Solar Cycle Dependence Research Articles

Seasonal and Solar Cycle Dependency of Relationship Between Equatorial Plasma Bubbles and Rayleigh‐Taylor Instability Growth Rate

AbstractThe relationship between the post‐sunset equatorial Plasma Bubbles (EPBs) and the Rayleigh‐Taylor instability growth rates was studied by means of the occurrence probabilities. EPB observations were obtained through the Rate of Total Electron Content Index (ROTI) measured by ground‐based Global Navigation Satellite System (GNSS) receivers in the South American equatorial region. Data from the period 2013 to 2022 were utilized. The calculations were based on F‐layer vertical drift measurements obtained from the São Luís ionosonde (2.33°S, 44.2°W, dip angle: −0.5°), the International Reference Ionosphere model (IRI‐2016), Horizontal Wind Model (HWM‐14), and Spectrometer Incoherent Scatter Model‐2,000 (NRLMSISE‐00). The EPB occurrence probability increased from 0% to 100% as increased from 0 to . Additionally, the occurrence probability exhibited seasonal variations, with a gradual increase during the equinox months, minimal occurrence during the June solstice, and a sudden increase during the December solstice. We found that the occurrence probability varied with day‐to‐day, season and solar activity for the same .

Solar Cycle Dependence of Migrating Diurnal Tide in the Equatorial Mesosphere and Lower Thermosphere

Atmospheric migrating diurnal tide (DW1) is one of the prominent variabilities in the mesosphere and lower thermosphere (MLT). The existence of the solar cycle dependence of DW1 is debated, and there exist different and even opposite findings at different latitudes. In this paper, the solar cycle dependence of temperature DW1 in the equatorial mesosphere and lower thermosphere (MLT) is investigated using temperature global observations from TIMED/SABER spanning 22 years (2002–2023). The results show that (a) the solar cycle dependence of temperature DW1 is seen very clearly at the equator. The maximum correlation coefficient between DW1 and the F10.7 index occurs at 87km, with 0.72; the second maximum coefficient occurs at 99 km, with 0.62. The coefficient could reach 0.87 at 87 km and 0.67 at 99 km after dropping the years influenced by the Stratosphere Quasi-biennial oscillation (SQBO) disruption event. (b) DW1 shows a lag response to the solar cycle at the equator. DW1 amplitudes show a 1-year lag to the F10.7 index at 87 km and a 2-year lag to the F10.7 index at 99 km.

Tidal Control of Equatorial Vertical E × B Drift Under Solar Minimum Conditions

AbstractObservations show that equatorial ionospheric vertical drifts during solar minimum differ from the climatology between late afternoon and midnight. By analyzing WACCM‐X simulations, which reproduce this solar cycle dependence, we show that the interplay of the dominant migrating tides, their propagating and in situ forced components, and their solar cycle dependence impact the F‐region wind dynamo. In particular, the amplitude and phase of the propagating migrating semidiurnal tide (SW2) in the F‐region plays a key role. Under solar minimum conditions, the SW2 tide propagate to and beyond the F‐region in the winter hemisphere, and consequently its zonal wind amplitude in the F‐region is much stronger than that under solar maximum conditions. Furthermore, its phase shift leads to a strong eastward wind perturbation near local midnight. This in turn drives a F‐region dynamo with an equatorial upward drift between 18 and 1 hr local times.

Solar Cycle Dependence of the Turbulence Cascade Rate at 1 au

We study the solar cycle dependence of various turbulence cascade rates based on the methodology developed by Adhikari et al. that utilizes Kolmogorov phenomenology. This approach is extended to derive the heating rates for an Iroshnikov–Kriachnan (IK) phenomenology. The observed turbulence cascade rates corresponding to the total turbulence energy, fluctuating magnetic energy density, fluctuating kinetic energy, and the normalized cross helicity are derived from WIND spacecraft plasma and magnetometer data from 1995 through 2020. We find that (i) the turbulence cascade rate derived from a Kolmogorov phenomenology and an IK phenomenology changes with solar cycle, such that the cascade rate is largest during solar maximum and smallest during solar minimum; (ii) the turbulence energy Kolmogorov cascade rate increases from θ UB (angle between mean magnetic field and velocity) = 0° to 90° and peaks near θ UB = 90°, and then decreases as θ UB tends to 180°; (iii) the 2D turbulence heating rate is larger than the slab heating rate; (iv) the 2D and slab fluctuating magnetic energy density cascade rates are larger than the corresponding cascade rates of the fluctuating kinetic energy; and (v) the total turbulence energy cascade rate is positively correlated with the solar wind speed and temperature and the normalized cross-helicity cascade rate. Finally, we find that the total turbulent energy Kolmogorov cascade rate is larger than the IK cascade rate.

