scholarly journals Seasonal prediction of US summertime ozone using statistical analysis of large scale climate patterns

2017 ◽  
Vol 114 (10) ◽  
pp. 2491-2496 ◽  
Author(s):  
Lu Shen ◽  
Loretta J. Mickley
Keyword(s):  
United States ◽  
Large Scale ◽  
Surface Ozone ◽  
Tropical Atlantic ◽  
Eastern United States ◽  
Northeast Pacific ◽  
Ozone Concentrations ◽  
Climate Patterns ◽  
Ocean Atmosphere ◽  
Ozone Episodes

We develop a statistical model to predict June–July–August (JJA) daily maximum 8-h average (MDA8) ozone concentrations in the eastern United States based on large-scale climate patterns during the previous spring. We find that anomalously high JJA ozone in the East is correlated with these springtime patterns: warm tropical Atlantic and cold northeast Pacific sea surface temperatures (SSTs), as well as positive sea level pressure (SLP) anomalies over Hawaii and negative SLP anomalies over the Atlantic and North America. We then develop a linear regression model to predict JJA MDA8 ozone from 1980 to 2013, using the identified SST and SLP patterns from the previous spring. The model explains ∼45% of the variability in JJA MDA8 ozone concentrations and ∼30% variability in the number of JJA ozone episodes (>70 ppbv) when averaged over the eastern United States. This seasonal predictability results from large-scale ocean–atmosphere interactions. Warm tropical Atlantic SSTs can trigger diabatic heating in the atmosphere and influence the extratropical climate through stationary wave propagation, leading to greater subsidence, less precipitation, and higher temperatures in the East, which increases surface ozone concentrations there. Cooler SSTs in the northeast Pacific are also associated with more summertime heatwaves and high ozone in the East. On average, models participating in the Atmospheric Model Intercomparison Project fail to capture the influence of this ocean–atmosphere interaction on temperatures in the eastern United States, implying that such models would have difficulty simulating the interannual variability of surface ozone in this region.

Identification of large scale climate patterns affecting snow variability in the eastern United States

2008 ◽  
Vol 28 (3) ◽  
pp. 315-328 ◽  
Author(s):  
Jennifer Morin ◽  
Paul Block ◽  
Balaji Rajagopalan ◽  
Martyn Clark
Keyword(s):  
United States ◽  
Large Scale ◽  
Eastern United States ◽  
Climate Patterns

scholarly journals The Response of surface ozone to climate change over the Eastern United States

2007 ◽  
Vol 7 (4) ◽  
pp. 9867-9897 ◽  
Author(s):  
P. N. Racherla ◽  
P. J. Adams
Keyword(s):  
Climate Change ◽  
United States ◽  
Surface Ozone ◽  
Future Climate ◽  
Future Climate Change ◽  
Eastern United States ◽  
Chemical Production ◽  
Annual Average ◽  
Mixing Ratios ◽  
Ozone Episodes

Abstract. We examined the response of surface ozone to future climate change over the eastern United States by performing simulations corresponding to present (1990s) and future (2050s) climates using an integrated model of global climate, tropospheric gas-phase chemistry, and aerosols. A future climate has been imposed using ocean boundary conditions corresponding to the IPCC SRES A2 scenario for the 2050 s decade, resulting in an increase in the global annual-average surface air temperature by 1.7°C, with a 1.4°C increase over the surface layer of the eastern United States. Present-day anthropogenic emissions and CO2/CH4 mixing ratios have been used in both simulations while climate-sensitive natural emissions were allowed to vary with the simulated climate. There is practically zero change in the spatiotemporally averaged ozone mixing ratios predicted over the eastern United States. However, the severity and frequency of ozone episodes over the eastern United States increased due to future climate change, primarily as a result of increased ozone chemical production due to increased natural isoprene emissions. The 95th percentile ozone mixing ratio increased by 5 ppbv and the largest frequency increase occured in the 80–90 ppbv range. The most substantial and statistically significant (p-value <0.05) increases in episode frequency occurred over the southeast and midatlantic United States, largely as a result of 20% higher annual-average natural isoprene emissions. Increased chemical production and shorter average lifetime are consistent features of the predicted seasonal surface ozone response, with the former's magnitude for a location largely a function of increased natural isoprene emissions, and the latter largely due to faster dry deposition removal rates. Future climate change is also predicted to lengthen the ozone season over the eastern United States to include late spring and early fall. Significant interannual variability is observed in the frequency of ozone episodes and we find that it is necessary to utilize 5 years or more of simulation data in order to separate the effects of interannual variability and climate change on ozone episodes.

scholarly journals Herbarium specimens reveal substantial and unexpected variation in phenological sensitivity across the eastern United States

2018 ◽  
Vol 374 (1763) ◽  
pp. 20170394 ◽  
Author(s):  
Daniel S. Park ◽  
Ian Breckheimer ◽  
Alex C. Williams ◽  
Edith Law ◽  
Aaron M. Ellison ◽  
...  
Keyword(s):  
United States ◽  
Climatic Change ◽  
Large Scale ◽  
Critical Role ◽  
Flowering Plant ◽  
Reproductive Phenology ◽  
Herbarium Specimens ◽  
Eastern United States ◽  
Regional Patterns ◽  
Continental Scale

