Welcome to the PICO-NARE site
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The Pico Mountain station (also known as PICO-NARE) is an air
pollution observatory. Measurements at Pico Mountain
are able to study the free atmosphere, not directly
affected by the ocean, and see pollution transport events
originating in North America and Europe. The station
was developed to study the global impacts of human activities
on the atmosphere. It has also proven valuable for learning
about the effects of large wild fires in North America and
even Siberia. The station is owned and operated by the
University of the
Azores, which
is working to develop the station into a long-term,
Global
Atmosphere Watch
station. The station attracts
researchers from other nations. Currently, scientists from
Michigan
Tech, the University of Colorado and
the U.S. National Oceanic and Atmospheric Administration are
also studying the atmosphere at the Pico Mountain station.
Measurements at the site began in mid-July, 2001.
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Objectivos
Este projecto estuda os impactos que os poluentes emitidos na
América do Norte e Europa têm sobre Oceânico
Atlântico Norte. Estas medidas permitirão um
melhor conhecimento da atmosfera sobre os Acores e à
escala global. |
Purpose
This project is designed to study the impacts that air pollutants
emitted in North America and Europe have on the atmosphere over the
North Atlantic Ocean. These measurements will improve our understanding
of the environment in the Azores and globally. |
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The PICO-NARE station is located on the summit caldera of Pico
mountain, an inactive volcano on Pico island in the Azores, Portugal
(38 degrees, 28.226 minutes N latitude, 28 degrees, 24.235 minutes W
longitude, 2225 m altitude).
Current Site Status
The Pico Mountain station is currently operating, with
observations of black carbon aerosol, carbon monoxide,
ozone, nitrogen oxides and non-methane hydrocarbons.
Measurements of peroxyacetyl nitrate (PAN, an organic nitrogen
compound) will be added during 2008.
Findings: What have we learned so far?
The PICO-NARE station was originally developed to study the impacts
of continental air pollution outflow upon the atmosphere over the
North Atlantic Ocean, Europe, and downwind regions. However,
research at the station has led to important findings on
several topics. These findings are summarized here, on the topics
of pollution outflow,
impacts of wildfires,
African dust, and
the value of the Pico station.
They have also been documented in the scientific literature.
Links to these publications are provided in
section:Documents.
Findings on pollution outflow
- Air pollution transported from eastern
North America results in increased levels of carbon monoxide (CO, an
indicator of combustion emissions), ozone (O3, an air pollutant),
and ozone precursors (hydrocarbons and nitrogen oxides). The air
pollutant concentrations in the Azores during these events are not
hazardous. However, they are useful for estimating the effect that
air pollutant emissions have on ``background'' concentrations of
these compounds. Increases in these background levels are important
because they can make it harder for downwind nations to meet their
air quality standards. Also, because ozone is a greenhouse gas as
well as an air pollutant, they contribute to greenhouse forcing.
Pollution outflow from Europe is also observed at the station, but
less frequently, because of the large-scale transport from west to
east at the mid-latitudes.
- CO sampled at the PICO-NARE station during several such events
was transported at low altitude, yet it was accompanied by increased
ozone levels. Since ozone is destroyed in the marine boundary layer
- the lowest layer of air above the ocean - this implies that Pico
measurements sample air transported above the marine boundary layer.
This finding contrasts with a common perception that low-altitude
transport over the ocean rapidly destroys ozone. Since a large
fraction of continental emissions are exported at low altitudes, and
since low-altitude export has a greater potential to reach ground
level over downwind continents, events of the type sampled at Pico
may be particularly important for assessing intercontinental impacts
on air quality. The details of atmospheric transport during
these events are provided by Owen 2006.
The amount by which ozone increases during North
American pollution events is larger than expected. The increase of
ozone (relative to CO) is an indicator of the amount of ozone formed
in the atmosphere due to ozone precursors that are emitted along
with CO. Over the eastern U.S., this ratio is typically 0.35 to
0.45. In contrast, the slope observed at Pico is typically 0.7 to
1.0, as shown for 2001 in the figure to the right.
Although there are multiple mechanisms that can affect the slope,
we have concluded that this difference indicates that ozone
formation during transport over the ocean toward the Azores is
significant. This analysis is described by
Honrath 2004.
.
