1

Funding  Opportunity:  Proposals  for  Conferences,  Symposia  and  Workshops  Title:      Mountain  Top  Cloud  Sampling:  Experimental  Design  for  Coordinated  Study  of  Multiphase  Chemical  Mechanisms  PI:  Annmarie  Carlton,  Rutgers  University;  Mary  Barth,  NCAR/ACOM;  Sara  Lance,  SUNY/Albany  

Period:  3/1/2016  –2/28/2017   Location:  New  Brunswick,  NJ/Whiteface  Mountain,  NY   Cost:   $20,000    

Summary:  Visible  clouds  cover  60%  of  the  Earth’s  surface  at  a  given  time  and  are  the  primary  means   by   which   constituents   from   the   polluted   boundary   layer   are   lofted   to   the   Free  Troposphere   (FT)   [1].   Clouds   also   play   an   important   role   as   atmospheric   aqueous   phase  reactors,  scavenging  soluble  gas  phase  precursors  and  supporting  oxidation  reactions  that  yield  lower   volatility   products   that   contribute   to   increased   aerosol   mass   when   the   cloud   drops  evaporate.   The   radiative   impacts   of   aerosols   in   the   FT   are   substantial,   in   particular   when  located  above  clouds  where  aerosols  scatter  and  absorb  not  only  incoming  solar  radiation  but  also   the   diffuse   back   scatter   reflected   by   clouds   [2].   In   the   FT,   aerosols   and   trace   gases   are  subject   to   fewer   removal   processes   and   experience   long-­‐range   transport.   Despite   the  abundance  and  importance  of  clouds,  they  are  sampled  infrequently,  and  there  is  a  persistent,  yet   implicit   clear   sky   bias   in   our   understanding   of   the   troposphere’s   composition.   During  atmospheric  chemistry  field  campaigns,  aircraft  typically  avoid  clouds  and  satellite  retrievals  of  trace   gases   and   aerosols   impacted   by   clouds   are   often   screened   from   final   data   products   to  avoid  potential  measurement  artifacts.  This  is  a  key  knowledge  gap.  

Whiteface  Mountain,  NY,  originally  part  of  the  acid  rain  deposition  network  and  now  part  of  the  National   Atmospheric   Deposition   Program   (CASTNet)   (Figure   1),   is   a   special   sampling   site  because  1)  of  its  historical  context  for  decades  of  chemically-­‐speciated  measurements  of  clouds  and  precipitation,  2)  it  is  in  cloud  25-­‐60%  of  the  time  during  summer,  and  3)  ample  cloud  liquid  water   is   collected  by   the  Adirondack  Lakes  Survey  Corporation   (1L   samples  are  collected  and  stored   each   cloud   event).   Key   limitations   in   the   current   cloud   sampling   approaches   are   the  small  number  of  constituents  that  are  quantified  in  clouds,  with  little  to  no  information  about  the   inflow   regions.   The   ability   to   consistently   sample   clouds   from   a   stationary   location  with  large  cloud  water  sample  size  is  ideal  for  simultaneously  measuring  many  trace  gas  and  aerosol  constituents  via  multiple  analytical  techniques  for  the  same  cloud  event.    

 

2

Figure 1. Existing Whiteface Mountain sampling infrastructure.

