The Photochemistry of Ozone Loss in the Arctic Region In Summer (POLARIS) is the latest in a series of high-altitude airborne investigations of atmospheric ozone spanning more than a decade. The objective of POLARIS is to understand the behavior of polar stratospheric ozone as it changes from very high concentrations in spring down to very low concentrations in autumn.
Ozone is an important component of our atmosphere; it screens the Earth from the biologically harmful effects of solar ultraviolet radiation. Because of the role ozone plays, we must have a clear understanding of the distribution, chemistry, and physics of stratospheric ozone that will allow us to determine whether various atmospheric changes such as those related to aircraft emissions or the release of chlorofluorocarbons might be causing stratospheric ozone changes.
The Arctic is a unique region for stratospheric ozone research. First, stratospheric temperatures are quite low during the winter polar night, enabling a variety of chemical reactions to occur on surfaces of particles which comprise polar stratospheric clouds. Second, the continuous daylight conditions of the polar summer enable a much different chemical environment than is observed at similar times in mid-latitude regions.
Campaigns similar to POLARIS have been conducted from bases all over the world, including Punta Arenas, Chile; Christchurch, New Zealand; Barbers Point, Hawaii; Moffett Field, California; Bangor, Maine; Stavanger, Norway; and Fairbanks, Alaska. This broad range of operational bases provided the latitudinal coverage required for the atmospheric studies being conducted.
Previous ER-2 aircraft missions have focused on understanding ozone loss in the polar regions and mid-latitudes of both hemispheres; atmospheric transport between the polar regions, mid-latitudes, and tropics, as well as between the troposphere and stratosphere; and the relative importance of various chemical cycles for ozone production and loss. The scientific data obtained on these missions have been used extensively in international assessments of stratospheric ozone depletion. These assessment documents represent the scientific basis for actions under the United Nations Montreal Protocol, which provides for the control of ozone-depleting chemicals. In a similar manner, results from the POLARIS mission will contribute to an assessment of the atmospheric effects of aviation emissions of gases and particles.
The scientific objective of the POLARIS campaign is to evaluate the reduction of stratospheric ozone over a range of altitudes and latitudes in the summer season of the Northern Hemisphere. Aircraft measurements of select species within the reactive nitrogen (NOy), halogen (Cly), and hydrogen (HOx) reservoirs; aerosols, and other long-lived species will be made at mid- to high latitudes in spring and summer in the lower stratosphere. These measurements will allow the effectiveness of the respective catalytic loss cycles of ozone to be calculated directly for sampled air parcels. These results along with computer models of the atmosphere, meteorological data, and satellite and balloon observations will be used to evaluate summer ozone changes due to chemistry and transport at high latitudes.
In areas removed from the ozone production region at tropical latitudes, ozone abundances show a distinct seasonal cycle. At northern high latitudes, ozone column amounts peak in spring and reach minimum values in late summer/early fall (Figures 1 and 2). The April-to-September decrease is attributed to in situ photochemical destruction of ozone enhanced by long periods of solar illumination. Several catalytic photochemical cycles contribute to this loss with the largest fractional loss associated with reactive nitrogen species. Losses associated with anthropogenic chlorine emissions are smaller in this case. As in previous studies of ozone loss in the winter polar stratosphere, confirmation of the underlying photochemical processes with in situ observations will greatly increase our confidence in explaining observed and future changes of ozone abundances.
In addition to anthropogenic chlorine emissions, the emission of NOx (= NO + NO2) from subsonic and supersonic aircraft is of contemporary concern. The NOx catalytic cycle contributes directly to the loss of ozone and NOx participates in controlling the effectiveness of the Clx (= Cl + ClO) and HOx(= OH + HO2) loss cycles. Model calculations predict that changes in ozone from aircraft emissions are greatest in summer at mid- to high latitudes [Stolarski and Wesoky, 1993]. Uncertainties in these estimated changes would likely be reduced if a quantitative evaluation of the photochemical processes associated with the response to aircraft emissions could be made in this important region [NRC, 1994].