Figure to the right: Ozone is plotted against CO for
PICO-NARE measurements obtained in air sampled during apparent
U.S.-outflow events. The slope of prior measurements
in U.S. outflow sampled near North America is shown by the purple
line. |
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Findings on the atmospheric
impacts of boreal wildfires
- The impact of boreal wildfires on air pollutant levels
at Pico is very significant. The highest carbon monoxide (CO)
level yet observed was the result of emissions from large
wildfires in Alaska and Canada in 2004, and significant
fire impacts have been observed during most years.
The year-to-year variations in fire sizes in both Siberia and
North America directly affect average summertime CO
levels at Pico. For example, 2001 was a year with low
fire emissions, while 2003 and 2004 had large emissions from
Siberia and Alaska/Canada, respectively. The result was a shift
in CO levels from 2001 to 2003 and 2004.
In addition, specific events of transport
from North America and Siberia lead to clearly detectable
increases in CO levels over periods of up to a day or two.
Fire impacts are also occasionally visible to the naked eye,
in the form of haze layers.
Additional details are provided by Honrath
2004 and Lapina
2006.
- Air pollution emissions from boreal fires also
increase levels of ozone and ozone
precursors (the compounds that cause formation of ozone) at Pico.
Whether or not boreal fires significantly affect tropospheric
ozone has been somewhat controversial. The Pico measurements
provide a sampling of large-scale impacts of the fires, because
Pico is so far downwind of the fire regions, and imply that
fire ozone impacts are indeed significant.
- An event-by-event analysis of measurements during
2001 and 2003 indicated that ozone levels increased
along with CO when long-range transport of pollution from
fires in both North America and Siberia occurred
[Honrath 2005].
- A comparison of ozone levels during periods when
upwind fire emissions were apparently present indicates
a signficant enhancement in ozone. The following figure
[Lapina 2006]
presents data from 3 years. For each year, it compares
the distribution of ozone during fire-impacted periods (the
right-hand lines) to ozone levels during non-fire-impacted
periods (the left-hand, shaded lines).
- Tropospheric ozone formation requires nitrogen oxides (NOx), and
NOx emissions from boreal fires are very uncertain. Nitrogen oxides
measurements were conducted during summer 2004, which was
characterized by large emissions from fires in Alaska and Canada.
Dramatic increases in NOx were found, indicating that even near the
Azores, 6 to 15 days downwind from the fires, ozone formation may
have been continuing. By analyzing the measured enhancements of
nitrogen oxides, ozone, and CO during these events, we conclude that
the fires were significant sources of NOx and ozone. For example,
for typical worldwide boreal fire emissions, the Pico measurements
imply NOx emissions comparable to total eastern North America
anthropogenic NOx emissions during the boreal fire season, and
monthly ozone production on the order of 10 to 20% of the total
middle- to high-latitude net tropospheric ozone production rate.
Significant enhancements of light-absorbing particles were also
observed during these events. Together, these findings suggest
that boreal wildfires have very large-scale impacts on climate
forcing by particle absorption and on ozone and NOx levels.
Further details on these analyses are provided by Val
Martin 2006. Simulations of fire impacts
using a global chemical transport model (a computer simulation)
are consistent with the PICO-NARE measurements, as described by
Pfister 2006.
Findings on African desert dust transport
and measurement
Using measurements of light-absorbing particles, several events in
which African desert dust was carried to the Azores have been
identified. Fialho and coworkers [2005,
2006] have developed a technique to
identify these events and separate them from biomass-burning and
anthropogenic particles. This technique is based on light absorption
measurements at multiple wavelengths, and is described in detail in
those two publications.
Findings on the value of atmospheric
measurements on Pico mountain
The PICO-NARE station was located on Pico summit in order to sample
the free troposphere (the region of the atmosphere above the marine
boundary layer, that is, above the marine cloud layer), and to ensure
that local pollution emissions do not affect the measurements. The
station was located in the Azores in order to sample the remote marine
environment, and thereby to determine the impacts of long-range
transport and mixing of emissions from upwind continents on the
regional atmosphere. We have analyzed each of these issues, and
find that Pico summit is ideal for sampling the regional free
troposphere, that it is rarely if ever affected by local Azorean
pollution emissions, and that it provides an excellent platform for
observing the seasonal and interannual variations of atmospheric
composition for assessments of human-influenced and
natural emission impacts. To date, most analyses of PICO-NARE
data have focused on summertime measurements. However, the
seasonal cycle of non-methane hydrocarbons (presented by
Tanner 2006), ozone, and carbon monoxide
in the background northern hemisphere is clearly detected at
the Pico station.
Value for the study of
urban-industrial and wildfire pollution.
