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Larisa Petrovna Goncharenko - One of the best experts on this subject based on the ideXlab platform.
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analysis and hindcast experiments of the 2009 Sudden Stratospheric Warming in waccmx dart
Journal of Geophysical Research, 2018Co-Authors: Larisa Petrovna Goncharenko, J L Chau, N M Pedatella, D R Marsh, Kevin Raeder, Jeffrey L Anderson, T A SiddiquiAbstract:The ability to perform data assimilation in the Whole Atmosphere Community Climate Model eXtended version (WACCMX) is implemented using the Data Assimilation Research Testbed (DART) ensemble adjustment Kalman filter. Results are presented demonstrating that WACCMX+DART analysis fields reproduce the middle and upper atmosphere variability during the 2009 major Sudden Stratospheric Warming (SSW) event. Compared to specified dynamics WACCMX, which constrains the meteorology by nudging toward an external reanalysis, the large‐scale dynamical variability of the stratosphere, mesosphere, and lower thermosphere is improved in WACCMX+DART. This leads to WACCMX+DART better representing the downward transport of chemical species from the mesosphere into the stratosphere following the SSW. WACCMX+DART also reproduces most aspects of the observed variability in ionosphere total electron content and equatorial vertical plasma drift during the SSW. Hindcast experiments initialized on 5, 10, 15, 20, and 25 January are used to assess the middle and upper atmosphere predictability in WACCMX+DART. A SSW, along with the associated middle and upper atmosphere variability, is initially predicted in the hindcast initialized on 15 January, which is ∼10 days prior to the Warming. However, it is not until the hindcast initialized on 20 January that a major SSW is forecast to occur. The hindcast experiments reveal that dominant features of the total electron content can be forecasted ∼10–20 days in advance. This demonstrates that whole atmosphere models that properly account for variability in lower atmosphere forcing can potentially extend the ionosphere‐thermosphere forecast range.
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total electron content disturbances during minor Sudden Stratospheric Warming over the brazilian region a case study during january 2012
Journal of Geophysical Research, 2017Co-Authors: F Vieira, Larisa Petrovna Goncharenko, P R Fagundes, K Venkatesh, V G PillatAbstract:The effects of Sudden Stratospheric Warming (SSW) on ionosphere have been investigated by several scientists, using different observational techniques and model simulations. However, the minor SSW event during January 2012 is one of those that are less studied. Influences of several types of possible drivers—minor SSW event, changing solar flux, moderate geomagnetic storm on 22–25 January, and one of the largest solar proton events on 23–30 January—make it a challenging period to interpret. In the present study, the GPS-total electron content (TEC) measurements from a network of 72 receivers over the Brazilian region are considered. This network of 72 GPS-TEC locations lies between 5°N and 30°S (35°) latitudes and 35°W and 65°W (30°) longitudes. Further, two chains of GPS receivers are used to study the response of the equatorial ionization anomaly (EIA) in the Brazilian eastern and western sectors, as well as its day-to-day variability before and during the SSW-2012. It was noted that the TEC is depleted to the order of 30% all over the Brazilian region, from equator to beyond the EIA regions and from east to west sectors. It is also noticed that the EIA strengths at the east and west sectors were weakened during the SSW-2012. However, the Brazilian eastern sector was found to be more disturbed compared to the western sector during this SSW-2012 event.
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ionospheric response to the 2009 Sudden Stratospheric Warming over the equatorial low and middle latitudes in the south american sector
Journal of Geophysical Research, 2015Co-Authors: P R Fagundes, Larisa Petrovna Goncharenko, A J Coster, R De Jesus, A J De Abreu, K Venkatesh, Michael Pezzopane, M Gende, V G PillatAbstract:The present study investigates the ionospheric total electron content (TEC) and F-layer response in the Southern Hemisphere equatorial, low, and middle latitudes due to major Sudden Stratospheric Warming (SSW) event, which took place during January–February 2009 in the Northern Hemisphere. In this study, using 17 ground-based dual frequency GPS stations and two ionosonde stations spanning latitudes from 2.8°N to 53.8°S, longitudes from 36.7°W to 67.8°W over the South American sector, it is observed that the ionosphere was significantly disturbed by the SSW event from the equator to the midlatitudes. During day of year 26 and 27 at 14:00 UT, the TEC was two times larger than that observed during average quiet days. The vertical TEC at all 17 GPS and two ionosonde stations shows significant deviations lasting for several days after the SSW temperature peak. Using one GPS station located at Rio Grande (53.8°S, 67.8°W, midlatitude South America sector), it is reported for the first time that the midlatitude in the Southern Hemisphere was disturbed by the SSW event in the Northern Hemisphere.
