IDEAL

The IDEAL (Instabilities, Dynamics, and Energetics accompanying Atmospheric Layering) field project was held at Dugway, Utah from 23 October 2017 through 15 November 2017.  This project combines ground-based in-situ observations with modeling efforts and will quantify the understanding of “sheet-and-layer” structures, morphologies, and underlying dynamics in the stable stratified lower troposphere.

NCAR/EOL deployed an ISS (Integrated Sounding System) to Dugway, Utah for the IDEAL field phase.

• ISS Summary Plots at Dugway

ISS Instruments

Location: Dugway Proving Grounds 40° 7' 16" N, 113° 7' 43" W, 1317m

IDEAL Project Scientific Overview

Under stable conditions, the vertical structure of the free atmosphere from the lower troposphere into the stratosphere is often characterized by thin, strongly stable, largely non-turbulent “sheets” separated by thicker, more weakly stratified, and often turbulent “layers”. Stable sheets often have strong wind shears, whereas layers typically exhibit weak shears. The causes and morphology of these “sheet-and-layer” (S&L) structures are poorly understood at present, but are believed to be governed by largerscale wind shears, gravity waves (GWs) having various frequencies, local S&L instability dynamics, turbulence, and mixing.

S&L structures have been known for several decades to play important roles in optical and radiowave propagation and in transport and mixing of heat, momentum, and constituents. There is also evidence that these small-scale flow features can have important implications at larger scales, including instabilities and momentum transport accompanying GWs propagating to higher altitudes. However, very few studies to date have addressed the underlying S&L dynamics, the roles of instabilities and turbulence, the interactions among them, or the consequences of these flows for transport and mixing. In addition, the sources, morphologies, and statistics of intermittent turbulence events in stable stratification, and their dependence on environmental conditions remain to be defined observationally and understood from a

modeling and theoretical perspective.

IDEAL (Instabilities, Dynamics and Energetics accompanying Atmospheric Layering) science goals:

1. Identify the multi-scale GW dynamics that appear contribute to local instabilities, intermittent turbulence, and the creation and evolution of S&L structures from ~50 m to ~2-3 km,
   
    
2. Identify the instability dynamics [i.e. Kelvin-Helmholtz Instability (KHI), GW breaking,intrusions, others?] that drive turbulence and transport, and their scales, amplitudes, and heat and momentum fluxes, for various S&L scales and energy sources, and
   
    
3. Quantify the scales, intensities, character, and consequences of turbulence events for various S&L and instability flows and strengths.