Poleward transport by mean meridional circulation =


Mean height of 500 hpa surface january

ATMOSPHERIC TRANSPORT BY EDDIES

Mean height of 500 hPa surface January

Hartmann (1994) Ch 6


Some aspects on the arctic energy budget and climatology

ATMOSPHERIC TRANSPORT

Total poleward heat tr = (tr by MMC) + (tr by qs eddies) + (tr by high freq eddies)


Annual average northward energy flux

Annual average northward energy flux

units in 1015 W


Zonally averaged northward flux of heat by eddies

Zonally averaged northward flux of heat by eddies

Hartmann (1994) Ch 6


Atmospheric heat transport

ATMOSPHERIC HEAT TRANSPORT

HEAT TRANSPORT ACROSS 60ºN

MMC - MEAN MERIDIONAL

CIRCULATION

SE - STATIONARY EDDIES

TE - TRANSIENT EDDIES

Largest portion below 500hPa

Max in 800-900hPa (1200-2500m)

Not much in the Atmospheric Boundary Layer


Some aspects on the arctic energy budget and climatology

LONGITUDINAL DEPENDENCE OF ΔF

W and E of N. American through

The seasonal in/out flow of energy is longitude dependent

Both quasistationary waves and eddies contribute.

Strong signatures from quasistationary waves in figure

Transport below 3000m -> N.Atl more pronounced here


Some aspects on the arctic energy budget and climatology

Ocean budget (+ atmosphere over ocean area only)

3 neglected 2,4,5,6 -> observed => 1 residual

5 – ice drift in the fram strait

4 – estimated from model runs. Sum out/inflow Fram, Bering, Barents, Can Arc

(may be dependent on comp method)

Serreze et al 2007


Some aspects on the arctic energy budget and climatology

S0/OE

Transport terms are steady =>

Annual cycle generated by Fsfc

Seasonal cycle comes mostly from Barents sea.

Large heat content on Nov – due to adv – This contributes to secondary max in Li in Dec

Cycle gets lagged with depth


Arctic climatology quality checked arctic stations for climate studies

ARCTIC CLIMATOLOGYQUALITY CHECKED ARCTIC STATIONSFORCLIMATE STUDIES

START YEAR

Polyakov, 2003


Examples of some drifiting stations

EXAMPLES OF SOME DRIFITING STATIONS

FRAM (1893-1896) MAUD (1922-1924) T-3 (1952-1971)

NP-STATIONS (1952-1993) RUSS. PATROL SHIPS (1952-1983) DARMS (1958-1975)

Russ. Drifting Automatic

Radiometeorological Stations

Example:

NP-22

(1973-1982)

Example:

Pol

(1953-1959, 1972)

Arctic Climatology Atlas, 2002


2m temperature

2m temperature

JANUARY

APRIL

Arctic Climatology Atlas, 2002


2m temperature1

2m temperature

JULY

OCTOBER

Arctic Climatology Atlas, 2002


Temperatures at svalbard

TEMPERATURES AT SVALBARD


Some aspects on the arctic energy budget and climatology

Northern hemisphere temperature

Johannessen, 2003


Precipitation

PRECIPITATION

JANUARY

APRIL

Arctic Climatology Atlas, 2002


Precipitation1

PRECIPITATION

JULY

OCTOBER

Arctic Climatology Atlas, 2002


Precipitation at svalbard

PRECIPITATION AT SVALBARD


Precipitation gadients coast innland

PRECIPITATION GADIENTS COAST/INNLAND


Measuring arctic precipitation

MEASURING ARCTIC PRECIPITATION


Some aspects on the arctic energy budget and climatology

Annual fractions of liquid, solid and mixed precipitation

at Svalbard Airport


Snowdepth over the ice

SNOWDEPTH OVER THE ICE

JANUARY

APRIL

Arctic Climatology Atlas, 2002


Snowdepth over the ice1

SNOWDEPTH OVER THE ICE

JULY

OCTOBER

Arctic Climatology Atlas, 2002


Surface shortwave radiation sw

SURFACE SHORTWAVE RADIATION: SW↓

80ºN

OBSERVATIONAL BASED

Curry and Ebert (1992)

SATELITE BASED (ISCCP, 1985)

Rossow and Chang (1995)

JUNE

Curry et al., 1996


Downward longwave radiation at surface lw

DOWNWARD LONGWAVE RADIATION AT SURFACE : LW↓

80ºN

OBSERVATIONAL BASED

Curry and Ebert (1992)

SATELITE BASED (ISCCP, 1985)

Rossow and Chang (1995)

JUNE

Curry et al., 1996


Cloud fraction

CLOUD FRACTION

60-90ºN

OBSERVATIONALLY BASED

(varying sky illumination corrected, Hahn et al., 1994)

OBSERVATIONALLY BASED

SATELLITE BASED (ISCCP, new cloud detection algorithm)

SATELLITE BASED (ISCCP)

