Person: Logan, Jennifer
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Logan
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Jennifer
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Logan, Jennifer
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Publication Optimized regional and interannual variability of lightning in a global chemical transport model constrained by LIS/OTD satellite data(Wiley-Blackwell, 2012) Murray, Lee Thomas; Jacob, Daniel; Logan, Jennifer; Hudman, Rynda C.; Koshak, William J.Nitrogen oxides (NOx≡ NO + NO2) produced by lightning make a major contribution to the global production of tropospheric ozone and OH. Lightning distributions inferred from standard convective parameterizations in global chemical transport models (CTMs) fail to reproduce observations from the Lightning Imaging Sensor (LIS) and the Optical Transient Detector (OTD) satellite instruments. We present an optimal regional scaling algorithm for CTMs to fit the lightning NOx source to the satellite lightning data in a way that preserves the coupling to deep convective transport. We show that monthly scaling using ~35 global regions significantly improves the tropical ozone simulation in the GEOS-Chem CTM as compared to a simulation unconstrained by the satellite data, and performs equally well to a simulation with local scaling. The coarse regional scaling preserves sufficient statistics in the satellite data to constrain the interannual variability (IAV) of lightning. After processing the LIS data to remove its diurnal sampling bias, we construct a monthly time series of lightning flash rates for 1998-2010 and 35ºS-35ºN. We find a correlation of IAV in tropical lightning with El Niño but not with the solar cycle or the quasi-biennial oscillation. The resulting global lightning NOx source in GEOS-Chem is 6.0 ± 0.5 Tg N a-1, compared to 5.5 ± 0.8 Tg N a-1 for the biomass burning source. Lightning NOx could have a large influence on the IAV of tropospheric ozone because it is released in the upper troposphere where ozone production is most efficient.Publication Intercomparison Methods for Satellite Measurements of Atmospheric Composition: Application to Tropospheric Ozone from TES and OMI(European Geosciences Union, 2010) Zhang, L.; Jacob, Daniel; Liu, Xiong; Logan, Jennifer; Chance, Kelly; Eldering, A.; Bojkov, B. R.We analyze the theoretical basis of three different methods to validate and intercompare satellite measurements of atmospheric composition, and apply them to tropospheric ozone retrievals from the Tropospheric Emission Spectrometer (TES) and the Ozone Monitoring Instrument (OMI). The first method (in situ method) uses in situ vertical profiles for absolute instrument validation; it is limited by the sparseness of in situ data. The second method (CTM method) uses a chemical transport model (CTM) as an intercomparison platform; it provides a globally complete intercomparison with relatively small noise from model error. The third method (averaging kernel smoothing method) involves smoothing the retrieved profile from one instrument with the averaging kernel matrix of the other; it also provides a global intercomparison but dampens the actual difference between instruments and adds noise from the a priori. We apply the three methods to a full year (2006) of TES and OMI data. Comparison with in situ data from ozonesondes shows mean positive biases of 5.3 parts per billion volume (ppbv) (10%) for TES and 2.8 ppbv (5%) for OMI at 500 hPa. We show that the CTM method (using the GEOS-Chem CTM) closely approximates results from the in situ method while providing global coverage. It reveals that differences between TES and OMI are generally less than 10 ppbv (18%), except at northern mid-latitudes in summer and over tropical continents. The CTM method further allows for CTM evaluation using both satellite observations. We thus find that GEOS-Chem underestimates tropospheric ozone in the tropics due to possible underestimates of biomass burning, soil, and lightning emissions. It overestimates ozone in the northern subtropics and southern mid-latitudes, likely because of excessive stratospheric influx of ozone.Publication Global Estimates of CO Sources with High Resolution by Adjoint Inversion of Multiple Satellite Datasets (MOPITT, AIRS, SCIAMACHY, TES)(European Geosciences Union, 2010) Kopacz, M.; Jacob, Daniel; Fisher, John; Logan, Jennifer; Zhang, L.; Megretskaia, Inna; Yantosca, Robert; Singh, K.; Henze, D. K.; Burrows, J. P.; Buchwitz, M.; Khlystova, I.; McMillan, W. W.; Gille, J. C.; Edwards, D. P.; Eldering, A.; Thouret, V.; Nedelec, P.We combine CO column measurements from the MOPITT, AIRS, SCIAMACHY, and TES satellite instruments in a full-year (May 2004–April 2005) global inversion of CO sources at 4°×5° spatial resolution and monthly temporal resolution. The