scholarly journals Mobile mini-DOAS measurement of the outflow of NO<sub>2</sub> and HCHO from Mexico City

2009 ◽  
Vol 9 (15) ◽  
pp. 5647-5653 ◽  
Author(s):  
M. Johansson ◽  
C. Rivera ◽  
B. de Foy ◽  
W. Lei ◽  
J. Song ◽  
...  
Keyword(s):  
Mexico City ◽  
Cross Section ◽  
Reasonable Agreement ◽  
Wrf Model ◽  
Wavelength Region ◽  
Urban Atmosphere ◽  
Optical Absorption Spectroscopy ◽  
Mobile Measurements ◽  
First Time ◽  
Calculated Flux

Abstract. We here present the results from mobile measurements using two ground-based zenith viewing Differential Optical Absorption Spectroscopy (DOAS) instruments. The measurement was performed in a cross-section of the plume from the Mexico City Metropolitan Area (MCMA) on 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO2 above the measurement route. This is the first time the mobile mini-DOAS instrument has been able to measure HCHO, one of the chemically most important and interesting gases in the polluted urban atmosphere. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO2 has been calculated from the measurements and the results are compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5–2.2) kg/s of HCHO and 4.4 (4.0–5.0) kg/s of NO2 using the UV instrument and 3.66 (3.63–3.73) kg/s of NO2 using the visible light instrument. The modeled values from CAMx for the outflow of both NO2 and HCHO, 1.1 and 3.6 kg/s, respectively, show a reasonable agreement with the measurement derived fluxes.

scholarly journals Mobile mini-DOAS measurement of the emission of NO<sub>2</sub> and HCHO from Mexico City

2009 ◽  
Vol 9 (1) ◽  
pp. 865-882 ◽  
Author(s):  
M. Johansson ◽  
C. Rivera ◽  
B. de Foy ◽  
W. Lei ◽  
J. Song ◽  
...  
Keyword(s):  
Wind Speed ◽  
Mexico City ◽  
Cross Section ◽  
Wrf Model ◽  
Wavelength Region ◽  
Optical Absorption Spectroscopy ◽  
Measured Cross Section ◽  
Mobile Measurement ◽  
Good Agreement ◽  
Calculated Flux

Abstract. We here present the result of one mobile measurement using two ground based zenith viewing Differential Optical Absorption Spectroscopy (DOAS) instrument performed in a cross-section of the plume from the MCMA on the 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO2 above the measurement route. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO2 has been calculated from the two measurements and the results compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5–2.2) kg/s of HCHO and 4.4 (4.0–5.0) kg/s of NO2 using the UV instrument and 3.66 (3.63–3.73) kg/s of NO2 using the visible light instrument. The comparison with modeled values from CAMx shows a good agreement for the outflow of both NO2 and HCHO at this occasion.

An effectiveness of training program on COVID-19 among healthcare students: A cross section study

2020 ◽  
Vol 11 (SPL1) ◽  
pp. 1250-1254
Author(s):  
Kurvatteppa Halemani ◽  
Merlin Cheema ◽  
Shabana Khatun ◽  
Yadidya ◽  
Bhumika Singh ◽  
...  
Keyword(s):  
Nursing Students ◽  
Training Program ◽  
Cross Section ◽  
Sampling Technique ◽  
Teaching Session ◽  
Post Intervention ◽  
Post Test ◽  
College Of Nursing ◽  
Novel Coronavirus ◽  
First Time

The pandemic COVID-19 is a highly infected disease caused by a novel coronavirus or SARS-Cov-2. The virus was reported for the first time  December 2019 in, China's Wuhan province. Later the virus has broken down into the world and claimed millions of lives. In India, the disease was reported for the first time in Kerala on 30th January 2020. a cross-section one group pre-test & post-test research design was used among the 40 final year BSc nursing students, College of Nursing SGPGIMS, Lucknow India. Samples were selected based on purposive sampling technique and sample criteria. An instrument, the first tool included demographic characteristics Similarly, second instrument used for knowledge assessment. After pre-test assessment, a teaching session was held at the seminar room, college of nursing SGPGIMS Lucknow, India. Subsequently post assessment was held after intervention.  A total of 40 participants responded to the study. Demographic variables like 30(75%) participants had less than 22 years of age, 22(55%) were girls, 14(35%) families income found INR 10000-15000, and the majority of participants obtained COVID-19 related knowledge from news paper16(40%). A gender was found significant with pretest knowledge, and other variables weren't found significant (P=0.05). Knowledge mean & standard deviation in pre & post-intervention, 11.90±2.16 vs15.82±1.39. The mean difference was found in a pre-test & post-test-1 &post-test-2, 3.9, 5.02, & 1.1, respectively. The effectiveness of the training program was checked by paired t-test -10.20 & -13.93, P=0.00.  The study revealed that the teaching session was efficient in the COVID-19 program among BSc nursing students.

scholarly journals On the shape of cicada’s wing leading-edge cross section

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rachel M. Starkweather ◽  
Svetlana V. Poroseva ◽  
David T. Hanson
Keyword(s):  
Cross Section ◽  
Insect Flight ◽  
Leading Edge ◽  
Flight Performance ◽  
Cross Section Shape ◽  
Section Shape ◽  
First Time

AbstractAn important role that the leading-edge cross-section shape plays in the wing flight performance is well known in aeronautics. However, little is known about the shape of the leading-edge cross section of an insect’s wing and its contribution to remarkable qualities of insect flight. In this paper, we reveal, in the first time, the shape of the leading-edge cross section of a cicada’s wing and analyze its variability along the wing. We also identify and quantify similarities in characteristic dimensions of this shape in the wings of three different cicada species.