Ozone is typically observed in the atmosphere as a total column abundance. Important data sets have been obtained with the ground-based Dobson spectrophotometer network and the Total Ozone Mapping Spectrometer (TOMS) satellite instruments. Figure 1 displays the global distribution of ozone from the TOMS data set on the equinox and solstice dates in 1985. The data reflect a pronounced annual cycle, particularly at high latitudes, with maximum values in spring and minimum values in early fall. Examining the extreme values over the last decade in the Northern Hemisphere (see Figure 2) confirms the regularity of this cycle for the region between 40°N and the pole and the relationship of the cycle to solstice and equinox dates. Recent departures from the decadal envelope are attributed to the effects of stratospheric aerosol produced from SO2 emitted by Mt. Pinatubo in 1991. Finally, the altitude dependence of the ozone column distribution and its seasonal changes can be found in the sonde data for the Northern Hemisphere (see Figure 3). The largest month-to-month decreases in column ozone are found at high latitudes in early spring (February to May), when ozone column amounts are at their largest values.
Poleward meridional transport brings ozone-rich air to high latitudes in the spring [Dobson, 1946; Bojkov, 1988]. From the annual cycle in Figures 2 and 3, the transport is effected over the course of a few months with month-to-month increases as large as 70 Dobson Units (DU). The resulting vertical distribution of ozone shows a maximum concentration in the 15- to 20- km range, where the ozone production rate from the photolysis of oxygen is low (see Figure 4). At these low, in situ production rates, the photochemical replacement time for ozone in the region of the maximum is approximately 20 years, much longer than the characteristic transport time from lower latitudes. The ozone-rich air at high latitudes in summer is in a quiescent region of the atmosphere with respect to large-scale rapid transport, since the wave activity that affects the poleward transport is at a minimum (see Figure 5).
During the months between spring and fall equinox in the northern summer, maximum ozone column amounts typically fall from 550 DU to 380 DU, a 31 % reduction (see Figure 2). Minimum values fall from 310 DU to 220 DU over the same period, a 29 % reduction. Losses are found in all summer months, with the largest month-to-month losses of about 50 DU occurring in the April-to-May period between 70° and 80°N (see Figure 3). Because transport is not effective in this period and because of the long photochemical replacement time of ozone, these changes are attributed to in situ photochemical loss processes [Johnston, 1975; Farman, 1985]. A two-dimensional (2-D) photochemical transport model of the atmosphere confirms that the high-latitude summer region is characterized by net ozone loss (see Figure 6). This region, extending from 40° to the pole and from 15 to 30 km, is unique in the atmosphere. At higher altitudes, ozone is in photochemical equilibrium. At lower latitudes, ozone production and destruction are in balance with transport. Within the 2-D model, the contribution of the various photochemical loss cycles for ozone can be examined over an annual cycle (see Figure 7). Solar illumination in the summer hemisphere leads to maxima in the rates of destruction in all cycles in the summer months. The resulting loss simulation creates fair agreement between the model values of ozone and those from the Solar Backscatter Ultraviolet Spectrometer (SBUV) satellite (see Figure 7a). Following these studies, the role of heterogeneous reactions in the partitioning of NOy was recognized [Hofmann and Solomon, 1989; McElroy et al., 1992; Prather, 1992; Fahey et al., 1993]. Specifically, the hydrolysis of dinitrogen pentoxide (H2O5) on the surface of stratospheric sulfate aerosol particles reduces the relative role of the NOx cycle in ozone loss. Thus, the quantitative features in Figure 7 may change somewhat when this new reaction is included.