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study of the thermospheric and ionospheric response to the 2009 Sudden Stratospheric Warming using time gcm and gsm tip models first results
Journal of Geophysical Research, 2015Co-Authors: M V Klimenko, Larisa Petrovna Goncharenko, F. S. Bessarab, Yu N Korenkov, V V Klimenko, M V TolstikovAbstract:This paper presents a study of mesosphere and low thermosphere influence on ionospheric disturbances during 2009 major Sudden Stratospheric Warming (SSW) event. This period was characterized by extremely low solar and geomagnetic activity. The study was performed using two first principal models: thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM) and global self-consistent model of thermosphere, ionosphere, and protonosphere (GSM TIP). The Stratospheric anomalies during SSW event were modeled by specifying the temperature and density perturbations at the lower boundary of the TIME-GCM (30 km altitude) according to data from European Centre for Medium-Range Weather Forecasts. Then TIME-GCM output at 80 km was used as lower boundary conditions for driving GSM TIP model runs. We compare models' results with ground-based ionospheric data at low latitudes obtained by GPS receivers in the American longitudinal sector. GSM TIP simulation predicts the occurrence of the quasi-wave vertical structure in neutral temperature disturbances at 80–200 km altitude, and the positive and negative disturbances in total electron content at low latitude during the 2009 SSW event. According to our model results the formation mechanisms of the low-latitude ionospheric response are the disturbances in the n(O)/n(N2) ratio and thermospheric wind. The change in zonal electric field is key mechanism driving the ionospheric response at low latitudes, but our model results do not completely reproduce the variability in zonal electric fields (vertical plasma drift) at low latitudes.
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ionospheric effects of Sudden Stratospheric Warming during moderate to high solar activity case study of january 2013
Geophysical Research Letters, 2013Co-Authors: Larisa Petrovna Goncharenko, J L Chau, P Condor, A J Coster, L BenkevitchAbstract:[1] A major Sudden Stratospheric Warming (SSW) occurred in January 2013 during moderate-to-high solar activity conditions. Observations during the winter of 2012/2013 reveal strong ionospheric disturbances associated with this event. Anomalous variations in vertical ion drift measured at the geomagnetic equator at Jicamarca (12°S, 77°W) are observed for over 40 days. We report strong perturbations in the total electron content (TEC) that maximize in the crests of equatorial ionization anomaly, reach 100% of the background value, exhibit significant longitudinal and hemispheric asymmetry, and last for over 40 days. The magnitude of ionospheric anomalies in both vertical drifts and TEC is comparable to the anomalies observed during the record-strong SSW of January 2009 that coincided with the extreme solar minimum. This observation contrasts with results of numerical simulations that predict weaker ionospheric response to the tidal forcing during high solar activity.
T J Fullerrowell - One of the best experts on this subject based on the ideXlab platform.
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ionospheric response to Sudden Stratospheric Warming events at low and high solar activity
Journal of Geophysical Research, 2014Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Houjun Wang, Fei WuAbstract:The sensitivity of the ionospheric response to a Sudden Stratospheric Warming (SSW) event has been examined under conditions of low and high solar activity through simulations using the whole atmosphere model (WAM) and the global ionosphere plasmasphere model (GIP). During non-SSW conditions, simulated daytime mean vertical drifts at the magnetic equator show similar solar activity dependence as an empirical model. Model results of ionospheric total electron content (TEC) and equatorial vertical drift for the January 2009 major SSW, which occurred at very low solar activity conditions, show reasonable agreement with observations. The simulations demonstrate that the E region dynamo is capable of creating the semidiurnal variation of vertical drift. WAM and GIP were also run at high solar activity conditions, using the same lower atmosphere conditions as present in the January 2009 SSW event. The simulations indicate that the amplitude and phase of migrating tides in the dynamo region during the event have similar magnitudes for both solar flux conditions. However, comparing the ionospheric responses to a major SSW under low and high solar activity periods, it was found that the changes in the ionospheric vertical drifts and relative changes in TEC decreased with increasing solar activity. The simulations indicate that the F region dynamo becomes more important throughout the daytime and contributes to the upward drift in the afternoon during the event when the solar activity is higher. Our test simulations also confirm that the increase of the ionospheric conductivity associated with increasing solar activity is responsible for the decrease of vertical drift changes during an SSW. In particular, first, the increase in F region conductivity allows the closure of E region currents through the F region, reducing the polarization electric field before noon. Second, the F region dynamo contributes an upward drift postnoon, maintaining upward drifts till after sunset. The direct changes of the thermospheric wind at higher solar activity due to increased dissipation of the tides from the lower atmosphere are relatively minor and do not contribute greatly to the changes of ionospheric responses in the low-latitude region.
