ON THE USE OF DIFFERENCE BANDS FOR MODELING SF6 ABSORPTION IN THE 10μm ATMOSPHERIC WINDOW

2016 ◽  
Author(s):  
Mbaye Faye ◽  
Michel Loete ◽  
Vincent Boudon ◽  
P. Roy ◽  
Laurent Manceron
Keyword(s):  
Atmospheric Window

NEW DATA AND ANALYSIS FOR SF6 ABSORPTION MODELLING IN THE 10 MICRON ATMOSPHERIC WINDOW

2018 ◽  
Author(s):  
Laurent Manceron ◽  
P. Roy ◽  
Cyril Richard ◽  
Michel Loete ◽  
Vincent Boudon ◽  
...  
Keyword(s):  
Atmospheric Window

Terahertz Radiators Based on Si~3C-SiC MQW IMPATT Diodes

2020 ◽  
Vol 10 (4) ◽  
pp. 501-506
Author(s):  
Monisha Ghosh ◽  
Arindam Biswas ◽  
Aritra Acharyya
Keyword(s):  
High Frequency ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Noise Performance ◽  
Rf Power ◽  
Drift Diffusion ◽  
Frequency Bands ◽  
Atmospheric Window ◽  
Lower Noise ◽  
Impatt Diodes

Aims:: The potentiality of Multiple Quantum Well (MQW) Impacts Avalanche Transit Time (IMPATT) diodes based on Si~3C-SiC heterostructures as possible terahertz radiators have been explored in this paper. Objective:: The static, high frequency and noise performance of MQW devices operating at 94, 140, and 220 GHz atmospheric window frequencies, as well as 0.30 and 0.50 THz frequency bands, have been studied in this paper. Methods: The simulation methods based on a Self-Consistent Quantum Drift-Diffusion (SCQDD) model developed by the authors have been used for the above-mentioned studies. Results: Thus the noise performance of MQW DDRs will be obviously better as compared to the flat Si DDRs operating at different mm-wave and THz frequencies. Conclusion:: Simulation results show that Si~3C-SiC MQW IMPATT sources are capable of providing considerably higher RF power output with the significantly lower noise level at both millimeter-wave (mm-wave) and terahertz (THz) frequency bands as compared to conventional flat Si IMPATT sources.

scholarly journals Performance simulation of polymer-based nanoparticle and void dispersed photonic structures for radiative cooling

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jay Prakash Bijarniya ◽  
Jahar Sarkar ◽  
Pralay Maiti
Keyword(s):  
Fdtd Method ◽  
Solar Spectrum ◽  
Thermal Infrared ◽  
Performance Estimation ◽  
Radiative Cooling ◽  
Slab Thickness ◽  
Slight Variation ◽  
Performance Simulation ◽  
Atmospheric Window ◽  
Substrate Independent

AbstractPassive radiative cooling is an emerging field and needs further development of material. Hence, the computational approach needs to establish for effective metamaterial design before fabrication. The finite difference time domain (FDTD) method is a promising numerical strategy to study electromagnetic interaction with the material. Here, we simulate using the FDTD method and report the behavior of various nanoparticles (SiO2, TiO2, Si3N4) and void dispersed polymers for the solar and thermal infrared spectrums. We propose the algorithm to simulate the surface emissive properties of various material nanostructures in both solar and thermal infrared spectrums, followed by cooling performance estimation. It is indeed found out that staggered and randomly distributed nanoparticle reflects efficiently in the solar radiation spectrum, become highly reflective for thin slab and emits efficiently in the atmospheric window (8–13 µm) over the parallel arrangement with slight variation. Higher slab thickness and concentration yield better reflectivity in the solar spectrum. SiO2-nanopores in a polymer, Si3N4 and TiO2 with/without voids in polymer efficiently achieve above 97% reflection in the solar spectrum and exhibits substrate independent radiative cooling properties. SiO2 and polymer combination alone is unable to reflect as desired in the solar spectrum and need a highly reflective substrate like silver.