inversion uses the GEOS-Chem chemical transport model (CTM) and its adjoint applied to MOPITT, AIRS, and SCIAMACHY. Observations from TES, surface sites (NOAA/GMD), and aircraft (MOZAIC) are used for evaluation of the a posteriori solution. Using GEOS-Chem as a common intercomparison platform shows global consistency between the different satellite datasets and with the in situ data. Differences can be largely explained by different averaging kernels and a priori information. The global CO emission from combustion as constrained in the inversion is \(1350 Tg a^{−1}\). This is much higher than current bottom-up emission inventories. A large fraction of the correction results from a seasonal underestimate of CO sources at northern mid-latitudes in winter and suggests a larger-than-expected CO source from vehicle cold starts and residential heating. Implementing this seasonal variation of emissions solves the long-standing problem of models underestimating CO in the northern extratropics in winter-spring. A posteriori emissions also indicate a general underestimation of biomass burning in the GFED2 inventory. However, the tropical biomass burning constraints are not quantitatively consistent across the different datasets.Publication Interannual Variability in Tropical Tropospheric Ozone and OH: The Role of Lightning(Wiley-Blackwell, 2013) Murray, Lee Thomas; Logan, Jennifer; Jacob, DanielNitrogen oxide radicals (NOx) produced by lightning are natural precursors for the production of the dominant tropospheric oxidants, OH and ozone. Observations of the interannual variability (IAV) of tropical ozone and of global mean OH (from the methyl chloroform proxy) offer a window for understanding the sensitivity of ozone and OH to environmental factors. We present the results of simulations for 1998–2006 using the GEOS-Chem chemical transport model (CTM) with IAV in tropical lightning constrained by satellite observations from the Lightning Imaging Sensor. We find that this imposed IAV in lightning NOx improves the ability of the model to reproduce observed IAV in tropical ozone and OH. Lightning is far more important than biomass burning in driving the IAV of tropical ozone, even though the IAV of NOx emissions from fires is greater than that from lightning. Our results indicate that the IAV in tropospheric OH is highly sensitive to lightning relative to other emissions and suggest that lightning contributes an important fraction of the observed IAV in OH inferred from the methyl chloroform proxy. Lightning affects OH through the HO2+ NO reaction, an effect compounded by positive feedback from the resulting increase in ozone production and in CO loss. We can account in the model for the observed increase in OH in 1998–2004 and for its IAV, but the model fails to explain the OH decrease in 2004–2006. We find that stratospheric ozone plays little role in driving IAV in OH during 1998–2006, in contrast to previous studies that examined earlier periods.Publication Atmospheric chemistry in the Arctic and subarctic: Influence of natural fires, industrial emissions, and stratospheric inputs(Wiley-Blackwell, 1992) Wofsy, Steven; Sachse, G. W.; Gregory, G. L.; Blake, D. R.; Bradshaw, J. D.; Sandholm, S. T.; Singh, H. B.; Barrick, J. A.; Harriss, R. C.; Talbot, R. W.; Shipham, M. A.; Browell, E. V.; Jacob, Daniel; Logan, JenniferHaze layers with perturbed concentrations of trace gases, believed to originate from tundra and forest wild fires, were observed over extensive areas of Alaska and Canada in 1988. Enhancements of CH, CH, CH, CH, and CH were linearly correlated with CO in haze layers, with mean ratios (mole hydrocarbon/mole CO) of 0.18 (± 0.04 (1 σ)), 0.0019 (± 0.0001), 0.0055 (± 0.0002), 0.0008 (± 0.0001), and 1.2 × 10 (±0.2× 10), respectively. Enhancements of NO, were variable, averaging 0.0056 (± 0.0030) mole NO/mole CO, while perturbations of NO were very small, usually undetectable. At least 1/3 of the NO in the haze layers had been converted to peroxyacetyl nitrate (PAN), representing a potential source of NO to the global atmosphere; much of the balance was oxidized to nitrate (HNO and paniculate). The composition of sub‐Arctic haze layers was consistent with aged emissions from smoldering combustion, except for CH, which appears to be partly biogenic. Inputs from the stratosphere and from biomass fires contributed major fractions of the NO in the remote sub‐Arctic troposphere. Analysis of aircraft and ground data indicates relatively little influence from mid‐latitude industrial NO in this region during summer, possibly excepting transport of PAN. Production of O was inefficient in sub‐Arctic haze layers, less than 0.1 O molecules per molecule of CO, reflecting the low NO/CO emission ratios from smoldering combustion. Mid‐latitude pollution produced much more O, 0.3 – 0.5 