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At least 163 records · Page 9

SAGE III/ISS v5.3 Level 2 Data Product Changes and Improvements

The Stratospheric Aerosol and Gas Experiment on the International Space Station (SAGE III/ISS) is an occultation instrument that acquires measurements of aerosols and gases within the Earth’s stratosphere and upper troposphere. SAGE III/ISS provides level 2 solar species products for aerosol extinction (9 channels), nitrogen dioxide (NO2), ozone (O3), and water vapor (H2O). The level 2 products currently provide three O3 profiles based on differing retrievals. The first O3 profile is based on measurements at short wavelengths within the Hartley-Huggins band (MesO3), the second O3 profile is based on measurements made at visible wavelengths within the Chappius band (MLR O3), and the final profile is found using a more SAGE II like approach (AO3). The SAGE III/ISS also provides level 2 lunar species products for ozone (O3), nitrogen dioxide (NO2), and nitrogen trioxide (NO3). Version 5.3 of the SAGE III/ISS retrieval algorithm introduces improvements that affect the level 2 data products. The largest change to the solar algorithm is the implementation of disturbance monitoring package (DMP) corrections to improve pointing accuracy. The DMP is comprised of a miniature inertial measurement unit that measures rotation in inertial space using ring laser gyroscopes oriented about three orthogonal axes which can be used to correct pointing errors caused by mechanical disturbances. A major change common to solar and lunar algorithms is meteorological input from the coarser 42 level Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) model data to the 72 level MERRA-2 model data. The final major change involves improving the automated quality assurance (QA) algorithm to recover events that were withheld from the public release because differences between the AO3 and MLR O3 for some events after the eruption of Tonga–Hunga Haʻapai. Other changes for v5.3 include minor bug fixes as well as restoration of some data quality flags that were removed in v5.21. This presentation presents the impacts of these changes as well as overall observations of interest from v5.3 level 2 data products.

Carter Hulsey↗

An intercomparison of airborne nitrogen dioxide instruments

Results on NO2 instruments are reported from the NASA Global Tropospheric Experiment Chemical Instrumentation Test and Evaluation 2 (CITE 2) program in summer 1986. The instruments tested were (1) a two-photon LIF system using a laser for NO2-NO photolysis, (2) a chemiluminescence (CL) detector using FeSO4 for NO2-NO conversion, (3) a CL detector using an arc lamp for NO2-NO photolysis, and (4) a tunable-laser-diode multipath-absorption system. The procedures for the CITE 2 ground-based and flight tests are described in detail, and the results are presented in extensive graphs. Instrument (2) was eliminated because the FeSO4 converted atmospheric PAN to NO, resulting in spuriously high NO2 values. The remaining instruments gave readings in 30-40-percent agreement at NO2 mixing ratios of 100-200 parts per trillion by volume (pptv). At ratios below 50 pptv, the correlation among the measurements was very poor, with a tendency for system (4) to give higher values than (1) or (3).

Gregory, G. L.↗

Role of nitrate and nitrite in the induction of nitrite reductase in leaves of barley seedlings

The role of NO3- and NO2- in the induction of nitrite reductase (NiR) activity in detached leaves of 8-day-old barley (Hordeum vulgare L.) seedlings was investigated. Barley leaves contained 6 to 8 micromoles NO2-/gram fresh weight x hour of endogenous NiR activity when grown in N-free solutions. Supply of both NO2- and NO3- induced the enzyme activity above the endogenous levels (5 and 10 times, respectively at 10 millimolar NO2- and NO3- over a 24 hour period). In NO3(-)-supplied leaves, NiR induction occurred at an ambient NO3- concentration of as low as 0.05 millimolar; however, no NiR induction was found in leaves supplied with NO2- until the ambient NO2- concentration was 0.5 millimolar. Nitrate accumulated in NO2(-)-fed leaves. The amount of NO3- accumulating in NO2(-)-fed leaves induced similar levels of NiR as did equivalent amounts of NO3- accumulating in NO3(-)-fed leaves. Induction of NiR in NO2(-)-fed leaves was not seen until NO3- was detectable (30 nanomoles/gram fresh weight) in the leaves. The internal concentrations of NO3-, irrespective of N source, were highly correlated with the levels of NiR induced. When the reduction of NO3- to NO2- was inhibited by WO4(2-), the induction of NiR was inhibited only partially. The results indicate that in barley leaves in NiR is induced by NO3- directly, i.e. without being reduced to NO2-, and that absorbed NO2- induces the enzyme activity indirectly after being oxidized to NO3- within the leaf.

