模拟的对流细胞和系统生长偏差对大气不稳定性和模型分辨率的依赖性
Zhixiao Zhang1,2, Adam C Varble1,3, Zhe Feng3
1Department of Atmospheric Sciences University of Utah Salt Lake City UT USA.
Journal of geophysical research. Atmospheres : JGR
|November 25, 2024
概括
天气模拟通过产生太多的浅细胞来高估对流降雨,这阻碍了分层形式的降雨形成. 改善对流细胞预测需要的不仅仅是更高的模型分辨率.
科学领域:
- 大气科学 大气科学
- 气象学 天气学
- 天气预报天气预报
背景情况:
- 流动和层状降雨是降水系统的关键组成部分.
- 准确模拟对流电细胞特性对于理解降雨动态至关重要.
- 在RELAMPAGO-CACTI实地活动中,为评估天气模型提供了有价值的数据.
研究的目的:
- 在允许对流的天气模型模拟中评估对流细胞特性.
- 分析模拟的对流电池与降雨类型 (对流与分层) 之间的关系.
- 调查模型分辨率对对流动和层状降雨偏差的影响.
主要方法:
- 在阿根廷中部利用了一个长期的对流允许WRF模拟.
- 模拟输出与雷达,卫星和无线电探测器数据进行了比较,这些数据来自RELAMPAGO-CACTI运动.
- 分析了对流细胞的特性 (数量,深度,生长) 以及它们与降雨分区的联系.
主要成果:
- 该模型高估了对流雨量 (+43%) 和低估了分层雨量 (-46%).
- 确定了沉对流细胞 (2.6x观察到) 的显著过度生产,特别是浅细胞.
- 增加模型分辨率并没有大大减少细胞特性或降雨分区的偏差.
结论:
- 浅层对流细胞的严重过度生产导致了过于高效的降水和降低了分层雨量.
- 电流可用的潜在能量 (CAPE) 影响细胞偏差,但仅仅通过分辨率改进无法解决分区问题.
- 准确预测对流性质可能取决于横格距离之外的因素,例如微物理或参数化.
相关概念视频
01:18Boundary Layer Characteristics
55
When a fluid encounters a solid surface, a boundary layer forms due to the interaction between the fluid's motion and the stationary surface. This phenomenon is characterized by a thin region adjacent to the surface where viscous forces dominate, influencing the fluid's velocity profile. The development of the boundary layer begins at the leading edge of the surface and evolves as the fluid moves downstream.As the fluid flows over the surface, friction between the fluid and the wall slows down...
55
01:12Precipitation Processes
426
The experimental conditions in a gravimetric analysis should be optimized to maximize the particle size and purity of the obtained precipitate. Ideally, the concentration of the precipitating reagent should be low with effective stirring to maintain low relative supersaturation for the growth of large crystals. In homogeneous precipitation, the precipitant is slowly generated by a chemical reaction in the solution to avoid local reagent excesses. For example, urea decomposes gradually to...
426
01:30Typical Model Studies
340
Fluid mechanics model studies often utilize scaled-down systems to predict fluid behavior in full-scale environments, such as river flows, dam spillways, and structures interacting with open surfaces. Maintaining Froude number similarity in river models is crucial, as it replicates surface flow features like wave patterns and velocities.
340
01:24Pole and System Stability
249
The transfer function is a fundamental concept representing the ratio of two polynomials. The numerator and denominator encapsulate the system's dynamics. The zeros and poles of this transfer function are critical in determining the system's behavior and stability.
Simple poles are unique roots of the denominator polynomial. Each simple pole corresponds to a distinct solution to the system's characteristic equation, typically resulting in exponential decay terms in the system's...
Simple poles are unique roots of the denominator polynomial. Each simple pole corresponds to a distinct solution to the system's characteristic equation, typically resulting in exponential decay terms in the system's...
249
01:18Variation of Atmospheric Pressure
2.1K
Change in atmospheric pressure with height is particularly interesting. The decrease in atmospheric pressure with increasing altitude is due to the decreasing gravitational force per unit area as we move away from the surface of the earth.
Assuming the air temperature is constant at a given altitude and that the ideal gas law of thermodynamics describes the atmosphere to a good approximation, one can find the variation of atmospheric pressure with height.
Let p(y) be the atmospheric pressure at...
Assuming the air temperature is constant at a given altitude and that the ideal gas law of thermodynamics describes the atmosphere to a good approximation, one can find the variation of atmospheric pressure with height.
Let p(y) be the atmospheric pressure at...
2.1K
01:28Magnetostatic Boundary Conditions
877
An electric field suffers a discontinuity at a surface charge. Similarly, a magnetic field is discontinuous at a surface current. The perpendicular component of a magnetic field is continuous across the interface of two magnetic mediums. In contrast, its parallel component, perpendicular to the current, is discontinuous by the amount equal to the product of the vacuum permeability and the surface current. Like the scalar potential in electrostatics, the vector potential is also continuous...
877