scholarly journals Applications of the Advanced Radiative Transfer Modeling System (ARMS) to Characterize the Performance of Fengyun–4A/AGRI

2021 ◽  
Vol 13 (16) ◽  
pp. 3120
Author(s):  
Fei Tang ◽  
Xiaoyong Zhuge ◽  
Mingjian Zeng ◽  
Xin Li ◽  
Peiming Dong ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Strong Dependence ◽  
Final Analysis ◽  
Analysis Data ◽  
Water Vapor Absorption ◽  
Absorption Bands ◽  
Geostationary Meteorological Satellite ◽  
Environmental Prediction ◽  
Radiative Transfer Modeling ◽  
Ir Bands

This study applies the Advanced Radiative Transfer Modeling System (ARMS), which was developed to accelerate the uses of Fengyun satellite data in weather, climate, and environmental applications in China, to characterize the biases of seven infrared (IR) bands of the Advanced Geosynchronous Radiation Imager (AGRI) onboard the Chinese geostationary meteorological satellite, Fengyun–4A. The AGRI data are quality controlled to eliminate the observations affected by clouds and contaminated by stray lights during the mid–night from 1600 to 1800 UTC during spring and autumn. The mean biases, computed from AGRI IR observations and ARMS simulations from the National Center for Environmental Prediction (NCEP) Final analysis data (FNL) as input, are within −0.7–1.1 K (0.12–0.75 K) for all seven IR bands over the oceans (land) under clear–sky conditions. The biases show seasonal variation in spatial distributions at bands 11–13, as well as a strong dependence on scene temperatures at bands 8–14 and on satellite zenith angles at absorption bands 9, 10, and 14. The discrepancies between biases estimated using FNL and the European Center for Medium–Range Weather Forecasts Reanalysis–5 (ERA5) are also discussed. The biases from water vapor absorption bands 9 and 10, estimated using ERA5 over ocean, are smaller than those from FNL. Such discrepancies arise from the fact that the FNL data are colder (wetter) than the ERA5 in the middle troposphere (upper–troposphere).

Assessment of the Quality of MODIS Cloud Products from Radiance Simulations

2009 ◽  
Vol 48 (8) ◽  
pp. 1591-1612 ◽  
Author(s):  
Seung-Hee Ham ◽  
Byung-Ju Sohn ◽  
Ping Yang ◽  
Bryan A. Baum
Keyword(s):  
Water Vapor ◽  
Radiative Transfer ◽  
Satellite Observation ◽  
Effective Radius ◽  
Radiative Transfer Model ◽  
Cloud Base ◽  
Transfer Model ◽  
Sufficient Information ◽  
Water Vapor Absorption ◽  
Absorption Bands

Abstract Observations made by the Moderate Resolution Imaging Spectroradiometer (MODIS), the Atmospheric Infrared Sounder (AIRS), the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), and CloudSat are synergistically used to evaluate the accuracy of theoretical simulations of the radiances at the top of the atmosphere (TOA). Specifically, TOA radiances of 15 MODIS bands are simulated for overcast, optically thick, and single-phase clouds only over the ocean from 60°N to 60°S, corresponding to about 12% of all the MODIS cloud observations. Plane parallel atmosphere is assumed in the simulation by restricting viewing/solar zenith angle to be less than 40°. Input data for the radiative transfer model (RTM) are obtained from the operational MODIS-retrieved cloud optical thickness, effective radius, and cloud-top pressure (converted to height) collocated with the AIRS-retrieved temperature and humidity profiles. In the RTM, ice cloud bulk scattering properties, based on theoretical scattering computations and in situ microphysical data, are used for the radiative transfer simulations. The results show that radiances for shortwave bands between 0.466 and 0.857 μm appear to be very accurate with errors on the order of 5%, implying that MODIS cloud parameters provide sufficient information for the radiance simulations. However, simulated radiances for the 1.24-, 1.63-, and 3.78-μm bands do not agree as well with the observed radiances as a result of the use of a single effective radius for a cloud layer that may be vertically inhomogeneous in reality. Furthermore, simulated radiances for the water vapor absorption bands located near 0.93 and 1.38 μm show positive biases, whereas the window bands from 8.5 to 12 μm show negative biases compared to observations, likely due to the less accurate estimate of cloud-top and cloud-base heights. It is further shown that the accuracies of the simulations for water vapor and window bands can be substantially improved by accounting for the vertical cloud distribution provided by the CALIPSO and CloudSat measurements.

scholarly journals Can turbulence within the field of view cause significant biases in radiative transfer modeling at the 183 GHz band?

2018 ◽  
Vol 11 (12) ◽  
pp. 6409-6417 ◽  
Author(s):  
Xavier Calbet ◽  
Niobe Peinado-Galan ◽  
Sergio DeSouza-Machado ◽  
Emil Robert Kursinski ◽  
Pedro Oria ◽  
...  
Keyword(s):  
Water Vapor ◽  
Radiative Transfer ◽  
Field Of View ◽  
Uniform Field ◽  
Water Vapor Absorption ◽  
Air Turbulence ◽  
Vapor Absorption ◽  
High Turbulence ◽  
Novel Method ◽  
Radiative Transfer Modeling

Abstract. The hypothesis whether turbulence within the passive microwave sounders field of view can cause significant biases in radiative transfer modeling at the 183 GHz water vapor absorption band is tested. A novel method to calculate the effects of turbulence in radiative transfer modeling is presented. It is shown that the turbulent nature of water vapor in the atmosphere can be a critical component of radiative transfer modeling in this band. Radiative transfer simulations are performed comparing a uniform field with a turbulent one. These comparisons show frequency dependent biases which can be up to several kelvin in brightness temperature. These biases can match experimentally observed biases, such as the ones reported in Brogniez et al. (2016). Our simulations show that those biases could be explained as an effect of high-intensity turbulence in the upper troposphere. These high turbulence phenomena are common in clear air turbulence, storm or cumulus cloud situations.