Observations made with the ER-2 payload can be used to evaluate quantitatively the principal loss cycles for ozone. During the NASA Stratospheric Photochemistry, Aerosol, and Dynamics Expedition (SPADE) held in 1993, measurements were obtained with this payload for the radical species NO, ClO, OH, and HO2 over a large part of several diurnal cycles. Simultaneous measurements of NOy, water vapor (H2O), ozone, and long-lived organic halogen species were used to predict abundances in the respective photochemical reservoirs. The observed diurnal variation of the radical species was well represented in a full-diurnal photochemical model constrained by the observed and calculated reservoir species. This agreement demonstrated that ozone-loss photochemistry is well represented by the model for the sampled air parcels. The model was then used to evaluate quantitatively the contribution from each cycle over the latitude and altitude range of the measurements. The results for May in Figure 8 reveal the hierarchy of the cycles and the change with latitude of the ozone tendency from net production at 30°N to net ozone loss at 60°N. A similar verification during the subsequent summer months at these and higher latitudes is a principal scientific objective of the POLARIS mission.
The loss of ozone in the high-latitude region in Figure 3 is attributed to the increase in the rate of catalytic loss cycles as solar illumination returns to the Northern Hemisphere (see Figure 9). The sharp onset of that loss near spring equinox is related to the onset of continuous solar illumination. Starting at spring equinox and ending at fall equinox, solar illumination through the day is always continuous at some latitude or latitude region above the Arctic circle (see Figure 9b). The absence of any period of darkness severely restricts the formation of reservoirs that undergo photolysis. Of particular importance are the nitrate radical, NO3, and N2O5, which control the abundance of NOx within the reactive nitrogen reservoir. Due to the rapid photolysis of NO3, N2O5 formation is slowed, thereby increasing the NOx/NOy ratio and the loss rate due to the NOx catalytic cycle. The abundance of N2O5 is estimated to change by orders of magnitude when solar illumination changes from continuous to intermittent (see Figure 10) [Farman et al., 1985]. Despite continued solar illumination, ozone loss rates slow after summer solstice as indicated in Figures 1 and 3. This results from the dependence of ozone loss rates on the vertical distribution of ozone itself.
A principal tool for the evaluation of changes in ozone in the lower stratosphere is the correlation with nitrous oxide, N2O, a long-lived tracer. Observations in other campaigns by the ER-2 aircraft have established that the correlation is linear in regions not influenced by the in situ ozone loss that occurs in polar regions and summer high latitudes [Proffitt et al., 1992; 1993]. The linear relation is confirmed by comparison with 2-D model results (see Figure 11). Furthermore, the model elucidates how the correlation is affected by in situ photochemical loss at high latitudes and the subsequent seasonal replenishment of ozone by transport from lower latitudes. The departure from a linear correlation follows a cycle similar to that of ozone column changes. The ability to monitor this correlation during the summer months at high latitudes will aid in establishing the absolute changes in ozone in a sampled air parcel. A related example is provided by measurements of another long-lived tracer, methane (CH4), and ozone from the Halogen Occultation Experiment (HALOE) instrument on the Upper Atmospheric Research Satellite (UARS). Figure 12 shows large variations in ozone at the same pressure level when CH4 values are essentially unchanged, indicating and quantifying in situ photochemical loss of ozone. The variations also indicate that wave activity is still present in these regions.
In situ The primary platform for POLARIS is the NASA ER-2 high-altitude aircraft . The aircraft has a cruise altitude near 20 km in the lower stratosphere and a radius of action of about 24° latitude. The ER-2 will carry a payload of mostly in situ instruments for the measurement of a wide variety of reactive and trace species (Figures 7 and Table 1 and 2) Flights will occur between summer solstice and fall equinox at mid- to high latitudes (Figure 8) using NASA Ames Research Center, Moffett Field, CA (37°N); Fort Wainwright Army Base, Fairbanks, AK (65°N); and Barbers Point Naval Air Station, Barbers Point, HI (24°N) as deployment locations. The three deployment phases have been selected to allow sampling throughout the period of decreasing ozone (Figure 9).
