Wind Streams Research Articles

Electron Flux Variability and Ultra‐Low Frequency Wave Activity in the Outer Radiation Belt Under the Influence of Interplanetary Coronal Mass Ejections and High‐Speed Solar Wind Streams: A Statistical Analysis From the Van Allen Probes Era

AbstractThe ultra‐low frequency (ULF) waves can stochastically accelerate radiation belt electrons. Radial diffusion is a well‐established mechanism that can enhance or reduce the electron population in combination with other processes. Using data from the Van Allen Probes, we investigated the response of the 2.10 MeV energy electrons and ULF waves to two types of solar wind structures interacting with Earth's magnetosphere, namely, interplanetary coronal mass ejections (ICMEs) and High‐Speed solar wind streams (HSS). We use measured electron differential flux and ULF waves in the Pc4–Pc5 frequency range from October 2012 to May 2019. We examine 155 events with changes in the outer radiation belt electron differential flux. Results considering all ICMEs and HSSs during the Van Allen Probes era show that for both solar wind structures, solar wind interplanetary magnetic field Bz, solar wind proton density, and speed are related to the outer radiation belt relativistic electrons' response. The persistent ULF power is present during enhancement cases, while for reduction, the ULF waves power is concentrated at the initial reduction on the outer radiation belt electron flux.

Continuous Enhancements of Electron Temperature in the Subauroral Ionosphere Over Eight Days During the 2015 St. Patrick’s Day Storm

AbstractWe have used measurements of the Defense Meteorological Satellite Program (DMSP) satellites to study variations of electron temperature in the subauroral ionosphere during the magnetic storm on 17–25 March 2015. This magnetic storm had a long recovery phase of 7 days, and the ionospheric behavior over the entire storm time was seldom investigated. In this study, we find that the electron temperature at subauroral latitudes was continuously enhanced for 8 days, from the storm onset to the end of the recovery phase. The maximum electron temperature during the storm times was 1000–4000 K higher than the maximum electron temperature during quiet times. This long‐lasting enhancement of subauroral electron temperature was attributed to energy transfer among the solar wind, magnetosphere, ring current, plasmasphere, and ionosphere driven by high‐speed solar wind streams and fluctuating interplanetary magnetic field during the entire 8‐day period of the storm. The electron temperature enhancements were quite symmetric in the post‐midnight sector but became strongly asymmetric near dawn between the southern and northern hemispheres. The asymmetric enhancements of electron temperature near dawn may be related to the magnetic declination and the daytime midlatitude trough in the southern hemisphere. Large daily variations of maximum electron temperature in the post‐midnight sector were observed and may be related to the offset between geomagnetic and geographic latitudes. These DMSP observations provide new insight on ionospheric response to intense magnetic storms.

Numerical design of self-pumped electrostatic precipitators for particle collection

Electrostatic precipitators (ESPs) have been widely used to remove particles from gas. However, an additional gas pumping system should be utilized to pump the particle-laden gas. A self-pumped ESP is proposed, in which the ESP itself pumps particle-laden gas. The gas flow and particle collection characteristics are evaluated numerically. Results demonstrate that a nearly unidirectional ion wind stream can be generated with a suitable arrangement of electrodes. Particles significantly restrain the corona discharge current and decelerate the gas accordingly. Particles with a smaller diameter and a higher concentration exert a more significant influence on the corona discharge and gas flow. The average velocity of 0.5 m/s at the inlet of the ESP (area of 0.3 m2) is achievable with a voltage of 23 kV and a power consumption of 20 W. A collection efficiency of more than 99 % is achievable for particles with a diameter of 5 µm.

