dust: data and sources dr richard washington university of oxford dr martin todd university college...

Dust: Data and Sources

Dr Richard Washington University of Oxford

Dr Martin ToddUniversity College London

Prof Andrew GoudieUniversity of Oxford

Dr Mike BithellUniversity of Cambridge

Outline• Dust Data

– Surface based synops (from GCOS, 117 stations, 3hrly 1980-2000)– Surface based synops (from local Met Agencies)– TOMS AI data– IDDI– Shuttle Photographs, NOAA images etc

• Climate Data and Trajectory modelling– Reanalysis Data (NCEP and ERA-15) 3D winds– 25 point forward trajectory clusters– every 6 hours for 10days, 1979-1998– Determine regional transport corridors– Re-circulation – Interannual variability

Zouerat

Atar

N ouakchott

D akar

K iff a

O uarzazate

BecharE l O ued

SirteE l G olea

I n SalahAdrar SebhaO bari

Tam anrasset

D j ibouti

KhargaD akhla

Kufrah Asw an

Agadez

N ’djam ena

Abeche

Faya-LargeauB ilm a

El FasherEl O beid

Khartoum

Potiskum M aiduguri

Sokoto

Tom buktuG ao

N guigm i

M aine-SoroaZinder

N iam eyO uagadougou

Bobo-D iou lasso

R iyadh

Kuw ait

D eir Zzor

Abu Kam al

Palm yra

AqabaElat

G hor El Safi

M a’anSafaw i

H am adan

Nr Missing Months 1980-2000

Kuw ait

D ohaD ahran Bahrain

H am adan

Kandahar

Kunduz

J ask

Q uetta

J iw an iB ikaner

D al BandinG anganagar

J odhpur

Ashabad

N ukusLeninskC im baj

Karakalpakia

J aslykKzyl-O rda

I rgiz TaupAralsk

Zam iin U de

Choibalsan

M inq in

U rum qiTurpan

Lanzhou

D ongsheng

Nr Missing Months 1980-2000

M ex ico C ity

Torreon Airport (M X)

D odge C ity (KS)

Lubbock (TX)

M idland (TX)

Nr Missing Months 1980-2000

OodnadattaMarla

OnslowLearmonth

Alice Springs

Birdsville

Mildura

Nr Missing Months 1980-2000

Nouakchott duststorm activity 1980-86.

0

5

10

15

20

25

30

Day

s/m

on

th

GCOS Data Compared with locally Obtained Data

Annual cycle of visibility 1980-2000 for station 606300 (In Salah, Algeria)

8000

9000

10000

11000

12000

13000

14000

15000

J F M A M J J A S O N D

Vis

ibil

ity

(m)

Annual cycle of visibility 1980-2000 for station 610240 (Agadez South, Niger)

8000

9000

10000

11000

12000

13000

14000

J F M A M J J A S O N D

Vis

ibil

ity

(m)

Annual cycle of visibility 1980-2000 for station 612020 ((Tessalit, Mali)

6000

8000

10000

12000

14000

16000

18000

20000

22000

J F M A M J J A S O N D

Vis

ibil

ity

(m)

Annual cycle of visibility 1980-2000 for station 655010 (Dori, Burkina Faso)

8000

10000

12000

14000

16000

18000

20000

J F M A M J J A S O N D

Vis

ibil

ity

(m)

In Salah visibility 80-00

Monthly mean visibility for station 606300 (In Salah, Algeria)

5000

7000

9000

11000

13000

15000

17000

19000

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

Vis

ibilit

y (

m)

12 per.Mov. Avg.

Outline• Dust Data

– Surface based synops (from GCOS, 117 stations)– Surface based synops (from local Met Agencies)

Niger, Chad, Algeria, Mali, Mari– TOMS AI data– IDDI– Shuttle Photographs, NOAA images etc

• Climate Data and Trajectory modelling– Reanalysis Data (NCEP and ERA-15) 3D winds– 25 point forward trajectory clusters– every 6 hours for 10days, 1979-1998– Determine regional transport corridors– Re-circulation

Niger visibility 70-00

Days of bad visibility/year for four stations in Niger 1970-2000.

0

20

40

60

80

100

120

140

160

180

Year

Day

s of

bad

vis

ibili

ty/y

r.

Zinder

Agadez

Bilma

Tahoua

Linear (Zinder)

Linear (Agadez)

N’Djamena, Chad: Haze Vs Obs RainfallBy season

Bilma, Niger: sandstorms Vs TOMSby season

North AfricanSurfaceDust stormsCorrelationTOMS1980-2000

Bilma surface visibility Vs TOMS (march 1980-2000)

Outline• Dust Data

– Surface based synops (from GCOS, 117 stations)– Surface based synops (from local Met Agencies)

Niger, Chad, Algeria, Mali, Mari– TOMS AI data– IDDI– Shuttle Photographs, NOAA images etc

• Climate Data and Trajectory modelling– Reanalysis Data (NCEP and ERA-15) 3D winds– 25 point forward trajectory clusters– every 6 hours for 10days, 1979-1998– Determine regional transport corridors– Re-circulation