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first forecast of a Sudden Stratospheric Warming with a coupled whole atmosphere ionosphere model idea
Journal of Geophysical Research, 2014Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Fei Wu, H Wang, Naomi MaruyamaAbstract:We present the first “weather forecast” with a coupled whole-atmosphere/ionosphere model of Integrated Dynamics in Earth's Atmosphere (IDEA) for the January 2009 Sudden Stratospheric Warming (SSW). IDEA consists of the Whole Atmosphere Model and Global Ionosphere-Plasmasphere model. A 30 day forecast is performed using the IDEA model initialized at 0000 UT on 13 January 2009, 10 days prior to the peak of the SSW. IDEA successfully predicts both the time and amplitude of the peak Warming in the polar cap. This is about 2 days earlier than the National Centers for Environmental Prediction operational Global Forecast System terrestrial weather model forecast. The forecast of the semidiurnal, westward propagating, zonal wave number 2 (SW2) tide in zonal wind also shows an increase in the amplitude and a phase shift to earlier hours in the equatorial dynamo region during and after the peak Warming, before recovering to their prior values about 15 days later. The SW2 amplitude and phase changes are shown to be likely due to the Stratospheric ozone and/or circulation changes. The daytime upward plasma drift and total electron content in the equatorial American sector show a clear shift to earlier hours and enhancement during and after the peak Warming, before returning to their prior conditions. These ionospheric responses compare well with other observational studies. Therefore, the predicted ionospheric response to the January 2009 SSW can be largely explained in simple terms of the amplitude and phase changes of the SW2 zonal wind in the equatorial E region.
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longitudinal variation of ionospheric vertical drifts during the 2009 Sudden Stratospheric Warming
Journal of Geophysical Research, 2012Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Fei Wu, Houjun Wang, D N AndersonAbstract:[1] The Whole Atmospheric Model (WAM) initialized with a data assimilation scheme is capable of simulating real Sudden Stratospheric Warming (SSW) events. The electrodynamics in the Coupled Thermosphere Ionosphere and Plasmasphere with Electrodynamics model (CTIPe) was driven by the WAM thermospheric winds in January 2009 to study the response of ionospheric drifts during the SSW. Simulation results are compared with observations of the vertical drift at Jicamarca and the equatorial electrojet (EEJ) in the Asian sectors. Early morning upward drift and afternoon downward drift are reproduced in all longitudes in the simulations, and are consistent with the available observations. Results also show that the occurrence time of the early morning upward drift and afternoon downward drift have significant phase differences between different longitudes. Simulations suggest that during the SSW the longitude dependence of the amplitude and phase of the equatorial vertical plasma drift is caused by the changing magnitudes of the migrating tides modulated by the geometry of the geomagnetic field. Some additional day-to-day variability and modulation of the phase structures at different longitudes in ionospheric vertical drifts during the SSW are possibly produced by the short-term changes in the non-migrating tides and by planetary waves.
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first simulations with a whole atmosphere data assimilation and forecast system the january 2009 major Sudden Stratospheric Warming
Journal of Geophysical Research, 2011Co-Authors: T J Fullerrowell, R A Akmaev, H Wang, Ming Hu, Daryl T Kleist, M IredellAbstract:[1] A Whole atmosphere Data Assimilation System (WDAS) is used to simulate the January 2009 Sudden Stratospheric Warming (SSW). WDAS consists of the Whole Atmosphere Model (WAM) and the 3-dimensional variational (3DVar) analysis system GSI (Grid point Statistical Interpolation), modified to be compatible with the WAM model. An incremental analysis update (IAU) scheme was implemented in the data assimilation cycle to overcome the problem of excessive damping by digital filter in WAM of the important tidal waves in the upper atmosphere. IAU updates analysis incrementally into the model, thus avoids the initialization procedure (i.e., digital filter) during the WAM forecast stage. The WDAS simulation of the January 2009 SSW shows a significant increase in TW3 (terdiurnal, westward propagating, zonal wave number 3) and a decrease in SW2 (semidiurnal, westward propagating, zonal wave number 2) wave amplitudes in the E region during the Warming, which can be attributed likely to the nonlinear wave-wave interactions between SW2, TW3 and DW1 (diurnal, westward propagating, zonal wave number 1). There is a delayed increase in SW2 in the E region after the Warming, indicating a modulation by the changing large-scale planetary waves in the loweratmosphere during the SSW. These tidal wave responses during SSW appeared to be global in scale. An extended WAM forecast initialized from WDAS analysis shows remarkably consistent tidal wave responses to SSW, indicating a potential forecasting capability of several days in advance of the effects of the large-scale tropospheric and Stratospheric dynamics on the thermospheric and ionospheric variability.