As described above, Pico
summit has proven to be an excellent platform for observation of aged
North American and European pollution outflow, and for sampling the
large-scale impacts of boreal wildfires. Findings on these topics
are described above.
In addition, the station was part of the 2004
multinational program International Consortium for Atmospheric
Research on Transport and Transformation (ICARTT), described by
Fehsenfeld 2006. As part of that
study, the U.K. FAAM research aircraft was based in Horta, on the
island adjacent to Pico, during July-August 2004. The U.K. aircraft
flew past the PICO-NARE station on most flights, to allow
intercomparison of measurements, as shown in the photo to the right. |
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Frequency of sampling free tropospheric air.
Many remote atmospheric observatories that are located on mountains
are affected by periodic upslope flow: airflow up the
mountainside, which can carry local pollution or air from near
sea-level to the observatory. During summer 2004, a set of
meteorological sensors was installed along the side of Pico mountain
to determine the degree to which this occurs on Pico mountain.
Buoyant upslope flow does occur on Pico mountain, but less frequently
(on about 24 to 39% of the study days) than at other mountains with
important atmospheric observatories, such as Mauna Loa and Izana.
More importantly, measurements of water vapor, ozone, and nitrogen
oxides indicated that little or none of this upslope-flowing air
reaches the station on most day. This is apparently the result of
the very steep slopes and narrow width of Pico mountain, which lead
to air flow around the mountain as well as up it. As a result, free
tropospheric air is sampled at the station during summer every night
and most days.
Upslope flow of boundary layer air can also result from high wind
speeds, which push air up the mountainside in a process referred to
as mechanically driven uplift. This is rare during summer, when the
atmosphere is relatively stable and wind speeds are relatively low.
However, during other seasons it is more frequent. The figure to the
right compares the seasonal variation of the minimum height of air
that mechanical uplift might carry to Pico summit, termed Zt,
to the seasonal variation of marine boundary layer (MBL) height.
During summer, Zt is much higher than MBL height, meaning that free
tropospheric air is sampled. However, during other seasons it is
possible that MBL air may be sampled as frequently as 50% of the
time. At present, we are not sure whether or not MBL air actually
is sampled during these periods. If it is, then this may provide
a way to study both MBL and FT composition using measurements at
Pico summit.
The analysis used to investigate mechanically driven upslope
flow has also been used to develop a method to predict the occurrence
of cloud cover at the mountain summit. Details of both that and the
upslope flow analyses are presented by Kleissl et al.
[2006a and
2006b] |
Caption: The dashed line shows the seasonal variation of Zt, the
minimum height from which air may be mechanically lifted
to Pico summit.
The solid line shows the seasonal variation
of marine boundary layer height.
The numerals at the bottom
indicate the percent of the time when Zt is below the MBL height,
implying that MBL air could be sampled at the PICO-NARE station. |
- Feasibility of measurements on Pico summit.
The environment at Pico summit is quite harsh, and access to
the station is difficult, especially during winter. As a result,
it was not clear initially whether or not it would be possible
to conduct long-term high-quality atmospheric measurements there.
However, the record of measurements to date has demonstrated that
it is indeed possible. A reliable internet connection has
been established, and all instruments at the station are fully
automated and remotely controllable. These include some highly
complex measurement systems, such as a trace-level NO, NO2, and
NOy detector and a non-methane hydrocarbon gas chromatograph.
(Details on the hydrocarbon instrument developed for use
at Pico are provided by Tanner 2006.)
The figure below shows the data coverage since station inception.
Periods when the station was shut down or off due to power issues
are colored grey; power outages have been very infrequent
since spring 2004. (The station has been shut down for the
winters of 2005-6 and 2006-7, and no nitrogen oxides measurements
were made during 2006, because of limited funding.)
Most importantly, measurements of all species have become
nearly continuous during the last two to three years.
Recent Weather
The following sections show the most recent data and images
from the station. During periods when the station is turned off,
these are simply the last images and data downloaded before the
station was shut down.
Please see the site status section for
information on site operation that may affect the quality or validity
of these data.
Note that these data may be several hours to several days old
at times, due to delays in transferring data from the station.
Wind direction is not shown, as wind directions at Pico summit are not
the same as wind direction away from the mountain, due to turbulence
over the summit. (A related plot of concentrations measured at the
station is available below.)
Site Photographs
Recent Measurements
The data plots below are meant to be a quick look at recent preliminary
measurements. Scientists interested in using data from the station
should refer to the PICO-NARE data exchange
web page
for
more information.