In concert with the POLARIS deployments, other instruments and payloads will be supported to provide information about reactive and trace species above ER-2 aircraft altitudes (Table 3a,Table 3b,Table 3c). In March/April, NASDA (Japan) and NASA will support the flights of two balloon payloads from Fairbanks associated with the validation of their Advanced Earth Observing Satellite (ADEOS). In addition to in situ instruments, these payloads will include several optical instruments to measure a wide variety of reactive and long-lived species. For example, of particular interest to POLARIS are measurements of NO, OH, HO2, ClO, O3, HNO3, NO2, and ClONO2. In addition, the MkIV instrument will acquire column measurements of many species from the ground in Fairbanks during the April-to-August time period as a direct component of POLARIS. Other POLARIS balloon launches are planned during the July ER-2 deployment for both the MkIV instrument and the Observations from the Middle Stratosphere (OMS) in situ payload, which consists of instruments that measure several long-lived tracers (Table 4). Near-simultaneous flights planned for the balloon and ER-2 instruments will permit a study of the homogeneity of the airmasses being sampled and provide an important intercomparison for many chemical species.
In addition to balloons, instruments aboard satellites and the NASA Space Shuttle will examine the ozone column above ER-2 aircraft altitudes. Tables 3a, 3b, 3c include a description of the respective instruments and measurements. These instruments have the added advantage of sampling large fractions of the stratosphere at high latitudes over long periods of time. Of great importance will be the TOMS measurements of daily ozone column amounts. The combination of intercompared aircraft, balloon, satellite, and Shuttle datasets available during POLARIS will permit an evaluation of ozone loss processes throughout a large fraction of the ozone column during the summer period (see Figure 3).
Meteorological data and models will be used to predict and analyze physical characteristics of air masses encountered along proposed and actual flight paths and to aid the interpretation of variability and structure in trace species observations. Models of atmospheric chemistry and transport will be used extensively to analyze the aircraft, balloon, and satellite data and to make predictions of ozone changes and other atmospheric processes that influence the summer high-latitude stratosphere. Models to be used include full-diurnal photochemical models that are constrained by the aircraft observations, and 2- and 3-D models of atmospheric photochemical and transport processes. The latter use meteorological data to constrain transport in the high-latitude region. Theoretical and meteorological modeling projects support by the POLARIS mission are listed in Table 5.
Deployment Locations:
ACTIVITY LOCATION DATE #_of_FLIGHTS
(1997)
DEPLOYMENT 1:
INTEGRATION MOFFETT FLD. 4/17
PACK/LOAD MOFFETT FLD. 4/23
TRANSIT MOFFETT FLD. to FT. WAINWRIGHT 4/24 1
SCIENCE FLTS. FT. WAINWRIGHT 4/26-5/13 4-8
DOWNLOAD INST. FT. WAINWRIGHT 5/14
TRANSIT/NO-SCI-FLT FT. WAINWRIGHT to MOFFETT FLD. 5/15
DEPLOYMENT 2:
INTEGRATION FT. WAINWRIGHT 6/24-6/25
SCIENCE FLTS. FT. WAINWRIGHT 6/26-7/11 4-6
PACK/LOAD FT. WAINWRIGHT 7/12
TRANSIT/NO-SCI-FLT FT. WAINWRIGHT to MOFFETT FLD. 7/13
DEPLOYMENT 3:
INTEGRATION FT. WAINWRIGHT 9/3-9/4
SCIENCE FLTS. FT. WAINWRIGHT 9/5-9/18 4-6
OPEN HOUSE FT. WAINWRIGHT 9/13
PACK/LOAD FT. WAINWRIGHT 9/19
TRANSIT FT. WAINWRIGHT to BARBERS PT. 9/20 1
SOUTH SURVEY FLT. BARBERS PT. 9/22 1
PACK/LOAD BARBERS PT. 9/23
EARLIEST TRANSIT BARBERS PT. to MOFFETT FLD. 9/24 1
In Deployment 1, flights from Fairbanks would allow sampling in latitude regions that would have continuous photolysis and that would make the transition from interrupted to continuous photolysis during the deployment (see Figure 9). These regions are associated with the largest loss rates of ozone (see Figure 3).
