Monitoring of the temporal evolution of water vapor in the stratosphere of Jupiter with the Odin space telescope between 2002 and 2019

2020 ◽  
Author(s):  
Bilal Benmahi ◽  
Thibault Cavalié ◽  
Michel Dobrijevic ◽  
Nicolas Biver ◽  
Kenneth Bermudez Diaz ◽  
...  
Keyword(s):  
Temporal Evolution ◽  
Line Emission ◽  
Chemical Species ◽  
Eddy Diffusion ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Loss Mechanism ◽  
Space Telescope ◽  
Photochemical Model ◽  
Vertical Eddy

<div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>In July 1994, comet Shoemaker-Levy 9 collided with Jupiter. This has introduced new chemical species into Jupiter’s atmosphere, notably H2O. We observed the disk-averaged emission H2O in Jupiter’s stratosphere at 556.936 GHz between 2002 and 2019 with the Odin space telescope with the initial goal of better constraining vertical eddy mixing (Kzz) in the layers probed by our observations (0.2-5 mbar).</p> <p>The Odin observations show a decrease of about 40% of the line emission from 2002 to 2019. We analyzed these observations by combining a 1D photochemical model with a radiative transfer model to constrain the vertical eddy diffusion Kzz in the stratosphere of Jupiter. We were able to reproduce this decrease by modifying a well-established Kzz profile, in the 0.2 mbar to 5 mbar pressure range. However, the Kzz obtained is incompatible with observations of the main hydrocarbons. We found that even if we increase locally the initial abundances of H2O and CO at impact, the photochemical conversion of H2O and CO to CO2 does not allow us to find the observed decrease of the H2O emission line over time, suggesting that there is another loss mechanism. We propose that auroral chemistry, not accounted for in our model, as a promising candidate to explain the loss of H2O seen by Odin. Modeling the temporal evolution of the chemical species deposited by comet SL9 in the atmosphere of Jupiter with a 2D photochemical model would be the next step in this study.</p> </div> </div> </div>

scholarly journals Monitoring of the evolution of H2O vapor in the stratosphere of Jupiter over an 18-yr period with the Odin space telescope

2020 ◽  
Vol 641 ◽  
pp. A140
Author(s):  
◽  
B. Benmahi ◽  
T. Cavalié ◽  
M. Dobrijevic ◽  
N. Biver ◽  
...  
Keyword(s):  
Pressure Range ◽  
Temporal Evolution ◽  
Line Emission ◽  
Eddy Diffusion ◽  
Space Telescope ◽  
1D Modeling ◽  
The Impact ◽  
Vertical Eddy ◽  
Vertical Eddy Diffusion

Context. The comet Shoemaker-Levy 9 impacted Jupiter in July 1994, leaving its stratosphere with several new species, with water vapor (H2O) among them. Aims. With the aid of a photochemical model, H2O can be used as a dynamical tracer in the Jovian stratosphere. In this paper, we aim to constrain the vertical eddy diffusion (Kzz) at levels where H2O is present. Methods. We monitored the H2O disk-averaged emission at 556.936 GHz with the space telescope between 2002 and 2019, covering nearly two decades. We analyzed the data with a combination of 1D photochemical and radiative transfer models to constrain the vertical eddy diffusion in the stratosphere of Jupiter. Results. Odin observations show us that the emission of H2O has an almost linear decrease of about 40% between 2002 and 2019. We can only reproduce our time series if we increase the magnitude of Kzz in the pressure range where H2O diffuses downward from 2002 to 2019, that is, from ~0.2 mbar to ~5 mbar. However, this modified Kzz is incompatible with hydrocarbon observations. We find that even if an allowance is made for the initially large abundances of H2O and CO at the impact latitudes, the photochemical conversion of H2O to CO2 is not sufficient to explain the progressive decline of the H2O line emission, which is suggestive of additional loss mechanisms. Conclusions. The Kzz we derived from the Odin observations of H2O can only be viewed as an upper limit in the ~0.2 mbar to ~5 mbar pressure range. The incompatibility between the interpretations made from H2O and hydrocarbon observations probably results from 1D modeling limitations. Meridional variability of H2O, most probably at auroral latitudes, would need to be assessed and compared with that of hydrocarbons to quantify the role of auroral chemistry in the temporal evolution of the H2O abundance since the SL9 impacts. Modeling the temporal evolution of SL9 species with a 2D model would naturally be the next step in this area of study.

