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

Abstract

A set of Observing System Simulation Experiments (OSSEs) are performed to assess the impact of assimilating Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) electron density profiles and ground-based Global Navigation Satellite System (GNSS) total electron content (TEC) observations in a whole atmosphere data assimilation system. The OSSEs are performed using the Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCMX) with data assimilation provided by the Data Assimilation Research Testbed (DART) ensemble adjustment Kalman filter. Results from the OSSEs demonstrate that the assimilation of ionosphere observations improves the short-term (1 hr) forecasts and analyses. The OSSEs show that the short-term forecasts and analyses are further improved when the ionosphere observations adjust the thermosphere neutral composition and temperature in addition to the ionosphere electron density. Based on an initialized forecast experiment, we find that adjusting the thermosphere neutral composition and temperature also leads to improved forecast skill in the ionosphere on longer time scales (i.e., beyond 1 hr). Additionally, it is shown that using a 1 hr data assimilation cycle, and removal of second-order divergence damping in WACCMX+DART significantly improves tidal amplitudes, which were previously found to be too small. These initial results represent the first whole atmosphere data assimilation system with capabilities to assimilate observations from the troposphere to the ionosphere-thermosphere.

Intercomparison of Middle Atmospheric Meteorological Analyses for the Northern Hemisphere Winter 2009–2010

“…The second order divergence damping results in tidal amplitudes that are 50-100% too small. Pedatella et al (2020) demonstrated that the tidal amplitudes can be improved by using hourly data assimilation cycling; however, the present study makes use of existing simulations that utilized a six-hour data 265 assimilation cycle. The WACCMX+DART six-hourly analysis fields are combined with short-term (1-5 hour)…”

“…This is related to additional second order divergence damping that was included in the version of WACCMX+DART used for the present study, and has subsequently been removed, leading to increased tidal amplitudes in WACCMX+DART (Pedatella et al, 2020). As Fig.…”

Tidal Variations in the Mesosphere and Lower Thermosphere Before, During, and After the 2009 Sudden Stratospheric Warming

“…Pedatella et al. (2020) demonstrated that the problem of weak tidal amplitudes could largely be mitigated, though not entirely removed, by using an hourly data assimilation cycle. We thus evaluate the tides in WACCMX + DART with hourly data assimilation cycling during the 2009 SSW event.…”

Numerical Prediction of the Migrating Diurnal Tide Total Variability in the Mesosphere and Lower Thermosphere

“…(2012) suggested that day‐to‐day variability in DW1 might have been due to nonlinear interactions with the 6‐day planetary wave. The day‐to‐day variation of the atmospheric tidal amplitudes are also important for driving the day‐to‐day weather in the ionosphere (Kumar et al., 2014; Li et al., 2015; Liu, 2014; Miyoshi & Fujiwara, 2003; Pedatella et al., 2020). For example, during sudden stratospheric warming (SSW) events, the ionosphere/thermosphere shows large short‐term variability in response to lower atmosphere changes (Chau et al., 2012; Goncharenko et al., 2012; Goncharenko & Zhang, 2008; Oberheide et al., 2020).…”