In Deployment 2, solar illumination and areas of continuous photolysis would be maximized at high latitudes. Ozone loss rates are expected to be diminished somewhat from early spring values.
In Deployment 3, flights from Fairbanks would allow sampling in high-latitude regions that make the transition from continuous photolysis to interrupted photolysis. Latitudes greater than 65°N are associated with smaller loss rates than expected at the same location during Deployment 1 in May. Ozone maximum column values also should reach minimum values in September (see Figure 2).
In each deployment phase, the transit flights and perhaps a southerly flight from Fairbanks would allow a contrast of the photochemistry of the mid- and high-latitude regions.
Deployment: Operation of the ER-2 from Moffett Field is standard practice for both the ground crew and many scientists. No special considerations are anticipated. Fort Wainwright in Fairbanks has been routinely used as an ER-2 deployment location. Weather conditions are expected to be generally favorable for routine science flights (see Table 2); however, some interference from freezing temperatures, precipitation, or winds may occur.
To facilitate taking science-quality data on the transit legs noted above and to minimize total deployment days, a transport aircraft will carry instrument teams and instrument support equipment between Moffett Field and Fairbanks.
ER-2 engine upgrade: The replacement of the Pratt and Whitney J75 engines in the NASA ER-2 fleet with the F118-GE-101 engine manufactured by General Electric began in mid-1996. The engine replacement for NASA 709 which will be used throughout POLARIS will be completed in early 1997. The new engine is significantly lighter and more fuel efficient. Greater fuel efficiency will result in lower takeoff weight and higher altitude in cruise operation. Initial and final cruise altitudes are expected to be approximately 3000 and 1500 ft higher, respectively, than with the current engine. Reaching greater altitudes will extend the range of observations in an important manner because of the large vertical gradients in the reactive and reservoir species of interest. The new engine may also enhance the maximum altitude attainable in the last flight plan proposed below.
Basic flight characteristics:
Northbound: Northbound to the pole (a) at constant large solar zenith angle (SZA) and (b) at constant small SZA. These flights would provide the basic sampling in the high-latitude sunlit region.
Southbound: Southbound to 40°N, centered at local noon. These flights would take advantage of the opportunity to extend the latitude coverage and further examine changes in ozone loss rates.
Solar terminator: Flights across the solar terminator either into or out of darkness. The examination of photolytically active species near the terminator is an important test of the modeled photochemistry in stratospheric air parcels.
The terminator velocity is approximately [460 cos q]m s-1, where q is latitude. The velocity matches that of the ER-2 at approximately 65°, the latitude of Fairbanks. Therefore, above 65° when a terminator is present (interrupted photolysis), the ER-2 velocity exceeds that of the terminator. This will allow flexibility to explore the terminator without prolonged operation in darkness, particularly at take-off and landing.The proposed science objective requires specific measurements of reactive and long-lived species. In many cases, more than one technique, science team, or institution is available to provide a needed observation. The ER-2 POLARIS payload is listed in Table 1, Figure 15a and Figure 15b. Each measurement category is essential for an optimum interpretation of ozone destruction rates.
Tracer species are essential to constrain the abundance of unmeasured reservoirs such as total inorganic chlorine and to identify air parcels of similar photochemical history. Based on the long time series of measurements of some tracers such as carbon dioxide (CO2) and nitrous oxide (H2O), transport features within the lower stratosphere and upper troposphere can be monitored. Correlations with ozone will be used to quantify in situ changes in ozone within sampled air parcels. The specific tracer complement has some flexibility, particularly with the airborne gas chromatograph that can be configured for various sets of tracer species.