O molecules per molecule of CO, a consequence of higher NO/CO emission ratios.Publication Global inventory of sulfur emissions with 1°×1° resolution(Wiley-Blackwell, 1992) Spiro, Peter A.; Jacob, Daniel; Logan, JenniferA global inventory of gaseous sulfur emissions with 1°×1° resolution is described. Emissions from fuel combustion and industrial activities are estimated for countries where no detailed inventories are available by using economic data for individual sulfur‐emitting activities, sulfur emission factors, and information on sulfur recovery. Fuel sulfur contents are specified as a function of fuel type and country of origin and are conserved during international trading. This procedure for estimating emissions reproduces well existing inventories for countries in Europe and North America, suggesting that it can be applied with some confidence to other countries. Emissions from biomass burning, volcanoes, and oceans are derived from existing data bases and are distributed with fine spatial resolution. Emissions from terrestrial vegetation are computed as a function of leaf area index, temperature, and solar radiation. The global emission of sulfur gases in 1980 is estimated to be 102 Tg S yr, apportioned among fuel combustion and industrial activities (76%), marine biosphere (12%), volcanoes (9%), biomass burning (2%), and terrestrial biosphere (1%). Detailed breakdowns of anthropogenic and natural sources are given for individual countries and regions. Anthropogenic sources account for 84% of total sulfur emissions in the northern hemisphere and for 50% in the southern hemisphere. Biomass burning dominates emissions in central Africa during the dry season but is of minor importance elsewhere. Smelters dominate anthropogenic emissions in the Arctic and in the southern hemisphere. Volcanoes are significant contributors to the sulfur budget in Central America, the East Indies, and some subarctic regions.Publication Passive tracer transport relevant to the TRACE A experiment(Wiley-Blackwell, 1996) Krishnamurti, T. N.; Sinha, M. C.; Kanamitsu, M.; Oosterhof, D.; Fuelberg, H.; Chatfield, R.; Jacob, Daniel; Logan, JenniferThis paper explores some of the mechanisms governing the accumulation of passive tracers over the tropical southern Atlantic Ocean during the northern hemisphere fall season. There has been a pioneering observation regarding ozone maxima over the South Atlantic during austral spring. The understanding of the formation of this maxima has been the prime motivation for this study. Using a global model as a frame of reference, we have carried out three kinds of experiments during the period of the Transport and Atmospheric Chemistry Near the Equator-Atlantic (TRACE A) project of 1992. The first of these is a simple advection of total ozone (a passive tracer) in time using the Florida State University global spectral model. Integration over the period of roughly 1 week showed that the model quite closely replicates the behavior of the observed total ozone from the total ozone mapping spectrometer (TOMS). This includes many of the changes in the features of total ozone over the tropical and subtropical region of the southern Atlantic Ocean. These studies suggest a correlation of 0.8 between the observed ozone over this region and ozone modeled from “dynamics alone,” i.e., without recourse to any photochemistry. The second series of experiments invoke sustained sources of a tracer over the biomass burn region of Africa and Brazil. Furthermore, sustained sources were also introduced in the active frontal “descending air” region of the southern hemisphere and over the Asian monsoon's east-west circulation. These experiments strongly suggest that air motions help to accumulate tracer elements over the tropical southern Atlantic Ocean. A third series of experiments address what may be required to improve the deficiencies of the vertical stratification of ozone predicted by the model over the flight region of the tropical southern Atlantic during TRACE A. Here we use the global model to optimally derive plausible accumulation of burn elements over the fire count regions of Brazil and Africa to provide passive tracer advections to closely match what was observed from reconnaissance aircraft-based measurements of ozone over the tropical southern Atlantic Ocean.Publication Sources and chemistry of nitrogen oxides over the tropical Pacific(Wiley-Blackwell, 2003) Staudt, A. C.; Jacob, Daniel; Ravetta, F; Logan, Jennifer; Bachiochi, D; Krishnamurti, T; Sandholm, S; Ridley, B; Singh, H; Talbot, BWe examine the sources and chemistry affecting nitrogen oxides (NOx = NO + NO2) over the tropical Pacific (30°S–20°N) using observations from the Pacific Exploratory Mission to the Tropics B (PEM-Tropics B) aircraft mission conducted in March–April 1999. A global model of