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Recent Submissions

Now showing 1 - 20 of 912
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    Estimating the climate significance of halogen-driven ozone loss in the tropical marine troposphere
    (EGU, 2012-05-04) Saiz-Lopez, A.; Lamarque, J.-F.; Kinnison, D. E.; Tilmes, S.; Ordóñez, C.; Orlando, J. J.; Conley, A. J.; Plane, J. M. C.; Mahajan, A. S.; Sousa Santos, G.; Atlas, E. L.; Blake, D. R.; Sander, S. P.; Schauffler, S.; Thompson, Anne M.; Brasseur, G.
    We have integrated observations of tropospheric ozone, very short-lived (VSL) halocarbons and reactive iodine and bromine species from a wide variety of tropical data sources with the global CAM-Chem chemistry-climate model and offline radiative transfer calculations to compute the contribution of halogen chemistry to ozone loss and associated radiative impact in the tropical marine troposphere. The inclusion of tropospheric halogen chemistry in CAM-Chem leads to an annually averaged depletion of around 10% (~2.5 Dobson units) of the tropical tropospheric ozone column, with largest effects in the middle to upper troposphere. This depletion contributes approximately -0.10 W m⁻² to the radiative flux at the tropical tropopause. This negative flux is of similar magnitude to the ~0.33 W m⁻² contribution of tropospheric ozone to present-day radiative balance as recently estimated from satellite observations. We find that the implementation of oceanic halogen sources and chemistry in climate models is an important component of the natural background ozone budget and we suggest that it needs to be considered when estimating both preindustrial ozone baseline levels and long term changes in tropospheric ozone.
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    A multi-sensor upper tropospheric ozone product (MUTOP) based on TES ozone and GOES water vapor: validation with ozonesondes
    (EGU, 2012-06-29) Moody, J. L.; Felker, S. R.; Wimmers, A. J.; Osterman, G.; Bowman, K.; Thompson, Anne M.; Tarasick, D. W.
    Accurate representation of ozone in the extratropical upper troposphere (UT) remains a challenge. However, the implementation of hyper-spectral remote sensing using satellite instruments such as the Tropospheric Emission Spectrometer (TES) provides an avenue for mapping ozone in this region, from 500 to 300 hPa. As a polar orbiting satellite TES observations are limited, but in this paper they are combined with geostationary satellite observations of water vapor. This paper describes a validation of the Multi-sensor UT Ozone Product (MUTOP). MUTOP, based on a statistical retrieval method, is an image product derived from the multiple regression of remotely sensed TES ozone, against geostationary (GOES) specific humidity (remotely sensed) and potential vorticity (a modeled dynamical tracer in the UT). These TES-derived UT ozone mixing ratios are compared to coincident ozonesonde measurements of layer-average UT ozone mixing ratios made during the NASA INTEX/B field campaign in the spring of 2006; the region for this study is effectively the GOES west domain covering the eastern North Pacific Ocean and the western United States. This intercomparison evaluates MUTOP skill at representing ozone magnitude and variability in this region of complex dynamics. In total, 11 ozonesonde launch sites were available for this study, providing 127 individual sondes for comparison; the overall mean ozone of the 500–300 hPa layer for these sondes was 78.0 ppbv. MUTOP reproduces in~situ measurements reasonably well, producing an UT mean of 82.3 ppbv, with a mean absolute error of 12.2 ppbv and a root mean square error of 16.4 ppbv relative to ozonesondes across all sites. An overall UT mean bias of 4.3 ppbv relative to sondes was determined for MUTOP. Considered in the context of past TES validation studies, these results illustrate that MUTOP is able to maintain accuracy similar to TES while expanding coverage to the entire GOES-West satellite domain. In addition MUTOP provides six-hour temporal resolution throughout the INTEX-B study period, making the visualization of UT ozone dynamics possible. This paper presents the overall statistical validation as well as a selection of ozonesonde case studies. The case studies illustrate that error may not always represent a lack of TES-derived product skill, but often results from discrepancies driven by observations made in the presence of strong meteorological gradients.
