bredom h. oetjen, f. wittrock, s. fietkau, a. ladstätter ... · 2 bro no 2 so 2 no 2 oclo o 4 io o...
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Observations of Atmospheric Trace Gasesfrom 1994 to 2003
H. Oetjen, F. Wittrock, S. Fietkau, A. Ladstätter-Weißenmayer,T. Medeke, A. Richter, F. Wittrock and J. P. Burrows
Institute of Environmental Physics, University of Bremen, Germany
www.doas-bremen.de
BREDOM sites Primary NDSC sites Complementary NDSC sites
Bremen
KaashidooNairobi
Merida
Summit Ny-Ålesund
Zugspitze
Introduction
References
Experimental Setup
Acknowledgements
Time Series and Off-Axis Applications
iup
B sr te
nm
eia mn er D usO
aA eS MN e cit rw eo hr pk s f oor mtA
DOE MRB --
Nairobi
Zugspitze
BremenSummit
Kaashidoo
Ny-Alesund
Merida
O3
HCHONO2
BrO
NO2SO2
NO2
OClOIOO4
O3
O3
O3
O4
O4
O3
O3
BrO
OClO IO
SO2
NO2
HCHO
HCHO
O4
NO2
O3
O3
NO2
This study presents ground-based measurements of atmospheric trace gases (ozone, NO and BrO) by means of UV/ visible spectroscopy from 1994 to 2003. The 2
measurement sites range from northern high latitudes (Ny-Ålesund, 79° N, 12°E) over mid-latitudes (Bremen, 53°N, 9°E) to equatorial regions (Nairobi, 1°S, 36° E). They are part of the Bremian DOAS network for atmospheric measurements (BREDOM).In 2002 all instruments have been substantially enhanced to use different line of sights close to the horizon as additional viewing geometries. With this MAX-DOAS (Multi Axis Differential Optical Absorption Spectroscopy) technique it is possible to derive profile information for the retrieved absorbers, which enables us to further investigate the consistency of trace column amounts derived from different platforms and/ or from model calculations.
OutlookThe Bremian DOAS Network for Atmospheric Measurements (BREDOM) consists of seven ground based stations at different latitudes:
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Ny-Ålesund (79°N, 12°E), Bremen (53°N, 9°E), Zugspitze (47°N, 10°E) and Nairobi (1°S, 37°E) in operationSetup of new sites: Summit (72°N, 38°W) June 2003, Merida (8°N, 71°W) fall 2003, Maledives not before fall 2003.
All BREDOM instruments will be operating with a similar setup and the new off-axis viewing geometry - a new application of the DOAS method to distinguish between stratospheric and tropospheric absorbers up to a determination of slightly resolved profiles. Our work has been funded in parts by:
! the German Federal Ministry of Education and Research (BMBF)
! the German Aerospace Agency (DLR)
! the German Research Council (DFG) and
! the State of Bremen and the University of Bremen.
We would like to thank the UNEP staff in Nairobi and the AWI staff in Ny-Ålesund for their assistance and support with which the establishment of the station and the routine measurements would not have been possible.
Figure 4a-c: Slant Columns of NO 2
for different viewing directions on Dec. 09-11, 2002 in Bremen.
Figure 6a-c: Vertical Columns of NO for different viewing directions 2
on Dec. 09-11, 2002 in Bremen.
Figure 5a-b: Estimated vertical profile of NO and resulting AMF 2
calculated from SCIATRAN.
! Rozanov, A., V. Rozanov, and J.P. Burows, A numerical radiative transfer model for a spherical plantary atmosphere: combined differential-integral approach involving the Picard iterative approximation, Journal of Quantitative Spectroscopy & Radiative Transfer, 69, 491, 2001.
! Wittrock, F., M. Eisinger, A. Ladstätter-Weißenmayer, A. Richter and J.P. Burrows, Groundbased UV/VIS measurements of O , NO , BrO and OClO over Ny Alesund (78°N), Polar stratospheric ozone, 3 2
Air pollution research report 56, Proceedings of the 3rd European Polar Ozone Symposium, Schliersee, Germany, CEC, 329-334, 1996.