Non-NASA Center↗

Global and Regional Decreases in Tropospheric Oxidants from Photochemical Effects of Aerosols

We evaluate the sensitivity of tropospheric OH, O3, and O3 precursors to photochemical effects of aerosols not usually included in global models: (1) aerosol scattering and absorption of ultraviolet radiation and (2) reactive uptake of HO', NO2, and NO3. Our approach is to couple a global 3-D model of tropospheric chemistry (GEOS- CHEM) with aerosol fields from a global 3-D aerosol model (GOCART). Reactive uptake by aerosols is computed using reaction probabilities from a recent review (gamma(sub HO2) = 0.2, gamma(sub NO2) = 10(exp -4), gamma(sub NO3) = l0(exp -3). Aerosols decrease the O3 - O((sup 1)D) photolysis frequency by 5-20% at the surface throughout the Northern Hemisphere (largely due to mineral dust) and by a factor of 2 in biomass burning regions (largely due to black carbon). Aerosol uptake of HO2 accounts for 10-40% of total HOx radical ((triple bonds)OH + peroxy) loss in the boundary layer over polluted continental regions (largely due to sulfate and organic carbon) and for more than 70% over tropical biomass burning regions (largely due to organic carbon). Uptake of NO2 and NO3 accounts for 10-20% of total HNO3 production over biomass burning regions and less elsewhere. Annual mean OH concentrations decrease by 9% globally and by 5-35% in the boundary layer over the Northern Hemisphere. Simulated CO increases by 5- 15 ppbv in the remote Northern Hemisphere, improving agreement with observations. Simulated boundary layer O3 decreases by 15- 45 ppbv over India during the biomass burning season in March and by 5-9 ppbv over northern Europe in August, again improving comparison with observations. We find that particulate matter controls would increase surface O3 over Europe and other industrial regions.

Martin, Randall V.↗

An Elevated Reservoir of Air Pollutants over the Mid-Atlantic States During the 2011 DISCOVER-AQ Campaign: Airborne Measurements and Numerical Simulations

During a classic heat wave with record high temperatures and poor air quality from July 18 to 23, 2011, an elevated reservoir of air pollutants was observed over and downwind of Baltimore, MD, with relatively clean conditions near the surface. Aircraft and ozonesonde measurements detected approximately 120 parts per billion by volume ozone at 800 meters altitude, but approximately 80 parts per billion by volume ozone near the surface. High concentrations of other pollutants were also observed around the ozone peak: approximately 300 parts per billion by volume CO at 1200 meters, approximately 2 parts per billion by volume NO2 at 800 meters, approximately 5 parts per billion by volume SO2 at 600 meters, and strong aerosol optical scattering (2 x 10 (sup 4) per meter) at 600 meters. These results suggest that the elevated reservoir is a mixture of automobile exhaust (high concentrations of O3, CO, and NO2) and power plant emissions (high SO2 and aerosols). Back trajectory calculations show a local stagnation event before the formation of this elevated reservoir. Forward trajectories suggest an influence on downwind air quality, supported by surface ozone observations on the next day over the downwind PA, NJ and NY area. Meteorological observations from aircraft and ozonesondes show a dramatic veering of wind direction from south to north within the lowest 5000 meters, implying that the development of the elevated reservoir was caused in part by the Chesapeake Bay breeze. Based on in situ observations, Community Air Quality Multi-scale Model (CMAQ) forecast simulations with 12 kilometers resolution overestimated surface ozone concentrations and failed to predict this elevated reservoir; however, CMAQ research simulations with 4 kilometers and 1.33 kilometers resolution more successfully reproduced this event. These results show that high resolution is essential for resolving coastal effects and predicting air quality for cities near major bodies of water such as Baltimore on the Chesapeake Bay and downwind areas in the Northeast.

