P. Kasibhatla's research while affiliated with Duke University and other places

Publications (39)

Article
Full-text available
Attribution of the causes of atmospheric trace gas and aerosol variability often requires the use of high resolution time series of anthropogenic and natural emissions inventories. Here we developed an approach for representing synoptic- and diurnal-scale temporal variability in fire emissions for the Global Fire Emissions Database version 3 (GFED3...
Article
Improved estimates of contemporary fire emissions are needed to better understand the effects of a changing fire regime on climate and air quality. At a global scale, uncertainties in fire emissions arise from several sources, including estimates of burned area, aboveground biomass, combustion completeness, and emission factors. The development of...
Article
We discuss major enhancements to the burned area component of the Global Fire Emissions Database (GFED3) over previous versions (GFED1 and GFED2), which now provides global, monthly burned area estimates at 0.5-degree spatial resolution for the time period 1997-2008. Estimates are produced by calibrating Terra MODIS active fire data with 500-m MODI...
Article
There has been considerable progress in recent years in characterizing trace gas emissions from vegetation fires on a global scale. This progress has been driven by the availability of remotely-sensed vegetation and fire products, combined with the development of global-scale, process-based terrestrial biogeochemistry models that explicitly include...
Presentation
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This study analyzes summertime ozone concentrations that have been simulated by various regional-scale photochemical modelling systems over the Eastern U.S. as part of more than ten independent studies. Results indicate that there has been a reduction of root mean square errors (RMSE) and an improvement in the ability to capture ozone fluctuations...
Article
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1] One of the largest uncertainties for the modeling of tropospheric carbon monoxide (CO) concentration is the timing, location, and magnitude of biomass burning emissions. We investigate the sensitivity of simulated CO in the Unified Chemistry Transport Model (UCTM) to several biomass burning emissions, including four bottom-up and two top-down in...
Article
Biomass burning is a significant global source of a variety of chemically and radiatively important trace gases. In this study, three-dimensional atmospheric chemical transport model (CTM) are used to simulate the distribution of CO from biomass burning emissions using GFED2 biomass burning emission inventory for the 2002-2006 period. Comparison wi...
Article
We assess how humans have changed the magnitude (and possibly the sign) of interannual variability of atmospheric carbon dioxide. Remote sensing and trace gas observations from the last decade show that humans take advantage of El Nino-induced drought to clear tropical forests for agriculture at a faster rate. During El Nino events of 1997/1998, 20...
Article
We report estimates of fire emissions from South America during 2000-2005. In our analysis, we used MODIS satellite observations to estimate burned area and burning of woody fuels, the CASA biogeochemical model to estimate fuel loads and emissions, and MOPITT satellite observations as a top-down constraint in an atmospheric CO inversion using the G...
Article
Carbon monoxide (CO) is important component of the tropospheric chemical system owing to its influence on OH concentrations. In addition, atmospheric CO concentrations provide information into the broader question of human impacts on atmospheric chemical composition since anthropogenic CO emissions are often closely coupled to the emissions of othe...
Article
We present an inverse analysis of global CO emissions by using network observations from NOAA's Global Monitoring Division (GMD) and a global three-demensional atmospheric chemical transport model (GEOS- CHEM) simulation from 1997-2005. A priori estimates of CO emissions are taken from various inventories, including the GFED2 biomass burning emissi...
Article
Biomass burning is a significant global source of a variety of chemical and radiatively important trace gases. In terms of understanding the effect of biomass burning emissions on atmospheric chemical composition, it is important to characterize the spatial and temporal variability of these emissions. In this study, three-dimensional atmospheric ch...
Article
Measurements of surface atmospheric CO2 concentrations show that atmospheric CO2 growth rates vary significantly from year to year. Understanding the driving mechanisms of these interannual growth rate variations is important in terms of predicting future levels of atmospheric CO2. In this study, we investigate the relative contributions of interan...
Article
Full-text available
Measurements of atmospheric trace gases provide evidence that fire emissions increased during the 1997/1998 El Niño event and these emissions contributed substantially to global CO2, CO, CH4, and δ13CO2 anomalies. Interpretation and effective use of these atmospheric observations to assess changes in the global carbon cycle requires an understandin...