A Statistical Analysis of the Morphology of Storm‐Enhanced Density Plumes Over the North American Sector

AbstractThe storm‐enhanced density (SED) is a large‐scale midlatitude ionospheric electron density enhancement in the local afternoon sector, which exhibits substantial spatial gradients and thus can impose detrimental effects on modern navigation and communication systems, causing potential space weather hazards. This study has identified a comprehensive list of 49 SED events over the continental US and adjacent regions, by examining strong geomagnetic storms occurring between 2000 and 2023. The ground‐based Global Navigation Satellite System (GNSS) total electron content and data from a new TEC‐based ionospheric data assimilation system were used to analyze the characteristics of SED. For each derived SED events, we have quantified its morphology by employing a Gaussian function to parameterize key characteristics of the SED, such as the plume intensity, central longitude, and half‐width. A statistical analysis of SEDs was conducted for the first time to characterize their climatological features. We found that the SED distribution exhibits a higher peak intensity and a narrower width as geomagnetic activity strengthens. The peak intensity of SED has maximum values around the equinoxes in their seasonal distribution. Additionally, we observed a solar cycle dependence in the SED distribution, with more events occurring during the solar maximum and declining phases compared to the solar minimum. SED plumes exhibit a sub‐corotation feature with respect to the Earth, characterized by a westward drift speed between 50 and 400 m/s and a duration of 3–10 hr. These information advanced the current understanding of the spatial‐temporal variation of SED characteristics.

Machine learning approach for prediction of ionospheric irregularities on ROTI index over the Northern anomaly crest in Egypt during solar cycle 24

This paper reports the prediction results of the ionospheric irregularities represented by the ROTI index close to the equatorial ionization anomaly's Northern peak. A feedforward backpropagation Neural Network (NN) approach is implemented using a time series Nonlinear Autoregressive approach with Exogenous inputs (NARX). We used the data from a dual frequency GPS-SCINDA station located at Helwan (geographic coordinates of 29.86°N, 31.32°E, and MLAT of 29.94°N) in Egypt. To allow the model to be independently tested during varying levels of solar activities, we collected a 5-minute resolution of ROTI data for the solar cycle 24 from 2009 to 2017. The factors that influence the development of ionospheric irregularities are involved in the established model representing the diurnal and seasonal variations as well as solar and geomagnetic activity parameters. To support learning, we included IRI-foF2 and IRI-hmF2 parameters in the input layer neurons to improve the model learning about the behavior of the ionospheric F layer. The results show that the NN-ROTI values precisely match the GPS-ROTI values with an RMSE of 0.106 TECU/min and a prediction efficiency of 95%. The predicted values are highly correlated with the originals, with a regression of 0.89. Furthermore, the irregularities were more prevalent during the equinox months than during the solstice months. It is also observed that predicted NN-ROTI values in all seasons have RMSEs less than 0.03 and 0.05 TECU/min for the low and high solar activity, respectively. The results also showed a clear correlation between solar activity and the occurrence percentage of ionospheric irregularities indicating a solar cycle dependency. The prediction values of the NN-ROTI occurrence % demonstrated a remarkable correlation with the observed GPS-ROTI occurrence % across SC24.

Extreme Geomagnetic Disturbances (GMDs) Observed in Eastern Arctic Canada: Occurrence Characteristics and Solar Cycle Dependence

AbstractExtreme (>20 nT/s) geomagnetic disturbances (GMDs, also denoted as MPEs—magnetic perturbation events)—impulsive nighttime disturbances with time scale ∼5–10 min, have sufficient amplitude to cause bursts of geomagnetically induced currents (GICs) that can damage technical infrastructure. In this study, we present occurrence statistics for extreme GMD events from five stations in the MACCS and AUTUMNX magnetometer arrays in Arctic Canada at magnetic latitudes ranging from 65° to 75°. We report all large (≥6 nT/s) and extreme GMDs from these stations from 2011 through 2022 to analyze variations of GMD activity over a full solar cycle and compare them to those found in three earlier studies. GMD activity between 2011 and 2022 did not closely follow the sunspot cycle, but instead was lowest during its rising phase and maximum (2011–2014) and highest during the early declining phase (2015–2017). Most of these GMDs, especially the most extreme, were associated with high‐speed solar wind streams (Vsw >600 km/s) and steady solar wind pressure. All extreme GMDs occurred within 80 min after substorm onsets, but few within 5 min. Multistation data often revealed a poleward progression of GMDs, consistent with a tailward retreat of the magnetotail reconnection region. These observations indicate that extreme GIC hazard conditions can occur for a variety of solar wind drivers and geomagnetic conditions, not only for fast‐coronal mass ejection driven storms.