Curry et al., 1996


Total cloudcover

TOTAL CLOUDCOVER

LOW CLOUDCOVER

APRIL

JANUARY

Arctic Climatology Atlas, 2002


Total cloudcover1

TOTAL CLOUDCOVER

LOW CLOUDCOVER

JULY

Arctic Climatology Atlas, 2002


Clouds

CLOUDS

1. Norwegian Sea Regime

High cloudiness all year round

Relatively large amounts of cumulus in winter

caused by warm water under cold air

2. East Siberian Regime

Very clear in winter due to anticyclone

Very dry

Cirrus dominates

3. Polar Ocean Regime

Pronounced spring/summer maximum

due to stratus

Forms over cooler ice surface

(warm advection. latent heat cooling)


Local effect of clouds on the radiation budget

LOCAL EFFECT OF CLOUDS ON THE RADIATION BUDGET

CLOUD RADIATIVE FORCING at a given level z is the difference in net radiation between cloudy and clear sky usually given in W/m2

f

LW longwave radiation

SW shortwave radiation


Local effect of clouds on the surface radiation budget

LOCAL EFFECT OF CLOUDS ON THE SURFACE RADIATION BUDGET

80ºN SURFACE

POSITIVE:

WARMING AT SURFACE

NEGATIVE:

COOLING AT SURFACE

OBSERVATIONALLY

BASED

Curry and Ebert (1992)

JUNE

Curry et al., 1996


Local effect of clouds on the surface radiation budget1

LOCAL EFFECT OF CLOUDS ON THE SURFACE RADIATION BUDGET

80ºN SURFACE

NET CLOUD FORCING

CRF POSITIVE:

CLOUDS CAUSE WARMING AT SURFACEMOST OF THE YEAR EXCEPT SUMMER

CRF NEGATIVE:

CLOUDS CAUSE COOLING AT SURFACEDURING SUMMER

OBSERVATIONAL

BASED

Curry and Ebert (1992)

SATELITE BASED (ISCCP, 1985)

Rossow and Chang (1995)

JUNE

Large uncertainty!

Curry et al., 1996


Links between energy budget and climatology

LINKS BETWEEN ENERGY BUDGET AND CLIMATOLOGY

SUMMARY:

Most times of the year two big terms are:

1. Heating by lateral advection

2. Cooling by longwave radiation to space

In summer:

1. Heating by lateral advection

2. Cooling by surface

(latent heat from ice/snow melting)

ANNUAL SUMMER WINTER

Nakamura and Oort, 1973

REMEMBER THE TRANSTORT IS A VERTICAL AND HORIZONTAL INTEGRAL


Wintertime atmospheric circulation and low level temperature

WINTERTIME ATMOSPHERIC CIRCULATION ANDLOW LEVEL TEMPERATURE


Low level atmospheric circulation

LOW LEVEL ATMOSPHERIC CIRCULATION

Semipermanent Highs and Lows

The Arctic is characterized by "semipermanent" patterns of high and low pressure.

These patterns are semipermanent because they appear in charts of long-term average

surface pressure.

Aleutian Low

This semipermanent low pressure center is located near the Aleutian

Islands. Most intense in winter, the Aleutian Low is characterized by many strong

cyclones. Travelling cyclones formed in the subpolar latitudes in the North Pacific

usually slow down and reach maximum intensity in the area of the Aleutian Low.

Icelandic Low

This low pressure center is located near Iceland, usually between Iceland and

southern Greenland. Most intense during winter, in summer, it weakens and

splits into two centers, one near Davis Strait and the other west of Iceland. Like its

counterpart the Aleutian Low, it reflects the high frequency of cyclones and the

tendency for these systems to be strong. In general, migratory lows slow down and

intensify in the vicinity of the Icelandic Low.


Atmospheric low level circulation

ATMOSPHERIC LOW LEVEL CIRCULATION

Siberian High

The Siberian High is an intense, cold anticyclone that forms over eastern Siberia in winter.

Prevailing from late November to early March, it is associated with frequent cold air

outbreaks over east Asia.

Beaufort High

The Beaufort High is a high pressure center or ridge over the Beaufort Sea present mainly

in winter. The North American High is a relatively weak area of high pressure that

covers most of North America during winter. This pressure system tends

to be centered over the Yukon, but is not as well-defined as its continental counterpart,

the Siberian High.


Some aspects on the arctic energy budget and climatology

A PARADOX?

Low level T is not representative?

Trends in other budget terms?

(sea-ice, radiation…)


Some aspects on the arctic energy budget and climatology

HOW WELL DO WE KNOW THE SURFACE

RADIATION BUDGET?


Some aspects on the arctic energy budget and climatology

OBSERVATIONAL ESTIMATES THAT

COVERS 70-90°N

  • The ECMWF (ERA40) reanalysis

    • 3-dimensional variational assimilation (T159L60)

    • Raw satellite radiances assimilated into the system

    • Satellite data from the Vertical Temperature Profile

    • Radiometer (VTPR) starting in 1973, TIROS Operational

      • Vertical Sounder (TOVS) data from late 1978

  • NCAR-NCEP reanalysis

    • 3-dimensional variational assimilation (T62L28)

    • No direct assimilation of radiative fluxes.

