Strong Jet Research Articles

A novel Bayesian approach for decomposing the radio emission of quasars: II. Link between quasar radio emission and black hole mass

Abstract Whether the mass of supermassive black hole (MBH) is directly linked to the quasar radio luminosity remains a long-debated issue, and understanding the role of MBH in the evolution of quasars is pivotal to unveiling the mechanism of AGN feedback. In this work, based on a two-component Bayesian model, we examine how MBH affects the radio emission from quasars, separating the contributions from host galaxy star formation (SF) and AGN activity. By modelling the radio flux density distribution of Sloan Digital Sky Survey (SDSS) quasars from the LOFAR Two-metre Sky Survey Data Release 2, we find no correlation between MBH and SF rate (SFR) at any mass for quasars at a given redshift and bolometric luminosity. The same holds for AGN activity across most MBH values; however, quasars with the top 20 % most massive SMBHs are 2 to 3 times more likely to host strong radio jets than those with lower-mass SMBHs at similar redshift and luminosity. We suggest defining radio quasar populations by their AGN and SF contributions instead of radio loudness; our new definition unifies previously divergent observational results on the role of MBH in quasar radio emissions. We further demonstrate that this radio enhancement in quasars with the 20 % most massive SMBHs affects only the $\sim 5~{{\%}}$ most radio bright quasars at a given redshift and bolometric luminosity. We discuss possible physical origins of this radio excess in the most massive and radio-bright quasar population, which remains an interest for future study.

Design and implementation of a waterless solar panel cleaning system

Manual cleaning of large solar installations is often labor-intensive and time-consuming, primarily due to the accumulation of dust on solar panels, which significantly impairs their efficiency. The study introduces a novel, waterless, cost-effective automatic cleaning system for small solar panels. The rationale behind this innovation stems from the necessity to mitigate efficiency losses caused by dirt and contaminants on solar surfaces. The automated system employs an Arduino microcontroller enhanced with a real-time clock to optimize cleaning schedules based on environmental conditions. The system consists of a two-stage mechanism which includes an ejector blower that produces a strong air jet, complemented by a flexible brush that effectively removes dust as well as sticky dirt. Cleaning intervals are strategically determined to ensure consistent maintenance without manual intervention, thus maximizing energy output. Tests on a 60 W solar panel revealed an impressive average power output increase of 26.23 % following cleaning. This prototype demonstrates the efficacy of the cleaning approach and underscores its potential to alleviate efficiency losses attributed to dust accumulation. Particularly advantageous in arid regions where water conservation is paramount, this automated system enhances energy production and operational efficiency for solar plant operators, promoting sustainable energy practices.

Atmospheric Circulation on Other Planets: Venus, Mars, Jupiter

Abstract. This review provides a comparative analysis of atmospheric circulation across four planets in our solar system: Venus, Mars, Jupiter, and Earth. By examining the unique characteristics of each planet, including atmospheric composition, rotation rates, axial tilt, and solar radiation, the study explores how these factors influence the dynamics of their respective atmospheres. Venus, with its dense CO atmosphere and slow retrograde rotation, exhibits a super-rotating atmosphere leading to extreme and uniform climate conditions. Marss thin atmosphere and significant seasonal variations, combined with global dust storms, result in highly variable and dynamic atmospheric patterns. Jupiters rapid rotation and internal heat contribute to complex and powerful atmospheric dynamics, including strong jet streams and long-lasting storms like the Great Red Spot. In contrast, Earth's atmospheric circulation is driven by a combination of solar radiation, rotation, and the presence of oceans and continents, resulting in relatively stable and predictable weather patterns. The study highlights the diversity of atmospheric processes within our solar system, providing insights that are crucial for understanding planetary climates and assessing the potential habitability of exoplanets.

Active Galactic Nucleus Jet-inflated Bubbles as Possible Origin of Odd Radio Circles

Odd radio circles (ORCs) are newly discovered extragalactic radio objects with an unknown origin. In this work, we carry out three-dimensional cosmic-ray (CR) magnetohydrodynamic simulations using the FLASH code and predict the radio morphology of end-on active galactic nucleus (AGN) jet-inflated bubbles considering hadronic emission. We consider CR proton (CRp)-dominated jets as they tend to inflate oblate bubbles, promising to reproduce the large inferred sizes of the ORCs when viewed end-on. We find that powerful and long-duration CRp-dominated jets can create bubbles with similar sizes (∼300–600 kpc) and radio morphology (circular and edge-brightened) to the observed ORCs in low-mass (M vir ∼ 8 × 1012 − 8 × 1013 M ⊙) halos. Given the same amount of input jet energy, longer-duration (thus lower-power) jets tend to create larger bubbles since high-power jets generate strong shocks that carry away a significant portion of the jet energy. The edge-brightened feature of the observed ORCs is naturally reproduced due to efficient hadronic collisions at the interface between the bubbles and the ambient medium. We further discuss the radio luminosity, X-ray detectability, and the possible origin of such strong AGN jets in the context of galaxy evolution. We conclude that end-on CR-dominated AGN bubbles could be a plausible scenario for the formation of ORCs.