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did the january 2009 Sudden Stratospheric Warming cool or warm the thermosphere
Geophysical Research Letters, 2011Co-Authors: T J Fullerrowell, R A Akmaev, Fei Wu, M Fedrizzi, Rodney Viereck, H WangAbstract:[1] It has recently been suggested that observations of neutral density from satellite accelerometer data indicate a strong cooling occurred in the upper thermosphere during the January 2009 Sudden Stratospheric Warming (SSW). The 2009 Warming was a major event with winter polar Stratospheric temperatures increasing by 70 K. This January period has been re-examined with three independent models: the NRLMSISE-00 empirical model; the physics-based coupled thermosphere, ionosphere, plasmasphere, electrodynamics model (CTIPe); and the whole atmosphere model (WAM). The analysis of this period and comparison with the neutral density observations reveals that there is, in fact, no evidence at any latitude for a large-scale or global decrease in upper thermosphere density or temperature in response to the SSW. The observed decrease in density and temperature can be amply accounted for by small changes in geomagnetic activity during this period. On the contrary, the WAM numerical simulations of the period suggest a possible small globally averaged upper thermosphere Warming and neutral density increase by 5% during the SSW. This Warming would have been difficult to discern in the local-time sampling of the CHAMP observations due to likely change in the diurnal density variation during the SSW, and due to a much larger contribution to the variability from geomagnetic sources. At this stage, therefore, it is not possible to ascertain if a cooling or Warming occurred in the upper thermosphere in response to the Stratospheric Warming.
Fei Wu - One of the best experts on this subject based on the ideXlab platform.
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ionospheric response to Sudden Stratospheric Warming events at low and high solar activity
Journal of Geophysical Research, 2014Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Houjun Wang, Fei WuAbstract:The sensitivity of the ionospheric response to a Sudden Stratospheric Warming (SSW) event has been examined under conditions of low and high solar activity through simulations using the whole atmosphere model (WAM) and the global ionosphere plasmasphere model (GIP). During non-SSW conditions, simulated daytime mean vertical drifts at the magnetic equator show similar solar activity dependence as an empirical model. Model results of ionospheric total electron content (TEC) and equatorial vertical drift for the January 2009 major SSW, which occurred at very low solar activity conditions, show reasonable agreement with observations. The simulations demonstrate that the E region dynamo is capable of creating the semidiurnal variation of vertical drift. WAM and GIP were also run at high solar activity conditions, using the same lower atmosphere conditions as present in the January 2009 SSW event. The simulations indicate that the amplitude and phase of migrating tides in the dynamo region during the event have similar magnitudes for both solar flux conditions. However, comparing the ionospheric responses to a major SSW under low and high solar activity periods, it was found that the changes in the ionospheric vertical drifts and relative changes in TEC decreased with increasing solar activity. The simulations indicate that the F region dynamo becomes more important throughout the daytime and contributes to the upward drift in the afternoon during the event when the solar activity is higher. Our test simulations also confirm that the increase of the ionospheric conductivity associated with increasing solar activity is responsible for the decrease of vertical drift changes during an SSW. In particular, first, the increase in F region conductivity allows the closure of E region currents through the F region, reducing the polarization electric field before noon. Second, the F region dynamo contributes an upward drift postnoon, maintaining upward drifts till after sunset. The direct changes of the thermospheric wind at higher solar activity due to increased dissipation of the tides from the lower atmosphere are relatively minor and do not contribute greatly to the changes of ionospheric responses in the low-latitude region.
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first forecast of a Sudden Stratospheric Warming with a coupled whole atmosphere ionosphere model idea
Journal of Geophysical Research, 2014Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Fei Wu, H Wang, Naomi MaruyamaAbstract:We present the first “weather forecast” with a coupled whole-atmosphere/ionosphere model of Integrated Dynamics in Earth's Atmosphere (IDEA) for the January 2009 Sudden Stratospheric Warming (SSW). IDEA consists of the Whole Atmosphere Model and Global Ionosphere-Plasmasphere model. A 30 day forecast is performed using the IDEA model initialized at 0000 UT on 13 January 2009, 10 days prior to the peak of the SSW. IDEA successfully predicts both the time and amplitude of the peak Warming in the polar cap. This is about 2 days earlier than the National Centers for Environmental Prediction operational Global Forecast System terrestrial weather model forecast. The forecast of the semidiurnal, westward propagating, zonal wave number 2 (SW2) tide in zonal wind also shows an increase in the amplitude and a phase shift to earlier hours in the equatorial dynamo region during and after the peak Warming, before recovering to their prior values about 15 days later. The SW2 amplitude and phase changes are shown to be likely due to the Stratospheric ozone and/or circulation changes. The daytime upward plasma drift and total electron content in the equatorial American sector show a clear shift to earlier hours and enhancement during and after the peak Warming, before returning to their prior conditions. These ionospheric responses compare well with other observational studies. Therefore, the predicted ionospheric response to the January 2009 SSW can be largely explained in simple terms of the amplitude and phase changes of the SW2 zonal wind in the equatorial E region.