Parametric Instability: An Evolutive Mechanism for the Alfvénic Turbulence in the Solar Wind

Fluctuations in fast streams or in slow Alfvénic streams of the solar wind, and in the high-latitude wind, are characterized by high cross-helicity and a low level of compressions. Such properties, which are typical of Alfvénic fluctuations, tend to decline with increasing heliocentric distance. Parametric decay, where the energy of an initial Alfvén wave is progressively transferred to both backward-propagating Alfvén and compressive modes, has been proposed as a mechanism responsible for such a behavior. Over the years, the parametric process has been studied, both analytically and numerically, in many configurations, from monochromatic waves to increasingly complex situations which include broad-band turbulent configurations with one- and two-dimensional spectra. In this paper, we give a brief review of this theoretical development, discussing its relevance in the context the evolution of Alfvénic turbulence in the solar wind.

Computational evaluation of air jet cooling from a perforated air ducting system to mitigate heat stress of cows in free stalls

Alleviating the heat stress suffered by dairy cows in order to increase their productivity depends on an effective ventilation system. For this reason, this study evaluated the heat mitigating performance of a perforated air ducting (PAD) system with special attention given to significant design parameters (e.g., the shape and size of the orifices and the speed and flow rate of the air jets) having to do with the jet flow pattern and its corresponding cooling efficiency. More specifically, this work aimed to evaluate, using numerical simulation, the effects produced by four different types of air-jet orifice (i.e., three-circular orifice, single-circular orifice, rectangular orifice, and slot orifice) and also the effects produced by different jet flow rates and by the bulk movement of indoor air with respect to the jet properties and their cooling performance in relation to cows reclining in free stalls. The outcomes show that the jet emitted from the slot orifice distributes air more effectively over the surface of a reclining cow and produces a more even range of skin temperatures. The jet cooling performance achieved with a jet flow rate of 470.4 m3 h−1 (50% of the recommended ventilation rate for 625 kg cow) and a jet temperature of 28 °C was equivalent to the cooling performance achieved by a 2 m s−1 wind stream of the same air temperature passing over the model cow’s body. Additionally, the convective heat dissipation rate of the reclining cow increased from 63.47 to 91.27 W m−2 as the jet flow rate increased from 212.0 to 564.5 m3 h−1, indicating that increasing the flow rate of a jet emitted through the slot orifice could improve the convective heat dissipation rate, but the rate of the increase in the convective heat transfer decreased simultaneously. The bulk movement of the indoor air (>0.2 m s−1) negatively affects jet flow and the corresponding cooling performance. Therefore, a PAD system equipped with slot orifices will most likely be more effective when atmospheric conditions are less agitated (such as those in naturally ventilated barns with minimal cross wind speeds or inside enclosed barns). In short, the findings of this study should warrant using the PAD system to ventilate free-stall dairy barns to mitigate heat stress of dairy cows.

Influence of Large-scale Interplanetary Structures on the Propagation of Solar Energetic Particles: The Multispacecraft Event on 2021 October 9

An intense solar energetic particle (SEP) event was observed on 2021 October 9 by multiple spacecraft distributed near the ecliptic plane at heliocentric radial distances R ≲ 1 au and within a narrow range of heliolongitudes. A stream interaction region (SIR), sequentially observed by Parker Solar Probe (PSP) at R = 0.76 au and 48° east from Earth (ϕ = E48°), STEREO-A (at R = 0.96 au, ϕ = E39°), Solar Orbiter (SolO; at R = 0.68 au, ϕ = E15°), BepiColombo (at R = 0.33 au, ϕ = W02°), and near-Earth spacecraft, regulated the observed intensity-time profiles and the anisotropic character of the SEP event. PSP, STEREO-A, and SolO detected strong anisotropies at the onset of the SEP event, which resulted from the fact that PSP and STEREO-A were in the declining-speed region of the solar wind stream responsible for the SIR and from the passage of a steady magnetic field structure by SolO during the onset of the event. By contrast, the intensity-time profiles observed near Earth displayed a delayed onset at proton energies ≳13 MeV and an accumulation of ≲5 MeV protons between the SIR and the shock driven by the parent coronal mass ejection (CME). Even though BepiColombo, STEREO-A, and SolO were nominally connected to the same region of the Sun, the intensity-time profiles at BepiColombo resemble those observed near Earth, with the bulk of low-energy ions also confined between the SIR and the CME-driven shock. This event exemplifies the impact that intervening large-scale interplanetary structures, such as corotating SIRs, have in shaping the properties of SEP events.