    • Estimate the vertical temperature and humidity profiles through a series of empirical and statistical relationships

    • Satellite data from TIROS TOVS data from late 1978


Some aspects on the arctic energy budget and climatology

OBSERVATIONAL ESTIMATES THAT

COVERS 70-90°N

  • SRB V2: Version 2 of the Surface Radiation Budget

    • ISCCP DX (30km res.) top of atmosphere (TOA) data and clouds

    • Atmospheric water vapor: 4-D data assimilation using the Goddard Earth Observing System model (GEOS-1).

  • POLAR ISCCP Version 1 polar radiation fluxes (Key et al. 1999).

    • ISCCP-D1 (280km res.) data top of atmosphere (TOA) data and clouds

    • Atmospheric water vapor: TOVS Pathfinder and ISCCP profiles

  • Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder dataset (APP-X), Version 1 (Key, 2001).

    • Extension of the standard clear sky products using the Cloud and Surface Parameter Retrieval (CASPR) system


Some aspects on the arctic energy budget and climatology

LW↓

225 W/m2

SW↓

99 W/m2

LW↑

260 W/m2

SW↑

45 W/m2

LW↓ 70%

SW↓30%

LW↓ + SW↓ 324 W/m2

LW↑+ SW↑ 305 W/m2

SOURCE:

ERA40, SRB V2, ISCCP


Some aspects on the arctic energy budget and climatology

HOW MUCH NET ENERGY IS AVAILABEL AT

THE SURFACE?

W/m2

W/m2

SURFACE LW↓-LW↑

SURFACE SW↓-SW↑

0

-10

-20

-30

-40

-50

-60

-70

160

140

120

100

80

60

40

20

0

  • Longwave radiation as an Arctic net energy sink ranges from 28 to 52

  • W/m2

  • There is no consensus on the seasonal cycle of net LW radiation.

  • Shortwave radiation as a net energy source ranges from 43 to 50 W/m2


Some aspects on the arctic energy budget and climatology

HOW WELL DO WE KNOW THE INCOMMING

ENERGY?

W/m2

W/m2

DIFFERENCE IN SURFACE LW↓

SURFACE LW↓

40

30

20

10

0

-10

-20

-30

-40

320

300

280

260

240

220

200

180

160

300

265

  • Annual downward LW radiation estimates range from 205 to 230 W/m2

  • The spread in monthly values is typically 10–30 W/m2

  • The amplitude of the seasonal cycle is not well constrained.

  • ERA40 has the largest seasonal cycle


Some aspects on the arctic energy budget and climatology

HOW WELL DO WE KNOW THE INCOMMING

ENERGY?

W/m2

W/m2

DIFFERENCE IN SURFACE SW↓

SURFACE SW↓

300

250

200

150

100

50

0

20

0

-20

-40

-60

-80

-100

  • The NCEP reanalyses has a strong bias in downward

  • shortwave radiation

  • Annual downward SW radiation estimates range from 87 to

  • 128 W/m2.

  • The monthly spread is typically 10–20 W/m2 during summer


Some aspects on the arctic energy budget and climatology

HOW WELL DO WE KNOW THE SURFACE

RADIATION BUDGET?

DIFFERENCE IN SURFACE LW↓+SW↓

W/m2

W/m2

SURFACE LW↓ +SW↓

30

10

0

-10

-30

-50

-70

600

500

400

300

200

  • Annual downward radiation estimates range from 306 to

  • 332 W/m2.

  • The monthly spread is typically 10–25 W/m2


Some aspects on the arctic energy budget and climatology

HOW WELL IS IT SIMULATED WITH

COUPLED GCMs?


Some aspects on the arctic energy budget and climatology

THE SURFACE RADIATION BUDGET IN COUPLED GCMs

INCOMING LONGWAVE ENERGY


Some aspects on the arctic energy budget and climatology

THE SURFACE RADIATION BUDGET IN COUPLED GCMs

INCOMING SHORWAVE ENERGY


Some aspects on the arctic energy budget and climatology

INCOMING ENERGY

LW↓

SW↓

W/m2

W/m2

IPCC ENSEMBLE MEAN


Some aspects on the arctic energy budget and climatology

ARCTIC CLIMATOLOGYATMOSPHERIC HEAT TRANSPORTHOW IMPORTANT IS IT ?ARCTIC ATM-SURFACE SYSTEM HAS A NET LOSS OF ENERGY

Hartmann, 1994


Some aspects on the arctic energy budget and climatology

ARCTIC CLIMATOLOGY

  • No Solar Radiation in Winter

  • Upward loss of heat from surface and atmosphere by longwave radiation

  • Heat must be replaced or else temperatures would drop to near absolute zero.

    Where does the heat come from that replaces what is lost

    from longwave radiation to space?

HORIZONTAL HEAT TRANSPORT


Arctic climatology atmospheric pressure systems

ARCTIC CLIMATOLOGYATMOSPHERIC PRESSURE SYSTEMS

WINTERTIME


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