scholarly journals DOAS measurements of NO<sub>2</sub> from an ultralight aircraft during the Earth Challenge expedition

2012 ◽  
Vol 5 (1) ◽  
pp. 1947-1984
Author(s):  
A. Merlaud ◽  
M. Van Roozendael ◽  
J. van Gent ◽  
C. Fayt ◽  
J. Maes ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Large Field ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Satellite Measurements ◽  
Po Valley ◽  
The Earth ◽  
Set Up ◽  
The One ◽  
Homogeneous Data

Abstract. We report on airborne Differential Optical Absorption Spectroscopy (DOAS) measurements of NO2 tropospheric columns above South Asia, Arabic peninsula, North Africa, and Italy in November and December 2009. The DOAS instrument was installed on an ultralight aircraft involved in the Earth Challenge project, an expedition of seven pilots flying on four ultralight aircraft between Australia and Belgium. The instrument recorded spectra in limb geometry with a large field-of-view, a set-up which provides a high sensitivity to the boundary layer NO2 while minimizing the uncertainties related to the attitude variations. We compare our measurements with OMI and GOME-2 tropospheric NO2 products when the latter are available. Above Rajasthan and the Po Valley, two areas where the NO2 field is homogeneous, data sets agree very well. Our measurements in this areas are respectively 0.1 ± 0.1 to 2.8 ± 1 × 1015 molec cm−2 and 2.5 ± 0.5 × 1016 molec cm−2. Flying downwind of Riyadh, our NO2 measurements show with a higher spatial resolution than OMI the structure of the megacities'exhaust plume. Moreover, our measurements indicate larger columns (up to 70%) than the one seen by satellites. We also derived tropopsheric columns when no satellite data was available, if it was possible to get information on the visibility from satellite measurements of aerosol optical thickness. The maximum column we measured was above Benghazi, with 5.7 ± 2 × 1016 molec cm−2. This experiment also provides a confirmation for the recent finding of a soil signature above desert.

scholarly journals DOAS measurements of NO<sub>2</sub> from an ultralight aircraft during the Earth Challenge expedition

2012 ◽  
Vol 5 (8) ◽  
pp. 2057-2068 ◽  
Author(s):  
A. Merlaud ◽  
M. Van Roozendael ◽  
J. van Gent ◽  
C. Fayt ◽  
J. Maes ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Large Field ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Ozone Monitoring Instrument ◽  
Satellite Measurements ◽  
Po Valley ◽  
The Earth ◽  
Ozone Monitoring ◽  
Set Up

Abstract. We report on airborne Differential Optical Absorption Spectroscopy (DOAS) measurements of NO2 tropospheric columns above South Asia, the Arabic peninsula, North Africa, and Italy in November and December 2009. The DOAS instrument was installed on an ultralight aircraft involved in the Earth Challenge project, an expedition of seven pilots flying on four ultralight aircraft between Australia and Belgium. The instrument recorded spectra in limb geometry with a large field of view, a set-up which provides a high sensitivity to the boundary layer NO2 while minimizing the uncertainties related to the attitude variations. We compare our measurements with OMI (Ozone Monitoring Instrument) and GOME-2 (Global Ozone Monitoring Experiment 2) tropospheric NO2 products when the latter are available. Above Rajasthan and the Po Valley, two areas where the NO2 field is homogeneous, data sets agree very well. Our measurements in these areas are 0.1 ± 0.1 to 3 ± 1 × 1015 molec cm−2 and 2.6 ± 0.8 × 1016 molec cm−2, respectively. Flying downwind of Riyadh, our NO2 measurements show the structure of the megacity's exhaust plume with a higher spatial resolution than OMI. Moreover, our measurements are larger (up to 40%) than those seen by satellites. We also derived tropospheric columns when no satellite data were available if it was possible to get information on the visibility from satellite measurements of aerosol optical thickness. This experiment also provides a confirmation for the recent finding of a soil signature above desert.