Observation of deep currents around a seamount between the Japan and Kuril trenches

Hydrographic observations and two-year current measurements revealed the flow around the Erimo Seamount between the Japan and Kuril trenches. Northward currents were observed to flow both around the seamount and on the eastern flank of the trench. Since the dissolved oxygen concentration of the former is higher than that of the latter, these currents correspond to the western and eastern branch currents of the deep western boundary current in the North Pacific, respectively. The western branch current forms a Taylor cap over the seamount, although during certain periods, it joins the eastern branch current. During such periods, a strong jet forms around the seamount and the Taylor cap is washed away. Such alternately intensified currents are consistent with previous observations of the Japan Trench. On the western flank of the trench, a southward current flows near the seafloor, while an eastward current is formed at a depth of 3360 m due to the confluence of the currents from north and south.

Dynamics of a laser-induced bubble near a cylinder within a confined space

The collapse of a laser-induced bubble near a cylinder within a confined space is investigated using high-speed photography and the Kelvin impulse theory. On the basis of an analysis of the liquid flow field and the Kelvin impulse, the effects of bubble–cylinder distance and radius ratio on bubble collapse behavior are investigated. Furthermore, the bubble motion during the first bubble oscillation period is quantitatively explored using the Kelvin impulse theory. The main conclusions of this study are as follows: (1) When the bubble is not restricted by the cylinder, three cases of jets are observed—strong jet, medium jet, and weak jet. When the bubble is restricted by the cylinder, three cases of bubble deformation are observed—fan-shaped collapse, ellipse-shaped collapse, and quasi circular shaped collapse. (2) The cylinder mainly affects the velocity of the surrounding liquid through the term of the point sink, and the bubble–cylinder distance mainly affects the liquid velocity from the bubble. (3) The Kelvin impulse intensity exhibits an exponentially decreasing trend with increasing bubble–cylinder distance, which is in good agreement with the experimentally observed jet velocities.

Causes of the extreme cold event in December 2023 on Eastern China

Abstract An extreme cold event outbreaks in Eastern China (EC) in December 16–22, 2023. Its maximum intensity (−8.30 °C) and duration (7 days) are in the second place in December during 1980–2023. In Early Stage (December 6–10), surface air temperature (SAT) anomalies reach the highest at 6.77 °C, exceeding mean value by two standard deviations. The variation of SAT anomalies (differences of SAT anomalies between the last day and the first day for a given period) is 0.60 °C. In Development Stage (December 11–15), SAT anomalies begin to decline but remain positive. In Outbreak Stage (December 16–22), the variation of SAT anomalies reaches a minimum of −3.17 °C, reflecting the cooling of EC. From December 1, cold air gradually gathers in Siberia under the influence of Arctic high moving southward. Cold air is locked in Siberia due to negative anomalies of geopotiential height (GH) and the westerlies anomalies between 40°–50°N. On December 11, these negative GH anomalies begin to move southeastward, and the westerlies anomalies weaken to a easterlies. From December 16–22, EC experiences an extreme cold event due to the southward of Arctic high and the eastward of Ural and Okhotsk high. On the basis of the zonal wind index (ZI) phase changes from negative to positive and the jet stream moves southeastward, the strong (weak) jet stream is spotted to block (promote) the southward of cold air. Linear regression shows that negative Arctic Oscillation (AO) conducts to the concentration of cold air in Siberia. Positive Siberia High (SH) pushes cold air to EC. SAT anomalies decrease by 2.29 °C in EC with the increase of 1 unit for SH. In empirical orthogonal function (EOF) analysis, EOF1 (28.07%) is characterized by warm Arctic and cold Siberia (WA-CS), which reflects the effect of SH on the occurrence of extreme cold events.