scholarly journals Odin/OSIRIS observations of stratospheric NO<sub>3</sub> through sunrise and sunset

2008 ◽  
Vol 8 (18) ◽  
pp. 5529-5534 ◽  
Author(s):  
C. A. McLinden ◽  
C. S. Haley
Keyword(s):  
Radiative Transfer ◽  
Current Knowledge ◽  
Strong Dependence ◽  
Rapid Evolution ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Spectral Fitting ◽  
Infrared Imager ◽  
Fitting In ◽  
Radiative Transfer Modeling

Abstract. The nitrate radical (NO3) has been detected in visible limb-scattered spectra measured by the Optical Spectrograph and InfraRed Imager System (OSIRIS) on-board the Odin satellite when observing at large solar zenith angles (91–97°). Apparent slant column densities of NO3 at tangent heights between 10 and 45 km are derived via spectral fitting in the 610–680 nm window. Using observations from multiple scans spanning solar zenith angles of 91–97°, the rapid evolution of NO3 through sunrise and sunset can be traced. Slant column densities are found to be generally consistent with those simulated using a radiative transfer model with coupled photochemistry. In addition, a strong dependence of NO3 with temperature is observed. These results indicate that our current knowledge of NO3 photochemistry is generally consistent with OSIRIS observations to within the limitations of the radiative transfer modeling. Furthermore, they reveal that OSIRIS possesses signal-to-noise sufficient to make useful measurements of scattered sunlight out to solar zenith angles of 91–97° and suggest the possibility of retrieving profile information for NO3 and other species at large solar zenith angles.

scholarly journals Fast Hyper-Spectral Radiative Transfer Model Based on the Double Cluster Low-Streams Regression Method

2021 ◽  
Vol 13 (3) ◽  
pp. 434
Author(s):  
Ana del Águila ◽  
Dmitry S. Efremenko
Keyword(s):  
Radiative Transfer ◽  
Single Scattering ◽  
Atmospheric Composition ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Absorption Bands ◽  
Acceleration Techniques ◽  
Scattering Approximation ◽  
Fine Resolution ◽  
Single Scattering Approximation

Fast radiative transfer models (RTMs) are required to process a great amount of satellite-based atmospheric composition data. Specifically designed acceleration techniques can be incorporated in RTMs to simulate the reflected radiances with a fine spectral resolution, avoiding time-consuming computations on a fine resolution grid. In particular, in the cluster low-streams regression (CLSR) method, the computations on a fine resolution grid are performed by using the fast two-stream RTM, and then the spectra are corrected by using regression models between the two-stream and multi-stream RTMs. The performance enhancement due to such a scheme can be of about two orders of magnitude. In this paper, we consider a modification of the CLSR method (which is referred to as the double CLSR method), in which the single-scattering approximation is used for the computations on a fine resolution grid, while the two-stream spectra are computed by using the regression model between the two-stream RTM and the single-scattering approximation. Once the two-stream spectra are known, the CLSR method is applied the second time to restore the multi-stream spectra. Through a numerical analysis, it is shown that the double CLSR method yields an acceleration factor of about three orders of magnitude as compared to the reference multi-stream fine-resolution computations. The error of such an approach is below 0.05%. In addition, it is analysed how the CLSR method can be adopted for efficient computations for atmospheric scenarios containing aerosols. In particular, it is discussed how the precomputed data for clear sky conditions can be reused for computing the aerosol spectra in the framework of the CLSR method. The simulations are performed for the Hartley–Huggins, O2 A-, water vapour and CO2 weak absorption bands and five aerosol models from the optical properties of aerosols and clouds (OPAC) database.

scholarly journals Microwave temperature and pressure measurements with the Odin satellite: I. Observational method

2002 ◽  
Vol 80 (4) ◽  
pp. 443-454 ◽  
Author(s):  
J R Pardo ◽  
M Ridal ◽  
D Murtagh ◽  
J Cernicharo
Keyword(s):  
Radiative Transfer ◽  
Outer Space ◽  
Atmospheric Temperature ◽  
Upper Atmosphere ◽  
Operational Mode ◽  
Altitude Range ◽  
Molecular Lines ◽  
Temperature And Pressure ◽  
Radiative Transfer Modeling ◽  
Temperature Vertical Profile

The Odin satellite is equipped with millimetre and sub-millimetre receivers for observations of several molecular lines in the middle and upper atmosphere of our planet (~25–100 km, the particular altitude range depending on the species) for studies in dynamics, chemistry, and energy transfer in these regions. The same receivers are also used to observe molecules in outer space, this being the astrophysical share of the project. Among the atmospheric lines that can be observed, we find two corresponding to molecular oxygen (118.75 GHz and 487.25 GHz). These lines can be used for retrievals of the atmospheric temperature vertical profile. In this paper, we describe the radiative-transfer modeling for O2 in the middle and upper atmosphere that we will use as a basis for the retrieval algorithms. Two different observation modes have been planned for Odin, the three-channel operational mode and a high-resolution mode. The first one will determine the temperature and pressure on an operational basis using the oxygen line at 118.75 GHz, while the latter can be used for measurements of both O2 lines, during a small fraction of the total available time for aeronomy, aimed at checking the particular details of the radiative transfer near O2 lines at very high altitudes (>70 km). The Odin temperature measurements are expected to cover the altitude range ~30–90 km. PACS Nos.: 07.57Mj, 94.10Dy, 95.75Rs

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