Statement   of   Need:  We   propose   to   organize   and  host   a   workshop   at   the   Whiteface   Mountain  Observatory,   with   a   focus   on   developing   a   field  study   on   clouds   and   chemistry   at   Whiteface  Mountain.  The  major  focus  of  this  workshop  will  be  on  designing  a  coordinated  measurement  strategy  to  understand  cloud  chemistry  in  the  context  of  the  cloud’s   physical   and   radiative   properties.   The  ultimate   goal   is   to   improve   our   fundamental  understanding   of   the   cloud   chemistry   processes  occurring  within  clouds  based  upon  intensive  multi-­‐week   inflow   air   and   in-­‐cloud   measurements   at   a  mountain   top   field   site.   The   outcome   will   be  improved  multi-­‐phase   chemistry   representation   in  regional   and   global-­‐scale   models.   These   cloud  chemistry   processes   include   gas-­‐aqueous   phase  partitioning   and   reactions   taking   place   within   the  aqueous  phase,  both  of  which  potentially  alter  gas  phase   reaction   rates   as   chemical   constituents   are  either  added  or   removed   from  the  gas  phase.  Gas  phase  chemical  processes  occurring  within  clouds  happen  within  the  context  of  elevated  water  vapor   concentrations   and   altered   actinic   flux   due   to   scattering   of   sunlight   by   cloud  droplets,  which   can   lead   to   new   particle   formation   events   in   the   near-­‐cloud   environment   [3]   (where  particles  nucleate  homogeneously  from  the  gas  phase).  

 

Whiteface Coordinated Investigation of Cloud Chemistry Workshop

Introduction   and   Summary:  Concentrations  of  many  atmospheric   trace  species   in   the  United  States  have  changed  dramatically  over  past  decades  in  response  to  pollution  control  strategies,  shifts  in  domestic  energy  policy,  and  economic  development  (and  emission  changes)  elsewhere  in  the  world.  Accurate  and  reliable  projections  for  the  future  atmosphere  require  that  models  not  only  accurately  describe  current  atmospheric   concentrations,  but  also  do   so   for   the   right  reasons.   Only   through   incorporation   of   reliable   comprehensive   chemical   mechanisms   can  future  projections  of  the  impacts  from  policy,  energy,  and  climate  scenarios  be  reliable.  Efforts  to   properly   design   and   implement   the   correct   fundamental   and   controlling   mechanisms   in  atmospheric   models   are   enhanced   during   intensive   observation   periods,   when   diverse,  speciated   chemicals   in  both   the  gas  and   condensed  phases  are  measured  with   co-­‐location   in  space  and  time.  Coordinated  studies  provide  an  opportunity  for  the  atmospheric  community  to  come   together   to   improve   our   understanding   of   atmospheric   processes,   and   to   evaluate,  

3

diagnose  and  advance  climate  and  air  quality  modeling  of  different  temporal  and  spatial  scales  for  improved  representation  of  fundamental  atmospheric  processes.    

Gas-­‐phase  chemical  mechanisms  employed  in  atmospheric  models  contain  hundreds  of  kinetic  expressions,  while  aqueous-­‐phase  chemical  mechanisms  currently  contain  only  on  the  order  of  ~5  kinetic  expressions  in  the  models,  primarily  due  to  lack  of  understanding  driven,  in  part,  by  the  dearth  of  direct  measurements  of  ambient  cloud  droplet  composition.  This  limits  atmospheric  analysis  primarily  to  observed  gas  phase  and  dry  aerosol  mixing  ratios  (e.g.,[4-8]).  

Objectives:  Conduct  a  small  workshop  (~30  participants)  to  design  coordinated  field,  laboratory  and  modeling   studies   that  address   key   scientific  questions  on   clouds  and  chemistry,   as   listed  below.  Provide  workshop  participants  with  cloud  liquid  water  samples  for  preliminary  analysis.  Sample  analysis  will  be  part  of  workshop  summary  report  to  NSF.  

Expected   results:   1)   State-­‐of-­‐the-­‐art   protocol   for   cloud   water   sampling   and   paired  measurements  of  key  aerosols  and  trace  gases,  2)  A  plan  for  a  coordinated  field,  modeling,  and  laboratory   investigation   to   improve   our   knowledge   of   cloud   chemistry   in   the   context   of   the  cloud’s   physical   and   optical   properties,   3)   A   strategic   model   development   plan   to   improve  representation  of  cloud  chemistry,  4)  Preliminary  and  publicly  available  chemical  characterized  cloud  samples.  