Article
We investigate regional and global CO and fine mode aerosol correlations by combining GOCART model simulations with various measurements from surface (CMDL /CO and AERONET / aerosol), satellite (MOPl3T / CO and MODIS / aerosol), and aircraft. CO mixing ratios and aerosol concentrations are examined using surface and aircraft measurements on several...
Chapter
This study demonstrated that several state-of-science photochemical modeling systems display significant model-to-model differences when applied to only episodic days, making their use in traditional ozone attainment demonstrations highly uncertain. It was shown that atmospheric processes operating on time scales ranging from several days to severa...
Article
The comparison of large-scale sulphate aerosol models study (COSAM) compared the performance of atmospheric models with each other and observations. It involved: (i) design of a standard model experiment for the world wide web, (ii) 10 model simulations of the cycles of sulphur and 222Rn/210Pb conforming to the experimental design, (iii) assemblage...
Article
Accurate representation of aerosols in chemical transport models (CTMs) requires treatment not just of the mass of particulate matter but also the aerosol size distribution, which influences chemical and physical evolution, wet and dry deposition, and important properties such as light scattering. Most CTMs to date represent only aerosol mass, with...
Article
Full-text available
Atmospheric distributions of carbonaceous aerosols are simulated using the Geophysical Fluid Dynamics Laboratory SKYHI general circulation model (GCM) (latitude-longitude resolution of ~3° × 3.6°). A number of systematic analyses are conducted to investigate the seasonal and interannual variability of the concentrations at specific locations and to...
Article
The one-year NASA-funded project was implemented to complete the analyses and model-simulations undertaken under the auspices of the 3-year research effort supported by NASA as an Interdisciplinary Earth System Science Investigation (IDS) entitled: China As An Evolving Metro-Agro-Plex (China-MAP). The primary goal of China-MAP was to assess the eff...
Article
Full-text available
The comparison of large-scale sulphate aerosol models study (COSAM) compared the performance of atmospheric models with each other and observations. It involved: (i) design of a standard model experiment for the world wide web, (ii) 10 model simulations of the cycles of sulphur and 222Rn/210Pb conforming to the experimental design, (iii) assemblage...
Article
The COSAM intercomparison exercise (comparison of large-scale sulfur models) was organized to compare and evaluate the performance of global sulfur cycle models. Eleven models participated, and from these models the simulated surface concentrations, vertical profiles and budget terms were submitted. This study focuses on simulated budget terms for...
Article
Full-text available
The COSAM intercomparison exercise (comparison of large-scale sulfur models) was organized to compare and evaluate the performance of global sulfur cycle models. Eleven models participated, and from these models the simulated surface concentrations, vertical profiles and budget terms were submitted. This study focuses on simulated budget terms for...
Article
Full-text available
The impact of ship emissions on marine boundary layer (MBL) NOx and SO2 levels over the Pacific Ocean has been explored by comparing predictions (with and without ships) from a global chemical transport model (GCTM) against compiled airborne observations of MBL NOx and SO2. For latitudes >15°N, which define that part of the Pacific having the heavi...
Article
This study reports comparisonsbetween model simulations, based on current sulfurmechanisms, with the DMS, SO2 and DMSOobservational data reported by Bandy et al.(1996) in their 1994 Christmas Island field study. For both DMS and SO2, the model results werefound to be in excellent agreement with theobservations when the observations were filtered so...
Article
We report on results from a World Climate Research Program workshop on representations of scavenging and deposition processes in global transport models of the atmosphere. 15 models were evaluated by comparing simulations of radon, lead, sulfur dioxide, and sulfate against each other, and against observations of these constituents. This paper provi...
Article
Full-text available
The potential impact of ship emissions on concentrations of nitrogen oxides and reactive nitrogen compounds in the marine boundary layer is assessed using a global chemical transport model. The model predicts significant enhancements of these compounds over large regions, especially over the northern midlatitude oceans. This result is consistent wi...
Article
In this study, we report on the results from a comprehensive model simulation of regional ozone (O3) throughout a season in the eastern United States. The model is shown to perform better in terms of simulating seasonal, rather than episodic, characteristics of the regional surface O3 distribution. This finding suggests that it may be more appropri...
