scholarly journals Horizontally Oriented Plates in Clouds

2004 ◽  
Vol 61 (23) ◽  
pp. 2888-2898 ◽  
Author(s):  
François-Marie Bréon ◽  
Bérengère Dubrulle
Keyword(s):  
Atmospheric Turbulence ◽  
Tilt Angle ◽  
Signal Amplitude ◽  
In Situ Observation ◽  
Horizontal Plate ◽  
Specular Reflectance ◽  
Aerodynamic Model ◽  
The Earth ◽  
The Impact

Abstract Horizontally oriented plates in clouds generate a sharp specular reflectance signal in the glint direction, often referred to as “subsun.” This signal (amplitude and width) may be used to analyze the relative area fraction of oriented plates in the cloud-top layer and their characteristic tilt angle to the horizontal. Use is made of spaceborne measurements from the Polarization and Directionality of the Earth Reflectances (POLDER) instrument to provide a statistical analysis of these parameters. More than half of the clouds show a detectable maximum reflectance in the glint direction, although this maximum may be rather faint. The typical effective fraction (area weighted) of oriented plates in clouds lies between 10−3 and 10−2. For those oriented plates, the characteristic tilt angle is less than 1° in most cases. These low fractions imply that the impact of oriented plates on the cloud albedo is insignificant. The largest proportion of clouds with horizontally oriented plates is found in the range 500– 700 hPa, in agreement with typical in situ observation of plates in clouds. A simple aerodynamic model is proposed that accounts for the orienting torque of the flow as the plate falls under its own gravity and the disorienting effects of Brownian motion and atmospheric turbulence. The model indicates that the horizontal plate diameters are in the range 0.1 to a few millimeters. For such sizes, Brownian forces have a negligible impact on the plate orientation. On the other hand, typical levels of atmospheric turbulence lead to tilt angles that are similar to those estimated from the glint observation.

An Overview of Maritime Transportation Dynamics-Mobilization and Livelihood in Galápagos Islands

2021 ◽  
pp. 52-90
Author(s):  
María Belén Arteaga-Custode ◽  
Claudia Fernanda Betancourt-Ruiz ◽  
María Serena López-Donoso ◽  
Sophia Veronique Nieto-Vasco ◽  
Carolina Stefanía Pantoja-Cabrera ◽  
...  
Keyword(s):  
Relevant Information ◽  
Population Based ◽  
Galapagos Islands ◽  
Maritime Transportation ◽  
Floating Population ◽  
In Situ Observation ◽  
Galápagos Islands ◽  
The Impact ◽  
Official Sources

The Galápagos Islands are one of the biggest marine reserves in the world, home to a complex dynamic between its inhabitants, tourists, and biodiversity. Therefore, control over the logistics surrounding the resulting human mobilization process is fundamental to minimize the impact on the Islands' natural resources. This research gathers relevant information regarding the operation of the maritime transportation system of the islands and the waste management of its floating population based on official sources as well as in-situ observation. This chapter includes three sections with the purpose of maximizing the range of information analyzed. The first section covers the maritime cargo transportation from the continent to the islands. The second one covers the transportation of people between the islands, and the third covers the transportation and management of waste produced by each island. The information covers the institutions and policies that govern each of the systems considered and can serve to optimize the transportation logistics of the Galápagos Islands.

scholarly journals BAECC: A Field Campaign to Elucidate the Impact of Biogenic Aerosols on Clouds and Climate

2016 ◽  
Vol 97 (10) ◽  
pp. 1909-1928 ◽  
Author(s):  
Tuukka Petäjä ◽  
Ewan J. O’Connor ◽  
Dmitri Moisseev ◽  
Victoria A. Sinclair ◽  
Antti J. Manninen ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Numerical Models ◽  
Cloud Formation ◽  
In Situ Observation ◽  
Forest Environment ◽  
Surface Precipitation ◽  
Biogenic Aerosols ◽  
Boreal Environment ◽  
The Impact

Abstract During Biogenic Aerosols—Effects on Clouds and Climate (BAECC), the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) Program deployed the Second ARM Mobile Facility (AMF2) to Hyytiälä, Finland, for an 8-month intensive measurement campaign from February to September 2014. The primary research goal is to understand the role of biogenic aerosols in cloud formation. Hyytiälä is host to the Station for Measuring Ecosystem–Atmosphere Relations II (SMEAR II), one of the world’s most comprehensive surface in situ observation sites in a boreal forest environment. The station has been measuring atmospheric aerosols, biogenic emissions, and an extensive suite of parameters relevant to atmosphere–biosphere interactions continuously since 1996. Combining vertical profiles from AMF2 with surface-based in situ SMEAR II observations allows the processes at the surface to be directly related to processes occurring throughout the entire tropospheric column. Together with the inclusion of extensive surface precipitation measurements and intensive observation periods involving aircraft flights and novel radiosonde launches, the complementary observations provide a unique opportunity for investigating aerosol–cloud interactions and cloud-to-precipitation processes in a boreal environment. The BAECC dataset provides opportunities for evaluating and improving models of aerosol sources and transport, cloud microphysical processes, and boundary layer structures. In addition, numerical models are being used to bridge the gap between surface-based and tropospheric observations.

