HAGAR-V: A new airborne five channel instrument for in situ measurements

of tracers with a wide range of lifetimes to study UTLS transport

Valentin Lauther, Johannes Wintel, Emil Gerhardt, Markus vom Scheidt, Andrea Rau, Peter Knieling, and C. Michael Volk

Institut für Atmosphären- und Umweltforschung, Bergische Universität Wuppertal

The upper troposphere/lower stratosphere (UTLS) is a key region in the climate system.

Radiative forcing is sensitive to the distribution of greenhouse gases (H2O, CO2, CH4, O3) in the UTLS.

Greenhouse gas distributions in the lowermost stratosphere (LMS) particularly, are determined by transport and mixing of air masses from various regions with widely differing chemical composition.

Time scales for transport along the various pathways, and for mixing in the LMS, range from days to years.

Recent observations indicate that transport patterns and transport times may be changing. Transport pathways into the lowermost stratosphere (LMS)

HAGAR-V (High Altitude Gas AnalyseR-V)

5 channels in 3 modules for in situ tracer measurements:

2-Channel GC/MS-Module for short- and long-lived tracers • sample enrichment on cold traps • separation on capillary columns • mass spectrometric (MS) detection

2-Channel GC/ECD-Module for long-lived tracers • direct sample injection • separation on packed columns • electron capture detection (ECD)

NDIR-Module for CO2 • Detection: IR-absorption

Total weight: 128.5 kg + 32 kg Rack

Target Species

Photochemical lifetime

Contribution to strat. organic chlorined

Time resolution

SF6 3200a yr

90 s

CH4 136b yr

CFC-12 102b yr

32.1 %

CFC-113 93b yr

6.8 %

CFC-11 52b yr

21.6 %

CCl4 44b yr 10.4 %

CFC-113 93b yr

6.8 %

180 s (per channel)

CFC-11 52b yr

21.6 %

CH3Cl 51b yr 16.5 %

CH2Cl2 632c days

1.4 %

CHCl3 601c days 0.5 %

C2Cl4 439c days 0.1 %

n-&iso-Butane 7c days

CO2 ~ infinite 3 s

a Ravishankara et al., 1993 b Stratospheric lifetime, SPARC lifetime assessment report, 2013 c Local lifetime at 15 km, 20°N/S, calculated from photo chemical kinetic data d Calculated from WMO-Scientific Assessment of O3 Depletion, 2014

What is the relative importance of different transport pathways into the lowermost stratosphere (LMS)?

What are the transport times along these pathways?

What are the time scales for mixing within the LMS?

Distributions of

tracers with a wide

range of lifetimes

Pathways and time

scales of transport

and mixing

Modernized and extended version of HAGAR instrument on M55 Geophysica

415410405400395390

CO2 (ppm)

420

400

380

360

340

320

300

280

Th

eta

(K

)

Mission PGS 1-3/2016

WISE 7-8/2017

410

405

400

395

390

CO

2 (

pp

m)

550500450400350

CFC-12 (ppt)

Mission PGS 1-3/2016

WISE 7-8/2017

10.0

9.5

9.0

8.5

8.0

7.5

SF

6 (

pp

t)

550500450400350300250

CFC-12 (ppt)

Mission PGS 1-3/2016

WISE 7-8/2017

250

200

150

100

50

CF

C-1

1 (

pp

t)

550500450400350300250

CFC-12 (ppt)

Mission PGS 1-3/2016

WISE 7-8/2017

Measurement of tracers with a wide range of photochemical lifetimes to investigate transport and mixing Species measured by HAGAR-V cover ~90% of the organic chlorine entering the stratosphere

Enrichment & thermal desorption unit for GC/MS-Module Per channel one adsorbent filled stainless steel tube is

wrapped with a heating wire which at the same time is used as a temperature sensor.

The system is thermally coupled to a stirling cooler.

Heating rates larger than 100K/s are achieved inside the tube, with temperature differences along the tube of ±~50K and a very good reproducibility.

Cooling rates inside the tube were determined to be up to -30K/s.

WISE flight #12 on 2017-10-12 Preliminary data from GC/MS-Module

Mixing ratios are plotted in normalized units relative to upper tropospheric values for all species, such that the correlations converge in the upper troposphere at the point 100%:100%.

The slope of each correlation is inversely proportional to the stratospheric lifetime of the respective species.

Correlations of VSLS (Very Short Lived Species) like CH2Cl2 and CHCl3 with long lived tracers (here CFC-11) exhibit more scatter than correlations between long lived tracers because tropospheric sinks of VSLS induce gradients in the upper troposphere.

GC/MS Module - WISE flight #12 on 2017-10-12 90

80

70

60

50

40

30

CH

2C

l 2 [%

of T

ropospheric S

tandard

]

65x103

605550454035

GMT [s]

16

14

12

10

8

6

4

Altitu

de [k

m]

250

240

230

220

210

200

190

CF

C-1

1 [p

pt]

80

70

60

50

40

30

20

CH

Cl 3

[%

of T

ropospheric S

tandard

]

WISE flight 12

CH2Cl2 CHCl3 CFC-11

Altitude

GC/ECD Module - WISE flight #13 on 2017-10-14

WISE flight #12 on 2017-10-12 Single injection of one GC/MS channel

The species of interest appear within a time window of 40s. The second channel runs countercyclical to use the detector during the waiting time of the first channel.

Some of the prominent peaks (e.g. at m/z=83, 101, 50) still have to be identified.

By using the electron ionization mode peaks do not necessarily need to be chromatographically separated.

10000

8000

6000

4000

2000

0

Co

un

ts

110100908070

Time since sample injection [s]

m/z 43 49 50 83 101 166

CFC

-11

CH

3C

l

iso

-Pen

tan

e

CFC

-11

3

n-P

enta

ne

CH

2C

l 2

CH

Cl 3

C2C

l 4

540

520

500

480

460

440

CF

C-1

2 [

ppt]

65x103

60555045403530

GMT [s]

240

220

200

180

160

CF

C-1

1 [

ppt]

130

120

110

100

90

80

70

60

CC

l4 [ppt]

9

8

7

6

5

SF

6 [ppt]

Species CFC-12

CFC-11

CCl4 SF6

100

80

60

40

Rela

tive

Mix

ing

Ra

tio

s [

% o

f U

T V

alu

es]

10098969492908886

CFC-11 [% of UT Values]

CFC-11 CH2Cl2 CHCl3 CH3Cl

CFC-113

Slope ~ 1/τStrat

Preliminary data

Sket

ch a

dap

ted

fro

m H

olt

on

et

al, A

GU

, 19

95