Non-conserved/reservoir species include ozone, H2O, hydrogen chloride (HCl), ClONO2, NOy, and aerosols. All of these species are essential for defining the photochemical context of ozone destruction processes.
Reactive species represent indices to the various catalytic cycles of ozone destruction and, hence, are all essential to this study.
Meteorological parameters and radiative fields are physical characteristics necessary to establish the meteorological context of the measurements and the basic kinetic rates of the photochemistry.
Mission flight planning and data analysis will require that various meteorological products be available in both forecast and analysis modes. These products will include winds and temperatures at constant pressure levels, potential vorticity on surfaces of constant potential temperature, and latitude-height cross-sections of potential temperature and potential vorticity. Flight planning will also utilize predictions of SZA and recent solar exposure along the flight track.
The interpretation of the ER-2 measurement suite will require the use of photochemical models that simulate the full-diurnal cycle of reactions that influence ozone and related constituents. These models will be constrained with measurements of reservoir species in order that the model results be representative of the sampled air parcels. Trajectory models will also be of value to investigate changes that have occurred in air parcels along the flight track up to 10 days prior to sampling. Three-dimensional models will be useful for interpreting the ER-2 in situ observations in the broader context of the Northern Hemisphere and for interpreting complementary balloon and satellite measurements as proposed below.
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Table 1. POLARIS ER-2 In Situ Payload
| Measurement | Technique | Institution | Investigator |
|---|---|---|---|
| N2O | Laser absorption | NASA/Ames, JPL | M. Loewenstein, C. Webster |
| CH4 | Laser absorption | JPL | C. Webster |
| Chlorofluorocarbons -11,-12,-113, CH3CCl3, SF6, H2, CCl4, N2O, CH4, Halon 1211 | Gas chromatograph | NOAA/CMDL, AL | J. Elkins |
| CO2 | Non-dispersive IR | Harvard | K. Boering, S. Wofsy |
| Whole air sampler | canisters | NCAR | E. Atlas |
| Reactive and Reservoir Species: | |||
| O3 | UV photometer | NOAA/AL,JPL | M. Proffitt, J. Margitan |
| H2O | Lyman-alpha hygrometer | Harvard U. | E. Hintsa |
| H2O | IR absorption | JPL | R. May |
| HCl | TDL | JPL | C. Webster |
| NOy | Catalysis/chemiluminescence | NOAA/AL | R. -S.Gao |
| ClONO2 | Thermal dissociation/ClO | Harvard U./ UC-Berkeley | J.Anderson,
R. Cohen, R. Stimpfle |
| CO | Tunable diode laser absorption | Jet Propulsion Lab | C.Webster |
| Aerosols: | |||
| Condensation nuclei | CN counter (+ impactor) | U. of Denver | J. Wilson |
| Particles (0.08 - 2µm diameter) | Light scattering spectrometer | U. of Denver | J. Wilson |
| Paritcles (0.4 - 10µm diameter) | Light scattering spectrometer | NCAR | B. Gandrud |
| Particles ( > 0.1µm diameter) | Impactor | NASA Ames | A. Strawa |
| Radical Species: | |||
| NO, NO2 | Chemiluminescence & Photolysis | NOAA/AL | R. -S. Gao |