ozone↗

Global 3-D Modeling Studies Of Tropospheric Ozone And Related Gases

Our research was targeted at three issues: (1) the factors controlling ozone in the tropical troposphere, (2) the Asian outflow of ozone and its precursors, and (3) the causes of decadal trends observed in ozone and CO. We have also used support from this ACMAP grant to (1) work with Kelly Chance on the retrieval and interpretation of HCHO and NO2 observations from GOME, and (2) develop GEOS-CHEM into a versatile model supporting the work of a large number of users including outside Harvard. ACMAP has provided the core support for GEOS-CHEM development. Applications of the GEOS-CHEM model with primary support from ACMAP are discussed below. A list of publications resulting from this grant is given at the end of the report.

Jacob, Daniel J.↗

Materials Data on H12Pd(N5O4)2 by Materials Project

PdN2(NH3)4(NO2)4 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two ammonia molecules, four ammonia molecules, four nitrous acid molecules, and one palladium molecule.

36 MATERIALS SCIENCE↗

Materials Data on CdRe2(NO2)4 by Materials Project

Cd(ReO4)2(N2)2 is Iron carbide-derived structured and crystallizes in the cubic F-43m space group. The structure is zero-dimensional and consists of sixteen ammonia molecules, four cadmium molecules, and eight rhenium;tetrahydrate molecules.

36 MATERIALS SCIENCE↗

Materials Data on UH14(NO2)4 by Materials Project

UO2(NH2O)2(NH2OH)2(H2O)2 crystallizes in the orthorhombic Pbca space group. The structure is zero-dimensional and consists of eight hydroxyammonium molecules; eight hydroxylamine molecules; four pitchblend, uranium(iv) oxide, uranium(iv) dioxide, uranium dioxide molecules; and eight water molecules.

36 MATERIALS SCIENCE↗

Properties of clusters in the gas phase. V - Complexes of neutral molecules onto negative ions

Ion-molecules association reactions of the form A(-)(B)n-1 + B = A(-)(B)n were studied over a range of temperatures in the gas phase using high pressure mass spectrometry. Enthalpy and entropy changes were determined for the stepwise clustering reactions of (1) sulfur dioxide onto Cl(-), I(-), and NO2(-) with n ranging from one to three or four, and onto SO2(-) and SO3(-) with n equal to one; and (2) carbon dioxide onto Cl(-), I(-), NO2(-), CO3(-), and SO3(-) with n equal to one. From these data and earlier hydration results, the order of the magnitude of the enthalpy changes on the association of the first neutral for a series of negative ions was found to parallel the gas-phase basicity of those anions.

Keesee, R. G.↗

Materials Data on CdH20C2S2(NO2)6 by Materials Project

Cd(NH)2(CNH2)2(H2)4(NO)2(H3SO4)2O2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two ac1nrvfo molecules, four hydrogen molecules, one hydrogen peroxide molecule, two methanimine molecules, two nitroxyl molecules, and one Cd(NH)2 cluster. In the Cd(NH)2 cluster, Cd2+ is bonded in a distorted linear geometry to two equivalent N+0.33- atoms. Both Cd–N bond lengths are 2.09 Å. N+0.33- is bonded in a distorted bent 120 degrees geometry to one Cd2+ and one H1+ atom. The N–H bond length is 1.04 Å. H1+ is bonded in a single-bond geometry to one N+0.33- atom.

36 MATERIALS SCIENCE↗

Materials Data on CdOs2(NO2)4 by Materials Project

Cd(OsO4)2(N2)2 is Iron carbide-derived structured and crystallizes in the cubic F-43m space group. The structure is zero-dimensional and consists of sixteen ammonia molecules, four cadmium molecules, and eight OsO4 clusters. In each OsO4 cluster, Os5+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All Os–O bond lengths are 1.73 Å. O2- is bonded in a single-bond geometry to one Os5+ atom.