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longitudinal variation of ionospheric vertical drifts during the 2009 Sudden Stratospheric Warming
Journal of Geophysical Research, 2012Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Fei Wu, Houjun Wang, D N AndersonAbstract:[1] The Whole Atmospheric Model (WAM) initialized with a data assimilation scheme is capable of simulating real Sudden Stratospheric Warming (SSW) events. The electrodynamics in the Coupled Thermosphere Ionosphere and Plasmasphere with Electrodynamics model (CTIPe) was driven by the WAM thermospheric winds in January 2009 to study the response of ionospheric drifts during the SSW. Simulation results are compared with observations of the vertical drift at Jicamarca and the equatorial electrojet (EEJ) in the Asian sectors. Early morning upward drift and afternoon downward drift are reproduced in all longitudes in the simulations, and are consistent with the available observations. Results also show that the occurrence time of the early morning upward drift and afternoon downward drift have significant phase differences between different longitudes. Simulations suggest that during the SSW the longitude dependence of the amplitude and phase of the equatorial vertical plasma drift is caused by the changing magnitudes of the migrating tides modulated by the geometry of the geomagnetic field. Some additional day-to-day variability and modulation of the phase structures at different longitudes in ionospheric vertical drifts during the SSW are possibly produced by the short-term changes in the non-migrating tides and by planetary waves.
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did the january 2009 Sudden Stratospheric Warming cool or warm the thermosphere
Geophysical Research Letters, 2011Co-Authors: T J Fullerrowell, R A Akmaev, Fei Wu, M Fedrizzi, Rodney Viereck, H WangAbstract:[1] It has recently been suggested that observations of neutral density from satellite accelerometer data indicate a strong cooling occurred in the upper thermosphere during the January 2009 Sudden Stratospheric Warming (SSW). The 2009 Warming was a major event with winter polar Stratospheric temperatures increasing by 70 K. This January period has been re-examined with three independent models: the NRLMSISE-00 empirical model; the physics-based coupled thermosphere, ionosphere, plasmasphere, electrodynamics model (CTIPe); and the whole atmosphere model (WAM). The analysis of this period and comparison with the neutral density observations reveals that there is, in fact, no evidence at any latitude for a large-scale or global decrease in upper thermosphere density or temperature in response to the SSW. The observed decrease in density and temperature can be amply accounted for by small changes in geomagnetic activity during this period. On the contrary, the WAM numerical simulations of the period suggest a possible small globally averaged upper thermosphere Warming and neutral density increase by 5% during the SSW. This Warming would have been difficult to discern in the local-time sampling of the CHAMP observations due to likely change in the diurnal density variation during the SSW, and due to a much larger contribution to the variability from geomagnetic sources. At this stage, therefore, it is not possible to ascertain if a cooling or Warming occurred in the upper thermosphere in response to the Stratospheric Warming.
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forecasting the dynamic and electrodynamic response to the january 2009 Sudden Stratospheric Warming
Geophysical Research Letters, 2011Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Fei Wu, H Wang, M IredellAbstract:[1] A whole atmosphere model has been used to simulate the changes in the global atmosphere dynamics and electrodynamics during the January 2009 Sudden Stratospheric Warming (SSW). In a companion paper, it has been demonstrated that the neutral atmosphere response to the 2009 Warming can be simulated with high fidelity and can be forecast several days ahead. The 2009 Warming was a major event with the polar Stratospheric temperature increasing by 70 K. The neutral dynamics from the whole atmosphere model (WAM) was used to drive the response of the electrodynamics. The WAM simulation predicted a substantial increase in the amplitude of the 8-hour terdiurnal tide in the lower thermosphere dynamo region in response to the Warming, at the expense of the more typical semidiurnal tides. The increase in the terdiurnal mode had a significant impact on the diurnal variation of the electrodynamics at low latitude. The changes in the winds in the dayside ionospheric E region increased the eastward electric field early in the morning, and drove a westward electric field in the afternoon. The initial large increase in upward drifts gradually moved to later local times, and decreased in magnitude. The change in the amplitude and phase of the electrodynamic response to the SSW is in good agreement with observations from the Jicamarca radar. The agreement with observations serves to validate the whole atmosphere dynamic response. Since WAM can forecast the neutral dynamics several days ahead, the simulations indicate that the electrodynamic response can also be predicted.
Tzuwei Fang - One of the best experts on this subject based on the ideXlab platform.