Phenology is a key biological trait that can determine an organism's survival and provides one of the clearest indicators of the effects of recent climatic change. Long time-series observations of plant phenology collected at continental scales could clarify latitudinal and regional patterns of plant responses and illuminate drivers of that variation, but few such datasets exist. Here, we use the web tool CrowdCurio to crowdsource phenological data from over 7000 herbarium specimens representing 30 diverse flowering plant species distributed across the eastern United States. Our results, spanning 120 years and generated from over 2000 crowdsourcers, illustrate numerous aspects of continental-scale plant reproductive phenology. First, they support prior studies that found plant reproductive phenology significantly advances in response to warming, especially for early-flowering species. Second, they reveal that fruiting in populations from warmer, lower latitudes is significantly more phenologically sensitive to temperature than that for populations from colder, higher-latitude regions. Last, we found that variation in phenological sensitivities to climate within species between regions was of similar magnitude to variation between species. Overall, our results suggest that phenological responses to anthropogenic climate change will be heterogeneous within communities and across regions, with large amounts of regional variability driven by local adaptation, phenotypic plasticity and differences in species assemblages. As millions of imaged herbarium specimens become available online, they will play an increasingly critical role in revealing large-scale patterns within assemblages and across continents that ultimately can improve forecasts of the impacts of climatic change on the structure and function of ecosystems. This article is part of the theme issue ‘Biological collections for understanding biodiversity in the Anthropocene’.

The importance of stratospheric–tropospheric transport in affecting surface ozone concentrations in the western and northern tier of the United States

2011 ◽  
Vol 45 (28) ◽  
pp. 4845-4857 ◽  
Author(s):  
Allen S. Lefohn ◽  
Heini Wernli ◽  
Douglas Shadwick ◽  
Sebastian Limbach ◽  
Samuel J. Oltmans ◽  
...  
Keyword(s):  
United States ◽  
Surface Ozone ◽  
The United States ◽  
Ozone Concentrations

scholarly journals Impact of lightning-NO on Eastern United States photochemistry during the summer of 2006 as determined using the CMAQ model

2011 ◽  
Vol 11 (6) ◽  
pp. 17699-17757 ◽  
Author(s):  
D. J. Allen ◽  
K. E. Pickering ◽  
R. W. Pinder ◽  
B. H. Henderson ◽  
K. W. Appel ◽  
...  
Keyword(s):  
United States ◽  
Air Quality ◽  
Wet Deposition ◽  
Surface Ozone ◽  
Convective Precipitation ◽  
Eastern United States ◽  
Ozone Monitoring Instrument ◽  
Monitoring Instrument ◽  
Ozone Monitoring ◽  
The Impact

Abstract. A lightning-nitrogen oxide (NO) algorithm is developed for the regional Community Multiscale Air Quality Model (CMAQ) and used to evaluate the impact of lightning-NO emissions (LNOx) on tropospheric photochemistry over the Eastern United States during the summer of 2006. The scheme assumes flash rates are proportional to the model convective precipitation rate but then adjusts the flash rates locally to match monthly average observations. Over the Eastern United States, LNOx is responsible for 20–25 % of the tropospheric nitrogen dioxide (NO2) column. This additional NO2 reduces the low-bias of simulated NO2 columns with respect to satellite-retrieved Dutch Ozone Monitoring Instrument NO2 (DOMINO) columns from 41 to 14 %. It also adds 10–20 ppbv to upper tropospheric ozone and 1.5–4.5 ppbv to 8-h maximum surface layer ozone, although, on average, the contribution of LNOx to surface ozone is 1–2 ppbv less on poor air quality days. Biases between modeled and satellite-retrieved tropospheric NO2 columns vary greatly between urban and rural locations. In general, CMAQ overestimates columns at urban locations and underestimates columns at rural locations. These biases are consistent with in situ measurements that also indicate that CMAQ has too much NO2 in urban regions and not enough in rural regions. However, closer analysis suggests that most of the differences between modeled and satellite-retrieved urban to rural ratios are likely a consequence of the horizontal and vertical smoothing inherent in columns retrieved by the Ozone Monitoring Instrument (OMI). Within CMAQ, LNOx increases wet deposition of nitrate by 50 % and total deposition of nitrogen by 11 %. This additional deposition reduces the magnitude of the CMAQ low-bias in nitrate wet deposition with respect to National Atmospheric Deposition monitors to near zero. In order to obtain an upper bound on the contribution of uncertainties in chemistry to upper tropospheric NOx low biases, sensitivity calculations with updated chemistry were run for the time period of the Intercontinental Chemical Transport Experiment (INTEX-A) field campaign (summer 2004). After adjusting for possible interferences in NO2 measurements and averaging over the entire campaign, these updates reduced 7–9 km biases from 32 to 17 % and 9–12 km biases from 57 to 46 %. While these changes lead to better agreement, a considerable NO2 low-bias remains in the uppermost troposphere.