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    Simulations of Infrared Radiances over a Deep Convective Cloud System Observed during TC⁴: Potential for Enhancing Nocturnal Ice Cloud Retrievals
    (MDPI, 2012-10-11) Minnis, Patrick; Hong, Gang; Ayers, J. Kirk; Smith, William L.; Yost, Christopher R.; Heymsfield, Andrew J.; Heymsfield, Gerald M.; Hlavka, Dennis L.; King, Michael D.; Korn, Errol; McGill, Matthew J.; Selkirk, Henry B.; Thompson, Anne M.; Tian, Lin; Yang, Ping
    Retrievals of ice cloud properties using infrared measurements at 3.7, 6.7, 7.3, 8.5, 10.8, and 12.0 mm can provide consistent results regardless of solar illumination, but are limited to cloud optical thicknesses τ < ~6. This paper investigates the variations in radiances at these wavelengths over a deep convective cloud system for their potential to extend retrievals of t and ice particle size Dₑ to optically thick clouds. Measurements from an imager, an interferometer, the Cloud Physics Lidar (CPL), and the Cloud Radar System (CRS) aboard the NASA ER-2 aircraft during the NASA TC⁴ (Tropical Composition, Cloud and Climate Coupling) experiment flight during 5 August 2007, are used to examine the retrieval potential of infrared radiances over optically thick ice clouds. Simulations based on coincident in situ measurements and combined cloud τ from CRS and CPL measurements are comparable to the observations. They reveal that brightness temperatures at these bands and their differences (BTD) are sensitive to t up to ~20 and that for ice clouds having τ > 20, the 3.7–10.8 µm and 3.7–6.7 µm BTDs are the most sensitive to Dₑ. Satellite imagery appears to be consistent with these results suggesting that τ and Dₑ could be retrieved for greater optical thicknesses than previously assumed. But, because of sensitivity of the BTDs to uncertainties in the atmospheric profiles of temperature, humidity, and ice water content, and sensor noise, exploiting the small BTD signals in retrieval algorithms will be very challenging.
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    Assimilated ozone from EOS-Aura: Evaluation of the tropopause region and tropospheric columns
    (AGU, 2008-05-29) Stajner, Ivanka; Wargan, Krzysztof; Pawson, Steven; Hayashi, Hiroo; Chang, Lang-Ping; Hudman, Rynda C.; Froidevaux, Lucien; Livesey, Nathaniel; Levelt, Pieternel F.; Thompson, Anne M.; Tarasick, David W.; Stübi, René; Andersen, Signe Bech; Yela, Margarita; König-Langlo, Gert; Schmidlin, F. J.; Witte, Jacquelyn C.
    Retrievals from the Microwave Limb Sounder (MLS) and the Ozone Monitoring Instrument (OMI) on EOS-Aura were included in the Goddard Earth Observing System version 4 (GEOS-4) ozone data assimilation system. The distribution and daily to seasonal evolution of ozone in the stratosphere and troposphere during 2005 are investigated. In the lower stratosphere, where dynamical processes dominate, comparisons with independent ozonesonde and Measurement of Ozone and Water Vapour by Airbus In-Service Aircraft (MOZAIC) data indicate mean agreement within 10%. In the troposphere, OMI and MLS provide constraints on the ozone column, but the ozone profile shape results from the parameterized ozone chemistry and the resolved and parameterized transport. Assimilation of OMI and MLS data improves tropospheric column estimates in the Atlantic region but leads to an overestimation in the tropical Pacific and an underestimation in the northern high and middle latitudes in winter and spring. Transport and data biases are considered in order to understand these discrepancies. Comparisons of assimilated tropospheric ozone columns with ozonesonde data reveal root-mean-square (RMS) differences of 2.9–7.2 Dobson units (DU), which are smaller than the model-sonde RMS differences of 3.2–8.7 DU. Four different definitions of the tropopause using temperature lapse rate, potential vorticity (PV), and isentropic surfaces or ozone isosurfaces are compared with respect to their global impact on the estimated tropospheric ozone column. The largest sensitivity in the tropospheric ozone column is found near the subtropical jet, where the ozone- or PV-determined tropopause typically lies below the lapse rate tropopause.