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ionospheric response to Sudden Stratospheric Warming events at low and high solar activity
Journal of Geophysical Research, 2014Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Houjun Wang, Fei WuAbstract:The sensitivity of the ionospheric response to a Sudden Stratospheric Warming (SSW) event has been examined under conditions of low and high solar activity through simulations using the whole atmosphere model (WAM) and the global ionosphere plasmasphere model (GIP). During non-SSW conditions, simulated daytime mean vertical drifts at the magnetic equator show similar solar activity dependence as an empirical model. Model results of ionospheric total electron content (TEC) and equatorial vertical drift for the January 2009 major SSW, which occurred at very low solar activity conditions, show reasonable agreement with observations. The simulations demonstrate that the E region dynamo is capable of creating the semidiurnal variation of vertical drift. WAM and GIP were also run at high solar activity conditions, using the same lower atmosphere conditions as present in the January 2009 SSW event. The simulations indicate that the amplitude and phase of migrating tides in the dynamo region during the event have similar magnitudes for both solar flux conditions. However, comparing the ionospheric responses to a major SSW under low and high solar activity periods, it was found that the changes in the ionospheric vertical drifts and relative changes in TEC decreased with increasing solar activity. The simulations indicate that the F region dynamo becomes more important throughout the daytime and contributes to the upward drift in the afternoon during the event when the solar activity is higher. Our test simulations also confirm that the increase of the ionospheric conductivity associated with increasing solar activity is responsible for the decrease of vertical drift changes during an SSW. In particular, first, the increase in F region conductivity allows the closure of E region currents through the F region, reducing the polarization electric field before noon. Second, the F region dynamo contributes an upward drift postnoon, maintaining upward drifts till after sunset. The direct changes of the thermospheric wind at higher solar activity due to increased dissipation of the tides from the lower atmosphere are relatively minor and do not contribute greatly to the changes of ionospheric responses in the low-latitude region.
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first forecast of a Sudden Stratospheric Warming with a coupled whole atmosphere ionosphere model idea
Journal of Geophysical Research, 2014Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Fei Wu, H Wang, Naomi MaruyamaAbstract:We present the first “weather forecast” with a coupled whole-atmosphere/ionosphere model of Integrated Dynamics in Earth's Atmosphere (IDEA) for the January 2009 Sudden Stratospheric Warming (SSW). IDEA consists of the Whole Atmosphere Model and Global Ionosphere-Plasmasphere model. A 30 day forecast is performed using the IDEA model initialized at 0000 UT on 13 January 2009, 10 days prior to the peak of the SSW. IDEA successfully predicts both the time and amplitude of the peak Warming in the polar cap. This is about 2 days earlier than the National Centers for Environmental Prediction operational Global Forecast System terrestrial weather model forecast. The forecast of the semidiurnal, westward propagating, zonal wave number 2 (SW2) tide in zonal wind also shows an increase in the amplitude and a phase shift to earlier hours in the equatorial dynamo region during and after the peak Warming, before recovering to their prior values about 15 days later. The SW2 amplitude and phase changes are shown to be likely due to the Stratospheric ozone and/or circulation changes. The daytime upward plasma drift and total electron content in the equatorial American sector show a clear shift to earlier hours and enhancement during and after the peak Warming, before returning to their prior conditions. These ionospheric responses compare well with other observational studies. Therefore, the predicted ionospheric response to the January 2009 SSW can be largely explained in simple terms of the amplitude and phase changes of the SW2 zonal wind in the equatorial E region.
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longitudinal variation of ionospheric vertical drifts during the 2009 Sudden Stratospheric Warming
Journal of Geophysical Research, 2012Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Fei Wu, Houjun Wang, D N AndersonAbstract:[1] The Whole Atmospheric Model (WAM) initialized with a data assimilation scheme is capable of simulating real Sudden Stratospheric Warming (SSW) events. The electrodynamics in the Coupled Thermosphere Ionosphere and Plasmasphere with Electrodynamics model (CTIPe) was driven by the WAM thermospheric winds in January 2009 to study the response of ionospheric drifts during the SSW. Simulation results are compared with observations of the vertical drift at Jicamarca and the equatorial electrojet (EEJ) in the Asian sectors. Early morning upward drift and afternoon downward drift are reproduced in all longitudes in the simulations, and are consistent with the available observations. Results also show that the occurrence time of the early morning upward drift and afternoon downward drift have significant phase differences between different longitudes. Simulations suggest that during the SSW the longitude dependence of the amplitude and phase of the equatorial vertical plasma drift is caused by the changing magnitudes of the migrating tides modulated by the geometry of the geomagnetic field. Some additional day-to-day variability and modulation of the phase structures at different longitudes in ionospheric vertical drifts during the SSW are possibly produced by the short-term changes in the non-migrating tides and by planetary waves.