scholarly journals Spectral studies of ocean water using DOAS

2007 ◽  
Vol 4 (3) ◽  
pp. 459-489
Author(s):  
M. Vountas ◽  
T. Dinter ◽  
A. Bracher ◽  
J. P. Burrows ◽  
B. Sierk
Keyword(s):  
Spectral Studies ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Technique ◽  
Phytoplankton Absorption ◽  
Visible Wavelengths ◽  
Scanning Imaging ◽  
Atmospheric Trace Gas ◽  
First Time ◽  
Chlorophyll Concentrations

Abstract. Methods enabling the retrieval of oceanic parameter from the space borne instrumentation Scanning Imaging Absorption Spectrometer for Atmospheric ChartographY (SCIAMACHY) using Differential Optical Absorption Spectroscopy (DOAS) are presented. SCIAMACHY onboard ENVISAT measures back scattered solar radiation at a spectral resolution (0.2 to 1.5 nm). The DOAS method was used for the first time to fit modelled Vibrational Raman Scattering (VRS) in liquid water and in situ measured phytoplankton absorption reference spectra to optical depths measured by SCIAMACHY. Spectral structures of VRS and phytoplankton absorption were clearly found in these optical depths. Both fitting approaches lead to consistent results. DOAS fits correlate with estimates of chlorophyll concentrations: low fit factors for VRS retrievals correspond to large chlorophyll concentrations and vice versa; large fit factors for phytoplankton absorption correspond with high chlorophyll concentrations and vice versa. From these results a simple retrieval technique taking advantage of both measurements is shown. First maps of global chlorophyll concentrations were compared to the corresponding MODIS measurements with very promising results. In addition, results from this study will be used to improve atmospheric trace gas DOAS-retrievals from visible wavelengths by including these oceanographic signatures.

scholarly journals Background Error in WRF Model

2020 ◽  
Vol 16 ◽  
Keyword(s):  
Data Assimilation ◽  
Physical Properties ◽  
Covariance Matrix ◽  
Numerical Weather Prediction ◽  
Weather Prediction ◽  
Wrf Model ◽  
Background Error ◽  
Numerical Weather ◽  
Error Covariance ◽  
First Time

WRF model have been tuned and tested over Georgia’s territory for years. First time in Georgia theprocess of data assimilation in Numerical weather prediction is developing. This work presents how forecasterror statistics appear in the data assimilation problem through the background error covariance matrix – B, wherethe variances and correlations associated with model forecasts are estimated. Results of modeling of backgrounderror covariance matrix for control variables using WRF model over Georgia with desired domain configurationare discussed and presented. The modeling was implemented in two different 3DVAR systems (WRFDA andGSI) and results were checked by pseudo observation benchmark cases using also default global and regional BEmatrixes. The mathematical and physical properties of the covariances are also reviewed.

scholarly journals Sources and transformations of particle-bound polycyclic aromatic hydrocarbons in Mexico City

2005 ◽  
Vol 5 (6) ◽  
pp. 12741-12773 ◽  
Author(s):  
L. C. Marr ◽  
K. Dzepina ◽  
J. L. Jimenez ◽  
F. Reisen ◽  
H. L. Bethel ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Mexico City ◽  
Aromatic Hydrocarbons ◽  
Heterogeneous Reactions ◽  
Field Campaign ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Polycyclic Aromatic ◽  
First Time

Abstract. Understanding sources, concentrations, and transformation of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere is important because of their potent mutagenicity and carcinogenicity. The measurement of particle-bound PAHs by three different methods during the Mexico City Metropolitan Area field campaign in April 2003 presents a unique opportunity for characterization of these compounds and assessment of the methods. The three methods are (1) collection and analysis of bulk samples for time-integrated gas- and particle-phase speciation by gas chromatography/mass spectrometry; (2) aerosol photoionization for fast detection of PAHs on particles' surfaces; and (3) aerosol mass spectrometry for fast analysis of size and chemical composition. This research represents the first time aerosol mass spectrometry has been used to measure ambient PAH concentrations and the first time that fast, real-time methods have been used to quantify PAHs alongside traditional filter-based measurements in an extended field campaign. Speciated PAH measurements suggest that motor vehicles and garbage and wood burning are important sources in Mexico City. The diurnal concentration patterns captured by aerosol photoionization and aerosol mass spectrometry are generally consistent. Ambient concentrations typically peak at ~110 ng m−3 during the morning rush hour and rapidly decay due to changes in source activity patterns and dilution as the boundary layer rises, although surface-bound PAH concentrations decay faster. The more rapid decrease in surface versus bulk PAH concentrations during the late morning suggests that freshly emitted combustion-related particles are quickly coated by secondary aerosol material in Mexico City's atmosphere and may also be transformed by heterogeneous reactions.

Quantitative Messung des Elektronenaffinitätskontinuums von Chlor mit dem Stoßwellenrohr / Quantitative Measurement Of The Electron Affinity Continuum Of Chlorine With The Shock Tube

1972 ◽  
Vol 27 (6) ◽  
pp. 989-995 ◽  
Author(s):  
G. Pletsch
Keyword(s):  
Shock Tube ◽  
Cross Section ◽  
Electron Affinity ◽  
Quantitative Measurement ◽  
Wavelength Region ◽  
Electron Attachment ◽  
Absolute Intensity ◽  
Intensity Measurements ◽  
Long Wave ◽  
Chlorine Ion

Abstract Using a mixture of chlorine with krypton the continuous spectrum resulting from electron attachment to chlorine atoms is produced in a shock tube. Absolute intensity measurements lead to the detachment cross-section of the negative chlorine ion in the wavelength region between the long-wave threshold at 3434 Å and 2700 Å. The cross-section is compared with known experimental and theoretical values.

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