Development of the Arctic Ocean Development of the Arctic Ocean statistical parameters describing statistical parameters describing variability of ice conditions for variability of ice conditions for the 20the 20thth century century

Vasily Smolyanitsky

Arctic and Antarctic Research Institute

St.Petersburg, Russian Federation

JCOMM Expert Team on Sea Ice (ETSI)

Summary of ice charts data collections within the WMO Global Digital Sea Ice Data Bank Project

Basic statistics describing “mean” sea ice state for the second part of the 20th century

Extended statistics, including PDFs approximation, describing special features of ice conditions

Analysis of temporal variability based on ice index data and revealed periods of sea ice variability

Summary of GDSIDB contentSummary of GDSIDB content

№ Title of data set Period / periodicity

Gaps ? Sea ice parameters

Number of charts

1a Arctic and Antarctic Research Institute (AARI) revised ice charts for the Eurasian Arctic

1950-1992 / 10 days, 1997-..

Yes CT, SD, FI >2000

1b Arctic and Antarctic Research Institute (AARI) ice charts for the Antarctic

1971-1990 / 10 days

Yes CT, SD, FI 475

2a National Ice Center (NIC) ice charts for the Northern Hemisphere (northward 39° N)

1972-1994 / 7 days, 1995-..

No CT, SD, FI >1500

2b National Ice Center (NIC) ice charts for the Southern Hemisphere (southward 50° S)

1973-1994 / 7 days, 1995-..

No CT >1200

3 Canadian Ice Service (CIS) ice charts for Canadian Arctic (4 sub-regions)

1968-1998 / 7 days, 1999-

Yes CT, SD, FI >3500

4 Baltic Sea Ice Meeting ice charts (Finland - FIMR and Sweden - SMHI)

1960-1979 / 3-4 days

No CT, SV, FI 1042

5 Ice charts for the Sea of Okhotsk from the Japan Meteorological Agency (JMA)

1970-2004 / 5 days

No CT >1100

CT – total concentration, SD – stage of development and partial concentration, SV – ice thickness, FI – fast ice information.

The main five GDSIDB datasets are described in the table. Included are also the period, covered by dataset, existence of gaps, sea ice parameters in dataset and number of charts in SIGRID format (WMO, 1989). Total number is > 10000. Samples are on next slide…

Samples of ice charts from national Samples of ice charts from national ice services, historic & modernice services, historic & modern

1. AARI, Russia1. AARI, Russia

4. FIMR, Finland 4. FIMR, Finland (for BSIM)(for BSIM)

2. NIC, USA2. NIC, USA 3. CIS, Canada3. CIS, Canada5. JMA, Japan5. JMA, Japan

Arctic total concentration Arctic total concentration blendedblended data set data set for for 19195050-1998 -1998 based on GDSIDB ice chartsbased on GDSIDB ice charts

First version was completed in December 2002 (thanks to Hadley First version was completed in December 2002 (thanks to Hadley Center support)Center support)

Blending was done on Blending was done on a 15’x15’ grid (45-90N) with monthly interval averaging

Additional monthly Northern Hemisphere 1 degree ice extent dataset (J.Walsh dataset) included

Gaps were populated by climatic monthly median values Result contains :-) 26%26% (GDSIDB), 25%25% (JW), 49%49% (Climate) :-( Output is user-friendly and includes 2 files: factual data and flags

of origin for each cell In 2005 extension of blended dataset was done by inserting values

(based on AARI data) for Eurasian Arctic for 1933-1949 period

Spatial statistical analysis (1950-1998):Spatial statistical analysis (1950-1998):1) sea ice 1) sea ice mean statemean state (blended dataset) (blended dataset)

August (median)August (median)

April (median)April (median) Winter (robust) meanWinter (robust) mean

Summer (robust) meanSummer (robust) mean

2) special features of ice conditions - 2) special features of ice conditions - extended set of statistics assessed on extended set of statistics assessed on individual datasets:individual datasets:

mean median mode

r.m.s. interquartile range range

minimum

maximum

enthropy Statistics for total concentration in summer period (AARI data)Statistics for total concentration in summer period (AARI data)