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    Trans-Pacific transport of reactive nitrogen and ozone to Canada during spring
    (EGU, 2010-09-07) Walker, T. W.; Martin, R. V.; van Donkelaar, A.; Leaitch, W. R.; MacDonald, A. M.; Anlauf, K. G.; Cohen, R. C.; Bertram, T. H.; Huey, L. G.; Avery, M. A.; Weinheimer, A. J.; Flocke, F. M.; Tarasick, D. W.; Thompson, Anne M.; Streets, D. G.; Liu, X.
    We interpret observations from the Intercontinental Chemical Transport Experiment, Phase B (INTEX-B) in spring 2006 using a global chemical transport model (GEOS-Chem) to evaluate sensitivities of the free troposphere above the North Pacific Ocean and North America to Asian anthropogenic emissions. We develop a method to use satellite observations of tropospheric NO2 columns to provide timely estimates of trends in NOx emissions. NOx emissions increased by 33% for China and 29% for East Asia from 2003 to 2006. We examine measurements from three aircraft platforms from the INTEX-B campaign, including a Canadian Cessna taking vertical profiles of ozone near Whistler Peak. The contribution to the mean simulated ozone profiles over Whistler below 5.5 km is at least 7.2 ppbv for Asian anthropogenic emissions and at least 3.5 ppbv for global lightning NOx emissions. Tropospheric ozone columns from OMI exhibit a broad Asian outflow plume across the Pacific, which is reproduced by simulation. Mean modelled sensitivities of Pacific (30° N–60° N) tropospheric ozone columns are at least 4.6 DU for Asian anthropogenic emissions and at least 3.3 DU for lightning, as determined by simulations excluding either source. Enhancements of ozone over Canada from Asian anthropogenic emissions reflect a combination of trans-Pacific transport of ozone produced over Asia, and ozone produced in the eastern Pacific through decomposition of peroxyacetyl nitrates (PANs). A sensitivity study decoupling PANs globally from the model's chemical mechanism establishes that PANs increase ozone production by removing NOx from regions of low ozone production efficiency (OPE) and injecting it into regions with higher OPE, resulting in a global increase in ozone production by 2% in spring 2006. PANs contribute up to 4 ppbv to surface springtime ozone concentrations in western Canada. Ozone production due to PAN transport is greatest in the eastern Pacific; commonly occurring transport patterns advect this ozone northeastward into Canada. Transport events observed by the aircraft confirm that polluted airmasses were advected in this way.
