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Erratum: “Harnessing the meta-generalized gradient approximation for time-dependent density functional theory” [J. Chem. Phys. 137, 164105 (2012)]
This erratum corrects a factor 2 error in previous work on current-dependent TDDFT.
Erratum: “DFTB+, a software package for efficient approximate density functional theory based atomistic simulations” [J. Chem. Phys. 152, 124101 (2020)]
The implementation of the GPU support in DFTB+, as described in Sec. III C of the original publication,1 was developed based on a previous unpublished implementation by Jacek Jakowski. In order to acknowledge his work on this first implementation, the authors of the original publication wish to include J. Jakowski as co-author. The scientific content of the original publication is not affected.
WRF-Chem & Data Assimilation: Reconstructing a Historic Dispersion Event
CONCLUSIONS • For this particular case and use, 3D-VAR was the most useful data assimilation method applied for modeling this plume. • Slight downside was the plume was modeled to move too quickly. • Whether this result is generalizable may be debatable based on the circumstances. • The atmospheric state altered how effective the data assimilation algorithms performed. • Nudging and 3D-VAR are not mutually exclusive, but their errors for wind speed may compound
Corrigendum to “The Emissions Model Intercomparison Project (Emissions-MIP): quantifying model sensitivity to emission characteristics” published in Atmos. Chem. Phys., 23, 14779–14799, 2023
Anthropogenic emissions of aerosols and precursor compounds are known to significantly affect the energy balance of the Earth–atmosphere system, alter the formation of clouds and precipitation, and have a substantial impact on human health and the environment. Global models are an essential tool for examining the impacts of these emissions. In this study, we examine the sensitivity of model results to the assumed height of SO 2 injection, seasonality of SO 2 and black carbon (BC) particulate emissions, and the assumed fraction of SO 2 emissions that is injected into the atmosphere as particulate phase sulfate (SO 4 ) in 11 climate and chemistry models, including both chemical transport models and the atmospheric component of Earth system models. We find large variation in atmospheric lifetime across models for SO 2 , SO 4 , and BC, with a particularly large relative variation for SO 2 , which indicates that fundamental aspects of atmospheric sulfur chemistry remain uncertain. Of the perturbations examined in this study, the assumed height of SO 2 injection had the largest overall impacts, particularly on global mean net radiative flux (maximum difference of -0.35?W?m-2), SO2 lifetime over Northern Hemisphere land (maximum difference of 0.8?d), surface SO 2 concentration (up to 59?% decrease), and surface sulfate concentration (up to 23?% increase). Emitting SO 2 at height consistently increased SO 2 and SO 4 column burdens and shortwave cooling, with varying magnitudes, but had inconsistent effects across models on the sign of the change in implied cloud forcing. The assumed SO 4 emission fraction also had a significant impact on net radiative flux and surface sulfate concentration. Because these properties are not standardized across models this is a source of inter-model diversity typically neglected in model intercomparisons. These results imply a need to ensure that anthropogenic emission injection height and SO 4 emission fraction are accurately and consistently represented in global models.
Mitigating Satellite‐Based Fire Sampling Limitations in Deriving Biomass Burning Emission Rates: Application to WRF‐Chem Model Over the Northern sub‐Saharan African Region
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Investigation of random thickness variations in chem-milled 2219-t37 aluminum final report
Random thickness variations in chemically milled aluminum alloy
Soviet scientists discuss the exploration of the cosmos- what do microbes report to us. <o chem signaliziruyut mikroby.<
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Ion composition of the bulk ring current during a magnetic storm - Observations with the CHEM-instrument on AMPTE-CCE
Ion composition measurements in the entire energy range of the ring current population, obtained with the Charge-, Energy-, Mass-spectrometer instrument on the Charge Composition Explorer in September 1984, are reported. From the energy spectra obtained for all major constituents during the main phase of a magnetic storm, the number densities, energy densities, and mean energies are calculated and displayed as radial profiles. The mean energies of He(2+) are found to be about twice that of H(+) and He(+) throughout this storm, and the time profiles for the mean energies of all major ions are seen to bunch together (when normalizing mean energies by the ionic charge), with the largest variations of the energy densities and mean energies occurring for O(+) ions.
US Team Member Participation in the Ozone Monitoring Experiment on EOS CHEM
Progress on OMI operational algorithms for BrO, OClO, and HCHO includes: A parameterization scheme for OMI instrument function lab measurements was developed for both UV and Visible instrument channels. The scheme was implemented for all three PGEs and extensively tested. PGEs now have the option of either using the parameterized lab measurements or fitting a symmetric or asymmetric Gaussian function on-line.