The Dynamic Evolution of Solar Wind Streams Following Interchange Reconnection

Interchange reconnection is thought to play an important role in determining the dynamics and material composition of the slow solar wind that originates from near coronal-hole boundaries. To explore the implications of this process we simulate the dynamic evolution of a solar wind stream along a newly-opened magnetic flux tube. The initial condition is composed of a piecewise continuous dynamic equilibrium in which the regions above and below the reconnection site are extracted from steady-state solutions along open and closed field lines. The initial discontinuity at the reconnection site is highly unstable and evolves as a Riemann problem, decomposing into an outward-propagating shock and inward-propagating rarefaction that eventually develop into a classic N-wave configuration. This configuration ultimately propagates into the heliosphere as a coherent structure and the entire system eventually settles to a quasi-steady wind solution. In addition to simulating the fluid evolution we also calculate the time-dependent non-equilibrium ionization of oxygen in real time in order to construct in situ diagnostics of the conditions near the reconnection site. This idealized description of the plasma dynamics along a newly-opened magnetic field line provides a baseline for predicting and interpreting the implications of interchange reconnection for the slow solar wind. Notably, the density and velocity within the expanding N-wave are generally enhanced over the ambient wind, as is the O7+/O6+ ionization ratio, which exhibits a discontinuity across the reconnection site that is transported by the flow and arrives later than the propagating N-wave.

Predictive Capabilities of Corotating Interaction Regions Using STEREO and Wind In‐Situ Observations

AbstractSolar wind stream interaction regions (SIRs) and corotating interaction regions (CIRs) can cause geomagnetic storms and change energetic particle environment, ionospheric composition on Earth. Therefore advanced warning of SIRs/CIRs is vital for mitigating the effect of space weather on critical infrastructures in modern society. Recently, several solar missions, for example, Vigil mission (Luntama et al., 2020) and Solar Ring mission (Wang et al., 2020), that can be served as a space weather monitor, have been proposed. To evaluate the capabilities of these future missions of predicting SIRs/CIRs, the Solar Terrestrial Relations Observatory (STEREO‐B) spacecraft is used to investigate the correlation between SIRs/CIRs detected by STEREO‐B and Wind spacecraft. The correlation coefficients of solar wind velocity in SIRs/CIRs are significantly higher than that of magnetic field intensity or plasma density. It indicates that the velocity structure of solar wind is more persistent than magnetic field and ion density. By assuming the SIR/CIR structures are stable and ideal corotation, 58.9% of SIRs/CIRs in the STEREO‐B CIR catalog can be used to predict CIR arrival time in near‐Earth space. With increasing longitudinal and latitudinal separations between STEREO‐B and Wind, the percentage of accurately predicted CIRs decreases gradually from 100% to 20%. If the separation angle between STEREO‐B and Wind is within 30° in longitude and approximately ±5° in latitude, more than 93.2% of SIRs/CIRs can be accurately predicted several days in advance. This demonstrates that a spacecraft situated 30° trailing Earth in its orbit, can optimize our space weather‐predicting capabilities for the Earth and lessen the risk of missing or “false alarms” CIRs.