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    Convective distribution of tropospheric ozone and tracers in the Central American ITCZ region: Evidence from observations during TC4
    (AGU, 2010-10-13) Avery, Melody; Twohy, Cynthia; McCabe, David; Joiner, Joanna; Severance, Kurt; Atlas, Eliot; Blake, Donald; Bui, T. P.; Crounse, John; Dibb, Jack; Diskin, Glenn; Lawson, Paul; McGill, Matthew; Rogers, David; Sachse, Glen; Scheuer, Eric; Thompson, Anne M.; Trepte, Charles; Wennberg, Paul; Ziemke, Jerald
    During the Tropical Composition, Clouds and Climate Coupling (TC4) experiment that occurred in July and August of 2007, extensive sampling of active convection in the ITCZ region near Central America was performed from multiple aircraft and satellite sensors. As part of a sampling strategy designed to study cloud processes, the NASA ER-2, WB-57 and DC-8 flew in stacked “racetrack patterns” in convective cells. On July 24, 2007, the ER-2 and DC-8 probed an actively developing storm and the DC-8 was hit by lightning. Case studies of this flight, and of convective outflow on August 5, 2007 reveal a significant anti-correlation between ozone and condensed cloud water content. With little variability in the boundary layer and a vertical gradient, low ozone in the upper troposphere indicates convective transport. Because of the large spatial and temporal variability in surface CO and other pollutants in this region, low ozone is a better convective indicator. Lower tropospheric tracers methyl hydrogen peroxide, total organic bromine and calcium substantiate the ozone results. OMI measurements of mean upper tropospheric ozone near convection show lower ozone in convective outflow. A mass balance estimation of the amount of convective turnover below the tropical tropopause transition layer (TTL) is 50%, with an altitude of maximum convective outflow located between 10 and 11 km, 4 km below the cirrus anvil tops. It appears that convective lofting in this region of the ITCZ is either a two-stage or a rapid mixing process, because undiluted boundary layer air is never sampled in the convective outflow.
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    High-resolution tropospheric ozone fields for INTEX and ARCTAS from IONS ozonesondes
    (AGU, 2010-10-19) Tarasick, D. W.; Jin, J. J.; Fioletov, V. E.; Liu, G.; Thompson, Anne M.; Oltmans, S. J.; Liu, J.; Sioris, C. E.; Liu, X.; Cooper, O. R.; Dann, T.; Thouret, V.
    The IONS-04, IONS-06, and ARC-IONS ozone sounding campaigns over North America in 2004, 2006, and 2008 obtained approximately 1400 profiles, in five series of coordinated and closely spaced (typically daily) launches. Although this coverage is unprecedented, it is still somewhat sparse in its geographical spacing. Here we use forward and back trajectory calculations for each sounding to map ozone measurements to a number of other locations and so to fill in the spatial domain. This is possible because the lifetime of ozone in the troposphere is of the order of weeks. The trajectory-mapped ozone values show reasonable agreement, where they overlap, to the actual soundings, and the patterns produced separately by forward and backward trajectory calculations are similar. Comparisons with MOZAIC profiles and surface station data show generally good agreement. A variable-length smoothing algorithm is used to fill data gaps: for each point on the map, the smoothing radius is such that a minimum of 10 data points are included in the average. The total tropospheric ozone column maps calculated by integrating the smoothed fields agree well with similar maps derived from TOMS and OMI/MLS measurements. The resulting three-dimensional picture of the tropospheric ozone field for the INTEX and ARCTAS periods facilitates visualization and comparison of different years and seasons and will be useful to other researchers.
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    Convective and wave signatures in ozone profiles over the equatorial Americas: Views from TC4 2007 and SHADOZ
    (AGU, 2010-11-06) Thompson, Anne M.; MacFarlane, Alaina M.; Morris, Gary A.; Yorks, John E.; Miller, Sonya K.; Taubman, Brett F.; Verver, Gé; Vömel, Holger; Avery, Melody A.; Hair, Johnathan W.; Diskin, Glenn S.; Browell, Edward V.; Canossa, Jéssica Valverde; Kucsera, Tom L.; Klich, Christopher A.; Hlavka, Dennis L.