Spacecraft Floating Potential Measurements for the Wind Spacecraft

Analysis of 8,804,545 electron velocity distribution functions, observed by the Wind spacecraft near 1 au between 2005 January 1 and 2022 January 1, was performed to determine the spacecraft floating potential, ϕ sc. Wind was designed to be electrostatically clean, which helps keep the magnitude of ϕ sc small (i.e., ∼5–9 eV for nearly all intervals) and the potential distribution more uniform. We observed spectral enhancements of ϕ sc at frequencies corresponding to the inverse synodic Carrington rotation period with at least three harmonics. The two-dimensional histogram of ϕ sc versus time also shows at least two strong peaks, with a potential third, much weaker peak. These peaks vary in time, with the intensity correlated with solar maximum. Thus, the spectral peaks and histogram peaks are likely due to macroscopic phenomena like coronal mass ejections (solar cycle dependence) and stream interaction regions (Carrington rotation dependence). The values of ϕ sc are summarized herein and the resulting data set is discussed.

The Sun’s Magnetic Power Spectra over Two Solar Cycles. I. Calibration between SDO/HMI and SOHO/MDI Magnetograms

The Sun’s magnetic field is strongly structured over a broad range of scales. Magnetic spatial power spectral analysis provides a powerful tool for understanding the various scales of magnetic fields and their interactions with plasma motions. We aim to investigate the power spectra using spherical harmonic decomposition of high-resolution Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) and Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI) synoptic magnetograms covering three consecutive solar cycle minima, in a series of papers. As the first of the series, we calibrate and analyze the power spectra based on cotemporal SDO/HMI and SOHO/MDI data in this paper. For the first time, we find that the calibration factor r between SOHO/MDI and SDO/HMI varies with the spatial scale l of the magnetic field, where l is the degree of the spherical harmonic. The calibration factor satisfies . With the calibration function, most contemporaneous SOHO/MDI and SDO/HMI magnetograms show consistent power spectra from about 8 Mm to the global scales over about three orders of magnitude. Moreover, magnetic power spectra from SOHO/MDI and SDO/HMI maps show peaks/knees at l ≈ 120, corresponding to the typical supergranular scale (about 35 Mm) constrained from direct velocimetric measurements. This study paves the way for investigating the solar cycle dependence of supergranulation and magnetic power spectra in subsequent studies.

Why Are Some Solar Wind Pressure Pulses Followed by Geomagnetic Storms?

AbstractRapid increases in solar wind dynamic pressure, known as solar wind pressure pulses, compress the Earth's magnetosphere and can rapidly restructure the electrodynamics within. The propagation of pressure pulse effects into the magnetosphere is known as a geomagnetic sudden commencement (SC). SCs can be further subdivided into compressions which are rapidly followed by a geomagnetic storm (a sudden storm commencement, SSC) and those which are not (a sudden impulse, SI). In this paper, SSCs and SIs are compared and contrasted, and we examine in particular the differences between the pressure pulses that drive SSCs/SIs, and explore the physical conditions of the magnetosphere before pressure pulse arrival. Firstly, it is shown that SSCs are more likely to be driven by pressure pulses with higher magnitude and/or shorter rise time. Secondly, the magnetosphere is primed by stronger driving conditions and higher geomagnetic activity prior to SSCs than SIs. Finally, there is a solar cycle dependence in the occurrence and magnitude of solar wind pressure pulses.

Magnetosheath Jets Over Solar Cycle 24: An Empirical Model.

Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft have been sampling the subsolar magnetosheath since the first dayside science phase in 2008, and we finally have observations over a solar cycle. However, we show that the solar wind coverage during these magnetosheath intervals is not always consistent with the solar wind conditions throughout the same year. This has implications for studying phenomena whose occurrence depends strongly on solar wind parameters. We demonstrate this with magnetosheath jets-flows of enhanced earthward dynamic pressure in the magnetosheath. Jets emerge from the bow shock, and some of them can go on and collide into the magnetopause. Their occurrence is highly linked to solar wind conditions, particularly the orientation of the interplanetary magnetic field, as jets are mostly observed downstream of the quasi-parallel shock. We study the yearly occurrence rates of jets recorded by THEMIS over solar cycle 24 (2008-2019) and find that they are biased due to differences in spacecraft orbits and uneven sampling of solar wind conditions during the different years. Thus, we instead use the THEMIS observations and their corresponding solar wind conditions to develop a model of how jet occurrence varies as a function of solar wind conditions. We then use OMNI data of the whole solar cycle to estimate the unbiased yearly jet occurrence rates. For comparison, we also estimate jet occurrence rates during solar cycle 23 (1996-2008). Our results suggest that there is no strong solar cycle dependency in jet formation.

Prediction Models of ≥2 MeV Electron Daily Fluences for 3 Days at GEO Orbit Using a Long Short-Term Memory Network

Geostationary satellites are exposed to harsh space weather conditions, including ≥2 MeV electrons from the Earth’s radiation belts. To predict ≥2 MeV electron daily fluences at 75°W and 135°W at geostationary orbit for the following three days, long short-term memory (LSTM) network models have been developed using various parameter combinations. Based on the prediction efficiency (PE) values, the most suitable time step of inputs and best combinations of two or three input parameters of models for predictions are recommended. The highest PE values for the following three days with three input parameters were 0.801, 0.658 and 0.523 for 75°W from 1995 to August 2010, and 0.819, 0.643 and 0.508 for 135°W from 1999 to 2010. Based on yearly PE values, the performances of the above models show the solar cycle dependence. The yearly PE values are significantly inversely correlated with the sunspot number, and they vary from 0.606 to 0.859 in predicting the following day at 75°W from 1995 to 2010. We have proven that the poor yearly PE is related to relativistic electron enhancement events, and the first day of events is the most difficult to predict. Compared with previous models, our models are comparable to the top performances of previous models for the first day, and significantly improve the performance for second and third days.

Cassini Radio Occultation Observations of Saturn's Ionosphere: Electron Density Profiles From 2005 to 2013

AbstractA set of electron density profiles of Saturn's ionosphere acquired by Cassini radio occultations is archived at the NASA Planetary Data System. However, the reference surface that defines zero altitude in these profiles is unknown and appears to vary by 1,500 km at fixed latitude. These profiles are immensely valuable for addressing questions pertaining to the vertical structure, meridional structure, diurnal variations, or solar cycle dependence of Saturn's ionosphere, but their value is severely limited by their questionable altitude scales. Here we have resolved this problem by independently generating the set of 60 electron density profiles. These profiles confirm that, as noted by previous authors, the structure of Saturn's ionosphere is highly variable. Nevertheless, the profiles suggest an underlying morphology of a broad layer at relatively high altitude (often at approximately 2,000–3,000 km altitude) and a series of narrower layers at lower altitude (often at approximately 1,000 km altitude). The vertical structure of Saturn's ionosphere depends on latitude and local time. At low latitudes, densities are greater at dusk than at dawn. Conversely, at mid latitudes, densities are greater at dawn than at dusk. The plasma scale height of the topside ionosphere is relatively small at low latitudes. The high, broad ionospheric layer is apparent at mid and high latitudes at both dawn and dusk, but is not present at low latitudes at either dawn or dusk. Total electron content also shows a strong dependence on latitude, with high latitudes having greater values than low and mid latitudes.

Implications of Different Solar Photospheric Flux-transport Models for Global Coronal and Heliospheric Modeling

The concept of surface-flux transport (SFT) is commonly used in evolving models of the large-scale solar surface magnetic field. These photospheric models are used to determine the large-scale structure of the overlying coronal magnetic field, as well as to make predictions about the fields and flows that structure the solar wind. We compare predictions from two SFT models for the solar wind, open magnetic field footpoints, and the presence of coronal magnetic null points throughout various phases of a solar activity cycle, focusing on the months of April in even-numbered years between 2012 and 2020, inclusively. We find that there is a solar-cycle dependence to each of the metrics considered, but there is not a single phase of the cycle in which all the metrics indicate good agreement between the models. The metrics also reveal large, transient differences between the models when a new active region is rotating into the assimilation window. The evolution of the surface flux is governed by a combination of large-scale flows and comparatively small-scale motions associated with convection. Because the latter flows evolve rapidly, there are intervals during which their impact on the surface flux can only be characterized in a statistical sense, thus their impact is modeled by introducing a random evolution that reproduces the typical surface flux evolution. We find that the differences between the predicted properties are dominated by differences in the model assumptions and implementation, rather than the selection of a particular realization of the random evolution.