Investigating Alfvénic Turbulence in Fast and Slow Solar Wind Streams

Solar wind turbulence dominated by large-amplitude Alfvénic fluctuations, mainly propagating away from the Sun, is ubiquitous in high-speed solar wind streams. Recent observations performed in the inner heliosphere (from 1 AU down to tens of solar radii) have proved that also slow wind streams show sometimes strong Alfvénic signatures. Within this context, the present paper focuses on a comparative study on the characterization of Alfvénic turbulence in fast and slow solar wind intervals observed at 1 AU where degradation of Alfvénic correlations is expected. In particular, we compared the behavior of different parameters to characterize the Alfvénic content of the fluctuations, using also the Elsässer variables to derive the spectral behavior of the normalized cross-helicity and residual energy. This study confirms that the Alfvénic slow wind stream resembles, in many respects, a fast wind stream. The velocity-magnetic field (v-b) correlation coefficient is similar in the two cases as well as the amplitude of the fluctuations although it is not clear to what extent the condition of incompressibility holds. Moreover, the spectral analysis shows that fast wind and Alfvénic slow wind have similar normalized cross-helicity values but in general the fast wind streams are closer to energy equipartition. Despite the overall similarities between the two solar wind regimes, each stream shows also peculiar features, that could be linked to the intrinsic evolution history that each of them has experienced and that should be taken into account to investigate how and why Alfvénicity evolves in the inner heliosphere.

Modulation of Solar Wind Impact on the Earth’s Magnetosphere during the Solar Cycle

The understanding of extreme geomagnetic storms is one of the key issues in space weather. Such phenomena have been receiving increasing attention, especially with the aim of forecasting strong geomagnetic storms generated by high-energy solar events since they can severely perturb the near-Earth space environment. Here, the disturbance storm time index Dst, a crucial geomagnetic activity proxy for Sun–Earth interactions, is analyzed as a function of the energy carried by different solar wind streams. To determine the solar cycle activity influence on Dst, a 12-year dataset was split into sub-periods of maximum and minimum solar activity. Solar wind energy and geomagnetic activity were closely correlated for both periods of activity. Slow wind streams had negligible effects on Earth regardless of their energy, while high-speed streams may induce severe geomagnetic storming depending on the energy (kinetic or magnetic) carried by the flow. The difference between the two periods may be related to the higher rate of geo-effective events during the maximum activity, where coronal mass ejections represent the most energetic and geo-effective driver. During the minimum period, despite a lower rate of high energetic events, a moderate disturbance in the Dst index can be induced.

Findings of the unusual plasma bubble occurrences at dawn during the recovery phase of a moderate geomagnetic storm over the Brazilian sector

In this work, we observe for the first time the unusual pre-sunrise Equatorial Plasma Bubbles (EPBs) during a moderate geomagnetic storm recovery phase caused by the High-Speed Solar Wind Stream (HSS) on February 17, 2015, over the Brazilian sector. Therefore, this study aims to explain the generation mechanism of this uncommon event, which started at 08:00 UT on February 18, 2015. We used Multiple Global Navigation Satellite Systems (Multi-GNSS, GPS, and GLONASS) data to produce two-dimensional maps of the Rate Of TEC index (ROTI) that show EPB features elongated in magnetic meridians. Also, Digisonde data from São Luís (2.53° S, 44.30° W, dip angle: 8.57°), Boa Vista (12.81° N, 60.67° W, dip angle: 33.71°), and Campo Grande (20.44° S, 54.64° W, dip angle: 25.98°), and magnetometer data at São Luís and Eusébio (3.89° S, 38.45° W, dip angle: 17.96°). Our analysis shows that the unusual pre-sunrise plasma bubbles lasted longer after sunrise, around 1 h. Finally, we showed that these EPBs are likely driven by a disturbance wind dynamo effect, which helps to understand the role of the external factors in EPBs development.

Urban growth and heat islands: A case study in micro-territories for urban sustainability

Rapid urbanization contributes to the development of phenomena such as climate variability, especially in tropical countries, which negatively impact ecosystems and humans, factors that influence urban sustainability. Additionally, the increase of building construction prevents the flow of wind streams contributing to the retention of pollutants and hot air masses, causing events such as urban heat islands (UHI). This study aimed to analyze from the micro-territorial level, the influence of urban growth on the UHI phenomenon over the last two decades (2000–2020) in the locality of Kennedy, in Bogotá, Colombia. For this purpose, environmental and socio-economic factors were evaluated. For the former, Landsat satellite images and spectral indices were used to evaluate the spatial–temporal variation in the quantity and quality of vegetation, bodies of water, urbanized areas, impervious surfaces, as well as to calculate the land surface temperature and its distribution in the study area. With regard to the socio-economic factors, the variables considered for analysis were population density and energy consumption. Lastly, a principal component analysis was carried out to identify possible associations between the variables and to identify the contribution of each micro-territory to the UHI phenomenon in the study area. The spatio-temporal variations reveal a growing trend over time, especially in impermeable areas where several economic activities, vehicular traffic, and population density converge, which require certain actions to be prioritized in territorial planning and the addition of public green spaces in urban zones.