Statistical Uncertainty in Long-Term Distributions of Significant Wave Height

1996 ◽  
Vol 118 (4) ◽  
pp. 284-291 ◽  
Author(s):  
C. Guedes Soares ◽  
A. C. Henriques
Keyword(s):  
Probability Distribution ◽  
Wave Height ◽  
Significant Wave Height ◽  
Data Sets ◽  
Monthly Basis ◽  
Significant Wave ◽  
Fitting Procedure ◽  
The One ◽  
Homogeneous Data

This work examines some aspects involved in the estimation of the parameters of the probability distribution of significant wave height, in particular the homogeneity of the data sets and the statistical methods of fitting a distribution to data. More homogeneous data sets are organized by collecting the data on a monthly basis and by separating the simple sea states from the combined ones. A three-parameter Weibull distribution is fitted to the data. The parameters of the fitted distribution are estimated by the methods of maximum likelihood, of regression, and of the moments. The uncertainty involved in estimating the probability distribution with the three methods is compared with the one that results from using more homogeneous data sets, and it is concluded that the uncertainty involved in the fitting procedure can be more significant unless the method of moments is not considered.

scholarly journals Measurements from mobile surface vehicles during LAPSE-RATE

2020 ◽  
Author(s):  
Gijs de Boer ◽  
Sean Waugh ◽  
Alexander Erwin ◽  
Steven Borenstein ◽  
Cory Dixon ◽  
...  
Keyword(s):  
Layer Structure ◽  
Unmanned Aircraft ◽  
Lapse Rate ◽  
Data Sets ◽  
San Luis Valley ◽  
San Luis ◽  
Remotely Piloted Aircraft ◽  
In Situ Sensors ◽  
Set Up ◽  
The One

Abstract. Between 14 and 20 July 2018, small unmanned aircraft systems (sUAS) were deployed to the San Luis Valley of Colorado (USA) alongside surface-based remote, in-situ sensors, and radiosonde systems as part of the Lower Atmospheric Profiling Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE). The measurements collected as part of LAPSE-RATE targeted quantities related to enhancing our understanding of boundary layer structure, cloud and aerosol properties and surface-atmosphere exchange, and provide detailed information to support model evaluation and improvement work. Additionally, intensive intercomparison between the different unmanned aircraft platforms was completed. The current manuscript describes the observations obtained using three different types of surface-based mobile observing vehicles. These included the University of Colorado Mobile UAS Research Collaboratory (MURC), the National Oceanic and Atmospheric Administration National Severe Storms Laboratory Mobile Mesonet, and two University of Nebraska Combined Mesonet and Tracker (CoMeT) vehicles. Over the one-week campaign, a total of 143 hours of data were collected using this combination of vehicles. The data from these coordinated activities provide detailed perspectives on the spatial variability of atmospheric state parameters (air temperature, humidity, pressure, and wind) throughout the northern half of the San Luis Valley. These data sets have been checked for quality and published to the Zenodo data archive under a specific community set up for LAPSE-RATE (https://zenodo.org/communities/lapse-rate/) and are accessible at no cost by all registered users. The primary dataset DOIs are https://doi.org/10.5281/zenodo.3814765 (CU MURC measurements; de Boer et al., 2020d), https://doi.org/10.5281/zenodo.3738175 (NSSL MM measurements; Waugh, 2020) and https://doi.org/10.5281/zenodo.3838724 (UNL CoMeT measurements; Houston and Erwin., 2020).

scholarly journals Matching and running sensitivity in non-renormalizable inflationary models

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Jacopo Fumagalli ◽  
Marieke Postma ◽  
Melvin van den Bout
Keyword(s):  
Particle Physics ◽  
Higgs Field ◽  
Effective Field ◽  
Large Field ◽  
Tree Level ◽  
Planck Data ◽  
The Standard Model ◽  
Set Up ◽  
The One ◽  
Inflationary Models

