A high-level analysis of complex Arctic mixed-phase cloud dynamics

Mixed-phase clouds play an important role in the Arctic climate system. However, accurate climate projections are seriously hampered due to uncertainties in representing these clouds. Understanding their dynamical behavior based on first principles is a challenging task which requires the disentanglement of mixed-phase micro-physical...

Gaussian-process emulation for integrating data-driven aerosol-cloud physics from simulation, satellite, and ground-based data

Data-driven quantification and parameterization of cloud physics in general, and of aerosol-cloud interactions in particular, rely on input data from observations or detailed simulations. These data sources have complementary limitations in terms of their spatial and temporal coverage and resolution; simulation data has the advantage of readily...

A fourth-order accurate adaptive solver for incompressible flow problems

We present a numerical solver for the incompressible Navier–Stokes equations that combines fourth-order-accurate discrete approximations and an adaptive tree grid (i.e. h-refinement). The scheme employs a novel compact-upwind advection scheme and a 4th-order accurate projection algorithm whereby the numerical solution exactly satisfies the...

Detecting nighttime inversions in the interior of a Douglas fir canopy

Despite the importance of forests in the water and carbon cycles, accurately measuring their contribution remains challenging, especially at night. During clear-sky nights current models and theories fail, as non-turbulent flows and spatial heterogeneity become more important. One of the standing issues is the ‘decoupling’ of the air masses...

Modeling the atmospheric diurnal cycle

Weather and climate influence life in many ways; varying climatic conditions can be associated with varying human cultures and on a day-to-day basis, the weather influences our plans and mood. As such, a proper prediction of the weather is of great importance. Ultimately, the weather is fueled by solar irradiation, which changes sharply over the...

Towards a physics-based understanding of fruit frost protection using wind machines

Wind machines are used in the agricultural sector to prevent or mitigate the adverse effects of night frost in spring. In this study we aim to quantify the impact of wind machine operation on the local temperature field in an orchard. To this end, a field experiment is conducted and experimental analysis is combined with numerical simulation...

A note on scalar-gradient sharpening in the stable atmospheric boundary layer

The scalar front generated by the horizontal self advection of a dipolar vortex through a mod-est scalar gradient is investigated. This physical scenario is an idealization of the emergenceof strong temperature ramps in the stable atmospheric boundary layer. The proposed mecha-nism is discussed and a two-dimensional analogy is studied in depth...

Dutch fog: On the observed spatio-temporal variability of fog in the Netherlands

The Netherlands is characterized by highly variable land use within a small area, and a strong influence of the North Sea on national climate. Devoid of significant topography, it is an excellent location for assessing the relative influence of various factors on fog occurrence in the absence of terrain effects. Using observations from a...

An idealized description for the diurnal cycle of the dry atmospheric boundary layer

We present a conceptual model for the diurnal cycle of the dry atmospheric boundary layer (ABL). It may serve as a framework for future numerical studies on the transitional dynamics that characterize the ABL over land. The conceptual model enables us to define expressions for relevant physical scales as a function of the most prominent...

Towards Adaptive Grids for Atmospheric Boundary-Layer Simulations

We present a proof-of-concept for the adaptive mesh refinement method applied to atmospheric boundary-layer simulations. Such a method may form an attractive alternative to static grids for studies on atmospheric flows that have a high degree of scale separation in space and/or time. Examples include the diurnal cycle and a convective...

Adaptive Cartesian meshes for atmospheric single-column models: A study using Basilisk 18-02-16

It is well known that the representation of certain atmospheric conditions in climate and weather models can still suffer from the limited grid resolution that is facilitated by modern-day computer systems. Herein we study a simple one-dimensional analogy to those models by using a single-column model description of the atmosphere. The model...

Local characteristics of the nocturnal boundary layer in response to external pressure forcing

Geostrophic wind speed data, derived from pressure observations, are used in combination with tower measurements to investigate the nocturnal stable boundary layer at Cabauw, the Netherlands. Since the geostrophic wind speed is not directly influenced by local nocturnal stability, it may be regarded as an external forcing parameter of the...

Regime transitions in near-surface temperature inversions: A conceptual model

A conceptual model is used in combination with observational analysis to understand regime transitions of near-surface temperature inversions at night as well as in Arctic conditions. The model combines a surface energy budget with a bulk parameterization for turbulent heat transport. Energy fluxes or feedbacks due to soil and radiative heat...