REOF2 of TOMS AI monthly anomalies for the period 1980-05/93 and 1997-2000

-800

-600

-400

-200

0

200

400

600

800

1000

REOF3 of TOMS AI monthly anomalies for the period 1980-05/93 and 1997-2000

-600

-400

-200

0

200

400

600

800

REOF5 of TOMS AI monthly anomalies for the period 1980-05/93 and 1997-2000

-600

-400

-200

0

200

400

600

REOF6 of TOMS AI monthly anomalies for the period 1980-05/93 and 1997-2000

REOF7 of TOMS AI monthly anomalies for the period 1980-05/93 and 1997-2000

-300

-200

-100

0

100

200

300

400

REOF8 of TOMS AI monthly anomalies for the period 1980-05/93 and 1997-2000

Apr Potential Sand Flux overlay TOMS q = 2.61 U3

* pg –1 (1-U*/U*)(1+U*/U*)2

Sahel TOMS (white contours), potential sand flux (black contours), with DEM (colour). LTM for JFM 80-00.

Central Asia TOMS (white contours), potential sand flux (black contours), with DEM (colour). Long term mean for 80-00.

Correlation of monthly visibility anomalies at Nouakchott (Mauritania) with global NCEP derived potential sand flux for 1980-2000

Correlation of monthly visibility anomalies at Bobo-Dioulasso (Burkina Faso) with global NCEP derived potential sand flux for 1980-2000

Outline• Dust Data

– Surface based synops (from GCOS, 117 stations)– Surface based synops (from local Met Agencies)

Niger, Chad, Algeria, Mali, Mari– TOMS AI data– IDDI– Shuttle Photographs, NOAA images etc

• Climate Data and Trajectory modelling– Reanalysis Data (NCEP and ERA-15) 3D winds– 25 point forward trajectory clusters– every 6 hours for 10days, 1979-1998– Determine regional transport corridors– Re-circulation

Bodele

Djouf region

Parcel trajectory climatology

May (1979-98)

Bodele depression (17.5N, 17E)

54% of trajectories cross the 15W meridian

27% of trajectories remain over N. Africa

21% of trajectories remain over Sahara (> 15N)

Parcel trajectory climatology

June (1979-98)

Bodele depression (17.5N, 17E)

79% of trajectories cross the 15W meridian

13% of trajectories remain over N Africa

9% of trajectories remain over Sahara (> 15N)

Parcel trajectory climatology

Dec (1979-98)

Bodele depression (17.5N, 17E)

66% of trajectories cross the 15W meridian

23% of trajectories remain over N. Africa

6% of trajectories remain over Sahara (> 15N)

0

20

40

60

80

100

0

18

36

54

72

90

10

8

12

6

14

4

16

2

18

0

19

8

21

6

23

4

Time (hours)

% t

raje

cto

ries

Dust Recycling potential

May

JuneJuly

Dec

Parcel trajectory climatology

May (1979-98)

Bodele depression (17.5N, 17E)

Mean 0-15N

Parcel trajectory climatology

Dec (1979-98)

Bodele depression (17.5N, 17E)

Mean 0-15N

TOMS AI over Bodele region (15-17N, 16-18E)

mean

May 1991

May 1989

Bilma: Dust Storms and Haze

02468

101214161820

May 1991

Long.

Lat.

Height (hPa)

May 1989

Height (hPa)

Lat.

Long.

Djouf region

TOMS AI over Djouf region (17.5-22.5N, 2.5-7.5W)

Parcel trajectory density climatology

July (1979-98)

Djouf region (17.5-22.5N, 2.5-7.5W)

% trajectories remain over Sahara (> 15N < 30N) 69 33 6

% trajectories crossing the 15W meridian 33 66 83

After days 3 5 10

Annual CMAP precipitation over Djouf region

Annual TOMS AI over Djouf region

Conclusions

• Surface Synops GCOS data: expensive and patchy

• Surface Synops from Met Agencies• Synops-TOMS AI: sensible but weak• Major mineral dust source regions identified

from TOMS AI data: Bodele and Djouf• Trajectory modelling allows definition of dust

transport corridors– Pronounced seasonal cycle and interannual

variability

500hPa

80W

40E

10S

40N

Parcel trajectory climatology May (1979-98)

Bodele depression (17.5N, 17E)

Parcel trajectory density climatology

July (1979-98)

Djouf region (17.5-22.5N, 2.5-7.5W)

West of 15W

0

20

40

60

80

100

0

18

36

54

72

90

10

8

12

6

14

4

16

2

18

0

19

8

21

6

23

4

Time (hours)

% t

raje

cto

ries

Over Sahara >15N <30N

Over Atlantic

Parcel trajectory climatology

May (1979-93)

Bodele depression (17.5N, 17E)

TOMS mean AI May 1980-93

Parcel trajectory climatology

July (1979-98)

Bodele depression (17.5N, 17E)

Parcel trajectory density climatology

July (1979-98)

Djouf region (17.5-22.5N, 2.5-7.5W)

Mean 10-25N