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An investigation of one-dimensional energy-balance models for simulating long-term climatic variationsSimmons, P. A. January 1984 (has links)
No description available.
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Žvaigždžių atmosferų modelių energijos kreivių tyrimas / A comparison of the stellar atmosphere model energy distributionsDailidka, Edgar 24 September 2008 (has links)
Šiame darbe buvo palygintos tarpusavyje Kurucz, Castelli ir Kurucz (ATLAS9), PHOENIX (NextGen) ir MARCS žvaigždžių atmosferų modelių energijos kreives ir patikrintas modelių energijos kreivių atitikimą realių žvaigždžių energijos pasiskirstymui spektre. / Stellar atmosphere models energy distribution curves were investigated. Energy distributions of synthetic spectra for Kurucz, Kurucz & Castelli(ATLAS9), PHOENIX(NextGen), MARCS stellar atmosphere models are compared together. Also the stellar atmosphere models energy distribution curves are compared with the observed energy distributions (Straižys V., Sviderskienė Z., 1996). The synthetic color indices of the Kurucz, Kurucz & Castelli(ATLAS9) model for the UBV and Vilnius photometric systems were calculated. The synthetic color indices were compared with the observed mean intrinsic color indices.
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An Assessment Of The Simulation Of Monsoon And Inter Tropical Convergence Zone In Coupled Ocean-Atmosphere ModelsVidyunmala, V 10 1900 (has links)
Monsoons and Intertropical Convergence Zones (ITCZ) exhibit variability at various temporal and spatial scales. The temporal scale of variability encompasses scales from the intraseasonal through interannual to interdecadal time scales. Anthropogenic climate change can also have an impact on ITCZ and monsoons. Thus it is necessary to assess the ability of coupled ocean atmospheric models (commonly known as AOGCM) to simulate these aspects of variability of tropical climate. This has been studied with simulations from 20 AOGCMs and their AGCM from IPCCAR4 archive. In addition, we have used our own 100 year simulation with CCSM2 and also simulations with its AGCM viz. CAM2.
Our analysis shows that most model have significant bias in tropical rainfall and SST. Most models underestimate SST except over a few regions such as the Eastern boundaries of Atlantic and Pacific Oceans. The AGCMs which are forced with observed SSTs have much higher annual mean rainfall as compared to AOGCMs. There is a strong correlation between error in shortwave reflectance at the top of the atmosphere and error in SST.
The ability of coupled ocean-atmosphere models and their atmosphere-alone counterparts to simulate the seasonal cycle of rainfall over major monsoon regions and also over oceanic ITCZ. It is found that over the Indian monsoon region, most AGCMs overestimate the seasonal cycle while AOGCMs have a more realistic seasonal cycle. This inspite of the fact that most AOGCMs underestimate the SST over the Indian region. It is shown that this is related to errors in precipitable water-rainfall relationship in most models i.e. for a given amount of precipitable water, most models overestimate the rainfall. Thus lower SST reduces the precipitable water and hence the amount of rainfall is reduced. Therefore, the mutual cancellation of errors leads to a more realistic seasonal cycle in AOGCMs.
The seasonal cycle over Africa was analysed with the help of a diagnostic model. Over Southern Africa, most models show simulate a less stable atmosphere and hence the rainfall is overestimated.
A technique based on Continous Wavelet Transform in Space and Time (CWTST) has been modified to seperate northward and southward propagating modes of BSISO over the Indian and West Pacific regions. It was seen that over the Indian region, northward propagating modes were more prominent in comparison to southward modes. It was also found that the predominant spatial scale (of about 30o) did not show much interannual variability but the associated temporal scale showed significant variation. Both AOGCMs and AGCMs simulations were analysed to investigate the impact of coupling on intraseasonal activity. Most AOGCMs were able to simulate the predominant spatial scale but were unable to simulate the associated temporal scale correctly. These problems persisted with AGCMs also. It was also found that for AGCMs, there were some variations between ensemble members of the AGCMs. Comparing BSISO in increased GHG scenarios with present day simulations we found that in general, power in the spectrum increases. This could be related to higher mean precipitation that has been simulated by most AOGCMs when GHG are increased.
The interannual variability in the tropics with special reference to Tropical Biennial Oscillation (TBO) and ENSO has been studied. The changes in these modes of variability due to anthropogenic climate change has also been assessed. We found that in most models over the Nino3.4 region, the mode of variation shifts from a near-four period (in pre-industrial simulations) to that of TBO mode in increased GHG (green house gas) scenario. This suggests that with increasing GHGs, ENSO quasi-periodicity might shift to about two years. It is also interesting to note that for observed rainfall, OLR and 850 hPa winds, the TBO mode has higher variance over the Eastern Indian Ocean, indicating that the TBO mode might be related to Indian Ocean Dipole Mode and EQUINOO (Equatorial Indian Ocean Oscillation).
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A Systems Framework and Analysis Tool for Rapid Conceptual Design of Aerocapture MissionsAthul Pradeepkumar Girija (11068791) 22 July 2021 (has links)
Aerocapture offers a near propellantless and quick method of orbit
insertion at atmosphere bearing planetary destinations. Compared to
conventional propulsive insertion, the primary advantage of using
aerocapture is the savings in propellant mass which could be used to
accommodate more useful payload. To protect the spacecraft from the
aerodynamic heating during the maneuver, the spacecraft must be enclosed
in a protective aeroshell or deployable drag device which also provides
aerodynamic control authority to target the desired conditions at
atmospheric exit. For inner planets such as Mars and Venus, aerocapture
offers a very attractive option for inserting small satellites or
constellations into very low circular orbits such as those used for
imaging or radar observations. The large amount of propellant required
for orbit insertion at outer planets such as Uranus and Neptune severely
limits the useful payload mass that can delivered to orbit as well as
the achievable flight time. For outer planet missions, aerocapture opens
up an entirely new class of short time of flight trajectories which are
infeasible with propulsive insertion. A systems framework for rapid
conceptual design of aerocapture missions considering the
interdependencies between various elements such as interplanetary
trajectory and vehicle control performance for aerocapture is presented.
The framework provides a step-by-step procedure to formulate an
aerocapture mission starting from a set of mission objectives. At the
core of the framework is the ``aerocapture feasibility chart", a
graphical method to visualize the various constraints arising from
control authority requirement, peak deceleration, stagnation-point peak
heat rate, and total heat load as a function of vehicle aerodynamic
performance and interplanetary arrival conditions. Aerocapture
feasibility charts have been compiled for all atmosphere-bearing Solar
System destinations for both lift and drag modulation control
techniques. The framework is illustrated by its application to
conceptual design of a Venus small satellite mission and a
Flagship-class Neptune mission using heritage blunt-body aeroshells.
The framework is implemented in the Aerocapture Mission Analysis Tool
(AMAT), a free and open-source Python package, to enable scientists and
mission designers perform rapid conceptual design of aerocapture
missions. AMAT can also be used for rapid Entry, Descent, and Landing
(EDL) studies for atmospheric probes and landers at any
atmosphere-bearing destination.
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Atmospheric Variability in Sulawesi, Indonesia / Regional Atmospheric Model Results and Observations / Atmosphärische Variabilität in Sulawesi, Indonesien / Ergebnisse und Beobachtungen zum regionalen, atmosphärischen ModellGunawan, Dodo 01 December 2006 (has links)
No description available.
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