The 5th TPE workshop Berlin, 8-9 Dec. 2014 The increasing dustiness in Tibetan Plateau ice cores over the past decades under warming perspective Guangjian

The 5th TPE workshop Berlin, 8-9 Dec. 2014

The increasing dustiness in Tibetan Plateau ice cores over the past decades under

warming perspective

Guangjian Wu, Tandong Yao, Baiqing Xu, Chenglong Zhang, et al.

[email protected] Institute of Tibetan Plateau Research, Chinese Academy of Sciences

Institute of Tibetan Plateau Research, CAS

1951–2012: 0.12 °C per decade


2

The dust trend under warming

-20~-60%

Also increasing dust loadings?


3


4

The Antarctic and North America

Nature Geoscience 2008

5

Dust trend and its impact on the Tibetan Plateau


Impacts of dust on snow and glaciers:

decrease snow albedo and induce enhanced melting

change the duration of snow cover

affect the glacier-fed rivers and water resource

6

Taklimakan

Central Asia

Africa

ArabThar

Adjacent to and largely surrounded by Asian deserts Located at the downwind (Westerlies) of arid regions Deposited and preserved in glaciers

Westerlies

7

Aerosol Optical Depth over and around the Tibetan Plateauand ice core drilling


Tanggula

Zuoqiupu

Udaoliang

Tanggula ice core (5743m asl, 33 m thick)

Shenza

Taklimakan

Dating the Tanggula ice core (back to 1850 AD)

8

0 1 2 3 4 5 6Depth (m)

-20

-18

-16

-14

-12

-10

-8

18 O

(o/ o

o)

0

200

400

600

800

10000

200000

400000

600000

800000

1000000 2004

200

3

200

2

200

1

200

0

199

9

19

98

199

7

199

6

19

95

19

94

199

3

199

2

199

1

199

0

198

9

198

8

198

7

1986

1985

198

4

Dust

NO3


Zuoqiupu (5565 m asl,116m long)

Shenza

Zedang

Ng Ali

9

Dating the Zuoqiupu ice core (back to 1935 AD)


Two dusty stages:1860-1874: high flux coarse grain size1930-1954: relatively low flux coarse grain size cold-dusty pattern

significant (α=0.01) increase

1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010Year (A .D .)

0

100

200

300

400

500

Acc

umu

latio

n (m

m)

-18

-16

-14

-12

-10

-8

18O

(p

er m

il)

0

15000

30000

45000

60000

Mas

s (

g kg

-1)

0

300

600

900

1200

1500

Flu

x (

g cm

-2 a

-1)

1 .41.61.82.02.22.42.6

Mea

n n

umbe

rdi

am

eter

(m

)

2 .02.53.03.54.04.55.0

Me

an v

olum

ed

iam

eter

(m

)

1860-74 1930-54

Cold ColdW arm Warm

Since 1960: moderate flux moderate grain size warm-dusty pattern

10

Annual average of Tanggula ice core recordInstitute of Tibetan Plateau Research, CAS

11

Annual average of Zuoqiupu ice core record

1930 1940 1950 1960 1970 1980 1990 2000 2010

-17

-16

-15

-14

-13

-12

18 O

(o /oo

)

0

40000

80000

120000

1600000

1000

2000

3000

4000

5000

60001.7

1.8

1.9

2.0

2.1Grain size (m)

Mass conc. (g kg-1)

Number conc. (m)

Dust particles became fine since 1965

Dust conc. kept on increasing, became much higher since 1980

Warming since 1965


Dataset: ECMWF ERA-40

Composite analysis on:

over and near the Tibetan Plateau

200 hPa zonal wind (high-level Westerlies)(unit: m s−1)

500 hPa height (unit: m)

six extremely high dust flux years vs. eight extremely low dust flux years(after the 1954 horizon)

12

Possible circulation mechanism for high dust


13

Tanggula: 200 hPa zonal wind strength anomaly

during high dust years, high-level Westerlies over the Tibetan Plateau strengthened

positive negative 95% confidence


14

Tanggula: 500 hPa height anomaly


During the dusty years, a negative anomaly was found over the upwind dust source regions (Tarim Basin and western Tibetan Plateau). The low pressure (cyclone) activities favor dust storm events


1930 1940 1950 1960 1970 1980 1990 2000 2010

-17

-16

-15

-14

-13

-12

18 O

(o /oo

)

0

40000

80000

120000

1600000

1000

2000

3000

4000

5000

60001.7

1.8

1.9

2.0

2.1Grain size (m)

Mass conc. (g kg-1)

Number conc. (m)

15

Zuoqiupu: 850-1000 hPa height anomaly



16

Eolian dust activities seem to be active on Tibetan Plateau

Shen et al., GPC 2010


Eolian sand deposition along Yarluzangbo valley

Telegraph poles and wires buried by dune at Xidatan, south of Golmud

Modern dunes along the Qinghai-Tibet Highway

17


1970 1975 1980 1985 1990 1995 2000 2005 2010

30000

31000

32000

33000

34000

Are

a (

km2 )

18

Desertification in the central Tibetan Plateau

area in the source region of Yangtze R. increased by 2,678 km2 (+8.8%)


Desertification and active eolian dust on the Tibetan Plateau seems intensified over the past decades

19

Summary

Along with warming, dustiness intensified since 1960s in the central and southeastern Tibetan Plateau

Possible warm-dusty type pattern in the central Tibetan Plateau within current warming perspective, while previously cold-dusty type

Possible circulation mechanisms for the increased dust: strengthened Westerlies; intensified low pressure activities in the upwind source regions


Future work More dust records from the Third Pole region Tracing the provenance of dust in snow/ice

Thank you for your attention!

Documents

The 5th TPE workshop Berlin, 8-9 Dec. 2014 The increasing dustiness in Tibetan Plateau ice cores over the past decades under warming perspective Guangjian