Solar Cycle and Solar Wind Dependence of the Occurrence of Large dB/dt Events at High Latitudes

AbstractWe investigate sharp changes in magnetic field that can produce Geomagnetically Induced Currents (GICs) which damage pipelines and power grids. We use one‐minute cadence SuperMAG observations to find the occurrence distribution of magnetic field “spikes.” Recent studies have determined recurrence statistics for extreme events and charted the local time distribution of spikes; however, their relation to solar activity and conditions in the solar wind is poorly understood. We study spike occurrence during solar cycles 23 and 24, roughly 1995 to 2020. We find three local time hotspots in occurrence: the pre‐midnight region associated with substorm onsets, the dawn sector often associated with omega band activity, and the pre‐noon sector associated with the Kelvin‐Helmholtz instability (KHI) occurring at the magnetopause. Magnetic field perturbations are mainly North‐South for substorms and KHI, and East‐West for omega bands. Substorm spikes occur at all phases of the solar cycle, but maximize in the declining phase. Omega‐band and KHI spikes are confined to solar maximum and the declining phase. Substorm spikes occur during moderate solar wind driving, omega band spikes during strong driving, and KHI spikes during quiet conditions but with high solar wind speed. We show that the shapes of these distributions do not depend on the magnitude of the spikes, so it appears that our results can be extrapolated to extreme events.

Comparison of the Composition of ICMEs from Active Regions and Quiet-Sun Regions

The composition of interplanetary coronal mass ejections (ICMEs), including the ionic charge states and elemental abundances of heavy elements, is tightly correlated with their source regions and eruption processes. This can help in analyzing the eruption mechanisms and plasma origins of CMEs, and deepen our understanding of energetic solar activities. The active regions and quiet-Sun regions have different physical properties; thus, from a statistical point of view, ICMEs originating from the two types of regions should exhibit different compositional characteristics. To demonstrate the differences comprehensively, we conduct survey studies on the ionic charge states of five elements (Mg, Fe, Si, C, and O) and the relative abundances of six elements (Mg/O, Fe/O, Si/O, C/O, Ne/O, and He/O) within ICMEs from 1998 February to 2011 August using data from the Advanced Composition Explorer. The results show that ICMEs from active regions have higher ionic charge states and relative abundances than those from quiet-Sun regions. For the active-region ICMEs, we further analyze the relations between their composition and flare class, and find a positive relationship between them, i.e., the higher the classes of the associated flares, the larger the means of the ionic charge states and relative abundances (except the C/O) within ICMEs. As more (less) fractions of ICMEs originate from active regions around the solar maximum (minimum), and active-region ICMEs usually are associated with higher-class flares, our studies might answer why the composition of ICMEs measured near 1 au exhibits a solar cycle dependence.

Latitudinal responses of the ionosphere over South America during HILDCAA intervals: Case studies

Aspects regarding the influence of High-Intensity Long-Duration Continuous Auroral Electrojet Activity (HILDCAA) intervals on ionospheric dynamics have been objecting to increasing interest in the last years. Notwithstanding, some key interconnections between the HILDCAA intervals impacts on the ionosphere over distinct latitudes, according to the solar cycle phase, remain to require further investigation. In this work, the F2 layer peak height and its critical frequency (hmF2 and foF2, respectively) from Digisonde data obtained over São Luís (2.60° S; 44.21° W), Cachoeira Paulista (22.70° S; 44.98° W), and Port Stanley (51.60° S, 57.9° W), were evaluated to unravel more details of the ionospheric responses to four HILDCAA intervals as case studies. Those are equatorial, low, and mid-latitude stations, respectively, and the main results over them presented a similar trend in terms of solar cycle dependence, with the greater impact on the ionospheric density along with solar maximum conditions, despite the higher frequency of HILDCAA occurrences in the descending and minimum phases. The variation of hmF2 due to HILDCAA effects in comparison to quiet time is about 20% in equatorial and mid-latitudes, while over the low latitude station the hmF2 ranges positively up to 40%. These results enhance our understanding of the HILDCAAs magnitude degree both regarding its solar cycle occurrence, and its effects in different ionospheric latitudinal sections.

