Outline:

1
Facility Strategic Plan Chemistry Perspective
Outline 1. Atmospheric Regimes Scientific
Questions Observational Needs UT/LS (HOx,
water ) Middle Lower Troposphere (clouds,
aerosols, NOx, regional vs global) Surface
(land, ocean) 2. ATD contributions
2
Scientific Questions Observational Needs
Upper Troposphere/Lower Stratosphere (few km
above below local tropopause, 7 18 km)
3
Radical Chemistry in the Upper Troposphere/Lower
Stratosphere A Summary of Current Scientific
Issues and a Proposed Observational Study
Alan Fried, Chris Cantrell, John Orlando, Brian
Ridley, Mary Barth, and Ian Faloona
Science Documents http//www.acd.ucar.edu/UTLS/ind
ex.htm
4
NCAR UTLS White Paper Integrated Study of
Dynamics, Chemistry, Clouds and Radiation of the
Upper Troposphere and Lower Stratosphere Laura
Pan, Brian Ridley, Bill Randel, Andrew Gettelman,
Andy Heymsfield, Mary Barth, Alan Fried, Chris
Cantrell, Todd Lane, Don Lenschow, Steve Massie,
Owen Cooper, Alyn Lambert, Mike Coffey, Sue
Schauffler, Paul Wennberg, Guy Brasseur
Science Documents http//www.acd.ucar.edu/UTLS/ind
ex.htm
5
Upper Troposphere/Lower Stratosphere

• Important to identify understand the various
  UT/LS processes that control water vapor, ozone,
  radicals, aerosols, and clouds. This is critical
  for predictions of climate change trends in
  global air quality. (strat. water, ozone, and
  carbon dioxide exert major influence on radiative
  forcing).
• The UT/LS is an under-sampled region The
  altitude range is often below the detection range
  of the spaceborne instruments and there are only
  a few high altitude airborne observing platforms.
  Ideal for HIAPER

6
O3 Chemistry in the UT/LS
Production (O3) Loss (O3)
Term 1 Term2 Term3 Term4 k1NOHO2
k4O(1D)H2O k6HO2O3 k5OHO3

• Term1 accounts for 80 of O3 Production
• Net O3 depends upon HOx (OH HO2)
• Net O3 depends upon NOx (NO NO2)
• Net O3 depends upon O3 photolysis which produces
  O(1D)
• Net O3 depends upon H2O (i.e., H2O is a reactant
  and not just a climatic gas)
• Net O3 depends upon peroxides, and OVOC which
  produce HOx when photolyzed
• In UT get O3 production with increasing HOx
  (Term 1)
• In LS get O3 destruction with increasing HOx
  (Terms 3 4)
• In UT/LS get admixture (3 regimes provides good
  testing of models)

7
Measurement-Model HOx Comparisons

• Growing body of evidence of persistent missing
  HOx
• sources in the UT/LS
• Photolysis of additional HOx precursors such as
  CH2O, H2O2, and CH3OOH, transported from lower
  altitudes and/or produced in situ from ???? are
  important in the UT/LS

8
Additional Sources of HOx in the UT/LS
From Wennberg et al., Science, Vol. 279, 49-53,
1998.
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Major Questions

• What are the key radical production and
  destruction rates and their contrast in the UT
  and LS?
• Can we reconcile HOx meas-model discrepancies
  simply with discrepancies in HOx precursors?
• Are there temporal and geographic dependencies
  to these discrepancies?

10
Major Questions (Cont.)

• Can we reconcile HOx precursor meas-model
  discrepancies in air masses affected by
• Convection
• Cirrus clouds
• At high solar zenith angles
• At high NOx levels
• What are the concentrations of NOx and reservoir
  species in the above affected air masses?

11
Major Questions (Cont.)

• How is the budget of O3 in the UT impacted by
  chemical processes?
• What are the regional and global effects of these
  chemical processes on tropospheric ozone?