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forecasting the dynamic and electrodynamic response to the january 2009 Sudden Stratospheric Warming
Geophysical Research Letters, 2011Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Fei Wu, H Wang, M IredellAbstract:[1] A whole atmosphere model has been used to simulate the changes in the global atmosphere dynamics and electrodynamics during the January 2009 Sudden Stratospheric Warming (SSW). In a companion paper, it has been demonstrated that the neutral atmosphere response to the 2009 Warming can be simulated with high fidelity and can be forecast several days ahead. The 2009 Warming was a major event with the polar Stratospheric temperature increasing by 70 K. The neutral dynamics from the whole atmosphere model (WAM) was used to drive the response of the electrodynamics. The WAM simulation predicted a substantial increase in the amplitude of the 8-hour terdiurnal tide in the lower thermosphere dynamo region in response to the Warming, at the expense of the more typical semidiurnal tides. The increase in the terdiurnal mode had a significant impact on the diurnal variation of the electrodynamics at low latitude. The changes in the winds in the dayside ionospheric E region increased the eastward electric field early in the morning, and drove a westward electric field in the afternoon. The initial large increase in upward drifts gradually moved to later local times, and decreased in magnitude. The change in the amplitude and phase of the electrodynamic response to the SSW is in good agreement with observations from the Jicamarca radar. The agreement with observations serves to validate the whole atmosphere dynamic response. Since WAM can forecast the neutral dynamics several days ahead, the simulations indicate that the electrodynamic response can also be predicted.
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a whole atmosphere model simulation of the impact of a Sudden Stratospheric Warming on thermosphere dynamics and electrodynamics
Journal of Geophysical Research, 2010Co-Authors: T J Fullerrowell, Tzuwei Fang, R A Akmaev, Fei Wu, E A AraujopradereAbstract:[1] A Whole Atmosphere Model (WAM) has been used to explore the possible physical connection between a Sudden Stratospheric Warming (SSW) and the dynamics and electrodynamics of the lower thermosphere. WAM produces SSWs naturally without the need for external forcing. The classical signatures of an SSW appear in the model with a Warming of the winter polar stratosphere, a reversal of the temperature gradient, and a breakdown of the Stratospheric polar vortex. Substantial changes in the amplitude of stationary planetary wave numbers 1, 2, and 3 occur as the zonal mean zonal wind evolves. The simulations also show a cooling in the mesosphere and a Warming in the lower thermosphere consistent with observations. The magnitude of this particular SSW is modest, belonging to the category of minor Warming. In the lower thermosphere the amplitude of diurnal, semidiurnal, and terdiurnal, eastward and westward propagating tidal modes change substantially during the event. Since the magnitude of the Warming is minor and the tidal interactions with the mean flow and planetary waves are complex, the one-to-one correspondence between tidal amplitudes in the lower thermosphere and the zonal mean and stationary waves in the stratosphere is not entirely obvious. The increase in the magnitude of the terdiurnal tide (TW3) in the lower thermosphere has the clearest correlation with the SSW, although the timing appears delayed by about three days. The fast group velocity of the long vertical wavelength TW3 tide would suggest a faster onset for the direct propagation of the tide from the lower atmosphere. It is possible that changes in the magnitude of the diurnal and semidiurnal tides, with their slower vertical propagation, may interact in the lower thermosphere to introduce a terdiurnal tide with a longer delay. An increase in TW3 in the lower thermosphere would be expected to alter the local time variation of the electrodynamic response. The day-to-day changes in the lower thermosphere winds from WAM are shown to introduce variability in the magnitude of dayside low latitude electric fields, with a tendency during the Warming for the dayside vertical drift to be larger and occur earlier, and for the afternoon minimum to be smaller. The numerical simulations suggest that it is quite feasible that a major SSW, with a magnitude seen in January 2009, could cause large changes in lower thermosphere electrodynamics and hence in total electron content.
H Wang - One of the best experts on this subject based on the ideXlab platform.
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first forecast of a Sudden Stratospheric Warming with a coupled whole atmosphere ionosphere model idea
Journal of Geophysical Research, 2014Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Fei Wu, H Wang, Naomi MaruyamaAbstract:We present the first “weather forecast” with a coupled whole-atmosphere/ionosphere model of Integrated Dynamics in Earth's Atmosphere (IDEA) for the January 2009 Sudden Stratospheric Warming (SSW). IDEA consists of the Whole Atmosphere Model and Global Ionosphere-Plasmasphere model. A 30 day forecast is performed using the IDEA model initialized at 0000 UT on 13 January 2009, 10 days prior to the peak of the SSW. IDEA successfully predicts both the time and amplitude of the peak Warming in the polar cap. This is about 2 days earlier than the National Centers for Environmental Prediction operational Global Forecast System terrestrial weather model forecast. The forecast of the semidiurnal, westward propagating, zonal wave number 2 (SW2) tide in zonal wind also shows an increase in the amplitude and a phase shift to earlier hours in the equatorial dynamo region during and after the peak Warming, before recovering to their prior values about 15 days later. The SW2 amplitude and phase changes are shown to be likely due to the Stratospheric ozone and/or circulation changes. The daytime upward plasma drift and total electron content in the equatorial American sector show a clear shift to earlier hours and enhancement during and after the peak Warming, before returning to their prior conditions. These ionospheric responses compare well with other observational studies. Therefore, the predicted ionospheric response to the January 2009 SSW can be largely explained in simple terms of the amplitude and phase changes of the SW2 zonal wind in the equatorial E region.