| NO2 | Laser absorption | Harvard U. | K. Perkins |
| ClO, BrO | Titration/resonance fluorescence | Harvard U. | R. Stimpfle |
| OH, HO2 | Titration/resonance fluorescence | Harvard U. | P. Wennberg |
| Meteorological: | |||
| Pressure, temperature, winds | A/C transducers | NASA/Ames | L. Pfister |
| Temperature profile | Radiometer | JPL | B. Gary |
| Radiation: | |||
| Photodissociative flux | UV-Vis Spectrometer | AES (Canada) | T. McElroy |
| Remote instruments: | |||
| O3, HNO3, H2O, ClO | Microwave radiometer | JPL | R. Stachnik |
| Apr | May | Jun | Jul | Aug | Sep | Oct | |
|---|---|---|---|---|---|---|---|
| Normal daily mean temperature (°F) | 30.2 | 48.2 | 59.3 | 61.5 | 56.6 | 44.9 | 25.0 |
| Normal daily max. temperature (°F) | 40.8 | 59.2 | 70.1 | 71.8 | 66.5 | 54.4 | 32.6 |
| Normal daily min. temperature (°F) | 19.5 | 37.2 | 48.5 | 51.2 | 46.5 | 35.4 | 17.5 |
| Temperature, highest of record (°F) | 74 | 89 | 96 | 94 | 90 | 84 | 65 |
| Temperature, lowest of record (°F) | -24 | -1 | 31 | 35 | 27 | 10 | -27 |
| Mean number of days with min. temperature 32°F or less | 27 | 6 | 0 | 0 | 1 | 8 | 28 |
| Normal precipitation (inches) | 0.27 | 0.57 | 1.32 | 1.77 | 1.86 | 1.09 | 0.74 |
| Mean number of days with precipitation 0.01 in or more | 5 | 7 | 11 | 12 | 13 | 10 | 11 |
| Snowfall (including ice pellets) Average total inches | 3.4 | 0.5 | T | T | T | 0.9 | 10.8 |
| Wind, average speed (mph) | 6.6 | 7.7 | 7.2 | 6.6 | 6.2 | 6.2 | 5.4 |
| Wind, maximum speed (mph) | 32 | 32 | 40 | 32 | 34 | 30 | 40 |
| Wind, direction (deg/10) from N | 242 | 3 | 25 | 27 | 27 | 22 | 25 |
| Cloudiness, mean number of days clear | 7 | 4 | 3 | 3 | 3 | 4 | 4 |
| partly cloudy | 7 | 11 | 10 | 9 | 7 | 6 | 5 |
| cloudy | 16 | 16 | 17 | 19 | 21 | 20 | 22 |
| Average relative humidity (%) | |||||||
| morning | 60 | 53 | 61 | 69 | 77 | 78 | 79 |
| afternoon | 46 | 38 | 43 | 50 | 55 | 55 | 67 |
| Instrument | Measurements | Technique | Institution | Principal Investigators |
|---|---|---|---|---|
| MkIV | O3, N2O, HNO3, NO2, CH4, H2O, CO, CFC-11, N2O5, H2O2, HOCl, ClONO2, HCl, HF, CFC-12, NO, HNO4, OCS, HCN, CCl4, CF4, COF2, CHF2Cl, CH3Cl, C2H2, C2H6 | Solar infrared absorption | Jet Propulsion Lab | G. Toon |
| SLS | O3, N2O, HNO3, HO2, ClO, HCL | Submillimeter limb sounder | Jet Propulsion Lab | R. Stachnik |
| FIRS-2 | O3, N2O, HNO3, NO2, H2O, N2O5, OH, HO2, H2O2, HOCl, ClONO2, HCl, HF | Far-infrared spectrometer | Smithsonian Astrophysical Observatory | W. Traub |
| O3 | Ozone | Ultraviolet absorption | Jet Propulsion Lab | J. Margitan |
| CAESR | O3, HNO3, CH4, CFC-11, CFC-12, N2O5, aerosol | Mid-infrared remote thermal emission grating spectrometer | Univ. of Denver | F. Murcray |
| Aerosol | Particle size and number | filter/impactor measurements | Nagoya U./Japan | M. Hayashi |
| Satellite | Instrument | Measurements | Institution | Principal Investigators |
|---|---|---|---|---|
| Upper Atmosphere Research Satellite (UARS) |
Halogen Occultation Experiment(HALOE) |
O3, NO, NO2, H2O, CH4, HCl, HF | NASA Langley | R.B.Pierce |
| Microwave Limb Sounder (MLS) | O3, HNO3, ClO | Jet Propulsion Lab | J.Waters | |