Accurate frequency measurements for H_2O and ^16O_3 in the 119-cm^−1 OH atmospheric window

1997 ◽  
Vol 36 (33) ◽  
pp. 8526 ◽  
Author(s):  
Paolo De Natale ◽  
Luca Lorini ◽  
Massimo Inguscio ◽  
Ira G. Nolt ◽  
Jae H. Park ◽  
...  
Keyword(s):  
Frequency Measurements ◽  
Atmospheric Window

Research on the Influence of Ocean Atmosphere to Infrared Detection

2012 ◽  
Vol 472-475 ◽  
pp. 1698-1701 ◽  
Author(s):  
Yu Chen ◽  
Yunan Hu ◽  
Kun Hu Kou ◽  
Hai Jun Li ◽  
Gang Zhang
Keyword(s):  
Boundary Layer ◽  
Infrared Detection ◽  
Infrared Transmission ◽  
Horizontal Path ◽  
Atmospheric Window ◽  
Ocean Atmosphere ◽  
Slant Path ◽  
Atmospheric Transmittance ◽  
Total Transmittance ◽  
Major Absorption Band

Ocean atmospheric transmittance is an important factor to influence detecting distance of infrared system. The influence efficiency of infrared detection is studied by using modtran, on the basis of studying the character of infrared transmission. Firstly, major absorption band of vapor, carbon dioxide, ozone and vapor continuum and the change of transmittance in boundary layer, troposphere and stratosphere are analyzed. Secondly, atmospheric window transmittance of navy maritime aerosol in horizontal path and slant path is analyzed, and the influence of four types of maritime aerosol is also analyzed for navy maritime aerosol. Lastly, the influence of five model atmospheres to total transmittance is analyzed.

Bio-skin inspired 3D porous cellulose/AlPO4 nano-laminated film with structure-enhanced selective emission for all-day non-power cooling

2021 ◽  
Author(s):  
Shuangjiang Feng ◽  
Yuming Zhou ◽  
Xi Chen ◽  
Shengnan Shi ◽  
Chenghuan Liu ◽  
...  
Keyword(s):  
Radiative Cooling ◽  
Preparation Technology ◽  
Cellulose Films ◽  
Highly Efficient ◽  
Atmospheric Window ◽  
Complex Preparation

Porous cellulose films have been reported as sustainable and highly-efficient non-power radiative cooling (PRC) materials but still challenged by their insufficient atmospheric window (AM) emissivity and complex preparation technology. Herein,...

scholarly journals Frequency of deep convective clouds in the tropical zone from 10 years of AIRS data

2013 ◽  
Vol 13 (21) ◽  
pp. 10795-10806 ◽  
Author(s):  
H. H. Aumann ◽  
A. Ruzmaikin
Keyword(s):  
Brightness Temperature ◽  
Frequency Of Occurrence ◽  
Tropical Zone ◽  
Convective Clouds ◽  
The Past ◽  
Atmospheric Window ◽  
Deep Convective Clouds ◽  
Sst Anomaly ◽  
The Difference ◽  
Global Precipitation

Abstract. Deep convective clouds (DCCs) have been widely studied because of their association with heavy precipitation and severe weather events. Changes in the properties of DCCs are likely in a changing climate. Ten years of data collected by Atmospheric Infrared Sounder (AIRS) allow us to identify decadal trends in frequency of occurrence of DCCs over land and ocean. In the past, DCCs have been identified in the thermal infrared by three methods: (1) thresholds based on the absolute value of an atmospheric window channel brightness temperature; (2) thresholds based on the difference between the brightness temperature in an atmospheric window channel and the brightness temperature centered on a strong water vapor absorption line; and (3) a threshold using the difference between the window channel brightness temperature and the tropopause temperature based on climatology. Simultaneous observations of these infrared identified DCCs with the Advanced Microwave Sounding Unit–Humidity Sounder for Brazil (AMSU-HSB) using 183 GHz water channels provide a statistical correlation with microwave deep convection and overshooting convection. In the past 10 years, the frequency of occurrence of DCCs has decreased for the tropical ocean, while it has increased for tropical land. The area of the tropical zone associated with DCCs is typically much less than 1%. We find that the least frequent, more extreme DCCs show the largest trend in frequency of occurrence, increasing over land and decreasing over ocean. The trends for land and ocean closely balance, such that the DCC frequency changed at an insignificant rate for the entire tropical zone. This pattern of essentially zero trend for the tropical zone, but opposite land/ocean trends, is consistent with measurements of global precipitation. The changes in frequency of occurrence of the DCCs are correlated with the Niño34 index, which defines the sea surface temperature (SST) anomaly in the east-central Pacific. This is also consistent with patterns seen in global precipitation. This suggests that the observed changes in the frequency are part of a decadal variability characterized by shifts in the main tropical circulation patterns, which does not fully balance in the 10-year AIRS data record. The regional correlations and anti-correlations of the DCC frequency anomaly with the Multivariate ENSO Index (MEI) provide a new perspective for the regional analysis of past events, since the SST anomaly in the Nino34 region is available in the form of the extended MEI from 1871.

