Institut für UmweltphysikUniversität Bremen

Ground-based passive remote sensing measurements of H2O at Spitsbergen and Suriname

Justus Notholt, Mathias Palm (FTIR), Harry Küllmann (MW)University of Bremen

Matthias Schneider (FTIR) IMK/FZK, Karlsruhe

Christian Mätzler (MW)University of Bern

Bing Tan (MW)University of Suriname, Paramaribo

Observations in Spitsbergen/Ny-Ålesund (78,9°N)

H2O total columns above Ny-Ålesund

0,0E+00

2,0E+22

4,0E+22

6,0E+22

8,0E+22

1,0E+23

1,2E+23

23.09.94 22.09.96 22.09.98 21.09.00 21.09.02 20.09.04

mol

ec/c

m2

Reihe3Reihe1Reihe2

sondelunarsolar

date (dd.mm.yy)

wat

er v

apou

r (m

olec

. cm

-2)

30 IWV

(kg m-2) or (m

m)

15

0

Frequency range: 823.5 – 827.0 cm-1 Channeling: 4 sinusoidial structures Interfering gases: O3 (profile retrieval), CO2, C2H6 (column retrieval) Solar lines included logarithmic state vector for H2O, normalised state vector for anything else diagonal covariance matrix SNR ~ 150 : 1 – 500 : 1 constant a priori

Frequency range: 3 microwindows in 780 - 800 cm-1

No channeling Interfering gases: O3, CO2 (column retrieval) normalised state vector diagonal covariance matrix SNR ~ 50 : 1 – 100 : 1 Constant a priori

Retrieval with SFIT-2solar spectra

lunar spectra

0,0E+005,0E+211,0E+221,5E+222,0E+222,5E+223,0E+223,5E+224,0E+224,5E+225,0E+22

01.10.01 31.10.01 01.12.01 31.12.01 31.01.02Date

mol

ec/c

m2

Lunar observations

- atmospheric emission up to 40%- full radiative transfer in SFIT-2 (absorption + emission in transmission spectra)

date (dd.mm.yy)

wat

er v

apou

r (m

olec

. cm

-2)

12 IWV

(kg m-2) or (m

m)

6

0

sondeFTIR

0,0E+00

5,0E+21

1,0E+22

1,5E+22

2,0E+22

2,5E+22

3,0E+22

25.12.01 28.12.01 31.12.01 03.01.02 06.01.02Date

mol

ec/c

m2

Zoom in lunar observations

date (dd.mm.yy)

wat

er v

apou

r (m

olec

. cm

-2)

7,50 IWV

(kg m-2) or (m

m)

3,75

0,00

sondeFTIR

0

100

200

300

400

500

600

700

800

1.1.95 31.12.96 31.12.98 30.12.00 30.12.02 29.12.04

Natural variability of H2Oco

l i – c

oli-1

col i-1

x 10

0 (%

)

average variability from day-to-day: 37±45%

date (dd.mm.yy)

varia

bilit

y

Variability of H2O within a day

1.0

4,0

IWV

(kg m-2) or (m

m)

3,0

2,0

sondeFTIR

Ny-Ålesund measurements evaluated with IMK retrieval: PROFFIT v9.4 (on logarithmic scale)

795 796 797 798 799 800

795 796 797 798 799 800-3

-2

-1

0

1

2

3

measurement simulation residuals

(meas. - simu.)

raw

dat

a [a

rbitr

ary

units

]852 853 854 855 856

1111 1112

1117,5

1121

1134 1135 1136 1137 1138 1139 1140

resi

dual

s (n

oise

/sig

nal)

[%]

852 853 854 855 856

1111 1112

1117,5

1121

wavenumber [cm-1]

1134 1135 1136 1137 1138 1139 1140-3

-2

-1

0

1

2

3

+ zero baseline, channeling, and phase error correction

795 796 797 798 799 800

795 796 797 798 799 800-3

-2

-1

0

1

2

3

measurement simulation residuals

(meas. - simu.)

raw

dat

a [a

rbitr

ary

units

]852 853 854 855 856

1111 1112

1117,5

1121

1134 1135 1136 1137 1138 1139 1140

resi

dual

s (n

oise

/sig

nal)

[%]

852 853 854 855 856

1111 1112

1117,5

1121

wavenumber [cm-1]

1134 1135 1136 1137 1138 1139 1140-3

-2

-1

0

1

2

3

+ zero baseline, chaneling, and phase error correction+ set of modified line parameters

795 796 797 798 799 800

795 796 797 798 799 800-3

-2

-1

0

1

2

3

measurement simulation residuals

(meas. - simu.)