Recent  Meetings:  We  are  aware  of  only  one  recent  workshop  focused  on  mountain  top  sampling  to  characterize  atmospheric  trace  species  1.)  Bioaerosol  Effects  on  Clouds,  August  5-­‐6,  2012,  Steamboat  Springs,  CO    

Current  questions  to  be  addressed  for  the  workshop:  

This  workshop  will  focus  on  developing  a  field  study  experimental  design  to  answer:  

1.  Can  the  clear-­‐sky  bias   in  chemical  characterization  of  the  troposphere  be  quantified  with  a  coordinated   field   study(s)?   How   well   can   an   intensive   cloud-­‐chemistry-­‐focused   field   study  reveal  oxidation  products  and  related  processes  from  aqueous  chemistry?  

2.   How   much   do   aqueous-­‐phase   oxidation   and   cloud   processing   affect   gas-­‐phase   organic  compound  mixing  ratios?  To  what  extent  is  the  fate  and  transport  different  from  gas-­‐phase  only  processing?  

3.   How   does   water-­‐mediated   processing   modify   the   size   and   composition   of   atmospheric  aerosols?     With   respect   to   organics,   how   does   cloud   processing   alter   the   organic   aerosol  oxidation  state  or  O:C   ratio?    Do  aqueous  phase   functionalization   reactions   lead   to   increased  organic   aerosol   mass,   or   do   fragmentation   mechanisms   dominate,   leading   to   a   decrease   in  organic  aerosol  mass  following  cloud  processing?  

4

4.    What   are   the   key  oxidants   driving   aqueous  phase   chemistry?    How  does   cloud   chemistry  change  between  daylight  and  nighttime  conditions?          

5.   Are   there   unique   (or   at   least   useful)   chemical   tracers   of   cloud   processing?  What   are   the  dominant  aqueous-­‐phase  chemical  mechanisms  involving  organic  aerosol?  

6.   Can   vertically-­‐resolved   measurements   of   chemical   species   in   clouds   provide   information  about  vertical  mixing  and  boundary  layer  free  troposphere  exchange?  

7.    Are  aqueous  phase  biological  processes  relevant/important?  

Chairperson and steering committee

Co-Chairs: Annmarie Carlton (Rutgers), Mary Barth (NCAR/ACOM), Sara Lance (SUNY-Albany)

Steering committee: Jeff Collett (Colorado State University), James Schwab (SUNY), Delphine Farmer (Colorado State University); Kerri Pratt (University of Michigan)

Meeting   organization   and   recruitment:   We   propose   a   two-­‐day   workshop   at   the   Whiteface  Mountain  Observatory.   Approximately   30  workshop  participants  will   be   invited.   The  meeting  announcement  will  be  posted  to  Earth  Science  Women’s  Network  website.  Some  funding  will  be  reserved  in  particular  for  early-­‐career  scientists.  Before  the  workshop  we  will  post  a  public  wiki   with   travel,   agenda,   attendee   information   etc.   After   the   workshop,   results   from   cloud  liquid   water   sample   analysis   by   workshop   attendees   will   be   posted,   and   we   will   write   a  workshop  summary  for  publication  in  Eos.    

5

Tentative Agenda

Whiteface Mountain Workshop Draft Agenda DAY1

8:00-8:30 Light breakfast and Welcome (A. Carlton and S. Lance)

8:30-9:00 Intro Whiteface Mtn. Observatory and history of cloud sampling and chemical climatology (J. Schwab)

9:00-10:00 Synthesis of mtn. top experiments, including Great Dun Fell and FEBUKO/HCCT, key knowledge gaps in cloud chemistry (J. Collett and M. Barth)

10:00-11:30 Group 1 Summit transport and tour (Paul Casson) 11:30-12:30 Group 1 Break and Lunch 12:30 - 1:30 Group 1 Tour lodge trailer and lower sampling site (Paul Casson) 10:00-10:15 Group 2 Break 10:15-11:15 Group 2 Tour lodge trailer and lower sampling site (Jim Schwab) 11:15-12:00 Group 2 Lunch 12:00-1:30 Group 2 Summit transport and tour (Jim Schwab)