scholarly journals Atmospheric Lifetimes, Infrared Absorption Spectra, Radiative Forcings and Global Warming Potentials of NF<sub>3</sub> and CFC-115

2016 ◽  
Author(s):  
Anna Totterdill ◽  
Tamás Kovács ◽  
Wuhu Feng ◽  
Sandip Dhomse ◽  
Christopher J. Smith ◽  
...  
Keyword(s):  
Global Warming ◽  
Cross Sections ◽  
Infrared Absorption ◽  
Radiative Forcing ◽  
Climate Model ◽  
Radiative Forcings ◽  
Atmospheric Window ◽  
Infrared Absorption Spectra ◽  
Global Warming Potentials ◽  
Good Agreement

Abstract. Fluorinated compounds such as NF3 and C2F5Cl (CFC-115) are characterised by very large global warming potentials (GWPs) which result from extremely long atmospheric lifetimes and strong infrared absorptions in the atmospheric window. In this study we have experimentally determined the infrared absorption cross-sections of NF3 and CFC-115, calculated the radiative forcing and efficiency using two radiative transfer models and identified the effect of clouds and stratospheric adjustment. The infrared cross sections are in good agreement with previous measurements, whereas the resulting radiative forcings and efficiencies are, on average, around 10 % larger. A whole atmosphere chemistry-climate model was used to determine the atmospheric lifetimes of NF3 and CFC-115 to be (616 ± 34) years and (492 ± 22) years, respectively. The GWPs for NF3 are estimated to be 14 600, 19 400 and 21 400 over 20, 100 and 500 years, respectively. Similarly, the GWPs for CFC-115 are 6120, 8060 and 8630 over 20, 100 and 500 years, respectively.

scholarly journals Frequency of deep convective clouds in the tropical zone from ten years of AIRS data

2013 ◽  
Vol 13 (4) ◽  
pp. 10009-10047
Author(s):  
H. H. Aumann ◽  
A. Ruzmaikin
Keyword(s):  
Water Vapor ◽  
Brightness Temperature ◽  
Frequency Of Occurrence ◽  
Tropical Zone ◽  
Convective Clouds ◽  
Atmospheric Window ◽  
Deep Convective Clouds ◽  
Sst Anomaly ◽  
The Difference ◽  
Global Precipitation

Abstract. Deep Convective Clouds (DCC) have been widely studied because of their association with heavy precipitation and severe weather events. To identify DCC with Atmospheric Infrared Sounder (AIRS) data we use three types of thresholds: (1) thresholds based on the absolute value of an atmospheric window channel brightness temperature; (2) thresholds based on the difference between the brightness temperature in an atmospheric window channel and the brightness temperature centered on a strong water vapor absorption line; and (3) a threshold using the difference between the window channel brightness temperature and the tropopause temperature based on climatology. We find that DCC identified with threshold (2) (referred to as DCCw4) cover 0.16% of the area of the tropical zone and 72% of them are identified as deep convective, 39% are overshooting based on simultaneous observations with the Advanced Microwave Sounding Unit-HSB (AMSU-HSB) 183 GHz water vapor channels. In the past ten years the frequency of occurrence of DCC decreased for the tropical ocean, while it increased for tropical land. The land increase-ocean decrease closely balance, such that the DCC frequency changed at an insignificant rate for the entire tropical zone. This pattern of essentially zero trend for the tropical zone, but opposite land/ocean trends, is consistent with measurements of global precipitation. The changes in frequency of occurrence of the DCC are correlated with the Niño34 index, which defines the SST anomaly in the East-Central Pacific. This is also consistent with patterns seen in global precipitation. This suggests that the observed changes in the frequency are part of a decadal variability characterized by shifts in the main tropical circulation patterns, which does not fully balance in the ten year AIRS data record. The regional correlations and anti-correlations of the DCC frequency anomaly with the Multivariate ENSO Index (MEI) provides a new perspective for the regional analysis of past events, since the SST anomaly in the Nino34 region is available in the form of the extended MEI since 1871. Depending on the selected threshold, the frequency of DCC in the tropical zone ranges from 0.06% to 0.8% of the area. We find that the least frequent, more extreme DCC also show the largest trend in frequency, increasing over land, decreasing over ocean. This finding fits into the framework of how weather extremes respond to climate change.

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