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GAW Workshop 5th7th May 2009

Measurements of reactive nitrogen compounds in GAW status and further needs

Stefan Gilge, Christian PlassDuelmer, Wolfgang Fricke

German Meteorological Service Hohenpeissenberg Meteorological Observatory

1



Outline: § Introduction / Definitions

§ Motivation / Examples for use of nitrogen oxide data

§ Data Availability

§ Measurement Techniques

§ Present status

§ Future Needs

2



3

Short Definition:

NOy

NOz

NOx



4

tropospheric ozone

production

impact on oxidation capacity of troposphere

model validation

gas to particle conversion

acid rain formation

scientific

control of NOx

emission reduction (prescriptive limits)

ozone mitigation strategies

NOx as tracer (key component)

for anthropogenic emission

acidification eutrophication human health

quantification of potential background concentrations

for evaluation of prescriptive limits

political

Motives for Nitrogen Oxides Measurement Motivation for Nitrogen Oxides Measurement

limit values

( limit values )


Examples for use of NOx data (I)

5

0

50

100

150

200

250

300

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

NO2 rel. de

viation [%

]

0

50

100

150

200

250

300 Ähtäri

Burgas

Fundata

Hohe Warte

MOHp

Jarczew

Jungf raujoch

Kamenicki V is

Kosetice

Kpuszta

Leba

Oulanka

Plovdiv

Pleven

Rucava

Sniezka

Sof ia

Schauinsland

Uto

V irolahti

Varna

Zabljak

Zoseni

mean all stat.

median all stat.

NO 2 : relative deviations from the mean annual variation 19812008


Examples for use of NOx data (II)

6

Model Validation:

⇒ To improve model calculations, a full data set .... of related trace gases must be compared.

⇒ NOx data are essential to improve ozone .....prediction models.

Source: GEMS, Flentje, privat comm.


Examples for use of NOx data (III)

7

• Influence on the tropospheric oxidation capacity

0.E+00

1.E+11

2.E+11

3.E+11

4.E+11

5.E+11

6.E+11

0.1 1 10 100

NOx, ppb

OH/j(O1D

), 1/cm

³/s

OH optimum at 12 ppb NOx

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan

NO2 [ppb

]

Annual variation of NO 2 at MOHp

⇒ chemical regime at MOHp optimum for self cleaning



Data availability : (at WDCGG)

NO: NO 2 : NO y :

8



Nitrogen Oxides Measurement Techniques

passive active

in situ integrating

remote sensing

integrating

• impregnated filter, ion chromat.

• Satellite applications ...(e.g. GOME)

• Brewer

• MAxDOAS

• O 3 – CLD (PLC/BLC) • O 3 CLD (Mo) • Luminol CLD • DOAS • TDLAS • cavity ring down

• Saltzman

• Sodium ..Iodide

column density profile

weekly daily ≤ hourly

9



The intercomparisons have shown good agreement between different monitors (using different standard gases) and even between different measuring techniques: • NO 2 measurements are principally reliable (issues with Mo) • it is possible to use existing data from different techniques (after careful QA/QC) for world wide monitoring of NO 2

• free choice of monitoring method according to objectives and resources

10

y = 0.8323x + 0.7686 R 2 = 0.8076

0

2

4

6

8

10

12

14

16

18

20

0 2 4 6 8 10 12 14 16 18 20

NO 2 Chemiluminescence (µg/m³)

NO

2 Pa

ssive Sa

mpling (µg/m³)

NO 2 : Comparison CLD and Passive Sampling at MOHp, Jan. '00 Dec. '03 NO 2 Intercomparison: NaI versus PLC/CLD at MOHp

y = 0.8406x + 0.5535 R 2 = 0.9342

0

2

4

6

8

10

12

14

16

0 2 4 6 8 10 12 14 16

NO2 (PLC/CLD) [µg/m³]

NO

2 (NaI) [µg

/m³]

chemiluminescence chemiluminescence

passive sampling

sodium

iodide



Current Situation: • some data from mostly European sites originating from different .:measuring methods,which in principle match • some informal intercomparisons • training courses on nitrogen oxides in GAWTEC • WDCGG • responsibility: SAG for Reactive Gases

11

But • no direct (Sub)SAG for nitrogen oxides • no QA / SAC • no DQO : no precision and accuracy or data completeness goals • no SOP‘s • no CCL / no primary standard • no WCC



12

Citations GAW Report 172 and 143:

• …Their (Nitrogen Oxides) measurement in the global atmosphere is ..very important since NO has a large influence on both ozone and on ..the hydroxyl radical.

•… the satellite community who require extensive NO2 measurements ..for validation purposes.

• Nitrogen oxides play a crucial role….

• … contribute to acid precipitation

• … the need for knowledge of the abundance of these compounds is ..unquestioned …



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Future needs: • Appointment of a SubSAG for Nitrogen Oxides

• Setup of DQO‘s and SOP‘s for nitrogen oxides (NO, NO 2 , NO y )

• Implementation of NO, NO 2 and NO y measurements at more GAW sites

• Intercomparison experiments to ensure comparability of different measurement methods (CLD, NaI, …)

• Implementation of CCL and WCC

• Implementation of PAN, HNO 3 , NO 3 , HNO 2 and other important NO y species at several GAW stations

Details should be discussed at an upcoming workshop on NO x at Hohenpeissenberg Observatory in autumn 2009

(Interested persons please contact me!)



Thank You

for Your Attention !

Photo: Claudia Hinz

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