Whole-Lake Model for the Distribution of Sediment-Derived Chemical Species

1980 ◽  
Vol 37 (3) ◽  
pp. 552-558 ◽  
Author(s):  
R. H. Hesslein
Keyword(s):  
Diffusion Coefficient ◽  
Dissolved Inorganic Carbon ◽  
Chemical Species ◽  
Eddy Diffusion ◽  
Sole Source ◽  
Experimental Lakes Area ◽  
Lake Model ◽  
Eddy Diffusion Coefficient ◽  
Vertical Eddy ◽  
Vertical Eddy Diffusion

The distribution of CH4, ΣCO2, and NH3-N below the thermocline of Lake 227 can be reproduced using a simple numerical model. The model uses a constant vertical eddy diffusion coefficient and assumes the sediments to be the sole source of the chemical species. Analogs dependent on oxygen concentration can effectively represent conditions at the interface of the modeled region and the shallower depths in the lake. The best tit value for the vertical eddy diffusion coefficient is 3.1 × 10−3 cm2∙s−1. This is in good agreement with other independent measurements of this phenomena. The best fit fluxes of CH4, dissolved inorganic carbon and NH3-N are respectively: 13 × 10−3 mol∙m−2∙d−1, 7.5 × 10−3 mol∙m−2∙d−1, and 1.65 × 10−3 mol∙m−2∙d−1. The flux of methane is similar to that found in other small productive northern lakes and the ratio of CH4:ΣCO2 production of 1.73 falls in the range of values established for fermentation of mixed organic materials and sediments. The flux of ΣCO2 is 50–75% of the bicarbonate flux (10–15 × 10−3 mol∙m−2∙d−1) found previously in Linsley Pond, Connecticut.Key words: sediment–water interactions, methane, CO2, and ammonia fluxes, diffusion from sediments, Experimental Lakes Area

First NIR interferometrically resolved high-order Brackett and forbidden Fe lines of a B[e] star: V921 Sco

2019 ◽  
Vol 492 (1) ◽  
pp. 566-571
Author(s):  
Alexander Kreplin ◽  
Stefan Kraus ◽  
Larisa Tambovtseva ◽  
Vladimir Grinin ◽  
Edward Hone
Keyword(s):  
Radiative Transfer ◽  
Thermodynamic Equilibrium ◽  
Spectral Resolution ◽  
Near Infrared ◽  
Local Thermodynamic Equilibrium ◽  
Line Emission ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Shock Excitation ◽  
First Time

ABSTRACT We present near-infrared interferometric AMBER observations of the B[e] binary V921 Sco at low (R ∼ 30) and medium spectral resolution (R∼ 1500) in the K and H bands. Low spectral resolution AMBER data were used to estimate the position of the companion V921 Sco B and confirmed a clockwise movement on sky with respect to the primary of 33° between 2008 and 2012. Our observations resolve for the first time higher order Brackett lines (Br6–Br12). The modelling of the different line transitions revealed a decrease in the size of the line-emitting regions from Br3 to Br12. We are able to reproduce this decrease with a simple radiative transfer model of an equatorial disc in local thermodynamic equilibrium. In addition to the Brackett series, we also resolve permitted and forbidden Fe line emission. Our modelling shows that these lines originate from ∼2 au from the star, corresponding roughly to the measured dust sublimation region. This might indicate that the forbidden line emission arises from shock excitation at the base of a disc wind.