Article
This study reports dimethyl sulfide (DMS) sea-to-air fluxes derived from a mass-balance/photochemical-modeling approach. The region investigated was the western North Pacific covering the latitude range of 0°-30°N. Two NASA airborne databases were used in this study: PEM-West A in September-October 1991 and PEM-West B in February-March 1994. A tota...
Article
This study examines the relationships between regional ozone (O3) pollution and emissions of nitrogen oxides (NOx) in the eastern United States during summer. Using measurements from rural sites during the summer of 1995, three 4-day time periods are identified during which significant enhancements of surface O3 occurred on spatial scales ranging f...
Article
Full-text available
A sulfur field study (SCATE) at Palmer Station Antarctica (January 18 to February 25) has revealed several major new findings concerning (dimethyl sulfide) DMS oxidation chemistry and the cycling of sulfur within the Antarctic environment. Significant evidence was found supporting the notion that the OH/DMS addition reaction is a major source of di...
Article
Full-text available
A regional air quality model is used to assess the impact of inert organic nitrate formation on ground-level ozone in the eastern United States during summer. The chemical mechanism used is the Carbon Bond Mechanism 4 (CBM4), which is widely used by regulatory agencies in the United States in air quality modeling applications. Recently, modificatio...
Article
Full-text available
Aircraft observations during the Pacific Exploratory Mission in the western Pacific Ocean, phase B (PEM-West B), taken in February–March 1994, have been used to constrain a numerical model that calculates local concentrations of gaseous H2SO4 rates of homogeneous nucleation, and concentrations of newly formed, nanometer-sized particles. The data wa...
Article
A global three-dimensional chemical transport model is used to investigate seasonal variations of anthropogenic sulfur in the troposphere. Particular emphasis is placed on detailed comparisons of the modeled surface sulfur dioxide (SO2) and sulfate (SO4) concentrations and sulfate wet deposition fluxes with measurements from the Eulerian Model Eval...
Article
A global three-dimensional chemical transport model is used to investigate seasonal variations of anthropogenic sulfur in the troposphere. Particular emphasis is placed on detailed comparisons of the modeled surface sulfur dioxide (SO 2) and sulfate (SO 4) concentrations and sulfate wet deposition fluxes with measurements from the Eulerian Model Ev...
Article
A global chemical transport model is used to study the three-dimensional structure of the tropospheric ozone (O3) distribution over the North Atlantic Ocean during summer. A simplified representation of summertime O3 photochemistry appropriate for northern hemisphere midlatitudes is included in the model. The model is evaluated by comparing simulat...

Citations

... The aerosol removal process by raindrops has been widely discussed in the literature (Loosmore and Cederwall, 2004;Pilat, 1975;Rasch et al., 2000;Wang et al., 1978). The study of this relationship comprises several processes, but the three most important ones involved in BCS are: i) Brownian diffusion (for particles with diameter (d p ) < 10 nm), ii) interception (for particles with d p between 10 and 1000 nm) and iii) inertial impaction (for particles with d p > 1000 nm). ...
... Formation of sulfate by SO 2 oxidation competes with removal of SO 2 by deposition (15). A complete understanding of the contribution of all pathways is important to quantify the SO 2 lifetime (τSO 2 ) against oxidation and the implied formation rate of sulfate, especially as recent studies showed that models underestimate sulfate in SO 2 source regions (16)(17)(18)(19)(20)(21)(22)(23). Competition between gas-phase and condensed-phase pathways has a crucial role in new particle formation (9). ...
... Accordingly, the dust aerosol contribution to the total AOD showed $ 711% seasonal variability relative to its annually averaged values. Further, the cold and dry weather conditions are unfavorable for SO 2 oxidation processes (i.e., limit the formation of tropospheric sulfate aerosols), while the hot and humid meteorological conditions are favorable for the formation of sulfate aerosols (Roelofs et al., 2001;Tesfaye et al., 2014a). As a result, the sulfate aerosol contribution to the total AOD exhibited $ 717% disparity relative to its annually averaged values. ...