36 MATERIALS SCIENCE↗

Materials Data on ZnOs2(NO2)4 by Materials Project

Zn(OsO4)2(N2)2 is Iron carbide-derived structured and crystallizes in the cubic F-43m space group. The structure is zero-dimensional and consists of sixteen ammonia molecules, eight OsO4 clusters, and four zinc molecules. In each OsO4 cluster, Os5+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All Os–O bond lengths are 1.73 Å. O2- is bonded in a single-bond geometry to one Os5+ atom.

36 MATERIALS SCIENCE↗

Materials Data on PtS2(NO2)4 by Materials Project

Pt(SO4)2(N2)2 crystallizes in the monoclinic C2/m space group. The structure is zero-dimensional and consists of eight ammonia molecules and two Pt(SO4)2 clusters. In each Pt(SO4)2 cluster, Pt2+ is bonded in a linear geometry to two equivalent O2- atoms. Both Pt–O bond lengths are 2.02 Å. S2- is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of S–O bond distances ranging from 1.46–1.59 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one S2- atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Pt2+ and one S2- atom. In the third O2- site, O2- is bonded in a single-bond geometry to one S2- atom.

36 MATERIALS SCIENCE↗

Materials Data on Ag(NO2)3 by Materials Project

(Ag(NO3)2)2N2 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of four ammonia molecules and two Ag(NO3)2 sheets oriented in the (0, 0, 1) direction. In each Ag(NO3)2 sheet, Ag1+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Ag–O bond distances ranging from 2.19–2.91 Å. There are two inequivalent N+3.67+ sites. In the first N+3.67+ site, N+3.67+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.22 Å) and two longer (1.29 Å) N–O bond length. In the second N+3.67+ site, N+3.67+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of N–O bond distances ranging from 1.23–1.29 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Ag1+ and one N+3.67+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Ag1+ and one N+3.67+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ag1+ and one N+3.67+ atom. In the fourth O2- site, O2- is bonded in a distorted L-shaped geometry to one Ag1+ and one N+3.67+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one N+3.67+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ag1+ and one N+3.67+ atom.

36 MATERIALS SCIENCE↗

Materials Data on ZnMo(NO2)4 by Materials Project

ZnMoO8(N2)2 crystallizes in the tetragonal I-4 space group. The structure is zero-dimensional and consists of eight ammonia molecules, two MoO8 clusters, and two zinc dust molecules. In each MoO8 cluster, Mo6+ is bonded in a distorted hexagonal bipyramidal geometry to eight O2- atoms. There are four shorter (1.99 Å) and four longer (2.02 Å) Mo–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Mo6+ and one O2- atom. The O–O bond length is 1.42 Å. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Mo6+ and one O2- atom.

36 MATERIALS SCIENCE↗

Materials Data on CuH14C4(NO2)4 by Materials Project

Cu(HCOO)2(CO(NH2)2)2(H2O)2 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of four hydrazinocarbinol molecules; four water molecules; and one Cu(HCOO)2 sheet oriented in the (0, 0, 1) direction. In the Cu(HCOO)2 sheet, Cu2+ is bonded in a distorted square co-planar geometry to four O2- atoms. There is two shorter (1.98 Å) and two longer (2.00 Å) Cu–O bond length. C3+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.27 Å) and one longer (1.28 Å) C–O bond length. H1+ is bonded in a single-bond geometry to one C3+ atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cu2+ and one C3+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cu2+ and one C3+ atom.

36 MATERIALS SCIENCE↗

Materials Data on CuC4(NO2)4 by Materials Project

CuO2(N2CO)2(CO2)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four carbon dioxide molecules, two copper(ii) hydroxide molecules, and four N2CO clusters. In each N2CO cluster, C4+ is bonded in a 1-coordinate geometry to two N+0.50- and one O2- atom. Both C–N bond lengths are 1.40 Å. The C–O bond length is 1.20 Å. There are two inequivalent N+0.50- sites. In the first N+0.50- site, N+0.50- is bonded in a 1-coordinate geometry to one C4+ and one N+0.50- atom. The N–N bond length is 1.32 Å. In the second N+0.50- site, N+0.50- is bonded in a 1-coordinate geometry to one C4+ and one N+0.50- atom. O2- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