Arctic–Antarctic asymmetry of the ionospheric weather

The state of the ionosphere is investigated on a global scale, in the Arctic and Antarctic regions poleward of 60° magnetic latitudes. The Total Electron Content, TEC, enhancement (as represented by the global WU, polar WUN and WUS indices) and depletion (WL, WLN and WLS), and the respective ranges (WE, WEN and WES) are evaluated from global GIM-W index maps. GIM-W maps are derived from JPL GIM-TECs converted to geomagnetic coordinate frame for Solar Cycles 23–24. Using a superimposed epoch analysis, we examined 380 geo-storms caused by high speed solar wind stream, Vsw, with time t0 set at onset of the Dst storm and Dstmin ≤ −50 nT. Single-sign positive and negative storm effects are detected in both Arctic and Antarctic, when the polar WUN, WLN, WUS or WLS index is equal to zero for 10–20% of the pre-storm period, 5–25% for the main storm phase, and 7–25% during recovery. These asymmetric single-sign conditions violate the correlation between WUS (WUN) and WLN (WLS) data and global Dst, WU, WL and WE indices, demonstrated for the extreme storm on 15–17 July 2000 (Dst = −301 nT). The persistent single-sign conditions are observed in the polar segments for the both disturbed and quiet times from 1994 to 2021. The peak of the monthly single-sign conditions up to 50% of time occurs during the polar summer when the solar wind – polar ionosphere interaction at the open field lines facing the Sun is strengthened due to reduced magnetosphere shielding the solar wind. A long-term Arctic–Antarctic asymmetry is observed from 1994 to 2021, with larger values of daily polar indices WUN, WUS, WUN and WLS found for the winter hemisphere (the ‘winter anomaly’) while contribution of the multiple single-sign zeros yields the reduced monthly values at summer. The asymmetry is likely caused by the difference in the solar irradiance that is minimized at the dominant high-latitude winter night-time, compared to the sunlit summer conditions in the opposite hemisphere. Higher values of asymmetry index AIWU and AIWL shows dominant North Hemisphere variance over South Hemisphere during December solstice reversed towards the June solstice presumably related with dynamical influences of the lower atmosphere.

The effect of onset turbulent flows on ventilation with a two-sided rooftop windcatcher

Wind tunnel experiments are conducted on a single zone building with a two-sided windcatcher and a window. Mean and fluctuating surface pressures are measured to investigate the effect of the turbulent onset flows on building ventilation. Additionally, an analytical model is developed to estimate the unsteady ventilation flow rates through the building. The results are presented at different wind incidence angles and relative to the room window condition (opened versus closed window), showing the performance behaviour of the windcatcher. It is found that the mean flows can indicate generalised ventilation aspects for designing considerations. Meanwhile, the unsteady analyses should be considered when the building openings face indirect wind streams and when both a windcatcher opening and the (opened) window are presented as windward openings. Furthermore, the room window is essential when implementing windcatcher ventilation systems, as it defines their performance and dominates the interior flow behaviour.