1:30-2:30 Reconvene at Lodge Cloud water sampling protocol: breakout groups design

2:30-3:00 Report out by break out groups to discuss mountain top sampling technique and common SOP

3:00-3:15 break

3:15-4:15

Cloud Experiment Outline breakout groups: Intentional pairing of younger and established scientists before the meeting and tasked to lead break out sessions to outline experimental design with aircraft and mountain top sampling components

4:15-5:15 Report out by break out groups 5:15-6:00 Organized and moderated group discussion of experiment design 6:00 Adjourn and organized group dinner DAY2

8:00-8:30 Light breakfast and daily organization

8:30 – 9:30

Cloud modeling: overview of cloud chemistry modeling in atmospheric models and process-level mechanisms (M. Barth) Highlights with what can be expected at Whiteface with preliminary new data and what are the key gaps M. Barth (WRFchem), B. Ervens (parcel), K Pratt (recent measurements)

9:30-11:00 Breakout groups: evaluation of experimental strategies’ ability to address key modeling gaps and potential experiment redesign.

11:00-10:15 break

11:15-12:00 Breakout into 3 Teams: 1.) cloud inflow team, 2.) cloud water team, 3.) modeling team

12:00 - 1:00 Working Lunch

1:00-3:00 30 min report out by each team with 15 min. of discussion 3:00-3:15 break

3:15-4:30 Breakout into 4 Teams: 1.) cloud inflow team, 2.) cloud water team, 3.) modeling team, 4.) synthesis team

6

4:30-5:30 Organized discussion addressing expected outcomes and future directions led by S. Lance and A. Carlton - planning with all attendees

5:30 adjourn

7

References

1. Barth, M.C., Sillman, S., Hudman, R., Jacobson, M.Z., Kim, C.H., Monod, A., Liang, J., Summary of the cloud chemistry modeling intercomparison: Photochemical box model simulation. J. Geophys. Res., 2003. 108(D7), 4214.

2. Seinfeld, J.H., Black carbon and brown clouds. Nature geoscience, 2008. 1: p. 15-16.

3. Wehner, B., Ditas, F., Shaw, R.A., Kulmala, M., Siebert, H., Observations of new particle formation in enhanced UV irradiance zones near cumulus clouds, Atmos. Chem. Phys., 2015. 15(20): p. 11701-11711.

4. Henderson, B.H., Pinder, R.W., Crooks, J., Cohen, R.C., Hutzell, W.T., Sarwar, G.,

Goliff, W.S., Stockwell, W.R., Gahr, A., Mathur., R. Carlton, A.G., Vizuete, W., Evaluation of simulated photochemical partitioning of oxidized nitrogen in the upper troposphere. Atmos. Chem. Phys., 2011. 11(1): p. 275-291.

5. Washenfelder, R. A., Young, C.J., Brown, S.S. Angevine, W.M., Atlas, E.L.,

Blake, D.R., Bon, D.M., Cubison, M.J., de Gouw, J.A., Dusanter, S. et al., The glyoxal budget and its contribution to organic aerosol for Los Angeles, California, during CalNex 2010, J. Geophys.Res., 2011, 116, D00V02.

6. Hennigan, C. J., Bergin, M.H., Russell, A.G., Nenes, A., Weber, R.J.,

Gas/particle partitioning of water-soluble organic aerosol in Atlanta, Atmos. Chem. .Phys., 2009, 9, p. 3613-3628.

7. Volkamer, R., Martini, F.S., Molina, L.T., Salcedo, D., Jimenez, J.L., Molina,

M.J., A missing sink for gas-phase glyoxal in Mexico City: Formation of secondary organic aerosol, 2007, Geophys. Res. Letts., 34, L19807.

8. Waxman, E. M., et al., Secondary organic aerosol formation from semi- and

intermediate-volatility organic compounds and glyoxal: Relevance of O/C as a tracer for aqueous multiphase chemistry, Geophys. Res. Letts., 2013, 40, p. 978-982.