So far, energetics studies related to climate change have focused on the disturbed and undisturbed kinetic and potential energies, as well as their transformations, without dealing with the energetics involved in the ...So far, energetics studies related to climate change have focused on the disturbed and undisturbed kinetic and potential energies, as well as their transformations, without dealing with the energetics involved in the phenomena of different spatial scales. Thus, the present work reports the first analysis of the spectral energetics for a condition of climate change, followed by the high-range emission scenario, RCP8.5, which originated from the new Max Planck Institute Earth System Model (MPI-ESM). The results showed that both types of generation (Go and Gn), baroclinic processes (Co and Cn), kinetic energies (Ko and Kn) and the barotropic process, Mn, significantly increase in the condition of a warming climate. Moreover, the results still reveal that in the most components of the energetics, is the planetary scale waves that are the most impacted under a climate change scenario. These results highlight that global warming can have different impacts on particular types of motions.展开更多
The effect of the surface gravity waves over sea surface roughness length (z0) is investigated from several idealized numerical experiments with the Wave-Watch-III (WW3) model. The WW3 model is combined with a simplif...The effect of the surface gravity waves over sea surface roughness length (z0) is investigated from several idealized numerical experiments with the Wave-Watch-III (WW3) model. The WW3 model is combined with a simplified model to estimate z0, CD, u* and U10 as function of the sea state. The impacts related to the presence of the ocean waves over z0 are obtained from conditions of growing (young waves) and mature seas (old waves). The wave spectrum is obtained from WW3 model for each idealized simulation under uniform wind conditions. Uniform wind experiments range from 15 to 45 m/s. The simplified algorithm determines z0, CD, u* and U10 for cases of young waves, old waves and by the Charnock method. The results show that when the ocean is characterized by young waves, both z0 and CD (drag coefficient) increase while U10 is reduced. In Charnock case, the values of z0, CD and U10 have no dependence with the presence of gravity waves. Experiments using winds higher than 30 m/s result in young waves’ CD values higher than the CD value for old waves. Even for young waves CD values are high for cases of strong winds. The results also show that in experiments using winds higher than 30 m/s the dependence between CD and wave age becomes stronger, which is in accordance with other studies.展开更多
Extreme rainfall events can be considered a natural manifestation of the environment in which they are embedded and foreknowledge about their future behavior is very important, especially for decision makers. In this ...Extreme rainfall events can be considered a natural manifestation of the environment in which they are embedded and foreknowledge about their future behavior is very important, especially for decision makers. In this context, we aimed to explore the future behavior of extreme rainfall intensity through numerical simulations with the ETA model. The model was forced with a scenario of high greenhouse gas emissions for the middle of the 21st Century as described for A1B emission scenario. We detailed the main changes in accumulated rainfall produced by heavy events, very heavy events and rare events over a broad area of South America with a focus on the tropical sector. The methodology applied here is capable of separating extreme events and establishing the quantity of rainfall yielded by them. We have found that in the near future (2041-2050) rare events will tend to increase over the Amazon basin, followed by reductions in heavy and very heavy events. Conversely, heavy, very heavy and rare events are expected to decline over north-east Brazil. Furthermore, increases were found for heavy, very heavy and rare events over southern Brazil.展开更多
In this study the effect of the surface waves over sea surface roughness (z0) and drag coefficient (CD) is investigated by combining an ocean wave model and a simplified algorithm, which estimates z0 and CD with and w...In this study the effect of the surface waves over sea surface roughness (z0) and drag coefficient (CD) is investigated by combining an ocean wave model and a simplified algorithm, which estimates z0 and CD with and without dependence on the sea state. This investigation was possible from several numerical simulations with the Wave-Watch-III (WW3) model for complex wind conditions. The numerical experiments were performed for idealized like-hurricanes with different translation speed (0, 5 and 10 m/s) and maximum wind speed (MWS) at the centre (35, 45 and 55 m/s). It is observed that z0 and CD are strongly dependent on the sea state, via substantial modification in Charnock parameterization (zch). As the hurricane translation speed increases more discrepancies in z0 and CD are observed in opposite quadrants around the region of MWS. As for instance, higher, longer and older (or more developed) waves, located in the front-right quadrant, produce lower values of z0 and CD. In the rear-left quadrant, where the waves are lower, shorter and younger (or less developed), higher values of z0 and CD are observed. In addition the difference between values on opposite quadrants increases as the hurricane intensity increases, showing the hurricane intensification dependence. Interesting aspects are observed in scatter plotting wave age versus Charnock coefficient. It is also observed that zch, which has a constant value of 0.0185, is modified by the sea state, where young waves produce higher values of zch, while old waves are related to lower values of zch when compared with zch without dependence on sea state.展开更多
文摘So far, energetics studies related to climate change have focused on the disturbed and undisturbed kinetic and potential energies, as well as their transformations, without dealing with the energetics involved in the phenomena of different spatial scales. Thus, the present work reports the first analysis of the spectral energetics for a condition of climate change, followed by the high-range emission scenario, RCP8.5, which originated from the new Max Planck Institute Earth System Model (MPI-ESM). The results showed that both types of generation (Go and Gn), baroclinic processes (Co and Cn), kinetic energies (Ko and Kn) and the barotropic process, Mn, significantly increase in the condition of a warming climate. Moreover, the results still reveal that in the most components of the energetics, is the planetary scale waves that are the most impacted under a climate change scenario. These results highlight that global warming can have different impacts on particular types of motions.
