Physical Processes

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Ronald M Errico - One of the best experts on this subject based on the ideXlab platform.

  • adjoint sensitivity of an idealized extratropical cyclone with moist Physical Processes
    Quarterly Journal of the Royal Meteorological Society, 2006
    Co-Authors: Rolf H Langland, Russell L Elsberry, Ronald M Errico
    Abstract:

    An adjoint model (MAMS1) that includes parametrizations for convective (subgrid-scale), and non-convective (grid-scale) precipitation, and surface latent-heat flux is used to investigate an idealized extratropical cyclogenesis. The adjoint sensitivity information demonstrates the effects that perturbations of model variables and parameters at various times during the cyclone life cycle have on forecast cyclone intensity. For a nonlinear trajectory that includes precipitation Processes and surface latent-heat flux, the accuracy of the tangent-linear and adjoint model is much higher when moist Physical Processes are included. Inclusion of moist Processes in the adjoint model increases sensitivity magnitude compared with sensitivity obtained with a dry adjoint model, but does not alter the primary spatial pattern of sensitivity. The larger cyclone deepening rates that occur with the inclusion of moisture are related to latent-heat release from condensation of water vapour in areas of the middle and lower troposphere (the warm-front region) that are strongly sensitive to temperature perturbations in both dry and moist cyclone simulations. The effects of diabatic heating on cyclone development are interpreted as a reinforcement of dry baroclinic instability, and not a separate development mechanism (which would have a unique non-baroclinic sensitivity signature). The sensitivity patterns explain why favourably positioned latent-heat release is an ingredient that can lead to explosive baroclinic development. Cyclone intensity is very sensitive to the vertical distribution of temperature perturbations, so this feature of diabatic heating is critical to the cyclone forecast. An increase in the transfer coefficient, CE, for the surface latent-heat flux can intensify the cyclone by adding moisture to the lower troposphere in the cyclone warm sector before the release of latent heat by precipitation Processes. Perturbations of CE have more effect on cyclone intensity than perturbations of the transfer coefficients involved in surface sensible-heat flux and surface stress during most of the cyclone life cycle.

  • evaluation of Physical Processes in an idealized extratropical cyclone using adjoint sensitivity
    Quarterly Journal of the Royal Meteorological Society, 1995
    Co-Authors: Rolf H Langland, Russell L Elsberry, Ronald M Errico
    Abstract:

    An adjoint model is used to examine the sensitivity of an idealized dry extratropical cyclogenesis simulation to perturbations of predictive variables and parameters during the cyclone life cycle. the adjoint sensitivity indicates how small perturbations of model variables or parameters anywhere in the model domain can influence cyclone central pressure. Largest sensitivity for both temperature and wind perturbations is located between 600 and 900 hPa in the baroclinic zone above the developing cyclone. Perturbations of a given size have more influence on cyclone intensity when located in high-sensitivity regions (the middle and lower troposphere in this simulation). the effects of Physical Processes can be interpreted with adjoint sensitivity by considering perturbations that are proportional to temperature and wind tendencies in the basic state (nonlinear forecast). In the early phase of the cyclone life cycle, temperature advection near the steering level in the lower troposphere (about 800 hPa) is strongly cyclogenetic and resembles a Charney mode of baroclinic instability. During the phase of most rapid deepening, temperature advection in the lower troposphere remains important, while interpretation of sensitivity to wind perturbations suggests that increased vorticity in the middle and upper troposphere above the surface low-pressure centre may also be significant for cyclone intensification. Adjoint techniques can provide insight into spatial and temporal sensitivity not easily obtained from other methods. Higher sea surface temperature (SST) has a cyclogenetic effect mainly in a localized region corresponding to the cyclone warm sector. Outside the areas of high sensitivity, small perturbations of SST have very little effect on central pressure of the forecast cyclone. When strong upward sensible-heat flux, Fs, exists, it can have a cyclogenetic (preconditioning) influence early in the cyclone life cycle, although downward Fs in the cyclone warm sector is anticyclogenetic during the phase of most rapid deepening. the sensitivity indicates that Fs can be cyclogenetic in one location and anticyclogenetic at the same time in another location, so that Fs effects on cyclone intensity are partially self-cancelling. Surface momentum stress is anticyclogenetic, with sensitivity highly localized in the cyclone warm sector.

Miguel Meirelles De Oliveira - One of the best experts on this subject based on the ideXlab platform.

