4.3.4.4 Radiative processes

2005 ◽  
pp. 100-106
Author(s):  
B. Baschek ◽  
M. Scholz
Keyword(s):  
Radiative Processes

scholarly journals Impacts of Ozone Changes in the Tropopause Layer on Stratospheric Water Vapor

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 291
Author(s):  
Jinpeng Lu ◽  
Fei Xie ◽  
Hongying Tian ◽  
Jiali Luo
Keyword(s):  
Water Vapor ◽  
Ozone Depletion ◽  
Climate Model ◽  
Global Climate ◽  
Stratospheric Water Vapor ◽  
Radiative Processes ◽  
Low Latitudes ◽  
Cold Point ◽  
The Impact ◽  
Tropopause Temperature

Stratospheric water vapor (SWV) changes play an important role in regulating global climate change, and its variations are controlled by tropopause temperature. This study estimates the impacts of tropopause layer ozone changes on tropopause temperature by radiative process and further influences on lower stratospheric water vapor (LSWV) using the Whole Atmosphere Community Climate Model (WACCM4). It is found that a 10% depletion in global (mid-low and polar latitudes) tropopause layer ozone causes a significant cooling of the tropical cold-point tropopause with a maximum cooling of 0.3 K, and a corresponding reduction in LSWV with a maximum value of 0.06 ppmv. The depletion of tropopause layer ozone at mid-low latitudes results in cooling of the tropical cold-point tropopause by radiative processes and a corresponding LSWV reduction. However, the effect of polar tropopause layer ozone depletion on tropical cold-point tropopause temperature and LSWV is opposite to and weaker than the effect of tropopause layer ozone depletion at mid-low latitudes. Finally, the joint effect of tropopause layer ozone depletion (at mid-low and polar latitudes) causes a negative cold-point tropopause temperature and a decreased tropical LSWV. Conversely, the impact of a 10% increase in global tropopause layer ozone on LSWV is exactly the opposite of the impact of ozone depletion. After 2000, tropopause layer ozone decreased at mid-low latitudes and increased at high latitudes. These tropopause layer ozone changes at different latitudes cause joint cooling in the tropical cold-point tropopause and a reduction in LSWV. Clarifying the impacts of tropopause layer ozone changes on LSWV clearly is important for understanding and predicting SWV changes in the context of future global ozone recovery.

Radiative processes in glasses in glasses in the system Ba(Po3)2-MgF2-LiF

1984 ◽  
Vol 41 (5) ◽  
pp. 1292-1294
Author(s):  
T. V. Bocharova ◽  
G. O. Karapetyan ◽  
V. D. Khalilev
Keyword(s):  
Radiative Processes

Theoretical studies of excitation dynamics in a peridinin-chlorophyll-protein coupled to a metallic nanoparticle

Open Physics ◽  
2011 ◽  
Vol 9 (2) ◽  
Author(s):  
Mikolaj Schmidt ◽  
Sebastian Mackowski
Keyword(s):  
Energy Transfer ◽  
Metallic Surface ◽  
Energy Transfer Rate ◽  
Metallic Nanoparticle ◽  
Light Harvesting Complex ◽  
Radiative Processes ◽  
Förster Energy Transfer ◽  
Chlorophyll Protein ◽  
Induced Changes ◽  
Excitation Dynamics

AbstractIn this work we study the influence of plasmon excitations on the excitation dynamics within a protein complex embedding two chlorophyll molecules coupled to a gold nanosphere. Small separation between the chlorophylls and metallic nanoparticle allows us to simplify the calculations of the Förster energy transfer rate and non-radiative processes by replacing a spherical nanoparticle with a metallic surface. Our results show modifications of all relevant processes and the energy transfer pathways within the system as well as the radiative processes. Plasmon induced changes result in strong qualitative effects of the fluorescence of the studied light-harvesting complex.

scholarly journals Lyα Emitting Galaxies as a Probe of Reionisation

2014 ◽  
Vol 31 ◽  
Author(s):  
Mark Dijkstra
Keyword(s):  
Rapid Evolution ◽  
Line Emission ◽  
Coherent Scattering ◽  
Neutral Fraction ◽  
Collisional Excitation ◽  
Intergalactic Gas ◽  
Star Forming ◽  
Bolometric Luminosity ◽  
Radiative Processes ◽  
Sudden Reduction

AbstractThe Epoch of Reionization (EoR) represents a milestone in the evolution of our Universe. Star-forming galaxies that existed during the EoR likely emitted a significant fraction ( ~ 5 − 40%) of their bolometric luminosity as Lyα line emission. However, neutral intergalactic gas that existed during the EoR was opaque to Lyα emission that escaped from galaxies during this epoch, which makes it difficult to observe. The neutral intergalactic medium (IGM) may thus reveal itself by suppressing the Lyα flux from background galaxies. Interestingly, a ‘sudden’ reduction in the observed Lyα flux has now been observed in galaxies at z > 6. This review contains a detailed summary of Lyα radiative processes: I describe (i) the main Lyα emission processes, including collisional-excitation & recombination (and derive the origin of the famous factor ‘0.68’), and (ii) basic radiative transfer concepts, including e.g. partially coherent scattering, frequency diffusion, resonant versus wing scattering, optically thick versus ‘extremely’ optically thick (static/outflowing/collapsing) media, and multiphase media. Following this review, I derive expressions for the Gunn-Peterson optical depth of the IGM during (inhomogeneous) reionisation and post-reionisation. I then describe why current observations appear to require a very rapid evolution of volume-averaged neutral fraction of hydrogen in the context of realistic inhomogeneous reionisation models, and discuss uncertainties in this interpretation. Finally, I describe how existing & futures surveys and instruments can help reduce these uncertainties, and allow us to fully exploit Lyα emitting galaxies as a probe of the EoR.

Sign in / Sign up

Export Citation Format

Share Document