A statistical study of convective and dynamic instabilities in the polar upper mesosphere above Tromsø

We have studied the convective (or static) and dynamic instabilities between 80 and 100 km above Tromsø (69.6° N, 19.2° E) using temperature and wind data of 6 min and 1 km resolutions primarily almost over a solar cycle obtained with the sodium lidar at Tromsø. First, we have calculated Brunt–Väisälä frequency (N) for 339 nights obtained from October 2010 to December 2019, and the Richardson number (Ri) for 210 nights obtained between October 2012 to December 2019. Second, using those values (N and Ri), we have calculated probabilities of the convective instability (N2 < 0) and the dynamic instability (0 ≤ Ri < 0.25) that can be used for proxies for evaluating the atmospheric stability. The probability of the convective instability varies from about 1% to 24% with a mean value of 9%, and that of the dynamic instability varies from 4 to 20% with a mean value of 10%. Third, we have compared these probabilities with the F10.7 index and local K-index. The probability of the convective instability shows a dependence (its correlation coefficient of 0.45) of the geomagnetic activity (local K-index) between 94 and 100 km, suggesting an auroral influence on the atmospheric stability. The probability of the dynamic instability shows a solar cycle dependence (its correlation coefficient being 0.54). The probability of the dynamic instability shows the dependence of the 12 h wave amplitude (meridional and zonal wind components) (C.C. = 0.52). The averaged potential energy of gravity waves shows decrease with height between 81 and 89 km, suggesting that dissipation of gravity waves plays an important role (at least partly) in causing the convective instability below 89 km. The probability of the convective instability at Tromsø appears to be higher than that at middle/low latitudes, while the probability of the dynamic instability is similar to that at middle/low latitudes.Graphical

Solar cycle variations in equatorial ionospheric zonal electric fields near sunrise

In this study, we investigate the solar cycle dependence of the sunrise ionospheric zonal electric fields at the equator under geomagnetically quiet conditions. Simulations using the Thermosphere–Ionosphere–Electrodynamics General Circulation Model (TIEGCM) reveal that the equatorial eastward electric field at sunrise decreases with the increase in solar activity, independent of longitude, season, and lower atmospheric tides. The solar cycle dependence of the sunrise zonal electric field is mainly related to the zonal wind dynamo. Moreover, this solar cycle dependence of sunrise electric fields at the equator is dominated by the corresponding variation in the F-region dynamo because the response of conductivity and neutral winds near sunrise to increasing solar flux is stronger in the F-region than in the E-region, although the sunrise eastward enhancement of electric fields is mainly driven by the E-region zonal wind dynamo. Specifically, the westward gradient of low-latitude F-region neutral winds near the dawn terminator tends to produce westward electric fields in the equatorial region that are more pronounced at solar maximum, whereas the midlatitude E-region dynamo induces an eastward enhancement of sunrise electric fields at the equator that decreases slightly with increasing solar activity. This study also reveals that the reason the eastward enhancement of equatorial zonal electric fields near dawn and dusk terminators show opposite solar cycle dependence is because of their different generation mechanisms.

The Solar Cycle Dependence of In Situ Properties of Two Types of Interplanetary CMEs during 1999–2020

Generally, in situ parameters of interplanetary coronal mass ejections (ICMEs) are analyzed as a whole, or ICMEs are classified by speed or whether they are with and without magnetic clouds. Zhai and colleagues found that ICMEs with and without flares can be extracted only by the average charge states of iron (Q Fe). In the present study, the ICMEs are categorized into two types, flare CMEs (FCs) and nonflare CMEs (NFCs) by the Q Fe. We find that the occurrence rates of FCs and NFCs are both decreased from solar maximum to minimum. The occurrence rates and proportions of FCs are both higher in solar cycle 23 than in solar cycle 24. In contrast, the occurrence rates of NFCs are almost the same during the two solar cycles. The durations of FCs are longer than those of NFCs. The fractions of FCs and NFCs that are associated with magnetic clouds (MCs) or magnetic field direction rotation evidence are 73% and 69%, respectively. The speed, Q Fe, O7+/O6+, helium abundance (A He), and first ionization potential bias are all higher for FCs than for NFCs. The above parameters inside NFCs and solar wind are almost the same. The solar cycle dependence of the parameters inside NFCs is more clear than that inside FCs. The statistical results demonstrate that the material sources of FCs are not completely the same as those of NFCs. Part of the material inside FCs should come from the lower atmosphere where the A He is higher. The statistical results indicate that all CMEs are associated with flux ropes on the Sun.