US Team Member Participation in the Ozone Monitoring Experiment on EOS Chem
Progress on OMI operational algorithms for BrO, OClO, and HCHO includes: Implemented changes to PGE_Description.txt that were required to promote the PGEs to Integration. Studies were initiated for a parameterization of the laboratory measurements of the OMi instrument function for use in the PGEs. V0.9.27 of the PGEs were delivered to the DAAC.
[School-Based UV-B Monitoring Project in Support of EOS-CHEM]
This grant is an extension of Grant NAG5-8929 (Drexel Project Number 230026), resulting from extensions necessary to meet changing science objectives as described in the final report for NAG5-8929, a copy of which is attached. The instrument configuration resulting from NAG54929 has remained basically intact. Cosine response measurements conducted by James Slusser s group at Fort Collins, Colorado, in support of the proposal for Aura ground validation mentioned in the final report for NAG5-8929, indicated that there was significant light leakage to the detector through the sides of the nylon housing. This was easily remedied by machining a removable opaque collar (made from the dark same grey rigid plastic plumbing tubing as the collimating tube) that fits around the detector collar. Also during this grant period, data logging procedures were established for the UV-A instrument, to record irradiance before, during, and after an Aura overflight. This is required in order to compare spatial and temporal variability as required for ground validation of data products derived from the Ozone Monitoring Instrument (OMI). Standalone 12-bit loggers from Onset Computer Corporation (the U12 series), which were not available at the start of these projects, makes possible relatively inexpensive logging for these instruments at a usable resolution. configuration and disposition of these instruments, including the final version of a GLOBE protocol for using the instruments, currently depend on action taken on the Aura ground validation proposal submitted in 2004. A copy of that proposal is attached.
Applications of cold hibernated elastic memory (CHEM) structures
Experiments and analyses have confirmed the feasibility of an innovative, new class of very simple, reliable, low mass, low packaging volume, and low-cost self-deployable structures for space and commercial applications.
On the Applications of the Adjoint Sensitivity Analysis to Assimilation of EOS Chem Level 3 Products
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The Microwave Limb Sounder on EOS-CHEM for Atmospheric Chemistry
The Microwave Limb Sounder for NASA's Earth Observing System.
First Directly Retrieved Global Distribution of Tropospheric Column Ozone from GOME: Comparison with the GEOS-CHEM Model
We present the first directly retrieved global distribution of tropospheric column ozone from Global Ozone Monitoring Experiment (GOME) ultraviolet measurements during December 1996 to November 1997. The retrievals clearly show signals due to convection, biomass burning, stratospheric influence, pollution, and transport. They are capable of capturing the spatiotemporal evolution of tropospheric column ozone in response to regional or short time-scale events such as the 1997-1998 El Nino event and a 10-20 DU change within a few days. The global distribution of tropospheric column ozone displays the well-known wave-1 pattern in the tropics, nearly zonal bands of enhanced tropospheric column ozone of 36-48 DU at 20degS-30degS during the austral spring and at 25degN-45degN during the boreal spring and summer, low tropospheric column ozone of <30 DU uniformly distributed south of 35 S during all seasons, and relatively high tropospheric column ozone of >33 DU at some northern high-latitudes during the spring. Simulation from a chemical transport model corroborates most of the above structures, with small biases of <+/-5 DU and consistent seasonal cycles in most regions, especially in the southern hemisphere. However, significant positive biases of 5-20 DU occur in some northern tropical and subtropical regions such as the Middle East during summer. Comparison of GOME with monthly-averaged Measurement of Ozone and Water Vapor by Airbus in-service Aircraft (MOZAIC) tropospheric column ozone for these regions usually shows good consistency within 1 a standard deviations and retrieval uncertainties. Some biases can be accounted for by inadequate sensitivity to lower tropospheric ozone, the different spatiotemporal sampling and the spatiotemporal variations in tropospheric column ozone.
Analysis of AIRS CO2 Sensitivity to Surface CO2 Flux Using Geos-chem Adjoint Model
No abstract available
GEOS-Chem and the GMAO: Reaction, Replay and Reanalysis
This presentation summarizes the evolution of chemical modeling in the GMAO, showing how the parallel tracks for mission support, using forecasts over several days, and chemistry-climate coupling, using multi-decadal simulations, are converging in the future. The presentation emphasizes the new GEOS Composition Forecasting system (GEOS CF) and its potential role in future reanalyses of NASA's EOS Aura data and the testing needed to use this in chemistry-climate simulations.