    During the TC4 (Tropical Composition, Clouds, and Climate Coupling) campaign in July–August 2007, daily ozonesondes were launched over coastal Las Tablas, Panamá (7.8°N, 80°W) and several times per week at Alajuela, Costa Rica (10°N, 84°W). Wave activity, detected most prominently in 100–300 m thick ozone laminae in the tropical tropopause layer, occurred in 50% (Las Tablas) and 40% (Alajuela) of the soundings. These layers, associated with vertical displacements and classified as gravity waves (GW, possibly Kelvin waves) by laminar identification, occur with similar structure and frequency over the Paramaribo (5.8°N, 55°W) and San Cristóbal (0.92°S, 90°W) Southern Hemisphere Additional Ozonesondes (SHADOZ) sites. GW-labeled laminae in individual soundings correspond to cloud outflow as indicated by DC-8 tracers and other aircraft data, confirming convective initiation of equatorial waves. Layers representing quasi-horizontal displacements, referred to as Rossby waves by the laminar technique, are robust features in soundings from 23 July to 5 August. The features associated with Rossby waves correspond to extratropical influence, possibly stratospheric, and sometimes to pollution transport. Comparison of Las Tablas and Alajuela ozone budgets with 1999–2007 Paramaribo and San Cristóbal soundings shows that TC4 is typical of climatology for the equatorial Americas. Overall during TC4, convection and associated waves appear to dominate ozone transport in the tropical tropopause layer; intrusions from the extratropics occur throughout the free troposphere.
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    Impact of electric and clean-fuel vehicles on future PM2.5 and ozone pollution over Delhi
    (IOP, 2024) Mogno, Caterina; Wallington, Timothy J.; Palmer, Paul; Hakkim, Haseeb; Sinha, Baerbel; Sinha, Vinayak; Steiner, Allison; Sharma, Sumit
    We investigate the impact of adoption of electric vehicles and cleaner fuels on future surface levels of PM2.5 and ozone over Delhi for two contrasting seasons, pre-monsoon and post-monsoon. We run the WRF-Chem atmospheric transport model at high resolution (4 km) with two transport emission scenarios for year 2030: 1) a scenario with electrification of two- and three-wheelers and light commercial vehicles, and 2) a scenario which also includes conversion of diesel vehicles to compressed natural gas (CNG). Compared to the baseline values in 2019, the scenario with both electrification and conversion of diesel vehicles to CNG has a greater reduction in PM2.5 concentrations (up to 5%) than the electrification of two- and three-wheelers and light commercial vehicles alone (within 1%), mainly due to the the greater reduction in primary emissions of PM2.5 and black carbon from diesel conversion to CNG. Vehicles electrification could result in an increase in the daily maximum 8-hours ozone concentrations, which are partially offset by additionally converting to CNG - by -1.9% and +2.4% during pre-monsoon and post-monsoon seasons. This reflects higher NOx emissions from the CNG vehicle scenario compared to electrification-alone scenario, which limits the increase of surface ozone in the VOC-limited chemical environment over Delhi.Our findings highlight the importance of a coordinated strategy for PM2.5 and ozone when considering traffic emission controls, and highlight that the transition to electric vehicles should be accompanied by the conversion of diesel vehicles to CNG to limit surface ozone increase and achieve greater reduction in PM2.5 concentrations over Delhi. However, the small changes in PM2.5 and in ozone compared to the baseline scenario highlight the importance of joint emissions reduction from other sectors to achieve substantial progress in PM2.5 and ozone air quality in Delhi.
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    Technical Note: Ozonesonde climatology between 1995 and 2011: description, evaluation and applications
    (EGU, 2012-08-17) Tilmes, S.; Lamarque, J.-F.; Emmons, L. K.; Conley, A.; Schultz, M. G.; Saunois, M.; Thouret, V.; Thompson, Anne M.; Oltmans, S. J.; Johnson, B.; Tarasick, D.
