2011 - Cooperative Institute for Research in Environmental Sciences ...

profiling radars with radio acoustic sounding systems
and surface meteorology towers at three key locations
in southern California for the CalNex field campaign in
the upcoming spring and summer (2010). Meteorological
observations collected at these sites will be accessed,
displayed, and archived and quality controlled.
The data sets were used heavily both during and after
the CalNex (Research at the Nexus of Air Quality and
Climate Change) field campaign.
Milestone 2. Develop, operate and maintain a wind profiler
trajectory tool for the CalNex field campaign. The
tool is used by scientists to document transport pathways
for air pollution and to help plan aircraft missions. Starting
this year, the trajectory tool will be maintained by the
PSD Water Cycle Branch, the same group responsible for
operating and maintaining the wind profilers.
The trajectory tool was implemented with quality-controlled
wind profiler data collected during CalNex.
Milestone 3. Execute the surface flux, boundary layer,
and cloud observations for the CalNex cruise. Process and
analyze the CalNex data set from the NOAA Ship Ronald
H. Brown cruise, including turbulent fluxes of momentum,
sensible heat and latent heat, down-welling radiative
fluxes, cloud radar statistics, ceilometer observations,
radio-soundings for boundary layer structure, microwave
radiometer observations of cloud liquid water and column
integrated water vapor, etc.
A preliminary analysis was done, and the results were
presented at the CalNex-Atlantis Data Workshop at the
University of California Davis, Jan. 11-13, 2011. All data have
been archived under ftp://ftp1.esrl.noaa.gov/psd3/cruises/
CALNEX_2010/Atlantis/Scientific_analysis/flux/.
Milestone 4. Deploy systems on the Gulf of Mexico oil platform
for the Minerals Management Service observational
program. Data include fluxes of sensible heat, latent heat,
momentum and sea surface temperature.
Meteorological and flux instruments are currently deployed
on the platform. A qualitative evaluation of the instruments
was performed. Comparison of bulk estimates
with eddy covariance air sea fluxes is ongoing.
CSD-08RegionalAirQuality
FEDERAL LEADS: DAVID PARRISH, JIM BURKHOLDER
AND MICHAEL HARDESTY
CIRES LEAD: CHRISTINE ENNIS
NOAA Goal 2: Climate
Project Goal: Conduct laboratory measurements, atmospheric
observations and diagnostic analyses that characterize the
chemical and meteorological processes involved in the formation
of pollutant ozone and fine particles. Undertake research
that enhances air-quality prediction and forecasting.
Milestone 1. Measure the reactivity and optical properties
of compounds that are replacements for ozone-depleting
substances, and evaluate their global warming potentials.
Impact: The determination of the atmospheric loss
processes and atmospheric lifetimes of replacement
compounds is critical decision-support information. This
research has implications for regional air quality, strato-
128 CIRES Annual Report 2011
spheric ozone and climate change.
In order to determine the impacts of the potential replacement
compounds, we are studying the reactivities
of these species toward OH, Cl and O3. The atmospheric
lifetimes of the hydrofluorocarbons (HFCs) due to loss by
OH reaction were estimated. The rate coefficients for the
OH reaction were measured as a function of temperature
(211–374 K) and pressure (20–200 Torr, He, N2) using a
pulsed laser photolysis – laser induced fluorescence (PLP
– LIF) technique, and at 296, 345 and 375 K using a relative
rate technique at pressures between 100 and 300 Torr (He).
The rate coefficients for the Cl reactions were measured
using a relative rate method. We also measured the infrared
and UV absorption cross sections of HFCs. The infrared
absorption measurements were used to determine global
warming potential (GWP) of these species. We have several
compounds, which need to be assessed. A manuscript on
atmospheric chemistry of (Z) CF3CH=CHCF3 is in preparation
and about to be submitted. One of the samples is a
mix of five or more structurally similar hydrofluoroethers.
We have three samples with different mixing ratios, which
will allow us to determine the reactivities of the individual
isomers better. This is work in progress.
Milestone 2. In the CalNex 2010 field campaign, use
surface, airplane-, ship- and satellite-borne sensors to
survey a wide variety of sources of directly emitted gas
and aerosol species that impact atmospheric air quality via
ozone and secondary organic aerosol formation. Impact:
This CIRES research will investigate the distribution and
source strengths of precursors to pollution, leading to an
improved understanding of anthropogenic, agricultural,
biogenic and geologic sources of pollutant species. The
study will also investigate the daytime and nighttime
chemical transformations and pollutant transport in the
atmosphere. These data and analyses will provide the State
of California with the scientific foundation for their efforts
to develop plans to bring several areas of the state into
compliance with federally mandated National Ambient Air
Quality Standards for ozone and particulate matter.
A principal focus of the 2010 CalNex study was on emissions
of species that affect air quality and the chemical and physical
processes that determine the fate of those species. CIRES
research contributed significantly to verifying and quantifying
these emissions and to understanding the transformation
processes that the emitted species undergo. Three examples
are provided here.
1) Nitryl chloride (ClNO2) is a species formed at night from
the reaction of oxides of nitrogen, ozone and chloride-containing
wet aerosols and may contribute to early-morning
chemistry that produces photochemical smog. It is produced
from a sequence of chemical reactions and intermediate
species that need certain environmental conditions to be met.
During CalNex, ClNO2 was observed over a large range of
mixing ratios from research vessel Atlantis and the NOAA
WP-3D aircraft. The cause of this variability is under investigation
but will likely be verified from currently understood
chemistry and from the environmental conditions (e.g.,
temperature, relative humidity) in which that chemistry
happened.
2) At the Pasadena, Calif., ground site, measurements of
a wide spectrum of organic compounds were made, which
will provide information not only on emission sources, but
also on chemical oxidation pathways that indicate the type
of oxidation chemistry (e.g., hydroxyl radical) occurring, the