| Advanced Earth Observing Satellite (ADEOS) | Improved Limb Atmospheric Spectrometer (ILAS) |
O3, HNO3, NO2, N2O, H2O, CFC-11, CH4, aerosols | Japan Environment Agency/National Institute for Environmental Studies | Y.Sasano |
| Advanced Earth Observing Satellite (ADEOS) |
Total Ozone Mapping Spectrometer (TOMS) | O3 column | NASA Goddard | A. Krueger |
| Earth Probe |
Total Ozone Mapping Spectrometer (TOMS) | O3 column | NASA Goddard | R. McPeters |
| Earth Radiation Budget Satellite | Stratospheric Aerosol and Gas Experiment II (SAGE II) | NO2, aerosols | Hampton Univ. | P.McCormick |
| Instrument | Measurements | Institution | Principal Investigators |
|---|---|---|---|
| Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) | CO2, NO2, H2O, CH4, N2O, N2O5, O3, CF2Cl2, HNO3, CFCl3, aerosol, CCl4, ClONO2 |
University of Wuppertal, Germany | D. Offermann |
| Instrument | Measurement | Technique | Institution | Principal Investigator |
|---|---|---|---|---|
| LACE | CFC-11, CFC-12, CFC-113, SF6 (sulfur hexafluoride) |
Gas chromatography with electron capture detection | NOAA CMDL | J. Elkins |
| CO2 | CO2 (carbon dioxide) | Non-dispersive infrared absorption | Harvard University | K. Boering S. Wofsy |
| ARGUS | N2O (nitrous oxide) CH4 (methane) | Tunable diode laser absorption | NASA Ames | M. Loewenstein |
| ALIAS II | N2O (nitrous oxide) CH4 (methane) | Tunable diode laser absorption | Jet Propulsion Lab | C. Webster |
| O3 | O3 (ozone) | Ultraviolet absorption | Jet Propulsion Lab | J. Margitan |
| H2O | H2O(water vapor) | Frost point hygrometer | NOAA CMDL | S. Oltmans |
| Project titles | Principal Investigator | Institution | Non-Hydrostatic Modeling of Summer Stratospheric Mixing Processes for POLARIS |
M.Hitchman | Univ. of Wisconsin |
|---|---|---|
| POLARIS Radical and Ozone Continuity Equation SimulationS (PROCESS) |
R. Kawa | NASA Goddard |
| Contribution to Data Analysis Using AER 2-D Assessment Model |
M. K. W. Ko | Atmospheric and Environmental Research, Inc. |
| Radiative and Photochemical Modeling during POLARIS |
S. Lloyd | Johns Hopkins Univ. |
| Meteorological Support for POLARIS | P. Newman | NASA Goddard |
| Meteorological Satellite Data Support for POLARIS | L. Pfister | NASA Ames |
| HALOE Airmass Trajectory and Photochemical Modeling Studies for the POLARIS Campaign | R. Pierce | NASA Langley |
| Photochemistry of Ozone during Polar Summer | R. Salawitch | Jet Propulsion Laboratory |
| Interpretation of Observations of O3, NOy, and Other
Trace Gases during the POLARIS Using a Two-Dimensional Chemical/Dynamical Model |
S. Solomon | NOAA Aeronomy Laboratory |
| Flight Planning and Constituent Modeling for the POLARIS/STRAT Campaign Using the GEOS-1 Data Assimilation System | S. Strahan | NASA Goddard |
| SAGE II and HALOE Data Analysis and Modeling in Support of the POLARIS Campaign | A. Tuck | NOAA Aeronomy Laboratory |
| CRC-SHM Meteorological Support and Chemical Modeling of the POLARIS Measurements |
D. Waugh | Monash University, Australia |
| Analysis of Ozone Changes during POLARIS Using SAGE II Data and Trajectory Calculations |
S. Wofsy | Harvard University |
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