Abstract Most of the inflationary models that are in agreement with the Planck data rely on the presence of non-renormalizable operators. If the connection to low energy particle physics is made, the renormalization group (RG) introduces a sensitivity to ultraviolet (UV) physics that can be crucial in determining the inflationary predictions. We analyse this effect for the Standard Model (SM) augmented with non-minimal derivative couplings to gravity. Our set-up reduces to the SM for small values of the Higgs field, and allows for inflation in the opposite large field regime. The one-loop beta functions in the inflationary region are calculated using a covariant approach that properly accounts for the non-trivial structure of the field space manifold. We run the SM parameters from the electroweak to the inflationary scale, matching the couplings of the different effective field theories at the boundary between the two regimes, where we also include threshold corrections that parametrize effects from UV physics. We then compute the spectral index and tensor-to-scalar ratio and find that RG flow corrections can be determinant: a scenario that is ruled out at tree level can be resurrected and vice versa.

scholarly journals Amateur Astronomers and the IAU Central Bureau for Astronomical Telegrams and Minor Planet Center

1988 ◽  
Vol 98 ◽  
pp. 64-76 ◽  
Author(s):  
Brian G. Marsden
Keyword(s):  
Minor Planet ◽  
Central Bureau ◽  
Minor Planets ◽  
X Ray ◽  
The Earth ◽  
International Astronomical ◽  
Set Up ◽  
The One ◽  
Natural Satellites ◽  
To Receive

Of all the sections of the International Astronomical Union the Central Bureau for Astronomical Telegrams is undoubtedly the one that most concerns amateur astronomers. Just about anybody in the world with at least some familiarity with the sky has the potential to discover (or to think he or she has discovered) a comet or nova. If the object is real and sufficiently bright, it is very probably already known. Somebody has to be the first discoverer of every comet or nova, however, and soon after the IAU was established in 1919 it set up the Central Bureau to receive and to disseminate to the astronomical community news of such discoveries. Discoveries of supernovae in other galaxies, natural satellites of the planets, erupting x-ray sources and transient features on the planets are also dealt with by the Central Bureau, which since 1965 has operated at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts. The Central Bureau handles unusual minor planets in the vicinity of the earth, although the thousand or more ordinary minor planets routinely discovered each year (and with which amateurs are being increasingly involved) are more appropriately the province of the Minor Planet Center, set up by the IAU in 1947 and since 1978 also operated at the Smithsonian Astrophysical Observatory. About one-quarter of the subscribers to the various services of the Central Bureau and/or the Minor Planet Center are individual amateur astronomers or organizations of amateurs.

scholarly journals Bjerknes Compensation in a Coupled Global Box Model

2021 ◽  
Author(s):  
Jiaqi Shi ◽  
Haijun Yang
Keyword(s):  
Analytical Solution ◽  
Thermohaline Circulation ◽  
Climate System ◽  
Box Model ◽  
Climate Feedback ◽  
Local Climate ◽  
The Earth ◽  
Set Up ◽  
The One ◽  
Heat And Moisture

Abstract The Earth climate system has an intrinsic mechanism to maintain its energy conservation by impelling opposite changes in meridional ocean and atmosphere heat transports, in response to climate change or variability. This mechanism is briefed as the Bjerknes compensation (BJC). We set up a global coupled two-hemisphere box model in this study, and obtain an analytical solution to the BJC of this system. In the two-hemisphere model, the thermohaline circulation is interhemispheric and parameterized by the density difference between two polar boxes. The symmetric poleward atmosphere heat and moisture transports are considered and parameterized by the temperature gradient between tropical and polar boxes. Different from the BJC in the one-hemisphere box model that depends only on the local climate feedback, the BJC here is determined by both local climate feedback and temperature change. The asymmetric thermohaline circulation leads to a better BJC in the Northern Hemisphere than in the Southern Hemisphere. Furthermore, an analytical solution to the probability of a valid BJC (i.e., negative BJC) is derived, which is determined only by the local climate feedback. The probability of a valid BJC is usually very high under reasonable climate feedback, which is also found to be robust in the real world based on observational data, implying that the Earth climate system maintains it energy balance very well during the past one hundred years.

scholarly journals Report of the IAU Working Group on ‘Nonrigid-Earth Nutation Theory’

2000 ◽  
Vol 180 ◽  
pp. 201-211
Author(s):  
Véronique Dehant
Keyword(s):  
Working Group ◽  
Transfer Functions ◽  
International Astronomical Union ◽  
The Earth ◽  
Independent Information ◽  
International Astronomical ◽  
Rigid Earth ◽  
Set Up ◽  
The One ◽  
Nutation Series