12
Major Questions Regarding UT/LS H2O

• Stratospheric H2O increasing 1/year over past
  45 years 50 of increase due to increases in
  strat. CH4 while other 50 highly uncertain.
• While general overall agreement amongst various
  water-vapor measurements, there are still
  unexplained differences.

13
Observational Needs

• Need a dedicated radical study on HIAPER
• Need instruments to measure
• (significant instr. dev for autonomous operation)
• OH, HO2, RO2 (ACD or PSU)
• NO, NO2, NOy, O3 (ACD/ATD)
• H2O, cloud water content, aerosol surface area
  density (ATD)
• CO NMHCs (ATD/ACD)

14
Observational Needs (Cont.)

• J-values (ACD)
• CH2O (ATD/ACD)
• MHP, H2O2 (????)
• Acetone, Ethanol, Methanol, C2 C5
  Carbonyls (ACD)

15
Observational Needs H2O
Need systematic, sustained, well designed long-
term effort to compare instruments in both the
laboratory and the field Need systematic,
sustained effort to ensure continuity of
measurements and their validity over time for
long-term measurements. Need simultaneous
measurements of CH4 and other precursors of H2O
(OVOCs) in strat.
16
Potential Avenues for ATDInvolvement

• ATD/ACD led HOx studies in partnership with
  university and gov. colleagues.
• Partnership with ACD and/or universities in
  selective inst. dev. (our involvement UC/SB for
  meas. of HCl one example).
• HIAPER technology transfer of new instr. to and
  from ATD (ex., sustained operations of research
  instruments from MRE proposals)

17
Potential Avenues for ATDInvolvement

• ATD design, engineering, electronic, and data
  acquisition/processing support of HIAPER
  instruments (both research and routine)
• ATD should play a larger role in H2O UT/LS vapor
  measurements, and perhaps establish its role as a
  standard for H2O measurements.

18
Middle Lower TroposphereScientific Questions
Observational Needs

• Large uncertainties in exchange of chemicals (O3,
  HCs, NOx, HOx) and aerosols between continents
  and the global troposphere. Need more
  observations on a variety of platforms.
• How much of the carbon from natural carbon
  emissions (isoprene and terpenes) can we account
  for in the observations? Need a carbon cycle
  budget experiment.
• Large uncertainties still for the total
  production of reactive nitrogen by lightning and
  its distribution with altitude. Need more
  observations.

19
Middle Lower Troposphere Scientific Questions
Observational Needs (Cont.)

• In the remote troposphere, partitioning between
  NOx and its principal reservoir (HNO3) is poorly
  understood (model NOx/HNO3 unknown reactions that convert HNO3 back to NOx.
  Need more observations with complete suite of
  measurements.
• Large uncertainties in processing of soluble
  gases in clouds and on marine aerosol haze. Need
  more observations of soluble gases (fast meas
  sec.) with comprehensive aerosol meas.

20
Middle Lower Troposphere Scientific Questions
Observational Needs (Cont.)

• Large uncertainties in separating out the uptake
  component from elevated levels from the vertical
  transport of pollution in and around clouds. Need
  more observations vs altitude.
• Need to develop robust chemical signatures to
  identify the effects of past clouds. Could
  explain unusual clear-air observations.

21
Surface (Land Oceans) Scientific Questions
Observational Needs

• Large uncertainties for the flux of many species
  on land and particularly over the oceans. Need to
  continue with or develop new partnerships with
  groups that have flux facilities (Niwot Ridge,
  Woods Hole Air Sea Interaction Tower).
• Need new tools based on CO2 isotopes to better
  distinguish between photosynthetic and
  respiratory fluxes.

22
Potential Avenues for ATDInvolvement in Middle
Lower Trop. Surface Meas.

• Continued dev. of CO2 isotopic ratio instr.
  partnerships with CU, Rice Univ., etc.
• Continued development efforts to measure soluble
  gases.
• In partnership with M3, ACD, Universities,
  continued effort to develop and prove
  capabilities to identify the effects of past
  clouds.