Statistical Tests of the Relativistic Beaming Indicators of jetted AGNs and Implication for the Revised Blazar Sequence

The latest detection by the Fermi Large Area Telescope (Fermi-LAT) of strong relativistic jets of very high-energy (VHE, above 100 GeV) from the Narrow-Line Seyfert 1 Galaxies (NLS1s) has opened a new unified scheme of active galactic nuclei (AGN) in which jetted Seyfert galaxies are viewed as counterparts to a subclass of AGNs. In this paper, we report a systematic investigation of the revised blazar sequence using the γ-ray Doppler factor () and the radio core-dominance parameter (R) of AGN samples of NLS1s and blazar subtypes of flat-spectrum radio quasars (FSRQs) and BL Lac objects (BLs). Furthermore, we explore the γ-ray properties of NLS1s and blazar subtypes in the context of the blazar unification scheme at different scales. The main results are as follows: (a) The average values of R and γ-ray luminosity () of our sample agree with the sequence BLs – FSRQs – NLS1s and provide quantitative explanations for the observed relativistic beaming effects in these objects. (b) Through a parameter t-test and non-parametric K-S test with chance probability p <10-3, we find that the distributions of R and Lγ for NLS1s and the blazar subtypes are not significantly different. (c) There is a regular positive trend (r > +0.79) in the variation of Lγ – data from BLs to NLS1s through FSRQs which is consistent with the prediction of the revised blazar sequence. These results imply that NLS1s could fit very well into the conventional blazar sequence.

Helicopter rotor in a propeller slipstream: Aerodynamic and rotor blade flapping responses

During helicopter air-to-air refueling the helicopter's rotor can engage the tanker aircraft's wing and flap end tip vortices and the slipstream of its propellers. The tip vortices represent a swirl around an axis that is essentially parallel to the rotor longitudinal axis. The slipstream of the propellers includes a strong air jet downstream that can cover a significant amount of the helicopter's main rotor. This phenomenon was recently treated analytically for a rigid rotor by means of blade-element momentum theory and the rotor control angles required to reject the disturbance were computed. In this article, the rotor blade flapping is introduced as degree of freedom. It is shown that the rotor coning is affected by the slipstream position with respect to the rotor hub. Without retrim, the largest amount of coning and cyclic flapping occurs for slipstream positions on the retreating side of the rotor.

Biomass Burning Aerosol Observations and Transport over Northern and Central Argentina: A Case Study

The characteristics of South American biomass burning (BB) aerosols transported over northern and central Argentina were investigated from July to December 2019. This period was chosen due to the high aerosol optical depth values found in the region and because simultaneously intensive biomass burning took place over the Amazon. More specifically, a combination of remote sensing observations with simulated air parcel back trajectories was used to link the optical and physical properties of three BB aerosol events that affected Pilar Observatory (PO, Argentina, 31°41′S, 63°53′W, 338 m above sea level), with low-level atmospheric circulation patterns and with types of vegetation burned in specific fire regions. The lidar observations at the PO site were used for the first time to characterize the vertical extent and structure of BB aerosol plumes as well as their connection with the planetary boundary layer, and dust particles. Based mainly on the air-parcel trajectories, a local transport regime and a long transport regime were identified. We found that in all the BB aerosol event cases studied in this paper, light-absorbing fine-mode aerosols were detected, resulting mainly from a mixture of aging smoke and dust particles. In the remote transport regime, the main sources of the BB aerosols reaching PO were associated with Amazonian rainforest wildfires. These aerosols were transported into northern and central Argentina within a strong low-level jet circulation. During the local transport regime, the BB aerosols were linked with closer fires related to tropical forests, cropland, grassland, and scrub/shrubland vegetation types in southeastern South America. Moreover, aerosols carried by the remote transport regime were associated with a high aerosol loading and enhanced aging and relatively smaller particle sizes, while aerosols associated with the local transport pattern were consistently less affected by the aging effect and showed larger sizes and low aerosol loading.

Fluid Dynamic Study of the Penn State Pediatric Total Artificial Heart.

