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´╗┐The neutral atmosphere

[I. Mueller-Wodarg]

Astrid Maute

High Altitude Observatory, NCAR

CEDAR workshop, Santa Fe, June 2019

The National Center for Atmospheric Research is a major facility sponsored by the National Science Foundation under Cooperative Agreement No. 1852977.

Outline

1. Energetics temperature

2. Dynamics winds

3. Composition Density of species Overarching points: Energetics, dynamics, and composition are interconnected Atmospheric regions are coupled CEDAR ? Coupling, Energetics, and Dynamics of Atmospheric Regions

Solar Radiation & thermal structure

Neutral temperature [K]

750nm-1mm

10-100nm 200-300nm

120-200nm

10-100nm 0.01-10nm

Climate change effects

Global mean model

~-50K double

~-40K half

Whodleouabtlmeosphere model (WACCM-X) ~-8K

~-10K

~+10K

-20% ~-40%

half

[Roble & Dickinson, 1989]

CO2 & CH4 concentration specified at ~60 km (1950 global mean values: 330ppmv & 0.1ppmv)

[Solomon et al., 2018]

CO2, CH4, CFC concentration specified surface (CO2 from 330ppmv to 375ppmv)

Stan Solomon's science highlight on Monday "CEDAR and climate change" workshop on Wednesday

Coldest place: summer mesopause

Schematic of zonal mean temperatures [oC]

COLD

mesopause

Warm

stratopause

Clouds at ~80 km height! Noctilucent clouds

NLC: Portland July2009

COLD

Warm

COLD

summer hemisphere

winter hemisphere

[Holton, 1976 ]

(Picture from Varnas)

Heating in the mesosphere mostly due to absorption of radiation by ozone which is stronger in the summer than the winter hemisphere which creates a meridional circulation. Upwind over the polar summer region causes temperature to drop due to expansion. Gravity wave breaking deposit eastward momentum increasing the upwind and the cooling.

Xinzhao Chu's prize lecture

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