DOAS measurements on HALO • Scientific Objectives • Technical

DOAS measurements on HALO • Scientific Objectives • Technical

DOAS measurements on HALO
K. Pfeilsticker, F. Weidner, M. Dorf, H. Bösch,
T. Wagner, K.-P. Heue, A. Richter(2), M. Bruns, P. Wang, U. Platt et al.,
Institut für Umweltphysik (IUP)
Universität Heidelberg
(2)
Institut für Umweltphysik (IUP)
Universität Bremen
• Scientific Objectives
• Technical details of the actual DOAS instruments
• Results of balloon borne measurements
• Results of Airborne Multi AXis DOAS instrument
• Status & Summary
Institut für Umweltphysik
University of Heidelberg
Scientific Objectives
DOAS (UV/Vis) profile measurements in the UT/LS and TTL may address
1.
bromine oxide
budget and photochemistry (Dorf et al., 2005)
trend in total stratospheric bromine
role of VSLS
2.
iodine oxide
budget and photochemistry (Bösch et al., 2003)
sources (VSLS) and sinks (aerosols ?) of iodine oxides
role in photochemistry
3.
Skylight radiance and photolysis rates
4.
Ozone loss in combined BrOx/HOx and BrOx/ClOx cycles
Institut für Umweltphysik
University of Heidelberg
Technical Details Airborne DOAS
Observation mode:
• use (UV/Vis) scattered skylight near the horizon
Scanning mini DOAS
- Small, light instrument
- Small power consumption
Flew on several balloons but it is
in principle easy to handle and
install
(2) +2°elevation
(1) Zenith
AMAXDOAS (with IUP Bremen)
- Good Spectral resolution
- Linear dispersion
- 2-D CCD Chip
=> Stray light correction
Flew on Falcon D-CMET
(1)
(2)
(4)
(3)
(3) -2°elevation
(4) Nadir
400
450
500
550
Wavelength [nm]
Institut für Umweltphysik
University of Heidelberg
Technical Details Airborne DOAS
Data evaluation:
• DOAS procedure on measured spectra for targeted gases
• post flight Radiative Transfer calculation of air mass factors
using aircraft altitude data, solar ephemerids and atmospheric
data (T, P, aerosol and cloud droplet density)
• Mathematical inversion of measured differential slant column
amounts into absolute concentrations
Institut für Umweltphysik
University of Heidelberg
Results (1): Time-dependent O3 and NO2 mini-DOAS observations
on LPMA/IASI at Teresina/Brazil on June 30, 2005.
45
Altitude [km]
40
72
65
53
47
41
30
29
30
33
12
O3
0
1.0
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
35
30
25
20
15
40
3
10 molec/cm
45
10
Altitude [km]
59
SZA[°]
37
33
NO2
Envisat/SCIAMACHY
overpass
#17412
#17441
9
35
30
25
20
15
10
11:00
12:00
3
10 molec/cm
13:00
14:00
Time[UT]
15:00
16:00
0
0.0
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
(courtesy: Kritten et al., IUP-Heidelberg)
Institut für Umweltphysik
University of Heidelberg
Results (2): NO2 and BrO profiling mini DOAS
on LPMA/DOAS at Kiruna on March 24, 2004.
HALO F.A.
HALO F.A.
(Weidner et al. 2005)
Institut für Umweltphysik
University of Heidelberg
AMAXDOAS Detection of BL BrO
•
AMAXDOAS -BrO
Falcon flight track from Iceland
over Greenland and back
• during last part of measurements
close to but not above regions
with large BrO concentrations
• large BrO signals in nadir off-axis
88° direction
⇒ has BrO been lifted into the free
troposphere?
P. Wang, K.-P. Heue, M. Bruns, T. Wagner, and A. Richter
Institut für Umweltphysik
University of Heidelberg
OClO Slant columns AMAXDOAS - GOME
molec cm-2
76
14
x 10
5
OClO slant column 92° viewing angle
75
4
74
Latitude (°N)
73
3
72
2
71
70
1
69
0
68
Kiruna
67
20
21
22
23
Longitude (°E)
24
25
-1
Return flight OClO slant columns
smaller than during first part of the
flight due to different radiative
transport and chemistry
Different solar zenith angle
Different solar azimuth
OClO photolysis
Go to / leave vortex
Wang et al. 16th SA/PAC Symposium 5 June 2003, St. Gallen, Switzerland
Institut für Umweltphysik
University of Heidelberg
Status & Summary
Mini-DOAS measurements have been successfully performed
on 8 balloon flights from high, mid and low latitudes (Weidner et al., 2005).
AMAXDOAS measurements have been successfully performed
on 29 Falcon flights between Greenland and the Seychelles
on 20 boundary layer flights in the Po basin (Partenavia 68)
Past/present studies addressed
• Feasibility of the methods (Weidner, 2005; Heue, 2005; Bruns, 2004)
• Validation of the limb method employed e.g. on ENVISAT/SCIAMACHY
• Validation of SCIAMACHY tropospheric columns (Heue et al.,2005)
• NO2 and cloud studies (Wang et al., 2005)
• HCHO, SO2 and NO2 observed in boundary layer flights (Wang et al., 2005)
Upcoming projects
• Deployment on HALO !!
Institut für Umweltphysik
University of Heidelberg