Penn State University is developing a pediatric total artificial heart (TAH) as a bridge-to-transplant device that supports infants and small children with single ventricle anomalies or biventricular heart failure to address high waitlist mortality rates for pediatric patients with severe congenital heart disease (CHD). Two issues with mechanical circulatory support devices are thrombus formation and thromboembolic events. This in vitro study characterizes flow within Penn State's pediatric total artificial heart under physiological operating conditions. Particle image velocimetry (PIV) is used to quantify flow within the pump and to calculate wall shear rates (WSRs) along the internal pump surface to identify potential thrombogenic regions. Results show that the diastolic inflow jets produce sufficient wall shear rates to reduce thrombus deposition potential along the inlet side of the left and right pumps. The inlet jet transitions to rotational flow, which promotes wall washing along the apex of the pumps, prevents flow stasis, and aligns flow with the outlet valve prior to systolic ejection. However, inconsistent high wall shear rates near the pump apex cause increased thrombogenic potential. Strong systolic outflow jets produce high wall shear rates near the outlet valve to reduce thrombus deposition risk. The right pump, which has a modified outlet port angle to improve anatomical fit, produces lower wall shear rates and higher thrombus susceptibility potential (TSP) compared to the left pump. In summary, this study provides a fluid dynamic understanding of a new pediatric total artificial heart and indicates thrombus susceptibility is primarily confined to the apex, consistent with similar pulsatile heart pumps.

AirCore Observations at Northern Tibetan Plateau During the Asian Summer Monsoon

AbstractWe present data and analysis of a set of balloon‐borne sounding profiles, which includes co‐located O3, CO, CH4, and particles, over the northern Tibetan Plateau during an Asian summer monsoon (ASM) season. These novel measurements shed light on the ASM transport behavior near the northern edge of the anticyclone. Joint analyses of these species with the temperature and wind profiles and supported by back trajectory modeling identify three distinct transport processes that dominate the vertical chemical structure in the middle troposphere, upper troposphere (UT), and the tropopause region. The correlated changes in profile structures in the middle troposphere highlight the influence of the strong westerly jet. Elevated constituent concentrations in the UT identify the main level of convective transport at the upstream source regions. Observed higher altitude maxima for CH4 characterize the airmasses' continued ascent following convection. These data complement constituent observations from other parts of the ASM anticyclone.

Multiscale drivers of catastrophic heavy rainfall event in early August 2022 in South Korea

On 8–11 August 2022, South Korea experienced a catastrophic heavy rainfall event (HRE) with 14 fatalities. To elucidate its driving mechanisms, the present study performs a multiscale analysis by hierarchically delineating the synoptic and large-scale characteristics of the HRE. Its synoptic condition was featured by the confrontation of the western North Pacific subtropical high and the continental cyclone in the north of the Korean Peninsula. At their interface, a tremendous amount of moisture was transported in an elongated shape (i.e., atmospheric river) along with strong frontogenetic activity. This provided a favorable environment for potential instability. The continental cyclone was maintained throughout the HRE period, while a transient cyclone was superposed contributing to more intense rainfall in the early stage of the HRE. This persistent cyclone in the north of the Korean Peninsula originated from a far-upstream-originated cutoff low that became a part of the quasi-stationary wave train along the Asian subtropical jet. A linear model experiment suggests that the quasi-stationary wave train was excited by the enhanced tropical convection related to the boreal summer intraseasonal oscillation. The anomalously strong subtropical jet also acted as an effective waveguide. These results suggest that the integration of synoptic and large-scale processes is essential to understand this unprecedented HRE.

Three-dimensional particle image velocimetry experimental study of transient motion characteristics of different scale vortices in gasoline engine

The paper adopted three-dimensional (3D) Particle Image Velocimetry (PIV) combined with high-speed measurement technology to study the transient motion characteristics of tumble flow induced by small and medium-sized vortices on an optical gasoline engine. Meanwhile, the Proper Orthogonal Decomposition (POD) method was introduced to analyze the evolution of transient vortices, revealing the three-dimensional motion principle of vortices with different spatial scales within the cylinder. The results showed that increasing the engine speed can cause boosted in-plane and out-of-plane velocity, especially for the in-plane velocity. However, the average velocity in the plane was higher than that out of the plane with the difference generally within an order of magnitude. The strong intake jet was the main reason for bringing turbulent kinetic energy in the cylinder. The average kinetic energy and turbulent kinetic energy in the cylinder are both significantly improved at high engine speed. From the results of this experiment, it was revealed that there exists isotropic turbulent pulsation characteristics. Overall, the corresponding flow characteristics of different decomposed modes were different. The first mode section had the lowest average velocity ratio, while the other two had the highest. Due to the dissipation of large vortices into small vortices or the shear action between flow layers, new vortices were generated, leading to the intermittent phenomenon of the motion path of the vortex cluster in the target plane. The average vortex size and velocity circularity corresponding to two varied engine speeds presented a downward trend. The average vortex size was smaller at high engine speed, while the vortex intensity was higher. In addition, increasing the engine speed would decrease the vortex scale but increase the vortex strength. This work provided new fundamental insights into analyzing the characteristics of micro-scaled vortices in turbulent flow, as well as the organization of intake in the gasoline engine.