文摘The effect of the surface gravity waves over sea surface roughness length (z0) is investigated from several idealized numerical experiments with the Wave-Watch-III (WW3) model. The WW3 model is combined with a simplified model to estimate z0, CD, u* and U10 as function of the sea state. The impacts related to the presence of the ocean waves over z0 are obtained from conditions of growing (young waves) and mature seas (old waves). The wave spectrum is obtained from WW3 model for each idealized simulation under uniform wind conditions. Uniform wind experiments range from 15 to 45 m/s. The simplified algorithm determines z0, CD, u* and U10 for cases of young waves, old waves and by the Charnock method. The results show that when the ocean is characterized by young waves, both z0 and CD (drag coefficient) increase while U10 is reduced. In Charnock case, the values of z0, CD and U10 have no dependence with the presence of gravity waves. Experiments using winds higher than 30 m/s result in young waves’ CD values higher than the CD value for old waves. Even for young waves CD values are high for cases of strong winds. The results also show that in experiments using winds higher than 30 m/s the dependence between CD and wave age becomes stronger, which is in accordance with other studies.
文摘Extreme rainfall events can be considered a natural manifestation of the environment in which they are embedded and foreknowledge about their future behavior is very important, especially for decision makers. In this context, we aimed to explore the future behavior of extreme rainfall intensity through numerical simulations with the ETA model. The model was forced with a scenario of high greenhouse gas emissions for the middle of the 21st Century as described for A1B emission scenario. We detailed the main changes in accumulated rainfall produced by heavy events, very heavy events and rare events over a broad area of South America with a focus on the tropical sector. The methodology applied here is capable of separating extreme events and establishing the quantity of rainfall yielded by them. We have found that in the near future (2041-2050) rare events will tend to increase over the Amazon basin, followed by reductions in heavy and very heavy events. Conversely, heavy, very heavy and rare events are expected to decline over north-east Brazil. Furthermore, increases were found for heavy, very heavy and rare events over southern Brazil.
文摘In this study the effect of the surface waves over sea surface roughness (z0) and drag coefficient (CD) is investigated by combining an ocean wave model and a simplified algorithm, which estimates z0 and CD with and without dependence on the sea state. This investigation was possible from several numerical simulations with the Wave-Watch-III (WW3) model for complex wind conditions. The numerical experiments were performed for idealized like-hurricanes with different translation speed (0, 5 and 10 m/s) and maximum wind speed (MWS) at the centre (35, 45 and 55 m/s). It is observed that z0 and CD are strongly dependent on the sea state, via substantial modification in Charnock parameterization (zch). As the hurricane translation speed increases more discrepancies in z0 and CD are observed in opposite quadrants around the region of MWS. As for instance, higher, longer and older (or more developed) waves, located in the front-right quadrant, produce lower values of z0 and CD. In the rear-left quadrant, where the waves are lower, shorter and younger (or less developed), higher values of z0 and CD are observed. In addition the difference between values on opposite quadrants increases as the hurricane intensity increases, showing the hurricane intensification dependence. Interesting aspects are observed in scatter plotting wave age versus Charnock coefficient. It is also observed that zch, which has a constant value of 0.0185, is modified by the sea state, where young waves produce higher values of zch, while old waves are related to lower values of zch when compared with zch without dependence on sea state.