Probing clouds in planets with a simple radiative transfer model: the Jupiter case

2012 ◽  
Vol 33 (6) ◽  
pp. 1611-1624 ◽  
Author(s):  
Iñigo Mendikoa ◽  
Santiago Pérez-Hoyos ◽  
Agustín Sánchez-Lavega
Keyword(s):  
Radiative Transfer ◽  
Radiative Transfer Model ◽  
Transfer Model

scholarly journals A Proof-of-Concept Algorithm for the Retrieval of Total Column Amount of Trace Gases in a Multi-Dimensional Atmosphere

2021 ◽  
Vol 13 (2) ◽  
pp. 270
Author(s):  
Adrian Doicu ◽  
Dmitry S. Efremenko ◽  
Thomas Trautmann
Keyword(s):  
Trace Gases ◽  
Three Dimensional ◽  
Principal Component ◽  
Radiative Transfer Model ◽  
Computational Time ◽  
Transfer Model ◽  
Proof Of Concept ◽  
Discrete Ordinate ◽  
Distribution Method ◽  
Total Column

An algorithm for the retrieval of total column amount of trace gases in a multi-dimensional atmosphere is designed. The algorithm uses (i) certain differential radiance models with internal and external closures as inversion models, (ii) the iteratively regularized Gauss–Newton method as a regularization tool, and (iii) the spherical harmonics discrete ordinate method (SHDOM) as linearized radiative transfer model. For efficiency reasons, SHDOM is equipped with a spectral acceleration approach that combines the correlated k-distribution method with the principal component analysis. The algorithm is used to retrieve the total column amount of nitrogen for two- and three-dimensional cloudy scenes. Although for three-dimensional geometries, the computational time is high, the main concepts of the algorithm are correct and the retrieval results are accurate.

scholarly journals Mapping barrier island soil moisture using a radiative transfer model of hyperspectral imagery from an unmanned aerial system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rehman S. Eon ◽  
Charles M. Bachmann
Keyword(s):  
Soil Moisture ◽  
Radiative Transfer ◽  
Moisture Content ◽  
Layer Thickness ◽  
Soil Moisture Content ◽  
Hyperspectral Imagery ◽  
Barrier Island ◽  
Water Layer ◽  
Radiative Transfer Model ◽  
Transfer Model

AbstractThe advent of remote sensing from unmanned aerial systems (UAS) has opened the door to more affordable and effective methods of imaging and mapping of surface geophysical properties with many important applications in areas such as coastal zone management, ecology, agriculture, and defense. We describe a study to validate and improve soil moisture content retrieval and mapping from hyperspectral imagery collected by a UAS system. Our approach uses a recently developed model known as the multilayer radiative transfer model of soil reflectance (MARMIT). MARMIT partitions contributions due to water and the sediment surface into equivalent but separate layers and describes these layers using an equivalent slab model formalism. The model water layer thickness along with the fraction of wet surface become parameters that must be optimized in a calibration step, with extinction due to water absorption being applied in the model based on equivalent water layer thickness, while transmission and reflection coefficients follow the Fresnel formalism. In this work, we evaluate the model in both field settings, using UAS hyperspectral imagery, and laboratory settings, using hyperspectral spectra obtained with a goniometer. Sediment samples obtained from four different field sites representing disparate environmental settings comprised the laboratory analysis while field validation used hyperspectral UAS imagery and coordinated ground truth obtained on a barrier island shore during field campaigns in 2018 and 2019. Analysis of the most significant wavelengths for retrieval indicate a number of different wavelengths in the short-wave infra-red (SWIR) that provide accurate fits to measured soil moisture content in the laboratory with normalized root mean square error (NRMSE)< 0.145, while independent evaluation from sequestered test data from the hyperspectral UAS imagery obtained during the field campaign obtained an average NRMSE = 0.169 and median NRMSE = 0.152 in a bootstrap analysis.

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