AbstractThe last precession-nutation model adopted by the IAU (International Astronomical Union) in 1980 is the nutation series built on Wahr’s Earth transfer function for the nutations of an oceanless elastic Earth (Wahr, 1979, 1981), and on Kinoshita’s rigid-Earth precession-nutation series (Kinoshita, 1977; Kinoshita et al., 1979). The resulting precession and nonrigid-Earth nutation series have been used since that time and have been compared with observations. This comparison, which has been done by different teams all-over the world, shows that the theoretical series must be improved to meet observational precision. A Working Group (WG) was set up to examine the possibility of adopting a new nonrigid-Earth nutation series and to study the existing possibilities. On the one hand, the rigid-Earth nutation series have been improved (three new series) and the mutual differences have been shown to be less than a few hundreds of microarcseconds. On the other hand, new Earth transfer functions have been derived based on additional physical considerations within the Earth. The problem with these transfer functions however is that there is no reliable, independent information about the geophysical parameters needed to improve a theoretical model. Instead, the discrepancies with the nutation observations themselves are used to infer those parameters. Recent fits of geophysical parameters to the observed nutations have provided a series that is suitable for practical use, and is also a source of important information on the physics of the Earth’s interior. This paper reviews the recent work of the WG and establishes the reasons and criteria for the choice of the new model ‘IAU 2000’ which is proposed for adoption at the next IAU General Assembly.

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

Potential of Palm Oil Empty Fruit Bunch as Biogas Substrate

2019 ◽  
Vol 2 (1) ◽  
pp. 59-64
Author(s):  
Vincentius Vincentius ◽  
Evita H. Legowo ◽  
Irvan S. Kartawiria
Keyword(s):  
Palm Oil ◽  
Fermentation Process ◽  
Biogas Production ◽  
Wastewater Sludge ◽  
Empty Fruit Bunch ◽  
Alternative Source ◽  
The Earth ◽  
The One ◽  
Wet Fermentation ◽  
Water Ratio

Natural gas is a source of energy that comes from the earth which is depleting every day, an alternative source of energy is needed and one of the sources comes from biogas. There is an abundance of empty fruit bunch (EFB) that comes from palm oil plantation that can become a substrate for biogas production. A methodology of fermentation based on Verein Deutscher Ingenieure was used to utilize EFB as a substrate to produce biogas using biogas sludge and wastewater sludge as inoculum in wet fermentation process under mesophilic condition. Another optimization was done by adding a different water ratio to the inoculum mixture. In 20 days, an average of 6gr from 150gr of total EFB used in each sample was consumed by the microbes. The best result from 20 days of experiment with both biogas sludge and wastewater sludge as inoculum were the one added with 150gr of water that produced 2910ml and 2185ml of gas respectively. The highest CH 4 produced achieved from biogas sludge and wastewater sludge with an addition of 150gr of water to the inoculum were 27% and 22% CH 4 respectively. This shows that biogas sludge is better in term of volume of gas that is produced and CH percentage.

Global Warming and Its Multiple Causes

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Romdhane Ben Slama
Keyword(s):  
Global Warming ◽  
Greenhouse Gases ◽  
Greenhouse Effect ◽  
Infrared Radiation ◽  
Fossil Fuels ◽  
Ambient Air ◽  
The Earth ◽  
The One ◽  
Heat Released ◽  
Emission Of Greenhouse Gases

The global warming which preoccupies humanity, is still considered to be linked to a single cause which is the emission of greenhouse gases, CO2 in particular. In this article, we try to show that, on the one hand, the greenhouse effect (the radiative imprisonment to use the scientific term) took place in conjunction with the infrared radiation emitted by the earth. The surplus of CO2 due to the combustion of fossil fuels, but also the surplus of infrared emissions from artificialized soils contribute together or each separately,  to the imbalance of the natural greenhouse effect and the trend of global warming. In addition, another actor acting directly and instantaneously on the warming of the ambient air is the heat released by fossil fuels estimated at 17415.1010 kWh / year inducing a rise in temperature of 0.122 ° C, or 12.2 ° C / century.

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