Very long baseline interferometry observations of the high-redshift X-ray-bright blazar SRGE J170245.3+130104

Aims. The X-ray luminous and radio-loud active galactic nucleus (AGN) SRGE J170245.3+130104 discovered at z ∼ 5.5 provides unique chances to probe the growth and evolution of a supermassice black hole (SMBH) with powerful jets in the early Universe. Methods. We present 1.35 − 5.1 GHz Very Long Baseline Array (VLBA) results regarding the radio continuum emission and a spectral analysis of this quasar in a low-flux-density state. Results. This source is unresolved at three frequencies, with total flux densities of 8.35 ± 0.09 Jy beam−1, 7.47 ± 0.08 Jy beam−1, and 6.57 ± 0.02 Jy beam−1 at 1.73 GHz, 2.26 GHz, and 4.87 GHz, respectively. Meanwhile, the brightness temperature is higher than 109 K. Conclusions. Compared with previous radio observations with arcsecond-scale resolution, nearly all the radio emission from this source is concentrated in the very central milliarcsecond (mas) scale area. We confirm this source is a bright blazar at z > 5. This young AGN provides a great opportunity to understand the mechanisms behind the generation of strong jets in the early Universe.

Liquid film burst caused by perpendicularly blowing gas jet

Blowing gas perpendicularly onto a liquid film may lead to various kinds of film deformations. When the jet is steady and mild, a protrusion structure will appear on the film and stretches in length, as jet velocity continue to increase, separated bubbles will detach from the protruded surface. Compared with continuously blowing gentle gas jets, short duration pulsed strong jets are more realistic and generally existing, yet the in-depth mechanism studies are insufficient, thus need further investigation. We have observed that the liquid film protrusion tends to stretch to a critical length then burst into tiny droplets when blown by the pulsed jet. After theoretical analysis, we discover that during the stretching process, rather than the jet velocity that was presumed as the driving factor, the two physical properties of the fluid, namely the surface tension and viscosity, play the dominant role to cause the structure collapsing. The critical burst length of the protrusion structure correlates with the ratio of these two properties. We conducted experiments using various test fluids, gas nozzle diameters, and jet velocities. The experimental results confirmed our theoretical analysis. This discovery provides a critical insight into the physics of liquid film deformation and atomization under gaseous crossflow, which can be commonly seen in fuel injection and aerosol droplet generation related fields.

Strong multiperiod forerunning light jet within a double-prism gap: a counterintuitive manifestation of causality

We report on the effect of a strong and protracted advanced response in pulse transmission and reflection in a double-prism scheme. In distinction to the well-known activity on superluminal-like tunneling of an electromagnetic pulse through a gap of a double prism, we consider an optical pulse refracting to a gap and sliding therein. The formation of a multiperiod light jet running within the gap well before the incident pulse is shown with account of normal material dispersion and excitation of leaky modes in the gap. Conditions for the paradoxical appearance of the forerunning jet are revealed to have a geometrical nature with a specific relation between phase and group velocities involved. This deduction assigns the stated effect to the counterintuitive manifestation of causality with no reference to superluminal propagation.

Observing Gravity Waves Generated by Moving Sources With Ground‐Based Rayleigh Lidars

AbstractTemperature measurements by zenith‐pointing ground‐based Rayleigh lidars are often used to detect middle atmospheric gravity waves. In time‐height diagrams of temperature perturbations, stationary mountain waves are identifiable by horizontal phase lines. Vertically tilted phase lines, on the other hand, indicate that the wave source or the propagation conditions are transient. Idealized numerical simulations illustrate that and how a wave source moving in the direction of the mean wind entails upward‐tilted phase lines. The inclination angle depends on the horizontal wavelength and the wave source’s propagation speed. On this basis, the goal is to identify and characterize non‐orographic gravity waves (NOGWs) from propagating sources, for example, upper‐level jet/front systems, in simulated lidar observations and actual Rayleigh lidar measurements. Compositions of selected atmospheric variables from a meteorological forecast or reanalysis are thoughtfully combined to associate NOGWs with processes in the troposphere and stratosphere. For a virtual observation over the Southern Ocean, upward‐tilted phase lines indeed dominate the time‐height diagram during the passage of an upper‐level trough. The example also emphasizes that temporal filtering of temperature measurements is appropriate for NOGWs, especially in the presence of a strong polar night jet that implies large vertical wavelengths. During two selected observational periods of the COmpact Rayleigh Autonomous Lidar (CORAL) in the lee of the southern Andes, upward‐tilted phase lines are mainly associated with mountain waves and transient background wind conditions. One nighttime measurement by CORAL coincides with the passage of an upper‐level trough, but large‐amplitude mountain waves superpose the small‐amplitude NOGWs in the middle atmosphere.