... In most applications of regional-scale air quality models, statistical metrics such as bias, root mean square error (RMSE), correlation, index of agreement are being used to judge the quality of model predictions and determine if the model is suitable for forecasting or regulatory purposes (e.g., Fox, 1981Fox, , 1984Solazzo et al., 2011;Appel et al., 2012;Simon et al., 2012;Foley 25 et al., 2014;Ryan et al., 2016;Emory et al. 2016;Zhang, 2016;U.S. EPA, 2018). While significant improvements in the formulation, physical and chemical parameterizations, and numerical techniques have been implemented in atmospheric models over the past three-decades, it is not clear if the improvement claimed in the model's performance relative to the routine network measurements is statistically significant based on these metrics (Hogrefe et al., 2008). Also, no assessments have been made to date on the errors to be expected in regional-scale air quality models. ...
... Historically, sulfur-containing species originating from oceanemitted dimethyl sulfide (DMS) have long been identified as significant components of marine aerosols (Charlson et al., 1987;Shaw, 1983;Bates et al., 1992). Methanesulfonic acid (CH 3 S(O) 2 OH, MSA), as a well-known oxidation product of DMS Hatakeyama et al., 1982), is widely dispersed throughout the world's oceans and has considerable atmospheric concentrations , comparable to or higher than sulfuric acid (SA), i.e., [MSA] / [SA] = 10 %-250 % (Berresheim et al., 2002;Davis et al., 1998;Eisele and Tanner, 1993). Moreover, MSA has been experimentally demonstrated to be a significant nucleating precursor in coastal and remote oceans (Dawson et al., 2012;Karl et al., 2007). ...
... Other studies have emphasized the need for even finer horizontal resolution for modeling local events such as shipping (D. D. Davis et al., 2001;Vinken et al., 2011), power plants (Valin et al., 2011), urban/industrial regions (Colette et al., 2014;Gan et al., 2016;Liang & Jacobson, 2000;Yamaji et al., 2014) especially at night (Zakoura & Pandis, 2018), and complex terrain/coastal regions (Gan et al., 2016). Here, CESM/CAM-chem-SE is used to explore the importance of finer horizontal resolution on accurately simulating ozone and ozone precursors at the regional scale. ...
... Altitude-based thresholds highlight significant injection trends up to 7 km altitude for the Sierra Nevada, Southern Rockies, Colorado Plateau, and Arizona-New Mexico mountains (Fig. 4i). A diurnal breakdown of the aforementioned PBL injection trends, based on a 3-h rolling window, indicates that trends are most robust near 18:00 local time (Fig. S1), a result that corresponds to the late afternoon maximum in wildfire activity 54,55 and the expectation of midday PBL growth. The relevance of enhanced injection above the PBL and at altitudes from 1 to 8 km (Fig. 4) to climate impacts is drawn from recognition of the importance of altitude to extending the aerosol atmospheric lifetime 29,31,32 , enhancing the direct radiative effects of an absorbing aerosol layer 29,68 , and expanding the potential for impact on cloud processes. ...
... 6,11 The modelmeasurement disagreements for SO 2 and sulfate are lessened when hypothetical heterogeneous processing of SO 2 proceeds on aerosol particles at a rate comparable to the gas-phase oxidation of SO 2 in the northern hemisphere summer. 12 It is also possible that multiphase processing of SO 2 in aerosol particles during long-range transport contributes to the sulfate burden in Arctic region. 13 In recent years, scientific interest in the multiphase oxidation of SO 2 in aqueous aerosol particles has been rekindled by the observation of rapid sulfate aerosol production during cloudfree, severe haze events in East Asia. ...
... Ozone is a secondary pollutant formed in the presence of solar light and other gases. Ozone levels typically become particularly high when considerable emissions of gases occur (Kasibhatla et al. 2018;Wang et al. 2019). Therefore, automobile exhaust emissions, exhaust emissions from petrochemical enterprises, and photochemical reactions of volatile organic compounds contribute to ozone pollution (Shu et al. 2019;Liu et al. 2020). ...
... Table 2 shows that the overall trend of the predicted SO 42:5 agrees well with measurement, with the correlation efficient of 0.81, better than OC 2.5 . Relative modeling studies found that winter underestimation of sulfate is a common issue detected with CMAQ over Europe (Matthias, 2008), which may be explained by a lack of model calculated oxidants or missing reactions (Kasibhatla et al., 1997). The results of the carbonaceous aerosol (including OC 2.5 and EC 2.5 ) are far from being representative. ...