scholarly journals Muses-C as a Benchmark Mission for the S-Type Asteroid Group

2005 ◽  
Vol 13 ◽  
pp. 729-729
Author(s):  
Akira Fujiwara ◽  
Masanao Abe ◽  
Hajime Yano
Keyword(s):  
Spectroscopic Data ◽  
Near Infrared ◽  
In Situ Observation ◽  
Surface Material ◽  
Surface Sampling ◽  
X Ray ◽  
The Earth ◽  
Near Infrared Spectra ◽  
Asteroid Surface

MUSES-C is launched in May 2003, and arrives in the vicinity of a near-Earth asteroid (25143)1998 SF36 in June 2005. The spectral type is S and its diameter is 300-600 m. During four months stay multi-band imaging, near-infrared spectra, and X-ray spectra will be taken at the nominal altitude of about 6km above the asteroid surface.. Sampling of the surface material will be made at two different locations. The total mass collected will be about 1 g. A miniature hopping lander on which imaging cameras are boarded will be dropped onto the surface. The sample will be returned to the earth in June 2007. These methods, the close-up global observation from the spacecraft, in situ observation from the lander, and detailed analysis of the returned sample, can, as well as ground-based observation of the targeted asteroid, provide information of surface material distribution in various scales, and also provide powerful benchmarks to interpretation of spectroscopic data obtained through ground-based observation of S-type asteroids.

Analysis of the impact of biomass burning emissions on global ozone production in the upper troposphere with MOCAGE CTM and IAGOS airborne data.

2020 ◽  
Author(s):  
Martin Cussac ◽  
Virginie Marécal ◽  
Valérie Thouret ◽  
Béatrice Josse
Keyword(s):  
Significant Role ◽  
Biomass Burning ◽  
Transport Model ◽  
Chemical Species ◽  
Ozone Production ◽  
In Situ Observation ◽  
Transport Pathway ◽  
Upper Troposphere ◽  
The Impact

<p>The UTLS (Upper Troposphere/Lower Stratosphere) is a key layer of the atmosphere as its chemical composition impacts both the troposphere and the stratosphere, and therefore plays a significant role in the climate system. Ozone at this altitude for instance plays a great role on surface temperature. Unlike in the stratosphere; it can be produced from the photolysis of precursors originating in the troposphere; mainly nitrous oxides (NO<sub>x</sub>) and carbon monoxide (CO) at this pressure range. Biomass burning emissions in particular are likely to play a significant role in the quantities of these species in the upper troposphere and thus impacting ozone balance. This effect is investigated thanks to the global chemistry transport model MOCAGE. Because of the strong vertical gradients in this layer of the atmosphere, well resolved in-situ observation dataset are valuable for model evaluation. As of measurements used to validate MOCAGE results, IAGOS in-situ measurements from equipped commercial aircraft were chosen for their fine vertical resolution as well as their wide geographical coverage. Using both of these tools, upper tropospheric air composition is studied, with a focus on ozone precursors and production linked to biomass burning emissions.</p><p>Firstly is investigated the direct impact of biomass burning emissions on CO concentration in the upper troposphere, as it is both a good tracer of wildfire plumes in the atmosphere and it plays a role in the upper troposphere chemical balance. For this purpose MOCAGE simulations spaning over the year of 2013 where biomass burning emissions were turned on and off are compared to estimate a contribution to upper tropospheric CO. These simulations were validated using all the available data from the IAGOS database. It was found that biomass burning impacted CO levels globally, with the strongest enhancement happening above the most emitting areas (equatorial Africa and the Boreal forests). The importance of a fast vertical transport pathway above the fires was also highlighted with the possible occurrence of pyroconvection in addition to deep convection. Secondly, other chemical species related to ozone production were looked upon. Peroxyacetyl Nitrates (PAN) for instance were found to be impacted by biomass burning as it is a product of NOx oxidation as well as the main "reservoir" specie for NOx in the upper troposphere. Ultimately, ozone production resulting from biomass burning emissions is investigated, both in biomass burning plumes encountered by IAGOS aircraft, and on a more global scale using the MOCAGE simulations.</p>

On the interaction of interplanetary shocks and solar wind turbulence

2021 ◽  
Author(s):  
Alexander Pitna ◽  
Jana Šafránková ◽  
Zdeněk Němeček
Keyword(s):  
Leading Edge ◽  
In Situ Observation ◽  
Interplanetary Shocks ◽  
Collisionless Shocks ◽  
Turbulent Dissipation ◽  
Turbulent Fluctuations ◽  
The Earth ◽  
Downstream Region ◽  
Fluctuation Energy