Impact of bathymetry on Indian Ocean circulation in a nested regional ocean model

The Regional Indian Ocean model based on Modular Ocean Model (MOM4p1) was used to understand the importance of a realistic representation of bathymetry on Ocean General Circulation. The model has 1/4° uniform horizontal resolution and is forced with Coordinated Ocean-Ice Reference Experiments (CORE-II) inter-annual forcing with two simulations named BLND (realistic bathymetry) and OM3 (smoothed bathymetry), which only differ in the representation of bathymetry for the years 1992–2005. We also used recent reanalysis products from ORAS5 and SODA3 and ADCP observation to compare the subsurface currents. We show that by the inclusion of realistic bathymetry, there is a significant improvement in the upper ocean salinity, temperature, and currents, particularly near the coast. The salinity and temperature of the upper ocean are very close to the observed value near the coast. The bias in the salinity and temperature was reduced to half in BLND simulation compared to OM3, which led to a more realistic East India Coastal Current (EICC). We show the first evidence of a basin-wide cyclonic gyre over the Bay of Bengal at 1000 m depth during spring, which is just opposite to that of a basin-wide anti-cyclonic gyre at the surface. We found the presence of poleward EICC during spring at 1000 m and 2000 m depth, which is opposite to that of the surface. The presence of this deeper EICC structure is completely absent during fall. We show the presence of a boundary current along the coast of Andaman and Nicobar Island at a depth of 2000 m. The observed Wyrtki Jet (WJ) magnitude and spatial structure are most realistically reproduced in BLND simulation as compared to OM3 simulations. Both ORAS5 and SODA reanalysis products underestimate the WJ magnitude. The presence of the Maldives Islands is responsible for the westward extent of Equatorial Under Current (EUC). The presence of Maldives also creates wakes on the leeward side in the EUC zonal current. During fall, EUC is better defined in the eastern Equatorial Indian Ocean and lies at a depth of between 50 and 100 m, unlike its spring counterpart, in which its core is located slightly deeper, between 100 and 150 m depth. During peak summer months, June–July, a strong eastward zonal jet is present at 1000 m depth, similar to Wyrtki Jet (WJ). Inter-monsoon Jets, i.e., spring and fall jets, are also seen but are in the opposite direction, i.e., westward, unlike eastward in WJ.

Long‐Term Variability and Tendencies in Mesosphere and Lower Thermosphere Winds From Meteor Radar Observations Over Esrange (67.9°N, 21.1°E)

AbstractLong‐term variabilities of monthly zonal (U) and meridional winds (V) in northern polar mesosphere and lower thermosphere (MLT, ∼80–100 km) are investigated using meteor radar observations during 1999–2022 over Esrange (67.9°N, 21.1°E). The summer (June‐August) mean zonal winds are characterized by westward flow up to ∼88–90 km and eastward flow above this height. The summer mean meridional winds are equatorward with strong jet at ∼85–90 km and it weakens above this height. The U and V exhibit strong interannual variability that varies with altitude and month or season. The responses of U and V anomalies (from 1999 to 2003) to solar cycle (SC), Quasi Biennial Oscillation at 10 and 30 hPa, El Niño‐Southern Oscillation, North Atlantic Oscillation, ozone (O3) and carbon dioxide (CO2) are analyzed using multiple linear regression. From analysis, significant regions of correlations between MLT winds and above potential drivers vary with altitude and month. The positive responses of U and V to SC (up to 15 m/s/100 sfu) indicates the strengthening of eastward winds in mid‐late winter, and poleward winds in late autumn and early winter. The O3 likely intensifies the eastward and poleward winds (∼100 m/s/ppmv) in winter and early spring. The CO2 significantly influence the eastward flow in late winter and summer (above ∼90–95 km) and strengthen the meridional circulation. The significant positive trend in U peaks in summer, late autumn and early winter (∼0.6 m/s/year), the negative trend in V is more prominent in summer above ∼90–95 km.