A series of idealized model simulations are analyzed to determine the sensitivity of model results to different configurations of the lateral boundary conditions (LBCs) in simulating mesoscale shallow convection over ...A series of idealized model simulations are analyzed to determine the sensitivity of model results to different configurations of the lateral boundary conditions (LBCs) in simulating mesoscale shallow convection over hilly terrain. In the simulations with steady thermal forcing at the model surface, a radiation condition at both boundaries is the best choice under high wind conditions, and the best results are produced when both the normal velocities and the temperature are treated with the radiation scheme in which the phase speed is the same for different variables. When the background wind speed is reasonably small, the LBC configuration with either the radiation or the zero gradient condition at both boundaries tends to make the numerical solution unstable. The choice of a constant condition at the inflow boundary and a radiation outflow boundary condition is appropriate in most cases. In the simulations with diurnal thermal forcing at the model surface, different LBC schemes are combined together to reduce spurious signals induced by the outflow boundary. A specification inflow boundary condition, in which the velocity fields at the inflow boundary are provided using the time-dependent results of a simulation with periodic LBCs over a flat domain, is tested and the results indicate that the specification condition at the inflow boundary makes it possible to use a smaller model domain to obtain reasonable results. The model horizontal domain length should be greater than a critical length, which depends on the domain depth H and the angle between gravity wave phase lines and the vertical. An estimate of minimum domain length is given by , where N and U are the background stability and wind speed, respectively, Lx is the typical gravity wavelength scale, and Zi is the convective boundary layer (CBL) depth.展开更多
Ants show collective and individual behavioral flexibility in their response to immediate context,choosing for example between different foraging strategies.In Pachycondyla striata,workers can forage solitarily or rec...Ants show collective and individual behavioral flexibility in their response to immediate context,choosing for example between different foraging strategies.In Pachycondyla striata,workers can forage solitarily or recruit and guide nestmates to larger food sources through tandem running.Although considered more ancestral and less efficient than pheromone trail-laying,this strategy is common especially in species with small colony size.What is not known is how the decision to recruit or follow varies according to the immediate context.That is,how fine adjustments in information transfer affect immediate foraging decisions at the colony level.Here,we studied individually marked workers and evaluated their foraging decisions when food items varied in nature(protein versus carbohydrate),size,and distance from the nest at different temperatures and humidity levels.Our results show that tandem run leaders and potential followers adjust their behavior according to a combination of external factors.While 84.2%of trips were solitary,most ants(81%)performed at least 1 tandem run.However,tandem runs were more frequent for nearby resources and at higher relative humidity.Interestingly,when food items were located far away,tandem runs were more successful when heading to protein sources(75%)compared with carbohydrate sources(42%).Our results suggest that the social information transfer between leaders and followers conveys more information than previously thought,and also relies on their experience and motivation.展开更多
基金The first author was supported by an Overseas Research ScholarshipThis work was supported by the National Natural Science Foundation of China under Grant No.40233031.
文摘A series of idealized model simulations are analyzed to determine the sensitivity of model results to different configurations of the lateral boundary conditions (LBCs) in simulating mesoscale shallow convection over hilly terrain. In the simulations with steady thermal forcing at the model surface, a radiation condition at both boundaries is the best choice under high wind conditions, and the best results are produced when both the normal velocities and the temperature are treated with the radiation scheme in which the phase speed is the same for different variables. When the background wind speed is reasonably small, the LBC configuration with either the radiation or the zero gradient condition at both boundaries tends to make the numerical solution unstable. The choice of a constant condition at the inflow boundary and a radiation outflow boundary condition is appropriate in most cases. In the simulations with diurnal thermal forcing at the model surface, different LBC schemes are combined together to reduce spurious signals induced by the outflow boundary. A specification inflow boundary condition, in which the velocity fields at the inflow boundary are provided using the time-dependent results of a simulation with periodic LBCs over a flat domain, is tested and the results indicate that the specification condition at the inflow boundary makes it possible to use a smaller model domain to obtain reasonable results. The model horizontal domain length should be greater than a critical length, which depends on the domain depth H and the angle between gravity wave phase lines and the vertical. An estimate of minimum domain length is given by , where N and U are the background stability and wind speed, respectively, Lx is the typical gravity wavelength scale, and Zi is the convective boundary layer (CBL) depth.
基金J.P.S.,N.C.,and M.E.L.V.received funding grants from the Brazilian Science Ministry(Conselho Nacional de Desenvolvimento Cientı´fico e Tecnolo´gico,CNPq)MCTI/CNPq/Universal 14/2014,Processo 458736/2014,PQ 311790/2017-8.L.V.receives a funding grant from FYSSEN foundationThis research was supported by CAPES(Programa de Pos-Graduacao em Psicologia Experimental[PROEX]2016/1964).
文摘Ants show collective and individual behavioral flexibility in their response to immediate context,choosing for example between different foraging strategies.In Pachycondyla striata,workers can forage solitarily or recruit and guide nestmates to larger food sources through tandem running.Although considered more ancestral and less efficient than pheromone trail-laying,this strategy is common especially in species with small colony size.What is not known is how the decision to recruit or follow varies according to the immediate context.That is,how fine adjustments in information transfer affect immediate foraging decisions at the colony level.Here,we studied individually marked workers and evaluated their foraging decisions when food items varied in nature(protein versus carbohydrate),size,and distance from the nest at different temperatures and humidity levels.Our results show that tandem run leaders and potential followers adjust their behavior according to a combination of external factors.While 84.2%of trips were solitary,most ants(81%)performed at least 1 tandem run.However,tandem runs were more frequent for nearby resources and at higher relative humidity.Interestingly,when food items were located far away,tandem runs were more successful when heading to protein sources(75%)compared with carbohydrate sources(42%).Our results suggest that the social information transfer between leaders and followers conveys more information than previously thought,and also relies on their experience and motivation.