<p>The propagation of collisionless shocks through the turbulent magnetized plasmas has been investigated for decades. The processes connected with the formation and propagation of Interplanetary (IP) shocks play a key role in the acceleration of particles and in the coupling to the Earth’s magnetosphere. However, many aspects of the interactions are poorly understood, e.g., the regime of turbulence in downstream/upstream medium, heating of the downstream plasma via turbulent dissipation, etc. Recently, a few authors have addressed the nature of fluctuations within the downstream regions of IP shocks and sheaths of ICMEs. In general, they have found that an IP shock enhances the fluctuation energy within the downstream plasma. Consequently, this should lead to the enhanced heating of the shocked plasma. In this study, we investigate whether the downstream region exhibits such a heating. In the analysis, we stress that the downstream region (in situ observation by a spacecraft) of an IP shock is an evolutionary record of the shocked plasma, i.e., the leading edge of a sheath is plasma that has been just shocked, while the plasma recorded 1 hour after the shock passage has been shocked roughly 5–6 hours earlier, on average. We illustrate this point investigating the relation of the enhanced levels of turbulent fluctuations by the IP shocks and the temperature evolution in the downstream plasma. Preliminary results suggest that the level of enhanced fluctuations affects the temperature profile in this region.</p>

scholarly journals In situ observation of the impact of hydrogen bubbles in Al–Cu melt on directional dendritic solidification

2021 ◽  
Vol 56 (13) ◽  
pp. 8225-8242
Author(s):  
T. Werner ◽  
M. Becker ◽  
J. Baumann ◽  
C. Pickmann ◽  
L. Sturz ◽  
...  
Keyword(s):  
Solidification Front ◽  
Bubble Diameter ◽  
Alloy System ◽  
Local Variation ◽  
Bubble Nucleation ◽  
In Situ Observation ◽  
Cu Alloy ◽  
Solidification Speed ◽  
The Impact

AbstractMuch research has already been focused on the solid-bubble interaction in the interdendritic space for solidifying materials. However, commonly, bubble nucleation is not limited to the mushy zone but also occurs in the liquid melt. In the present research on an Al-$$10 \, \%\mathrm {wt. \,}$$ 10 % wt . Cu alloy, the interaction between these bubbles and the approaching solidification front becomes apparent under in situ X-radiography and allows for new insights into the influence of bubbles on the solidifying microstructure. The observed effects comprise bulging of the solidification front toward the bubble, bending of dendrites in front of the bubble, coronal outgrowths surrounding the bubbles, as well as bubble growth, bubble pushing, and bubble eruption. It is found that for the present Al–Cu alloy, the local variation in the solidification speed can be attributed to the bubbles’ insulating properties. The range of this effect was observed to be up to $$900 \,\upmu \text {m}$$ 900 μ m , depending on the bubble diameter, locally increasing solidification speed by up to $$350 \, \%$$ 350 % . The influences of Marangoni vortices and coronal nucleation of misoriented dendrites around bubbles on the homogeneity of the microstructure are discussed. A comparison with experiments on model alloys and simulations from various other studies highlights the similarities and differences to this metallic alloy system.

scholarly journals Observation Impact Assessment on the Prediction of the Earth System Dynamics Using the Adjoint-Based Method

2018 ◽  
Vol 6 (61) ◽  
pp. 5-28
Author(s):  
Peter Steinle ◽  
Chris Tingwell ◽  
Sergei Soldatenko
Keyword(s):  
Earth System ◽  
Initial State ◽  
Future State ◽  
The Earth ◽  
Observation Network ◽  
Australian Community ◽  
Accuracy Of Prediction ◽  
The Impact

Mathematical models of the Earth system and its components represent one of the most powerful and effective instruments applied to explore the Earth system's behaviour in the past and present, and to predict its future state considering external influence. These models are critically reliant on a large number of various observations (in situ and remotely sensed) since the prediction accuracy is determined by, amongst other things, the accuracy of the initial state of the system in question, which, in turn, is defined by observational data provided by many different instrument types. The development of an observing network is very costly, hence the estimation of the effectiveness of existing observation network and the design of a prospective one, is very important. The objectives of this paper are (1) to present the adjoint-based approach that allows us to estimate the impact of various observations on the accuracy of prediction of the Earth system and its components, and (2) to illustrate the application of this approach to two coupled low-order chaotic dynamical systems and to the ACCESS (Australian Community Climate and Earth System Simulator) global model used operationally in the Australian Bureau of Meteorology. The results of numerical experiments show that by using the adjoint-based method it is possible to rank the observations by the degree of their importance and also to estimate the influence of target observations on the quality of predictions.

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