tropospheric chemistry driven by assimilated meteorological data is used to interpret the observations. Median concentrations observed over the South Pacific during PEM-Tropics B were 7 pptv NO, 16 pptv peroxyacetyl nitrate (PAN), and 34 pptv nitric acid (HNO3); the model generally reproduces these observations but overestimates those over the North Pacific. Lightning was the largest source of these species in the equatorial and South Pacific tropospheric column and in the tropical North Pacific upper troposphere. The oceanic source of acetone implied by high observations of acetone concentrations (mean 431 pptv) allows an improved simulation of PAN/NOx chemistry. However, the high acetaldehyde concentrations (mean 78 pptv) measured throughout the troposphere are inconsistent with our understanding of acetaldehyde and PAN chemistry. Simulated concentrations of HNO3 and HNO3/NOx are highly sensitive to the model representation of deep convection and associated HNO3 scavenging. Chemical losses of NOx during PEM-Tropics B exceed chemical sources by a factor of 2 in the South Pacific upper troposphere. The chemical imbalance, also apparent in the low observed HNO3/NOx ratio, is explained by NOx injection from lightning and by frequent convective overturning which depletes HNO3. The observed imbalance was less during the PEM-Tropics A campaign in September 1996, when aged biomass burning effluents over the South Pacific pushed the NOx budget toward chemical steady state.Publication Climate forcings in Goddard Institute for Space Studies SI2000 simulations(Wiley-Blackwell, 2002) Hansen, J.; Sato, M; Nazarenko, L; Ruedy, R; Lacis, A; Koch, D; Tegen, I; Hall, T; Shindell, D; Santer, B; Stone, P; Novakov, T; Thomason, L; Wang, R; Wang, Y; Jacob, Daniel; Hollandsworth, S; Bishop, L; Logan, Jennifer; Thompson, A; Stolarski, R; Lean, J; Willson, R; Levitus, S; Antonov, J; Rayner, N; Parkerm, D; Christy, JWe define the radiative forcings used in climate simulations with the SI2000 version of the Goddard Institute for Space Studies (GISS) global climate model. These include temporal variations of well-mixed greenhouse gases, stratospheric aerosols, solar irradiance, ozone, stratospheric water vapor, and tropospheric aerosols. Our illustrations focus on the period 1951–2050, but we make the full data sets available for those forcings for which we have earlier data. We illustrate the global response to these forcings for the SI2000 model with specified sea surface temperature and with a simple Q-flux ocean, thus helping to characterize the efficacy of each forcing. The model yields good agreement with observed global temperature change and heat storage in the ocean. This agreement does not yield an improved assessment of climate sensitivity or a confirmation of the net climate forcing because of possible compensations with opposite changes of these quantities. Nevertheless, the results imply that observed global temperature change during the past 50 years is primarily a response to radiative forcings. It is also inferred that the planet is now out of radiation balance by 0.5 to 1 W/m2 and that additional global warming of about 0.5°C is already “in the pipeline.”Publication An intercomparison and evaluation of aircraft-derived and simulated CO from seven chemical transport models during the TRACE-P experiment(Wiley-Blackwell, 2003) Kiley, Christopher M.; Fuelberg, Henry; Palmer, Paul; Allen, Dale J.; Carmichael, Gregory; Jacob, Daniel; Mari, Celine; Pierce, R. Bradley; Pickering, Kenneth; Tang, Yoshua; Wild, Oliver; Fairlie, T. Duncan; Logan, Jennifer; Sachse, Glen; Shaack, Todd; Streets, DavidFour global scale and three regional scale chemical transport models are intercompared and evaluated during NASA's Transport and Chemical Evolution over the Pacific (TRACE-P) experiment. Model simulated and measured CO are statistically analyzed along aircraft flight tracks. Results for the combination of 11 flights show an overall negative bias in simulated CO. Biases are most pronounced during large CO events. Statistical agreements vary greatly among the individual flights. Those flights with the greatest range of CO values tend to be the worst simulated. However, for each given flight, the models generally provide similar relative results. The models exhibit difficulties simulating intense CO plumes. CO error is found to be greatest in the lower troposphere. Convective mass flux is shown to be very important, particularly near emissions source regions. Occasionally meteorological lift associated with excessive model-calculated mass fluxes leads to an overestimation of middle and upper tropospheric mixing ratios. Planetary Boundary Layer (PBL) depth is found to play an important role in simulating intense CO plumes. PBL depth is shown to cap plumes, confining heavy pollution to the very lowest levels.