3) …skew, curtosis and PDFs (app.by 3) …skew, curtosis and PDFs (app.by Pirson curves):Pirson curves):

AARI and NIC total concentration dataAARI and NIC total concentration data

PDF app., winterPDF app., winter

PDF type = f(r3,r4)PDF type = f(r3,r4)

PDF app., summerPDF app., summer

Skew (r3), curtosis (r4), winterSkew (r3), curtosis (r4), winter Skew (r3) and curtosis (r4), summerSkew (r3) and curtosis (r4), summer

3add) …PDFs based on SSMR-SSMI data 3add) …PDFs based on SSMR-SSMI data (app.by Pirson curves), useful for near NP (app.by Pirson curves), useful for near NP region:region:

Data: SSMR-SSM/I Bootstrap total concentration daily patterns for 1978-2002Data: SSMR-SSM/I Bootstrap total concentration daily patterns for 1978-2002

PDF app., FebruaryPDF app., February PDFs app., MayPDFs app., May PDFs app., AugustPDFs app., August

J-typeJ-type

y = -1.2603x + 989.27

y = -2.5993x + 600.03

y = -0.9572x + 299.6

y = -2.5367x + 183.060

200

400

600

800

1000

1200

1968 1973 1978 1983 1988 1993 1998 2003

y = - 5.1265 x + 1270.4

400

600

800

1000

1200

1400

1600

1800

2000

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

km 2 *1000

y = - 1.2033 x + 1092

200

400

600

800

1000

1200

1400

1600

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

km 2 *1000

Temporal analysis of ice index data:Variability and linear trends in August for Eurasian (1900-2003) and Canadian Arctic (1968-2004)

Greenland, Barents, Kara Laptevs, Eastern-Siberian, Chukcha

Western CA (blue)

Eastern CA (green)

East Coast (red) (April)

Hudson Bay (light blue)

Validity of linear trend coefficients by regions (95%)

a № Area Month

Mean Min95% Max95% Period of observations 1900 – 2003 гг.

1 Greenland VIII -0.954 -1.463 -0.446 2 Barents VIII -2.638 -3.324 -1.952 3 Kara VIII -1.533 -2.488 -0.578 4 Greenland – Barents – Kara -2.863 -4.389 -1.337 5 Laptevs VIII -0.381 -1.023 +0.261 6 Eastern - Siberian VIII -0.368 -1.068 +0.332 7 Chukcha VIII -0.453 -0.743 -0.163 8 Laptevs – Eastern- Siberian – Chukcha -1.202 -2.488 +0.084 9 Eurasian Arctic VIII -2.737 -4.381 -1.093

Period of observations 1968 – 2004 гг. 10 Eastern Canadian Arctic VIII -2.599 -6.377 +1.179 11 Western Canadian Arctic VIII -1.260 -4.053 +1.532 12 Hudson Bay VIII -2.537 -5.240 +0.166 13 Ca nadian Arctic VIII -7.079 - 13.580 -0.578

Wavelet analysis of sea ice extent variations for Eurasian Arctic Seas (based on 1900-2003 period) and Canadian Arctic Seas (based on 1968-2004 period) in August (red – more ice, blue – less ice)

Greenland Barents Kara

Laptev Eastern-Siberian Chukcha

Western CA Eastern CA Hudson Bay

Conclusions

• Ice charts collections and blended datasets within the GDSIDB project provide possibility to assess various climatic statistics including sea ice “mean state” for the second part of the 20th century

• Different statistics may and should be chosen for climatic analysis and to underline special features of ice conditions, robust and PDFs are preferable

• Abnormal types of PDF like U, I, J-form are predominant for sea ice total and partial concentrations in seasonal cycle, approximations of PDFs may be used for classification schemes or in modelling

• Linear trend analysis based on ice charts and index data gives a typical picture of a negative trend from 1900s to ~2000, however transition to sub-periods or regions gives a much more complex picture with coefficients varying in magnitude and sign

• There is a strong indication that the sea ice variability in at least Eurasian and Canadian Arctic has a polycyclic structure with noticeable periods of approximately 10, 20 and 60 years and periods of longer duration revealed as linear trend