    An ozone climatology based on ozonesonde measurements taken over the last 17 yr has been constructed for model evaluation and comparisons to other observations. Vertical ozone profiles for 42 stations around the globe have been compiled for the period 1995–2011, in pressure and tropopause-referenced altitudes. For each profile, the mean, standard deviation, median, the half-width are provided, as well as information about interannual variability. Regional aggregates are formed in combining stations with similar ozone characteristics. The Hellinger distance is introduced as a new diagnostic to identify stations that describe similar shapes of ozone probability distribution functions (PDFs). In this way, 12 regions were selected covering at least 2 stations and the variability among those stations is discussed. Significant variability with longitude of ozone distributions in the troposphere and lower stratosphere in the northern mid- and high latitudes is found. The representativeness of regional aggregates is discussed for high northern latitudes, Western Europe, Eastern US, and Japan, using independent observations from surface stations and MOZAIC aircraft data. Good agreement exists between ozonesondes and aircraft observations in the mid-troposphere and between ozonesondes and surface observations for Western Europe. For Eastern US and high northern latitudes, surface ozone values from ozonesondes are biased 10 ppb high compared to independent measurements. An application of the climatology is presented using the NCAR CAM-Chem model. The climatology allows evaluation of the model performance regarding ozone averages, seasonality, interannual variability, and the shape of ozone distributions. The new assessment of the key features of ozone distributions gives deeper insights into the performance of models.
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    Look Angle Correction for SMAP L-Band Radiometer Using Geolocation Measurements
    (IEEE, 2024-05-29) Le Vine, David M.; Dinnat, Emmanuel P.; De Matthaeis, Paolo; Peng, Jinzheng
    Geolocation of the radiometer footprint in scanning instruments such as SMAP has been successfully demonstrated using the change in antenna temperature as the radiometer scans across land/water boundaries (coastlines). This measurement provides the distance of the footprint from the nominal coastline, but it does not provide information about the error in look angle and azimuth of the antenna boresight vector needed to correct for the geolocation error. A method for doing this is reported using fore and aft crossings of the boundary. The approach is demonstrated using the SMAP radiometer simulator and then applied to SMAP data over the west coast of Madagascar. The error estimates of 0.3 degrees for look angle and 0.15 degrees for azimuth are consistent with independent estimates.
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    Characteristics of tropospheric ozone depletion events in the Arctic spring: analysis of the ARCTAS, ARCPAC, and ARCIONS measurements and satellite BrO observations
    (EGU, 2012-10-29) Koo, J.-H.; Wang, Y.; Kurosu, T. P.; Chance, K.; Rozanov, A.; Richter, A.; Oltmans, S. J.; Thompson, Anne M.; Hair, J. W.; Fenn, M. A.; Weinheimer, A. J.; Ryerson, T. B.; Solberg, S.; Huey, L. G.; Liao, J.; Dibb, J. E.; Neuman, J. A.; Nowak, J. B.; Pierce, R. B.; Natarajan, M.; Al-Saadi, J.
    Arctic ozone depletion events (ODEs) are caused by halogen catalyzed ozone loss. In situ chemistry, advection of ozone-poor air mass, and vertical mixing in the lower troposphere are important factors affecting ODEs. To better characterize the ODEs, we analyze the combined set of surface, ozonesonde, and aircraft in situ measurements of ozone and bromine compounds during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS), the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC), and the Arctic Intensive Ozonesonde Network Study (ARCIONS) experiments (April 2008). Tropospheric BrO columns retrieved from satellite measurements and back trajectory calculations are also used to investigate the characteristics of observed ODEs. In situ observations from these field experiments are inadequate to validate tropospheric BrO columns derived from satellite measurements. In view of this difficulty, we construct an ensemble of tropospheric column BrO estimates from two satellite (OMI and GOME-2) measurements and with three independent methods of calculating stratospheric BrO columns. Furthermore, we select analysis methods that do not depend on the absolute magnitude of column BrO, such as time-lagged correlation analysis of ozone and tropospheric column BrO, to understand characteristics of ODEs. Time-lagged correlation analysis between in situ (surface and ozonesonde) measurements of ozone and satellite derived tropospheric BrO columns indicates that the ODEs are due to either local halogen-driven ozone loss or short-range (∼1 day) transport from nearby regions with ozone depletion. The effect of in situ ozone loss is also evident in the diurnal variation difference between low (10th and 25th percentiles) and higher percentiles of surface ozone concentrations at Alert, Canada. Aircraft observations indicate low-ozone air mass transported from adjacent high-BrO regions. Correlation analyses of ozone with potential temperature and time-lagged tropospheric BrO column show that the vertical extent of local ozone loss is surprisingly deep (1–2 km) at Resolute and Churchill, Canada. The unstable boundary layer during ODEs at Churchill could potentially provide a source of free-tropospheric BrO through convective transport and explain the significant negative correlation between free-tropospheric ozone and tropospheric BrO column at this site.
