scholarly journals Modeling of Nonlocal Thermodynamic Equilibrium Effects in the Classical and Principal Component-Based Version of the RTTOV Fast Radiative Transfer Model

2018 ◽  
Vol 123 (11) ◽  
pp. 5741-5761 ◽  
Author(s):  
Marco Matricardi ◽  
Manuel López-Puertas ◽  
Bernd Funke
Keyword(s):  
Radiative Transfer ◽  
Thermodynamic Equilibrium ◽  
Principal Component ◽  
Radiative Transfer Model ◽  
Transfer Model

scholarly journals kCARTA: a fast pseudo line-by-line radiative transfer algorithm with analytic Jacobians, fluxes, nonlocal thermodynamic equilibrium, and scattering for the infrared

2020 ◽  
Vol 13 (1) ◽  
pp. 323-339 ◽  
Author(s):  
Sergio DeSouza-Machado ◽  
L. Larrabee Strow ◽  
Howard Motteler ◽  
Scott Hannon
Keyword(s):  
Radiative Transfer ◽  
Thermodynamic Equilibrium ◽  
Local Thermodynamic Equilibrium ◽  
Singular Value ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Clear Sky ◽  
Non Local ◽  
Value Decomposition ◽  
Current Database

Abstract. A fast pseudo-monochromatic radiative transfer package using a singular value decomposition (SVD) compressed atmospheric optical depth database has been developed, primarily for simulating radiances from hyperspectral sounding instruments (resolution ≥0.1 cm−1). The package has been tested extensively for clear-sky radiative transfer cases, using field campaign data and satellite instrument data. The current database uses HITRAN 2016 line parameters and is primed for use in the spectral region spanning 605 to 2830 cm−1. Optical depths for other spectral regions (15–605 and 2830–45 000 cm−1) can also be generated for use by kCARTA. The clear-sky radiative transfer model computes the background thermal radiation quickly and accurately using a layer-varying diffusivity angle at each spectral point; it takes less than 30 s (on a 2.8 GHz core using four threads) to complete a radiance calculation spanning the infrared. The code can also compute non-local thermodynamic equilibrium effects for the 4 µm CO2 region, as well as analytic temperature, gas and surface Jacobians. The package also includes flux and heating rate calculations and an interface to an infrared scattering model.

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.

scholarly journals Assessment of Shortwave Infrared Sea Surface Reflection and Nonlocal Thermodynamic Equilibrium Effects in the Community Radiative Transfer Model Using IASI Data

2013 ◽  
Vol 30 (9) ◽  
pp. 2152-2160 ◽  
Author(s):  
Yong Chen ◽  
Yong Han ◽  
Paul van Delst ◽  
Fuzhong Weng
Keyword(s):  
Radiative Transfer ◽  
Data Assimilation ◽  
Thermodynamic Equilibrium ◽  
Weather Prediction ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Surface Reflection ◽  
Brightness Temperatures ◽  
Temperature Retrieval ◽  
Shortwave Infrared

Abstract The nadir-viewing satellite radiances at shortwave infrared channels from 3.5 to 4.6 μm are not currently assimilated in operational numerical weather prediction data assimilation systems and are not adequately corrected for applications of temperature retrieval at daytime. For satellite observations over the ocean during the daytime, the radiance in the surface-sensitive shortwave infrared is strongly affected by the reflected solar radiance, which can contribute as much as 20.0 K to the measured brightness temperatures (BT). The nonlocal thermodynamic equilibrium (NLTE) emission in the 4.3-μm CO2 band can add a further 10 K to the measured BT. In this study, a bidirectional reflectance distribution function (BRDF) is developed for the ocean surface and an NLTE radiance correction scheme is investigated for the hyperspectral sensors. Both effects are implemented in the Community Radiative Transfer Model (CRTM). The biases of CRTM simulations to Infrared Atmospheric Sounding Interferometer (IASI) observations and the standard deviations of the biases are greatly improved during daytime (about a 1.5-K bias for NLTE channels and a 0.3-K bias for surface-sensitive shortwave channels) and are very close to the values obtained during the night. These improved capabilities in CRTM allow for effective uses of satellite data at short infrared wavelengths in data assimilation systems and in atmospheric soundings throughout the day and night.

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