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HL­TWiM Empirical Model of High­Latitude Upper Thermospheric Winds

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HL­TWiM Empirical Model of High­Latitude Upper Thermospheric Winds
Other Titles
고위도 열권 바람 경험 모델 HL-TWiM
Dhadly, Manbharat S.
Emmert, John T.
Drob, Douglas P.
Conde, Mark G.
Aruliah, Anasuya
Doornbos, Eelco
Shepherd, Gordon G.
Wu, Qian
Makela, Jonathan J.
Niciejewski, Rick J.
Lee, Changsup
Jee, Geonhwa
Ridley, Aaron J.
Astronomy & Astrophysics
ionosphere; data assimilation; empirical modeling; thermosphere; neutral dynamics; high-latitude
Issue Date
Manbharat S. Dhadly, et al. 2019. "HL­TWiM Empirical Model of High­Latitude Upper Thermospheric Winds". JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 124(12): 10592-10618.
We present an empirical model of thermospheric winds (HL-TWiM - High-latitude Thermospheric Wind Model) which speci es F region high-latitude horizontal neutral winds as a function of dayday-of-year, latitude, longitude, local time, and geomagnetic activity. HL-TWiM represents the large-scale neutral wind circulation, in geomagnetic coordinates, for the given inputconditions. The model synthesizes the most extensive collection to date of historical high-latitude wind measurements; it is based on statistical analyses of several decades of F region thermospheric wind measurements from 21 ground-based stations (Fabry-Perot Interferometers (FPIs) and Scanning Doppler Imaging FPIs (SDIs)) located at various northern and southern high latitudes and 2 space-based instruments (UARS WINDII and GOCE). The geomagnetic latitude and local time dependences in HL-TWiM are represented using Vector Spherical Harmonics (VSH), day-of-year and longitude variations are represented using simple harmonic functions, and the geomagnetic activity dependence is represented using quadratic B-splines. In this paper, we describe the HLTWiM formulation and tting procedures, and we verify the model against the neutral wind databases used in its formulation. HL-TWiM provides a necessary benchmark for validating new wind observations and tuning our physical understanding of complex wind behaviors. Results show stronger Universal Time (UT) variation in winds at southern than northern-high latitudes. Model-data intra-annual comparisons in this study show semi-annual oscillation (SAO) like behavior of GOCE winds, rarely observed before in wind data.
Appears in Collections  
2019-2019, Understanding polar upper atmospheric changes by energy inputs from the space environment and the lower atmosphere (19-19) / Jee, Geonhwa (PE19020)
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