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    The Water Vapor Variability - Satellite/Sondes (WAVES) Field Campaigns
    (2008-07-07) Whiteman, D. N.; Adam, M.; Barnet, C.; Bojkov, B.; Delgado, Ruben; Demoz, B.; Fitzgibbon, J.; Forno, R.; Herman, R.; Hoff, Raymond; Joseph, E.; Landulfo, E.; McCann, K.; McGee, T.; Miloshevich, L.; Restrepo, I.; Schmidlin, F. J.; Taubman, B.; Thompson, Anne M.; Twigg, L.; Venable, D.; Vomel, H.; Walthall, C.
    Three NASA-funded field campaigns have been hosted at the Howard University Research Campus in Beltsville, MD. In each of the years 2006, 2007 and 2008, WAVES field campaigns have coordinated ozonesonde launches, lidar operations and other measurements with A-train satellite overpasses for the purposes of satellite validation. The unique mix of measurement systems, physical location and the interagency, international group of researchers and students has permitted other objectives, such as mesoscale meteorological studies, to be addressed as well. We review the goals and accomplishments of the three WAVES missions with the emphasis on the nonsatellite validation component of WAVES, as the satellite validation activities have been reported elsewhere.
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    Abrupt reduction in shipping emission as an inadvertent geoengineering termination shock produces substantial radiative warming
    (Springer Nature, 2024-05-30) Yuan, Tianle; Song, Hua; Oreopoulos, Lazaros; Wood, Robert; Bian, Huisheng; Breen, Katherine; Chin, Mian; Yu, Hongbin; Barahona, Donifan; Meyer, Kerry; Platnick, Steven
    Human activities affect the Earth’s climate through modifying the composition of the atmosphere, which then creates radiative forcing that drives climate change. The warming effect of anthropogenic greenhouse gases has been partially balanced by the cooling effect of anthropogenic aerosols. In 2020, fuel regulations abruptly reduced the emission of sulfur dioxide from international shipping by about 80% and created an inadvertent geoengineering termination shock with global impact. Here we estimate the regulation leads to a radiative forcing of $$+0.2\pm 0.11$$Wm?2 averaged over the global ocean. The amount of radiative forcing could lead to a doubling (or more) of the warming rate in the 2020?s compared with the rate since 1980 with strong spatiotemporal heterogeneity. The warming effect is consistent with the recent observed strong warming in 2023 and expected to make the 2020?s anomalously warm. The forcing is equivalent in magnitude to 80% of the measured increase in planetary heat uptake since 2020. The radiative forcing also has strong hemispheric contrast, which has important implications for precipitation pattern changes. Our result suggests marine cloud brightening may be a viable geoengineering method in temporarily cooling the climate that has its unique challenges due to inherent spatiotemporal heterogeneity.
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    Bay Breeze Impact on Surface Ozone at Edgewood, Maryland During July 201
    (2012-09-19) Stauffer, Ryan M.; Thompson, Anne M.; Martins, Douglas K.; Clark, Richard D.; Goldberg, Daniel L.; Loughner, Christopher P.; Delgado, Ruben; Dickerson, Russell R.; Stehr, Jeffrey W.; Tzortziou, Maria A.