  • using Physical Processes to improve physicochemical and structural characteristics of fresh and frozen thawed sheep milk
    Innovative Food Science and Emerging Technologies, 2020
    Co-Authors: Alline Artigiani Lima Tribst, Luiza Toledo Piza Falcade, Nathalia Silva Carvalho, Marcelo Cristianini, Bruno Ricardo De Castro Leite, Miguel Meirelles De Oliveira
    Abstract:

    Abstract We assessed the impact of stirring (ST), high shear dispersing (HSD) and low (LPH, 3.5 MPa) and high pressure homogenization (HPH, 50 MPa) on physicochemical and structural characteristics of whole and skimmed sheep milk fresh or previously frozen and thawed (FT). Freezing affected the size of the fat globules, their interaction with caseins, reduced calcium solubility (10%) and buffering capacity (5–11%). Amongst the studied Processes, HSD was the only one unable to improve the milk stability. The other ones reduced the size of the fat globules and increased fat and casein interactions, favoring milk stability and reducing the creaming occurrence (>22%). LPH and HPH also reduced the sedimentation in skimmed milk (>37%). Moreover, all Processes recovered the buffering capacity of FT samples. The effectiveness of the Processes can be ordered as ST  Practical application Sheep milk is normally not homogenized because it has a lower fat globule size than cow milk, which reduces the creaming occurrence. However, creaming happens in some instances and it can be intensified if the milk is preserved frozen (to accumulate enough volume) prior to the dairy production, causing defects in the final products (mainly yogurts). The studied Physical Processes can be strategically used to solve this problem, increasing the milk emulsion stability, reducing the sedimentation occurrence and changing the buffering capacity to reach the same value of fresh milk.

Rolf H Langland - One of the best experts on this subject based on the ideXlab platform.

  • adjoint sensitivity of an idealized extratropical cyclone with moist Physical Processes
    Quarterly Journal of the Royal Meteorological Society, 2006
    Co-Authors: Rolf H Langland, Russell L Elsberry, Ronald M Errico
    Abstract:

    An adjoint model (MAMS1) that includes parametrizations for convective (subgrid-scale), and non-convective (grid-scale) precipitation, and surface latent-heat flux is used to investigate an idealized extratropical cyclogenesis. The adjoint sensitivity information demonstrates the effects that perturbations of model variables and parameters at various times during the cyclone life cycle have on forecast cyclone intensity. For a nonlinear trajectory that includes precipitation Processes and surface latent-heat flux, the accuracy of the tangent-linear and adjoint model is much higher when moist Physical Processes are included. Inclusion of moist Processes in the adjoint model increases sensitivity magnitude compared with sensitivity obtained with a dry adjoint model, but does not alter the primary spatial pattern of sensitivity. The larger cyclone deepening rates that occur with the inclusion of moisture are related to latent-heat release from condensation of water vapour in areas of the middle and lower troposphere (the warm-front region) that are strongly sensitive to temperature perturbations in both dry and moist cyclone simulations. The effects of diabatic heating on cyclone development are interpreted as a reinforcement of dry baroclinic instability, and not a separate development mechanism (which would have a unique non-baroclinic sensitivity signature). The sensitivity patterns explain why favourably positioned latent-heat release is an ingredient that can lead to explosive baroclinic development. Cyclone intensity is very sensitive to the vertical distribution of temperature perturbations, so this feature of diabatic heating is critical to the cyclone forecast. An increase in the transfer coefficient, CE, for the surface latent-heat flux can intensify the cyclone by adding moisture to the lower troposphere in the cyclone warm sector before the release of latent heat by precipitation Processes. Perturbations of CE have more effect on cyclone intensity than perturbations of the transfer coefficients involved in surface sensible-heat flux and surface stress during most of the cyclone life cycle.

  • evaluation of Physical Processes in an idealized extratropical cyclone using adjoint sensitivity
    Quarterly Journal of the Royal Meteorological Society, 1995
    Co-Authors: Rolf H Langland, Russell L Elsberry, Ronald M Errico
    Abstract:

    An adjoint model is used to examine the sensitivity of an idealized dry extratropical cyclogenesis simulation to perturbations of predictive variables and parameters during the cyclone life cycle. the adjoint sensitivity indicates how small perturbations of model variables or parameters anywhere in the model domain can influence cyclone central pressure. Largest sensitivity for both temperature and wind perturbations is located between 600 and 900 hPa in the baroclinic zone above the developing cyclone. Perturbations of a given size have more influence on cyclone intensity when located in high-sensitivity regions (the middle and lower troposphere in this simulation). the effects of Physical Processes can be interpreted with adjoint sensitivity by considering perturbations that are proportional to temperature and wind tendencies in the basic state (nonlinear forecast). In the early phase of the cyclone life cycle, temperature advection near the steering level in the lower troposphere (about 800 hPa) is strongly cyclogenetic and resembles a Charney mode of baroclinic instability. During the phase of most rapid deepening, temperature advection in the lower troposphere remains important, while interpretation of sensitivity to wind perturbations suggests that increased vorticity in the middle and upper troposphere above the surface low-pressure centre may also be significant for cyclone intensification. Adjoint techniques can provide insight into spatial and temporal sensitivity not easily obtained from other methods. Higher sea surface temperature (SST) has a cyclogenetic effect mainly in a localized region corresponding to the cyclone warm sector. Outside the areas of high sensitivity, small perturbations of SST have very little effect on central pressure of the forecast cyclone. When strong upward sensible-heat flux, Fs, exists, it can have a cyclogenetic (preconditioning) influence early in the cyclone life cycle, although downward Fs in the cyclone warm sector is anticyclogenetic during the phase of most rapid deepening. the sensitivity indicates that Fs can be cyclogenetic in one location and anticyclogenetic at the same time in another location, so that Fs effects on cyclone intensity are partially self-cancelling. Surface momentum stress is anticyclogenetic, with sensitivity highly localized in the cyclone warm sector.

