Evaluating Different Techniques for Constraining Lower Atmospheric Variability in an Upper Atmosphere General Circulation Model: A Case Study During the 2010 Sudden Stratospheric Warming

Abstract

We analyze the effects specified dynamics (SD) and 4D Tendency nudging have on accurately reproducing the middle and upper atmospheric variability induced by the 2010 sudden stratospheric warming (SSW) event in the National Center for Atmospheric Research thermosphere‐ionosphere‐mesosphere‐electrodynamics general circulation model (TIME‐GCM). TIME‐GCM numerical experiments were performed using constrained middle atmospheric winds and temperatures from a high‐altitude version of the Navy Global Environmental Model to compare the previously implemented SD scheme, with the newly implemented 4D Tendency scheme. Model comparisons focused on zonal mean winds, composition, planetary waves, and tides in the thermosphere‐ionosphere system. Through 4D Tendency nudging we reveal that coupling coefficients of the one‐way SD coupling approach between the TIME‐GCM and observed SSW conditions were too strong. Prior implementations produced unusually strong vertical shears in the zonal mean winds in the mesosphere and lower thermosphere (MLT), where the model is free running. Differences in zonal mean MLT winds between SD and 4D Tendency nudging simulations resulted in migrating diurnal (DW1) and semidiurnal (SW2) tidal amplitude differences at lower thermospheric altitudes. The consequences of simulating different MLT dynamics using SD and 4D Tendency nudging in the overlaying ionosphere are reported and validated using electron density data from the Constellation Observing System for Meteorology, Ionosphere, and Climate satellites. Although we demonstrate that SD and 4D Tendency nudging techniques are approximately equivalent, results presented herein establish that 4D Tendency nudging has the added potential to identify physical model parameters that contribute to data‐model differences during the 2010 SSW.

On the relative roles of dynamics and chemistry governing the abundance and diurnal variation of low-latitude thermospheric nitric oxide

“…All this is important because satellites such as ODIN are in sunsynchronous orbits and acquire both sunrise and sunset data. The recent ODIN-based model of Kiviranta et al (2018) did not distinguish between sunrise and sunset data; our results suggest it would be useful to do so.…”

“…This results either from satellites in sun-synchronous orbits or from satellites which might be in varying local time orbits but use a technique such as solar occultation that is inherently limited to a single local time. Examples of the first case include the Student Nitric Oxide Explorer (SNOE; Barth et al, 2003), the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) dataset on the European research satellite Envisat (Bermejo-Pantaleón et al, 2011;Bender et al, 2015) and the submillimeter radiometer (SMR) on the Swedish Odin satellite (Sheese et al, 2013;Kiviranta et al, 2018). Examples of the second case include the Solar Occultation for Ice Experiment (SOFIE; Gómez-Ramírez et al, 2013) on the Aeronomy of Ice in the Mesosphere (AIM; Russell III et al, 2009), the ACE Fourier Transform Spectrometer (ACE-FTS; Bernath et al, 2005;Bender et al, 2015) and the Halogen Occultation Experiment (HALOE) data on the NASA Upper Atmosphere Research Satellite (UARS; Russell III et al, 1993;Siskind et al, 1998).…”

Comparative study between ground-based observations and NAVGEM-HA analysis data in the mesosphere and lower thermosphere region

“…During the winter of 2009/10, a major sudden stratospheric warming occurred at the end of January when the polar vortex was markedly displaced from the pole (Stober et al, 2012) and then separated into two unequally strong lobes (e.g., Dörnbrack et al, 2012;Jones et al, 2018). Following previous studies involving NAVGEM-HA, we mark the onset of the SSW as occurring on 27 January (McCormack et al, 2017).…”

“…NAVGEM-HA is a high-altitude numerical weather prediction (NWP) system extending from the surface to ∼ 116 km altitude that provides atmospheric winds, temperatures and constituent information. It is based on the operational system described in Hogan et al (2014), which combines the NAVGEM global spectral forecast model with a hybrid fourdimensional variational (4D-Var) data assimilation algorithm (Kuhl et al, 2013).…”

response to reviewer 3

“…This results either from satellites in sun-synchronous orbits or from satellites which might be in varying local time orbits but use a technique such as solar occultation that is inherently limited to a single local time. Examples of the first case include the Student Nitric Oxide Explorer (SNOE; Barth et al, 2003), the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) dataset on the European research satellite Envisat (Bermejo-Pantaleón et al, 2011;Bender et al, 2015) and the submillimeter radiometer (SMR) on the Swedish Odin satellite (Sheese et al, 2013;Kiviranta et al, 2018). Examples of the second case include the Solar Occultation for Ice Experiment (SOFIE; Gómez-Ramírez et al, 2013) on the Aeronomy of Ice in the Mesosphere (AIM; Russell III et al, 2009), the ACE Fourier Transform Spectrometer (ACE-FTS; Bernath et al, 2005;Bender et al, 2015) and the Halogen Occultation Experiment (HALOE) data on the NASA Upper Atmosphere Research Satellite (UARS; Russell III et al, 1993;Siskind et al, 1998).…”