Techno-economic analysis of the transition towards the large-scale hybrid wind-tidal supported coastal zero-energy communities

In the current academic fields of zero-energy community, there is still limited knowledge on the integration of a coastal community with hybrid ocean-related energy systems. This study investigates the feasibility of a coastal community to reach zero-energy with the support of a hybrid offshore wind and tidal stream energy generation system, as well as an ocean and solar thermal energy supported district cooling and heating system. TRNSYS simulation was performed to demonstrate a proposed community that comprises 8 high-rise residential buildings and 2 mid-rise office buildings with a 9.86 MW community peak power demand. This study considered 21 hybrid renewable energy cases and investigated their performance in 2 scenarios – scenario 1 without battery and scenario 2 with battery. The system performance is assessed from the technical, economic, and emission perspectives by analysing the system load matching, net present value, discounted payback period, and equivalent CO2 emission. In scenario 1, the hybrid renewable energy case 5 with 6 offshore wind turbines (12 MW) and 117 tidal stream converters (29.25 MW) has the best annual load matching (56.68% “onsite energy matching” and 57.84% “onsite energy fraction”) mainly due to their complementary generation pattern during specific periods. In scenario 2, the community-scale electricity storage significantly increases the system technical performance by raising the “onsite energy matching” and “onsite energy fraction” of case 5 to 75.25% and 74.75%, respectively. In addition, the techno-economic analysis reveals the market competitiveness of the 21 RE cases and demonstrates the significant economic impact of the FiT policy. The comparison between scenario 1 and scenario 2 indicates that the community-scale battery diminishes the operation-cycle profits but reduces the equivalent CO2 emission. Furthermore, with the current price settings, tidal stream energy generation is considered less profitable than offshore wind energy generation. This study could provide important insights into the development of coastal zero-energy communities with hybrid offshore wind and tidal stream energy generation at other locations worldwide, especially densely populated coastal cities.

High-frequency heating of the solar wind triggered by low-frequency turbulence

The fast solar wind’s high speeds and non-thermal features require that considerable heating occurs well above the Sun’s surface. Two leading theories seem incompatible: low-frequency ‘Alfvénic’ turbulence, which transports energy outwards and is observed ubiquitously by spacecraft but seems insufficient to explain the observed dominance of ion over electron heating; and high-frequency ion-cyclotron waves, which explain the non-thermal heating of ions but lack an obvious source. Here we argue that the recently proposed ‘helicity barrier’ effect, which limits electron heating by inhibiting the turbulent cascade of energy to the smallest scales, can unify these two paradigms. Our six-dimensional simulations show how the helicity barrier causes the large-scale energy to grow through time, generating small parallel scales and high-frequency ion-cyclotron-wave heating from low-frequency turbulence, while simultaneously explaining various other long-standing observational puzzles. The predicted causal link between plasma expansion and the ion-to-electron heating ratio suggests that the helicity barrier could contribute to key observed differences between fast and slow wind streams.

Deployment of wind turbine in between cement silos for small power generation

This study provides an overview of Building-Integrated Wind Turbines, focusing on cement silos as wind concentrators, along with determining the amount of power that could be connected without regard to wind direction. The motivation of this research is the intermittency issue of wind stream in an open environment and non-exploration of wind turbines between cement silos. Building-Augmented Wind Turbines provide 717 W of aerodynamic power at 16 m/s, whereas Standalone Wind Turbines produce 562 W. This is due to the wind speed acceleration between buildings, which causes a concentration effect. Meanwhile, using the simulation software ANSYS, the turbine geometry is developed utilising a Computational Fluid Dynamics evaluation.

On Differentiating Multiple Types of ULF Magnetospheric Waves in Response to Solar Wind Periodic Density Structures.

Identifying the nature and source of ultra‐low frequencies (ULF) waves (f ⪅ 4 mHz) at discrete frequencies in the Earth's magnetosphere is a complex task. The challenge comes from the simultaneous occurrence of externally and internally generated waves, and the ability to robustly identify such perturbations. Using a recently developed robust spectral analysis procedure, we study an interval that exhibited in magnetic field measurements at geosynchronous orbit and in‐ground magnetic observatories both internally supported and externally generated ULF waves. The event occurred on 9 November 2002 during the interaction of the magnetosphere with two interplanetary shocks that were followed by a train of 90 min solar wind periodic density structures. Using the Wang‐Sheeley‐Arge model, we mapped the source of this solar wind stream to an active region and a mid‐latitude coronal hole just prior to crossing the Heliospheric current sheet. In both the solar wind density and magnetospheric field fluctuations, we separated broad power increases from enhancements at specific frequencies. For the waves at discrete frequencies, we used the combination of satellite and ground magnetometer observations to identify differences in frequency, polarization, and observed magnetospheric locations. The magnetospheric response was characterized by: (a) forced breathing by periodic solar wind dynamic pressure variations below ≈1 mHz, (b) a combination of directly driven oscillations and wave modes triggered by additional mechanisms (e.g., shock and interplanetary magnetic field discontinuity impact, and substorm activity) between ≈1 and 4 mHz, and (c) largely triggered modes above ≈4 mHz.