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    Environment Canada cuts threaten the future of science and international agreements
    (AGU, 2012-02-14) Thompson, Anne M.; Salawitch, Ross J.; Hoff, Raymond; Logan, Jennifer A.; Einaudi, Franco
    In August 2011, 300 Environment Canada scientists and staff working on environmental monitoring and protection learned that their jobs would be terminated, and an additional 400-plus Environment Canada employees received notice that their positions were targeted for elimination. These notices received widespread coverage in the Canadian media and international attention in Nature News. Environment Canada is a government agency responsible for meteorological services as well as environmental research. We are concerned that research and observations related to ozone depletion, tropospheric pollution, and atmospheric transport of toxic chemicals in the northern latitudes may be seriously imperiled by the budget cuts that led to these job terminations. Further, we raise the questions being asked by the international community, scientists, and policy makers alike: First, will Canada be able to meet its obligations to the monitoring and assessment studies that support the various international agreements inTable 1? Second, will Canada continue to be a leader in Arctic research.
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    Transpacific transport of ozone pollution and the effect of recent Asian emission increases on air quality in North America: an integrated analysis using satellite, aircraft, ozonesonde, and surface observations
    (EGU, 2008-10-22) Zhang, L.; Jacob, D. J.; Boersma, K. F.; Jaffe, D. A.; Olson, J. R.; Bowman, K. W.; Worden, J. R.; Thompson, Anne M.; Avery, M. A.; Cohen, R. C.; Dibb, J. E.; Flock, F. M.; Fuelberg, H. E.; Huey, L. G.; McMillan, W. W.; Singh, H. B.; Weinheimer, A. J.
    We use an ensemble of aircraft, satellite, sonde, and surface observations for April–May 2006 (NASA/INTEX-B aircraft campaign) to better understand the mechanisms for transpacific ozone pollution and its implications for North American air quality. The observations are interpreted with a global 3-D chemical transport model (GEOS-Chem). OMI NO2 satellite observations constrain Asian anthropogenic NOx emissions and indicate a factor of 2 increase from 2000 to 2006 in China. Satellite observations of CO from AIRS and TES indicate two major events of Asian transpacific pollution during INTEX-B. Correlation between TES CO and ozone observations shows evidence for transpacific ozone pollution. The semi-permanent Pacific High and Aleutian Low cause splitting of transpacific pollution plumes over the Northeast Pacific. The northern branch circulates around the Aleutian Low and has little impact on North America. The southern branch circulates around the Pacific High and some of that air impacts western North America. Both aircraft measurements and model results show sustained ozone production driven by peroxyacetylnitrate (PAN) decomposition in the southern branch, roughly doubling the transpacific influence from ozone produced in the Asian boundary layer. Model simulation of ozone observations at Mt. Bachelor Observatory in Oregon (2.7 km altitude) indicates a mean Asian ozone pollution contribution of 9±3 ppbv to the mean observed concentration of 54 ppbv, reflecting mostly an enhancement in background ozone rather than episodic Asian plumes. Asian pollution enhanced surface ozone concentrations by 5–7 ppbv over western North America in spring 2006. The 2000–2006 rise in Asian anthropogenic emissions increased this influence by 1–2 ppbv.
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    Bay Breeze Impact on Surface Ozone at Edgewood, Maryland
    (2022-09) Stauffer, R. M.; Thompson, Anne M.; Martins, D. K.; Clark, R.; Herman, Jay; Berkoff, T.; Baker, Barry; Delgado, Ruben
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    Report on the 4th SPARC General Assembly
    Baldwin, M.; Bodeker, G.; Burrows, J. P.; Eyring, V.; Eyring, Veronika; Hayashida, S.; Haynes, P. H.; Peter, T.; Thompson, Anne M.
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    Integrated analysis of the impact of long-range transport of midlatitude pollution on ozone abundances in the Arctic troposphere
    Walker, T.; Parrington, M.; Jones, D. B. A.; Henze, D. K.; Worden, J. R.; Bowman, K. W.; Bottenheim, J.; Anlauf, K.; Davies, J.; Tarasick, D. W.; Thompson, Anne M.