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first simulations with a whole atmosphere data assimilation and forecast system the january 2009 major Sudden Stratospheric Warming
Journal of Geophysical Research, 2011Co-Authors: T J Fullerrowell, R A Akmaev, H Wang, Ming Hu, Daryl T Kleist, M IredellAbstract:[1] A Whole atmosphere Data Assimilation System (WDAS) is used to simulate the January 2009 Sudden Stratospheric Warming (SSW). WDAS consists of the Whole Atmosphere Model (WAM) and the 3-dimensional variational (3DVar) analysis system GSI (Grid point Statistical Interpolation), modified to be compatible with the WAM model. An incremental analysis update (IAU) scheme was implemented in the data assimilation cycle to overcome the problem of excessive damping by digital filter in WAM of the important tidal waves in the upper atmosphere. IAU updates analysis incrementally into the model, thus avoids the initialization procedure (i.e., digital filter) during the WAM forecast stage. The WDAS simulation of the January 2009 SSW shows a significant increase in TW3 (terdiurnal, westward propagating, zonal wave number 3) and a decrease in SW2 (semidiurnal, westward propagating, zonal wave number 2) wave amplitudes in the E region during the Warming, which can be attributed likely to the nonlinear wave-wave interactions between SW2, TW3 and DW1 (diurnal, westward propagating, zonal wave number 1). There is a delayed increase in SW2 in the E region after the Warming, indicating a modulation by the changing large-scale planetary waves in the loweratmosphere during the SSW. These tidal wave responses during SSW appeared to be global in scale. An extended WAM forecast initialized from WDAS analysis shows remarkably consistent tidal wave responses to SSW, indicating a potential forecasting capability of several days in advance of the effects of the large-scale tropospheric and Stratospheric dynamics on the thermospheric and ionospheric variability.
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did the january 2009 Sudden Stratospheric Warming cool or warm the thermosphere
Geophysical Research Letters, 2011Co-Authors: T J Fullerrowell, R A Akmaev, Fei Wu, M Fedrizzi, Rodney Viereck, H WangAbstract:[1] It has recently been suggested that observations of neutral density from satellite accelerometer data indicate a strong cooling occurred in the upper thermosphere during the January 2009 Sudden Stratospheric Warming (SSW). The 2009 Warming was a major event with winter polar Stratospheric temperatures increasing by 70 K. This January period has been re-examined with three independent models: the NRLMSISE-00 empirical model; the physics-based coupled thermosphere, ionosphere, plasmasphere, electrodynamics model (CTIPe); and the whole atmosphere model (WAM). The analysis of this period and comparison with the neutral density observations reveals that there is, in fact, no evidence at any latitude for a large-scale or global decrease in upper thermosphere density or temperature in response to the SSW. The observed decrease in density and temperature can be amply accounted for by small changes in geomagnetic activity during this period. On the contrary, the WAM numerical simulations of the period suggest a possible small globally averaged upper thermosphere Warming and neutral density increase by 5% during the SSW. This Warming would have been difficult to discern in the local-time sampling of the CHAMP observations due to likely change in the diurnal density variation during the SSW, and due to a much larger contribution to the variability from geomagnetic sources. At this stage, therefore, it is not possible to ascertain if a cooling or Warming occurred in the upper thermosphere in response to the Stratospheric Warming.
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forecasting the dynamic and electrodynamic response to the january 2009 Sudden Stratospheric Warming
Geophysical Research Letters, 2011Co-Authors: Tzuwei Fang, T J Fullerrowell, R A Akmaev, Fei Wu, H Wang, M IredellAbstract:[1] A whole atmosphere model has been used to simulate the changes in the global atmosphere dynamics and electrodynamics during the January 2009 Sudden Stratospheric Warming (SSW). In a companion paper, it has been demonstrated that the neutral atmosphere response to the 2009 Warming can be simulated with high fidelity and can be forecast several days ahead. The 2009 Warming was a major event with the polar Stratospheric temperature increasing by 70 K. The neutral dynamics from the whole atmosphere model (WAM) was used to drive the response of the electrodynamics. The WAM simulation predicted a substantial increase in the amplitude of the 8-hour terdiurnal tide in the lower thermosphere dynamo region in response to the Warming, at the expense of the more typical semidiurnal tides. The increase in the terdiurnal mode had a significant impact on the diurnal variation of the electrodynamics at low latitude. The changes in the winds in the dayside ionospheric E region increased the eastward electric field early in the morning, and drove a westward electric field in the afternoon. The initial large increase in upward drifts gradually moved to later local times, and decreased in magnitude. The change in the amplitude and phase of the electrodynamic response to the SSW is in good agreement with observations from the Jicamarca radar. The agreement with observations serves to validate the whole atmosphere dynamic response. Since WAM can forecast the neutral dynamics several days ahead, the simulations indicate that the electrodynamic response can also be predicted.
