Institute of Environmental Physics University of Bremen

Retrieval of Tropospheric Water Vapour from FTIR Solar Absorption Measurements

1 Department of Physics, Addis Ababa University, Addis Ababa, Ethiopia2 Department of Physics, University of Bremen, Bremen, Germany3 Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven, Germany

1G. Mengistu Tsidu, 2J. Notholt, 2T. Warneke and 3O. Schrems

Remote sensing of in the infrared using the Fourier Transform Infrared Spectroscopy (FTIR)

wavenumber (cm-1)

inte

nsi

ty (

arb.

Uni

ts)

wavelength (m) 13.0 10.0 8.0

8.725 8.720

wavenumber (cm-1)

wavelength (m)

tran

smis

sion

total columns (molec. cm-2) 20 trace gases

profiles (vmr)for 10 trace gases

Spectral lines

ALFIP: Automatic Line Finding Programhttp://www.iup.physik.uni-bremen.de/ftir/alfip

Automatic search for lines with highest signal contribution in defined altitude region

Tropics:H2

160: 2429.5, 2485.3, 2497.1, 2940.9, 3145.5, 3147.8, 3158.6HDO: 2660.3, 2672.2, 2675.0, 2725.5, 2737.8, 2747.3, 2854.5, 2860.4H2

18O: 2900.4, 2942.55, 2954.95, 3000.45

Midlatitudes:H2

16O: 2911.2, 2930.6, 3050.55, 3146.75, 3147.9, 3152.5, 3189.6HDO: 2657.1, 2660.4, 2671.9, 2722.5, 2730.5, 2737.8, 2747.2H2

18O: 2955.0, 2976.2, 3001.0, 3023.6, 3043.6, 3091.0

Observations onboard of Polarstern

Polarstern campaign Oct./Nov. 1996

Oct/Nov 1996

0.0E+00

5.0E+22

1.0E+23

1.5E+23

2.0E+23

-60 -40 -20 0 20 40 60

latitude

H216

O

Oct/Nov 1996

-300

-250

-200

-150

-100

-50

0

-60 -40 -20 0 20 40 60

latitude

δH

DO

Oct/Nov 1996

0

5

10

15

20

25

30

-60 -40 -20 0 20 40 60

latitude

T s

urf

ac

e

Polarstern cruise

Oct./Nov. 1996

200

180

160

140

120

100

80

60

40

20

vmr (ppbv)

Dependancy of vmr-profile results on a-priori

Sensitive to a-priori profile, Adhoc covariance

Sensitive to a-priori profile, modified Tikhonov

balloon sonde constant vmr

modified TikhonovAdhoc approach

Spitsbergen, 79°N, 12°E

y = 1.321x + 2E+21

0

1E+22

2E+22

3E+22

4E+22

5E+22

6E+22

7E+22

0 1E+22 2E+22 3E+22 4E+22 5E+22

HDO

H216

O

Spitsbergen 2001

Temperature dependance

of HDO

y = 7.1384x - 332.98

R2 = 0.6729

-600

-500

-400

-300

-200

-100

0

-25 -20 -15 -10 -5 0 5 10

T surface

δ H

DO

y = 0.0317x - 1.224

R2 = 0.7484

-2.5

-2

-1.5

-1

-0.5

0

-25 -20 -15 -10 -5 0 5 10

T surface

δ H

DO

/ T

y = 0.0001x - 0.0045

R2 = 0.802

-0.01

-0.008

-0.006

-0.004

-0.002

0

-25 -20 -15 -10 -5 0 5 10

T surface

δ H

DO

/ T

2

y = 8.0229x + 8.9567

R2 = 0.9718

y = 1.4397x - 215.74

R2 = 0.3638

-600

-500

-400

-300

-200

-100

0

-200 -180 -160 -140 -120 -100 -80 -60 -40 -20 0

δ H218O

δ H

DO

Meteoric Water Line: δ HDO = 8 * δ H218O + 10

0

12

3

4

56

7

89

10

60 110 160 210 260

day of 2001

δ H

DO

/ δ

H218

OFTIR GNIP

Summary and conclusions

total columns of H216O, H2

18O and HDO

profiles with 2-3 degrees of freedom

tropopause region difficult to reach

work in progress