scholarly journals A UT/LS ozone climatology of the nineteen seventies deduced from the GASP aircraft measurement program

2007 ◽  
Vol 7 (2) ◽  
pp. 3451-3517 ◽  
Author(s):  
C. Schnadt Poberaj ◽  
J. Staehelin ◽  
D. Brunner ◽  
V. Thouret ◽  
V. Mohnen
Keyword(s):  
United States ◽  
Large Scale ◽  
The United States ◽  
Eastern United States ◽  
Nineteen Seventies ◽  
Large Variability ◽  
Tropical Regions ◽  
Mixing Ratios ◽  
Research Aircraft ◽  
Atmospheric Sampling

Abstract. The knowledge of historical ozone in the upper troposphere/lower stratosphere (UT/LS) region is mostly confined to regular measurements from a number of ozonesonde stations. We present ozone measurements of the Global Atmospheric Sampling Program (GASP) performed from four commercial and one research aircraft during 1975 to 1979. Using GASP data, a UT/LS ozone climatology of 1975–1979 was built. Seasonality and concentrations of GASP UT ozone in the middle, subtropical and tropical regions of the northern hemisphere (NH) are generally in agreement with other published observations, derived from ozonesondes or aircraft campaigns. In regions where both GASP (1970s) and MOZAIC (1990s) data are available, similar ozone concentrations are found and seasonal cycles agree well confirming the reliability of GASP ozone. GASP provides unique large-scale climatological information on UT/LS ozone above the NH Pacific region. Agreement is found with observations from individual ozonesonde sites and aircraft campaigns carried out over this region. Tropical UT ozone is seen to be lower near the dateline than further east, presumably related to uplift of ozone poor air within convection. Over the west coast of the United States, summer UT ozone is higher than over the adjacent Pacific, probably caused by air pollution over southern California in the 1970s. GASP offers an unprecedented opportunity to link to European, Canadian and U.S. American ozonesonde observations of the 1970s. For the quantitative comparison, an altitude offset was applied to the sonde data to account for the slow response time of the sensors. In the LS, the European and Canadian Brewer-Mast (BM) sensors then agree to ±10% with the GASP instruments in all seasons. In the UT, the European BM sondes record similar to slightly less average ozone than GASP, however, with large variability overlaid. Over the eastern United States, systematic positive deviations of the Wallops Island ECC sondes from GASP of +20% are found. The comparisons over Europe and the eastern United States corroborate earlier findings that the early ECC sensors may have measured 10 to 25% more ozone than the BM sensors. Our results further indicate that applying the correction factor to the 1970s BM ozonesondes is necessary to yield reliable ozone mixing ratios in the UT/LS.

Fluvial activity in major river basins of the eastern United States during the Holocene

The Holocene ◽  
2020 ◽  
Vol 30 (9) ◽  
pp. 1279-1295
Author(s):  
Ray Lombardi ◽  
Lisa Davis ◽  
Gary E Stinchcomb ◽  
Samuel E Munoz ◽  
Lance Stewart ◽  
...  
Keyword(s):  
United States ◽  
Large Scale ◽  
Gulf Coast ◽  
Human Impacts ◽  
Climatic Conditions ◽  
Ice Age ◽  
Cyclic Behavior ◽  
Eastern United States ◽  
Site Specific ◽  
The Holocene

In the eastern United States, existing paleo-reconstructions in fluvial environments consist primarily of site-specific investigations of climate and human impacts on riverine processes. This paper presents the first meta-analysis of fluvial reconstructions focused on regional watersheds of the eastern United States, including the Lower Mississippi, Tennessee, South Atlantic–Gulf Coast, Ohio, Mid-Atlantic, and New England regional watersheds. Chronologies of fluvial activity (i.e. alluvial deposition) and stability (i.e. landscape stability) were developed by synthesizing data from existing, published, and site-specific fluvial reconstruction studies conducted across the eastern United States. Overall, regional watersheds show variable patterns of synchronicity across watersheds and did not demonstrate cyclic behavior through the Holocene. During the last millennium, only the Lower Mississippi and Ohio regional watersheds exhibit high rates of fluvial activity active during the ‘Medieval Climate Anomaly’ (650–1050 yr BP), while nearly all other regional watersheds in the eastern United States were active during the ‘Little Ice Age’ (100–500 yr BP). These findings imply that fluvial activity may be more spatially restricted during warmer/drier climatic conditions than during cooler/wetter periods. We find an increase in fluvial activity during the era of Euro-American colonization (400 yr BP to present) in the southeastern United States but not the northeastern United States, implying a heterogeneous response of fluvial systems to human activities in the eastern United States related to climatic, cultural, and/or physiographic variability. These new insights gained from fluvial chronologies in the eastern United States demonstrate the utility of regionally synthesized paleo-records to understand large-scale climate variation effect on rivers.

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