Alline Artigiani Lima Tribst - One of the best experts on this subject based on the ideXlab platform.

  • using Physical Processes to improve physicochemical and structural characteristics of fresh and frozen thawed sheep milk
    Innovative Food Science and Emerging Technologies, 2020
    Co-Authors: Alline Artigiani Lima Tribst, Luiza Toledo Piza Falcade, Nathalia Silva Carvalho, Marcelo Cristianini, Bruno Ricardo De Castro Leite, Miguel Meirelles De Oliveira
    Abstract:

    Abstract We assessed the impact of stirring (ST), high shear dispersing (HSD) and low (LPH, 3.5 MPa) and high pressure homogenization (HPH, 50 MPa) on physicochemical and structural characteristics of whole and skimmed sheep milk fresh or previously frozen and thawed (FT). Freezing affected the size of the fat globules, their interaction with caseins, reduced calcium solubility (10%) and buffering capacity (5–11%). Amongst the studied Processes, HSD was the only one unable to improve the milk stability. The other ones reduced the size of the fat globules and increased fat and casein interactions, favoring milk stability and reducing the creaming occurrence (>22%). LPH and HPH also reduced the sedimentation in skimmed milk (>37%). Moreover, all Processes recovered the buffering capacity of FT samples. The effectiveness of the Processes can be ordered as ST  Practical application Sheep milk is normally not homogenized because it has a lower fat globule size than cow milk, which reduces the creaming occurrence. However, creaming happens in some instances and it can be intensified if the milk is preserved frozen (to accumulate enough volume) prior to the dairy production, causing defects in the final products (mainly yogurts). The studied Physical Processes can be strategically used to solve this problem, increasing the milk emulsion stability, reducing the sedimentation occurrence and changing the buffering capacity to reach the same value of fresh milk.

  • using Physical Processes to improve physicochemical and microestructural characteristics of fresh and frozen thawed sheep milk
    Revista dos Trabalhos de Iniciação Científica da UNICAMP, 2019
    Co-Authors: Luiza Toledo Piza Falcade, Alline Artigiani Lima Tribst, Nathalia Santos Carvalho
    Abstract:

    We acessed the efficacy of stirring (ST), high shear dispersion (HSD) and low (LPH) and high (HPH) pressure homogenization to improves the stability of fresh or frozen/ thawed sheep milk (whole and skimmed). After each process, milk samples were evaluated for color, buffering capacity, soluble calcium, pH, particle size distribution and near infrared backscaterring. From the results obtained, we observed that freezing changed the buffering capacity and particle size distribution of whole milk and the buffering capacity, sedimentation and soluble calcium in skimmed one. The Physical Processes caused changes in milk (mainly in the whole one) and most of them (except HSD) was able to reduced, at least partially, the defects caused by the freezing of the milk, improving the product stability. In addition, the HPH and LPH also improved the stability of fresh milk. In respect to their effectiveness, the Processes can be ordered as HPH> LHP> ST. Although less effective, the ST can be an interesting alternative to process previously frozen sheep milk, since it is a cheap, simple and easy to operate technology.

M Padovani - One of the best experts on this subject based on the ideXlab platform.

  • Physical Processes in star formation
    Space Science Reviews, 2020
    Co-Authors: Philipp Girichidis, Simon C. O. Glover, Ralf S Klessen, Stella S R Offner, Alexei G Kritsuk, Patrick Hennebelle, J Diederik M Kruijssen, Martin Krause, M Padovani
    Abstract:

    Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback Processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the Physical Processes at work, both individually and of their interactions. In this review we will give an overview of the main Processes that are important for the understanding of star formation. We start with an observationally motivated view on star formation from a global perspective and outline the general paradigm of the life-cycle of molecular clouds, in which star formation is the key process to close the cycle. After that we focus on the thermal and chemical aspects in star forming regions, discuss turbulence and magnetic fields as well as gravitational forces. Finally, we review the most important stellar feedback mechanisms.