The station is currently operational, and all instruments
are working. Measurements of
carbon monoxide (CO), ozone (O3),
non-methane hydrocarbons, and aerosol black carbon (BC),
and standard meteorological parameters are being made.
Nitrogen oxides measurements are not funded this summer.
Recently obtained data are shown in the figure below, and recent
photos are shown above. Occasional
periods when data are not transferred have been occurring recently, due to
heavy icing at Pico summit, which covers the cell phone antenna and
prevents data transfer. Data are still obtained during these periods,
and show up in the plot below when the ice melts.
The most recently processed data are shown in the following plot.
Note that this plot contains preliminary data, which may change
significantly when they are carefully analyzed. In addition, periods
of instrument tests may be included.
Shown are CO (carbon monoxide) in ppb (parts per 10^9) and O3 (ozone) in
ppb.
The temperature inside the station is also shown on the ozone plot, and
the third plot shows wind speed.
(A related plot of weather at the
station is available above.)
Additional details and documents
Findings from the following publications are summarized
above, in section Findings.
- Regional and hemispheric impacts of anthropogenic
and biomass burning emissions on summertime CO and O3 in the
North Atlantic lower free troposphere,
R. E. Honrath, R. C. Owen, M. Val Martin, J. S. Reid, K. Lapina,
P. Fialho,
M. P. Dziobak, J. Kleissl, and D. L. Westphal, J. Geophys. Res., 109, D25310, doi:10.1029/2004JD005147, 2004.
(available here).
-
An analysis of the mechanisms of North
American pollutant transport to the central North Atlantic
lower free troposphere,
R. C. Owen, O. Cooper, A. Stohl, and R. E. Honrath,
J. Geophys. Res.,
111, D23S58, doi:10.1029/2006JD007062.
(available here).
-
Evidence of significant large-scale impacts of boreal fires
on ozone levels in the midlatitude Northern Hemisphere free
troposphere, K. Lapina, R. E. Honrath, R. C. Owen, and M. Val Martin,
Geophys. Res. Lett., 33, L18015, doi:10.1029/2006GL025878,
2006.
(available here).
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Significant enhancements of nitrogen oxides, black carbon
and ozone in the North Atlantic lower free troposphere resulting
from North American boreal wildfires, M. Val Martin, R. E. Honrath,
R. C. Owen, G. Pfister, P. Fialho, and F. Barata,
J. Geophys. Res.,
111, D23S60, doi:10.1029/2006JD007530, 2006.
(available here).
-
Ozone production from the 2004 North American boreal fires,
G. G. Pfister, L. K. Emmons, P. G. Hess, R. Honrath, J.-F. Lamarque,
M. Val Martin, R. C. Owen, M. A. Avery, E. V. Browell,
J. S. Holloway, P. Nedelec, R. Purvis, R. B. Ryerson,
G. W. Sachse, and H. Schlager, J. Geophys. Res.,
111, D24S07,
doi:10.1029/2006JD007695
2006.
- The occurrence of upslope flows at the Pico mountain
observatory: a case study of orographic flows on small,
volcanic islands, J. Kleissl, R. E. Honrath, R. C. Owen, M. Val Martin,
and M. P. Dziobak, J. Geophys. Res.,
112,
doi:10.1029/2006JD007565, 2007.
(available here).
-
Aethalometer calibration and determination of
iron concentration in dust aerosols, P. Fialho, M. C. Freitas,
F. Barata, B. Vieira, A. D. A. Hansen, and R. E. Honrath,
J. Aerosol Sci., 37, 1497-1506, 2006.
(available here).
-
Gas chromatography system for the automated, unattended, and
cryogen-free monitoring of C2 to C6 non-methane hydrocarbons
in the remote troposphere, D. Tanner, D. Helmig, J. Hueber,
and P. Goldan, J. Chromatography A, 1111, 76-88, 2006.
- Analysis and application of Sheppard's airflow model to predict
mechanical orographic lifting and the occurrence of mountain
clouds, J. Kleissl and R. E. Honrath, J. Appl. Met. and Clim.,
Vol. 45, No. 10, pages 1376-1387, 2006.
(available here).
-
Absorption coefficients by aerosols in remote areas: a new
approach to decouple dust and black carbon absorption coefficients
using seven-wavelength Aethalometer data, P. Fialho,
A. D. A. Hansen, and R. E. Honrath, J. Aerosol Sci. (in
press), 2005.
(available here).
