frontiers summ vaa

Validation and AssimilationCassandra Fesen: 

Validation and Assimilation Cassandra Fesen Overview: what do we do with these observations and datasets? What’s the next step? Typically, it’s to invoke models to analyze and understand the data, to understand better the atmosphere/ionosphere system (Question: Can we get to forecasting/prediction?)

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Modeling and Observations Models put experimental data into a global context - they may also specify conditions far away from the measurements - they can provide quantities that were not measured. The coupling between models and experimental results can give a better context for testing theories than models alone or localized measurements. Validation studies provide an opportunity for improving our understanding of the global system by forcing researchers to examine the underlying physics of the models. …. resulting in a better physical understanding of the atmosphere and ionosphere and improvements in the simulations.

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Third Major Theme: Model* Validation and Assimilation Variability Chemistry, Energetics and Dynamics * “model” includes both theoretical and empirical models

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New “Tool”: Long-Duration Observations A movement to obtain simultaneous, coordinated observations by a wide range of instruments over many (sequential) days January, 1993 – 10 days October, 2002 – 30 days September, 2005 – 30 days March-April, 2006 – 30 days Modern ISRs such as ESR, AMISR, and ZIP will be able to operate for even longer periods, potentially 24/7

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(Some) Motivations for Long-Duration Observations Model initial conditions Compare with model responses over long time intervals Provide input to assimilative models Enable studies of long period waves and tides Theoretically simulate and empirically quantify the ionospheric and thermospheric variability (Space Weather implications) ( Question for the community: How do these data sets fit into the “World Day” framework for scheduling ISR observations?)

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Major new element in CEDAR Examples: WACCM (NCAR’s Whole Atmosphere Community Climate Model), USU GAIM (Global Assimilative Ionosphere Model) Must handle asynoptic data from multiple sources with differing uncertainties Sampling WACCM tidal fields with TIMED sampling geometry illustrates need for combined ground-based and satellite observations to resolve D and SD tides. Goal: Assimilative Models

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Goal: Improving Empirical Models Examples of existing empirical models: MSIS, HWM (harmonic wind model) Satellite data were not incorporated into HWM There are 15 years of data from WINDII, HRDI,and TIDI measurements Of particular note: longitudinal variability in the MLT winds. TIMED will continue to receive NASA support until ~2010. What happens after TIMED ????

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Goal: Fully Coupled Chemical-Dynamical Models Chemically active species may be transported by gravity waves, diffusion, tides or the mean flow auroral NO to the stratosphere O and its effect on airglow This will affect the energetics of the atmosphere, since heating & cooling may depend strongly on composition

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WINDII observations of variations of v and two airglow emissions associated with the diurnal tide These combine all longitudes, but if we use ground-based data, we need to account for the nonmigrating tides as well Can models simulate simultaneous variations of multiple parameters or layers at multiple sites? Goal: Fully Coupled Chemical-Dynamical Models, cont’d

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Goal: Coupled Chemistry and Energetics ENVISAT observations before and after a solar proton event reveal a major chemical modification deep in the atmosphere: a decrease in stratospheric ozone following the Halloween storm

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Goal: Energetics and Chemistry, cont’d Creation of molecular species by auroral precipitation. Molecular ions have vibrational-rotational state distributions that can be probed spectroscopically. Quantify the energetics of the auroral precipitation.

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Other Planets as Natural Laboratories Other planets provide opportunities to develop and validate atmospheric models. Different chemical composition of neutral atmosphere Different magnetic fields Different atmospheric circulation. Search for life.