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Ground-based passive remote sensing measurements of H 2 O 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) - PowerPoint PPT Presentation
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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