-
International Consortium for Atmospheric Research
on Transport and Transformation (ICARTT): North America
to Europe--Overview of the 2004 summer field study,
F. C. Fehsenfeld et al., J. Geophys. Res.,
111, D23S01,
doi:10.1029/2006JD007829, 2006.
- PICO-NARE, R. E. Honrath and P. Fialho,IGACtivities
Newsletter (International Global Atmospheric Chemistry Project),
August 2001 issue (available
here).
Note: The following list has not been updated recently; some of
the material included here is outdated.
- Description of atmospheric
measurement infrastructure
in the Azores
- The measurement period for the current, temporary PICO-NARE station
is nearing its end. We are currently working toward a permanent
GAW station at Pico to replace the current, temporary station.
A Townhall Meeting was held at the European Geophysical Union
meeting in Vienna, April 28, 2005.
- A general description of the site, its development, and
initial observations is available as a PDF document.
Select low-resolution (72 dpi, 855
kB)
or high-resolution (300 dpi,
3.2 MB).
- More in-depth information on the PICO-NARE study is available in the
following posters and documents.
- Regional and hemispheric impacts of anthropogenic
and biomass burning emissions on summertime CO and O3 in the
North Atlantic lower free troposphere,
Honrath, R. E., R. C. Owen, M. Val Martin, J. S. Reid, K. Lapina,
P. Fialho, M. P. Dziobak, J. Kleissl, and D. L. Westphal (2004),
J. Geophys. Res., 109, D24310, doi:10.1029/2004JD005147.
Download reprint.
- A description of the station, written prior to start-up,
was published in IGACActivities, the newsletter of the International
Global Atmospheric Chemistry program, and is available
here
- A poster describing the site further and presenting initial analyses
of measurements made during July-September 2001 was presented at the
December 2001 AGU meeting. A tabloid-size copy of the poster is
available in PDF form:
- A presentation at the September 2002 IGAC meeting in Crete
is available here
(2.6 MB).
- A poster presented at the spring 2003 joint meeting of
the American Geophysical Union and European Geophysical Society.
- A presentation
at the
AIRMAP
planning
meeting for the NENA-2004/ITCT research studies to take place during
summer 2004. Note that this presentation may begin in full-screen
mode. Return to your computer screen by pressing control-l. (3.6
MB)
- Additional information on the summer-2004 field intensives is
available from the following documents.
Links
Groups and agencies who have helped with the project
This project is possible as a result of the assistance of several
agencies and groups. They include the following.
Funding for this project has been provided by the following agencies.
- National Oceanic and Atmospheric
Administration (NOAA),
Office of Global
Programs, United States.
- Fundacão para Ciência e Tecnologia, Portugal.
- National Science Foundation,
United States. This material is based upon work supported by the
National Science Foundation under Grant Nos. INT-0110397,
ATM-0215843 and ATM-0720955. (Any opinions, findings, and conclusions or
recommendations expressed in this material are those of the author(s)
and do not necessarily reflect the views of the National Science
Foundation.)
- Governo Regional dos Acores: The Azores regional government
permitted the temporary installation of the PICO-NARE station on
Pico summit.
- U.S. Air Force: As a contribution to U.S.-Portugal scientific
collaboration, the U.S. Air Force has provided unpaid logistical
support by carrying equipment from the United States to Terceira
island.
- Forca Area Portuguesa: The Portuguese Air Force
has provided paid airlifts of equipment to the summit.
- Bombeiros Voluntários da Madalena do Pico: The Madalena
volunteer fire department has been extremely helpful. They
have assisted with airlifts each summer and have assisted students
visiting the station during other periods.
- United States Consulate, Ponta Delgada, Azores, Portugal;
William Meara, Consul.
The station was originally developed by Michigan Technological
University using funding from NOAA. On June 29, 2006, Michigan
Technological University donated the PICO-NARE station to the
University of the Azores, at a ceremony in Ponta Delgada. The
Regional Government of the Azores and the Portuguese Institute of
Meteorology participated in the ceremony and demonstrated their
commitment to support the further development of the station, to
create a permanent, Global Atmosphere Watch station at Pico summit.
International research will continue to be welcomed during and
after the transition to a permanent station.
(View the Michigan Tech news release on this topic)
- Martins Lda. is responsible for maintaining the generator
that provides power to the PICO-NARE station, and have provided
excellent support even when lightning strikes require weekend or
nighttime visits.
- Electrificador Picoense Lda. assists in maintenance of
the electrical power cable, and has repaired damage caused by
lightning strikes.
The PICO-NARE logo was created by Madalena Fialho.
Richard E Honrath
2008-08-28