Flux rope and dynamics of the heliospheric current sheet

Context. Solar Orbiter and Parker Solar Probe jointly observed the solar wind for the first time in June 2020, capturing data from very different solar wind streams: calm, Alfvénic wind and also highly dynamic large-scale structures. Context. Our aim is to understand the origin and characteristics of the highly dynamic solar wind observed by the two probes, particularly in the vicinity of the heliospheric current sheet (HCS). Methods. We analyzed the plasma data obtained by Parker Solar Probe and Solar Orbiter in situ during the month of June 2020. We used the Alfvén-wave turbulence magnetohydrodynamic solar wind model WindPredict-AW and we performed two 3D simulations based on ADAPT solar magnetograms for this period. Results. We show that the dynamic regions measured by both spacecraft are pervaded by flux ropes close to the HCS. These flux ropes are also present in the simulations, forming at the tip of helmet streamers, that is, at the base of the heliospheric current sheet. The formation mechanism involves a pressure-driven instability followed by a fast tearing reconnection process. We further characterize the 3D spatial structure of helmet streamer born flux ropes, which appears in the simulations to be related to the network of quasi-separatrices.

How the area of solar coronal holes affects the properties of high-speed solar wind streams near Earth: An analytical model

Since the 1970s it has been empirically known that the area of solar coronal holes affects the properties of high-speed solar wind streams (HSSs) at Earth. We derive a simple analytical model for the propagation of HSSs from the Sun to Earth and thereby show how the area of coronal holes and the size of their boundary regions affect the HSS velocity, temperature, and density near Earth. We assume that velocity, temperature, and density profiles form across the HSS cross section close to the Sun and that these spatial profiles translate into corresponding temporal profiles in a given radial direction due to the solar rotation. These temporal distributions drive the stream interface to the preceding slow solar wind plasma and disperse with distance from the Sun. The HSS properties at 1 AU are then given by all HSS plasma parcels launched from the Sun that did not run into the stream interface at Earth distance. We show that the velocity plateau region of HSSs as seen at 1 AU, if apparent, originates from the center region of the HSS close to the Sun, whereas the velocity tail at 1 AU originates from the trailing boundary region. Small HSSs can be described to entirely consist of boundary region plasma, which intrinsically results in smaller peak velocities. The peak velocity of HSSs at Earth further depends on the longitudinal width of the HSS close to the Sun. The shorter the longitudinal width of an HSS close to the Sun, the more of its “fastest” HSS plasma parcels from the HSS core and trailing boundary region have impinged upon the stream interface with the preceding slow solar wind, and the smaller is the peak velocity of the HSS at Earth. As the longitudinal width is statistically correlated to the area of coronal holes, this also explains the well-known empirical relationship between coronal hole areas and HSS peak velocities. Further, the temperature and density of HSS plasma parcels at Earth depend on their radial expansion from the Sun to Earth. The radial expansion is determined by the velocity gradient across the HSS boundary region close to the Sun and gives the velocity-temperature and density-temperature relationships at Earth their specific shape. When considering a large number of HSSs, the assumed correlation between the HSS velocities and temperatures close to the Sun degrades only slightly up to 1 AU, but the correlation between the velocities and densities is strongly disrupted up to 1 AU due to the radial expansion. Finally, we show how the number of particles of the piled-up slow solar wind in the stream interaction region depends on the velocities and densities of the HSS and preceding slow solar wind plasma.