Lake ice climatology

Сентябрь 16, 2022

Главная
Физика
Lake ice climatology

Содержание

2. Lake ice season Ice thickness --- stable ice --- Unstable periods (fixed) H tF tb t1
3. Warming climate ? ? Will the lake freeze in future ? How much are freezing date
4. Ice phenology Freezing date Strongly connected to air temperature (long-wave radiation, turbulent fluxes) Connection depends on
5. Breakup Freezing 80 P E R E N N I A L Freezing and breakup Extrapolated
6. Lake ice time series Ice phenology freezing date breakup date How to define? Ice cover properties
7. Lake Kallavesi, Finland 1830 – 2014 Trend 10 days/100 years Aperiodic Variability 80 days Extrema far
8. Colder climate ? less variability Kirillin et al. (2012)
9. Freezing date Breakup date Kilpisjärvi trends 1952 – 2010 (Lei et al., 2012)
12. 1st order: climate change impact Freezing date ~ 5 day/°C Ice thickness 5–10 cm/°C Breakup date
13. Lake Vanajavesi: model for climate change impact -1°C -6°C +6°C +1°C
14. Ice thickness cycle – albedo sensitivity, Prydz Bay α = 0.5 α = 0.5 α =
15. Lake Ladoga: Finnish – Soviet – Russian data 1913 – 1937 Ice charts and reports 1943
16. Ice concentration A A = relative area of ice in the lake Freezing ? depth: t
17. Lake Ladoga 1913–
19. Summary: warming (?) ? Freezing day delays Max annual ice thickness likely decreases Ice quality (congelation
20. … consequences to water body Shorter ice season AND More sunlight More transient open water periods
21. Climate warming ? Lake seasons Annual cycle: qualitative changes Summer stratification stronger Stable ice period shorter
23. Скачать презентацию

Слайд 2

Lake ice season
Ice thickness
--- stable ice ---
Unstable periods
(fixed)
H
tF
tb
t1
t2
H = min thickness

for stable ice,
10 cm (small lakes)–
50 cm (large lakes).

Stable ice (? climatology)

Слайд 3

Warming climate ? ?
Will the lake freeze in future ?
How much

are freezing date and break-up date affected ?
How much is ice thickness affected ? And ice quality?
Ice cover stability ?
Ice coverage ?

Слайд 4

Ice phenology
Freezing date
Strongly connected to air temperature (long-wave radiation, turbulent fluxes)
Connection

depends on lake depth
Freezing after 0oC downcrossing
Air temperature falling rate major factor

Breakup date
Solar radiation driving force – no long-term trend
Ice and snow thickness – weak positive trend
Turnover day from negative to positive heat balance key factor
Degree-days correlate with net solar flux

time

Thickness ~ ✔ freezing-degree-days

Слайд 5

Breakup
Freezing
80
P
E R E N N I A L
Freezing and breakup
Extrapolated from Kirillin et al. (2012)
No ice

Слайд 6

Lake ice time series
Ice phenology
freezing date
breakup date
How to define?
Ice cover properties
Ice

thickness – max annual value
Ice concentration (large lakes)

Variability
independent winters
interannual variability externally forced
Aperiodic time series outcome
weak intra-seasonal connections

Слайд 7

Lake Kallavesi, Finland 1830 – 2014
Trend 10 days/100 years
Aperiodic
Variability 80 days
Extrema

far from mean

Trend 10 days/100 years
Aperiodic
Variability 45 days

Breakup

Freezing

Слайд 8

Colder climate ? less variability
Kirillin et al. (2012)

Слайд 9

Freezing
date
Breakup
date
Kilpisjärvi trends 1952 – 2010 (Lei et al., 2012)

Слайд 10

Слайд 11

Слайд 12

1st order: climate change impact
Freezing date
~ 5 day/°C
Ice thickness
5–10 cm/°C
Breakup date

~ n days after zero
upcrossing of heating

Слайд 13

Lake Vanajavesi: model for climate change impact
-1°C
-6°C
+6°C
+1°C

Слайд 14

Ice thickness cycle – albedo sensitivity, Prydz Bay
α = 0.5
α =

0.5

α = 0.7

α = 0.6

Polar ice does not melt fully but breaks due to internal deterioration. Light transmissivity of ice also has an important role.

Yang et al.
(2016)

Слайд 15

Lake Ladoga: Finnish – Soviet – Russian data
1913 – 1937
Ice charts

and reports

1943 – 1992
Aircraft observations
Approx. twice a month
Plots of ice distribution’
1971 ->
NOAA and MODIS satellite images
On average 19 images /winter

Слайд 16

Ice concentration A
A = relative area of ice in the lake
Freezing

? depth: t = F(h)
Hypsographic curve = G(h)
Formally:
A(t) = G[F-1(t)/max(h)

Thus fall evolution of ice concentration is related on the hypsographic
curve. Also decrease of concentration depends on that as melting starts
From shallow parts. Wind and lake size add further modifications.

Слайд 17

Lake Ladoga 1913–

Слайд 18

Слайд 19

Summary: warming (?) ?
Freezing day delays
Max annual ice thickness likely decreases
Ice

quality (congelation ice/snow ice) ?
Period of stable ice cover shortens
Transient open water periods in smaller lakes than presently
Ice breakup date likely earlier

Слайд 20

… consequences to water body
Shorter ice season
AND
More sunlight
More transient open

water periods
Improved oxygen level
How winter ecology will be adapted?

Слайд 21

Climate warming ? Lake seasons
Annual cycle:
qualitative changes
Summer stratification stronger
Stable ice

period shorter

Lake ice climatology

Содержание

Lake ice seasonIce thickness--- stable ice ---Unstable periods(fixed)HtFtbt1t2H = min thickness

Warming climate ? ?Will the lake freeze in future ?How much

Ice phenologyFreezing dateStrongly connected to air temperature (long-wave radiation, turbulent fluxes)Connection

BreakupFreezing80PE R E N N I A LFreezing and breakupExtrapolated from Kirillin et al. (2012)No ice

Lake ice time seriesIce phenologyfreezing datebreakup dateHow to define?Ice cover propertiesIce

Lake Kallavesi, Finland 1830 – 2014Trend 10 days/100 yearsAperiodicVariability 80 daysExtrema

Colder climate ? less variabilityKirillin et al. (2012)

FreezingdateBreakupdateKilpisjärvi trends 1952 – 2010 (Lei et al., 2012)

1st order: climate change impactFreezing date ~ 5 day/°CIce thickness 5–10 cm/°CBreakup date

Lake Vanajavesi: model for climate change impact-1°C-6°C+6°C+1°C

Ice thickness cycle – albedo sensitivity, Prydz Bayα = 0.5α =

Lake Ladoga: Finnish – Soviet – Russian data1913 – 1937Ice charts

Ice concentration AA = relative area of ice in the lakeFreezing