! Wittrock, F., H. Oetjen, A. Richter, A. Rozanov, and J.P. Burrows, MAX-DOAS measurements of atmospheric trace gases, submitted to Applied Optics, 2003
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five viewing directions (4 off-axis between 0 and 30° above horizon, 1 zenith) with new telescope unit (see Figure 1)temporal resolution: 5 min for all directions
Czerny-Turner Spectrograph(s), UV (320-410 nm), visible (395-565 nm)CCD (2048 x 512 Pixel) and/or (1024 x 256 Pixel)spectral resolution: ~0.5 nmTargeted trace gases: O , NO , BrO, 3 2
HCHO, IO, OClO, HONO!
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! daily calibration measurements
Figure 2: Ozone time series for Bremen (top) and Ny-Ålesund (bottom).
Figure 1: Scheme of the new MAX-DOAS telescope.
Jan-94 Apr-94 Jul-94 Okt-94 Jan-95 Apr-95 Jul-95 Okt-95 Jan-96 Apr-96 Jul-96 Okt-96 Jan-97 Apr-97 Jul-97 Okt-97 Jan-98 Apr-98 Jul-98 Okt-98 Jan-99 Apr-99 Jul-99 Okt-99 Jan-00 Apr-00 Jul-00 Okt-00 Jan-01 Apr-01 Jul-01 Okt-01 Jan-02 Apr-02 Jul-02 Okt-02200
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Jan-94 Apr-94 Jul-94 Okt-94 Jan-95 Apr-95 Jul-95 Okt-95 Jan-96 Apr-96 Jul-96 Okt-96 Jan-97 Apr-97 Jul-97 Okt-97 Jan-98 Apr-98 Jul-98 Okt-98 Jan-99 Apr-99 Jul-99 Okt-99 Jan-00 Apr-00 Jul-00 Okt-00 Jan-01 Apr-01 Jul-01 Okt-01 Jan-02 Apr-02 Jul-02 Okt-02200
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015m
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Jan-95 Apr-95 Jul-95 Okt-95 Jan-96 Apr-96 Jul-96 Okt-96 Jan-97 Apr-97 Jul-97 Okt-97 Jan-98 Apr-98 Jul-98 Okt-98 Jan-99 Apr-99 Jul-99 Okt-99 Jan-00 Apr-00 Jul-00 Okt-00 Jan-01 Apr-01 Jul-01 Okt-01 Jan-02 Apr-02 Jul-02 Okt-020
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Figure 3: NO time series for Bremen (top) and Ny-Ålesund (bottom), am green, pm values black.2
Retrieval! iup Bremen DOAS algorithm to derive slant columns of trace gases! Radiative transport model SCIATRAN to combine results from different viewing directions - calculati-
on of air mass factors (AMF) to convert slant columns (SC) to vertical columns (VC)! CDIPI approach: combined differential-integral approach involving the Picard iterative approx.! Full spherical, refraction included, full Multiple scattering! interface to chemical model still under construction! examples for Off-Axis applications are shown in Figures 4 -7
Figure 7a-b: BrO vertical columns on February 21, 2003 above the Zugspitze calculated with (dottet values) and without (solid lines) BrO in the free troposphere. The agreement is quite good including a layer of 2 ppt BrO in an altitude of about 7 km.
Figure 8: First results from the setup in Nairobi. The reason for the unexpected large discrepancies between am and pm ozone values is still under investigation.
Time series available from BREDOM! Bremen: since summer 1993 zenith sky (ozone, , BrO),
since autumn 2002 off-axis (trop. , BrO, HCHO)! Ny-Ålesund: since February 1995 zenith sky (ozone, ,
BrO, OClO, IO), since April 2000 off-axis (trop. , BrO, HCHO, IO)
! Nairobi: since September 2002 zenith sky and off-axis (ozone, , BrO, HCHO)
! Zugspitze: since February 2003 zenith sky and off-axis (ozone, , BrO, HCHO)
Standard data sets (total ozone and ) are available on different data bases (e.g. NDSC and NILU), for additional data sets please contact Folkard Wittrock.
NO2
NO2
NO2
NO2
NO2
NO2
NO2