Future Directions for Whole Atmosphere Modeling: Developments in the Context of Space Weather

Abstract

Coupled Sun-to-Earth models represent a key part of the future development of space weather forecasting. With respect to predicting the state of the thermosphere and ionosphere, there has been a recent paradigm shift; it is now clear that any self-respecting model of this region needs to include some representation of forcing from the lower atmosphere, as well as solar and geomagnetic forcing. Here we assess existing modeling capability and set out a road map for the important next steps needed to ensure further advances. These steps include a model verification strategy, analysis of the impact of nonhydrostatic dynamical cores, and a cost-benefit analysis of model chemistry for weather and climate applications.Plain Language Summary Numerical models that comprehensively simulate the region between the Sun and the Earth represent a key part of the future development of space weather forecasting. With respect to predicting the Earth's upper atmosphere, there has been a recent paradigm shift; it is now clear that any self-respecting model of this region needs to include some representation of impacts from below (the lower atmosphere) as well as from above (solar variability and the effects of solar wind fluctuations). Here we assess existing modeling capability and set out a road map for the important next steps needed to ensure further advances. These steps include a strategy for checking the accuracy of the models, an analysis of the impact of methods chosen to represent upper atmosphere dynamics, and an assessment of the relative benefits of comprehensive (but expensive) and simplified (but inexpensive) model representations of upper atmosphere chemistry. Key Points:• We have reached a paradigm shift, where any self-respecting space weather model of the upper atmosphere now needs to have some representation of the lower atmosphere • Further model developments are required in several key areas, including dynamical cores and the improved representation of gravity waves • A road map of future actions is presented to ensure good progress continues to be made; this includes the development of a multi-model verification strategy

Assimilation of Ionosphere Observations in the Whole Atmosphere Community Climate Model with Thermosphere‐Ionosphere EXtension (WACCMX)

“…Whole atmosphere models have recently been developed in order to better account for the effects of the lower atmosphere on the ionosphere‐thermosphere (Akmaev, 2011; Jackson et al, 2019). By seamlessly modeling the atmosphere from the surface to the upper thermosphere, whole atmosphere models are capable of simulating the day‐to‐day variability in the ionosphere and thermosphere (Fang et al, 2013; Jin et al, 2011; H.‐L.…”

Stable extension of the unified model into the mesosphere and lower thermosphere

“…One of the Met Office's long term aims to achieve this fully coupled system is the development of the UM into a whole atmosphere model (e.g. Akmaev, 2011;Jackson et al, 2019) namely one that simulates the Earth's atmosphere from the surface up to the exobase (% 600 km). Such a model is crucial in obtaining accurate prediction of the upper atmosphere as the model resolution increases (e.g.…”

The Space Weather Atmosphere Models and Indices (SWAMI) project: Overview and first results

“…The upward propagating waves that contribute to the coupling are not represented in semi-empirical models, or are only represented incompletely. But, since an ability to model such coupling processes is important for thermospheric forecasting and LEO satellite operations, there is therefore a strong case for the use of a single whole atmosphere model that represents the neutral atmosphere from the surface up to the top of the thermosphere (see Jackson et al, 2019 for a summary). Examples of existing whole atmosphere models include the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X, Liu et al, 2010Liu et al, , 2018, the Whole Atmosphere Model (WAM, Akmaev et al, 2008;Fuller-Rowell et al, 2008) and the Ground to topside model of the Atmosphere and Ionosphere for Aeronomy (GAIA, Fujiwara & Miyoshi, 2010).…”