Connecting Land–Atmosphere Interactions to Surface Heterogeneity in CHEESEHEAD19

The Chequamegon Heterogeneous Ecosystem Energy-Balance Study Enabled by a High-Density Extensive Array of Detectors 2019 (CHEESEHEAD19) is an ongoing National Science Foundation project based on an intensive field campaign that occurred from June to October 2019. The purpose of the study is to examine how the atmospheric boundary layer (ABL) responds to spatial heterogeneity in surface energy fluxes. One of the main objectives is to test whether lack of energy balance closure measured by eddy covariance (EC) towers is related to mesoscale atmospheric processes. Finally, the project evaluates data-driven methods for scaling surface energy fluxes, with the aim to improve model–data comparison and integration. To address these questions, an extensive suite of ground, tower, profiling, and airborne instrumentation was deployed over a 10 km × 10 km domain of a heterogeneous forest ecosystem in the Chequamegon–Nicolet National Forest in northern Wisconsin, United States, centered on an existing 447-m tower that anchors an AmeriFlux/NOAA supersite (US-PFa/WLEF). The project deployed one of the world’s highest-density networks of above-canopy EC measurements of surface energy fluxes. This tower EC network was coupled with spatial measurements of EC fluxes from aircraft; maps of leaf and canopy properties derived from airborne spectroscopy, ground-based measurements of plant productivity, phenology, and physiology; and atmospheric profiles of wind, water vapor, and temperature using radar, sodar, lidar, microwave radiometers, infrared interferometers, and radiosondes. These observations are being used with large-eddy simulation and scaling experiments to better understand submesoscale processes and improve formulations of subgrid-scale processes in numerical weather and climate models

Semantics of Barriers in a Non-Strict, Implicitly-Parallel Language

Barriers in parallel languages may be used to schedule parallel activities, control memory usage and ensure proper sequentialization of side-effects. In this paper, we present operational semantics of barriers in Id and pH, which are non-strict, implicitly-parallel, functional languages extended with side-effects. The semantics are presented as a translation from a source language with barriers into a kernel language without barriers where the termination properties of an expression are represented explicitly as signals using a weak head-normal form operator (W) and controlled via a strict application operator (Sap). We present two versions of the semantics -- the first uses purely data-driven, eager evaluation and the second mixes eager evaluation with a demand-driven identifier reference mechanism. We compare and contrast the two for their ability to do resource management and preserve useful semantic properties