raw

dat

a [a

rbitr

ary

units

]852 853 854 855 856

1111 1112

1117,5

1121

1134 1135 1136 1137 1138 1139 1140

resi

dual

s (n

oise

/sig

nal)

[%]

852 853 854 855 856

1111 1112

1117,5

1121

wavenumber [cm-1]

1134 1135 1136 1137 1138 1139 1140-3

-2

-1

0

1

2

3

0

2

4

6

8

10

12

14

-0,2 0,0 0,2 0,4 0,6 0,8ln(VMR) averaging kernels

altit

ude

[km

]

surface 1.3 km 3.3 km 5.3 km 7.6 km 10.0 km 12.4 km 14.8 km

→ also for artic measurements at sea level sensitivity above 10km !

Sensitivity of profile retrieval

- SFIT-2 - same Sa matrix- log retrieval - different vmr-profiles

→ averaging kernels depend on assumed vmr→ vmr profile depends on tropopause altitude→ maximum altitude of profile retrieval depends on tropopause altitude→ maximum altitude of profile retrieval of H2O below tropopause (?)

altit

ude

(km

)

altit

ude

(km

)AVK

-0,2 0,0 0,2 0,4 0,6 0,8 1,00

2

4

6

8

10

12

14

-0,2 0,0 0,2 0,4 0,6 0,8 1,00

2

4

6

8

10

12

14

DOF: 3.02 DOF: 3.20

Subtropics Arctic

AVK

0,0E+00

2,0E+21

4,0E+21

6,0E+21

8,0E+21

1,0E+22

1,2E+22

1,4E+22

28.2.03 30.3.03 29.4.03 29.5.03

0,0E+00

5,0E+20

1,0E+21

1,5E+21

2,0E+21

2,5E+21

3,0E+21

28.2.03 30.3.03 29.4.03 29.5.030 – 3 km

> 3 km

date (dd.mm.yy)

wat

er v

apou

r (m

olec

. cm

-2)

profile retrieval

- SFIT-2- log- retrieval- constant a-priori

sondeFTIR

sondeFTIR

0,6IW

V (kg m

-2) or (mm

)

3,0

0,0

0,0

- water variability is log-normal distributed (all trace gases are log-normal distributed)

- retrieval often more stable

- for small absorption features positive bias

linear retrieval~ e-vmr

→ non linear dependance

log-retrievallmr = ln (vmr)vmr = elmr

~ e-elmr

→ non linear dependance

log-retrieval <-> linear retrieval

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0,0 0,5 1,0 1,5

Reihe1Reihe2

~ vmr

trans

mis

sion

linlog

TARA (Tragbares Radiometer) in Suriname (5,8°N)

measurements- Integrated Water Vapor (IWV)- Integrated Liquid Water (ILW)channels (20.9 GHz and 35.0 GHz)Intermediate frequency (IF) 10-400 MHzDicke switching (@ 70 Hz) to eliminate gain fluctuationslocationSuriname, Paramaribo, 5,8°N 56°W(since December 2006)PartnersInstitute of Applied Physics, University of BernFaculty of TechnologyUniversity of Suriname

Meteorological Service of Suriname

21 March 2007 (good day)

calibration wrong for IWV

1 3 2 31 2

Problems - dew on window at night [1] - rain hits window [2] - temperature sensor in shadow but heated from below

vapor (IWV) - slow decrease in the morning - sudden rise shortly after noon

Liquid water (ILW) - clouds in morning [3] and at noon [2]

Improvements - window heating - other temperature measurements - rain protection - more frequent calibrations

1 November 2007 (bad day)

Comparison with AMMA-observations, 9.6°N, 1.4°E (Crewell, University of Bonn)

http://www.amma-germany.de/doku.php/quicklooks_h

50

60

70

80

90

100

0 3 6 9 12

50

60

70

80

90

100

0 3 6 9 12

290

295

300

305

310

0 3 6 9 12

T min, T

max

(K)

RH

min, R

Hm

ax (%

)pr

ecip

atio

n (m

m)

month of year

0 50 100 150 200 250 300 350day of 2007

IWV

(arb

. uni

ts)

250

200

150

100

50

0

seasonal variability in 2007 climatology

Summary

FTIR observations in high Arctic- FTIR allows total column retrieval with sufficient accuracy- lunar observations give accurate total columns- suitable for trend studies- profile retrieval up to tropopause

2 channel MW observations in tropics- MW-observations in tropics successfully started- mechanical modifications required

high resolution MW observations in tropics (Merida)- measurements throughout whole year in 2007- channeling - study of tape recorder