Solar cycle variations of the solar wind

Throughout the course of the past one and a half solar cycles, solar wind parameters measured near the ecliptic plane at 1 AU varied in the following way: speed and proton temperature have maxima during the declining phase and minima at solar minimum and are approximately anti-correlated with number density and electron temperature, while magnetic field magnitude and relative abundance of helium roughly follow the sunspot cycle. These variations are described in terms of the solar cycle variations of coronal holes, streamers, and transients. The solar wind signatures of the three features are discussed in turn, with special emphasis on the signature of transients, which is still in the process of being defined. It is proposed that magnetic clouds be identified with helium abundance enhancements and that they form the head of a transient surrounded by streamer like plasma, with an optional shock front. It is stressed that relative values of a parameter through a solar cycle should be compared beginning with the declining phase, especially in the case of magnetic field magnitude

Investigation of the dayside boundary region of the magnetosphere

The region near the dayside boundary of the magnetosphere is of particular interest mainly because it is the most likely site for solar wind energy transfer. Exactly where and how this transfer occurs is one of the basic problems of magnetospheric physics. The global nature of the energy transfer is addressed in this research. In order to test whether energy transfer affects the large scale plasma flow in the magnetosheath, global properties of the magnetosheath were analyzed and compared to models with no energy transfer. Also, global models of merging sites on the magnetopause were modeled with the aid of the magnetosheath models. Since energy transfer and intrinsic magnetosheath properties depend upon the orientation of the interplanetary magnetic field (IMF), it was essential to have an IMF monitor for these studies. In the course of using ISEE 3 in this role, statistical studies were performed to test the accuracy of using data from an orbit so far upstream. Global properties of the magnetosheath energetic ion population, magnetic field strength and orientation, and flow pattern, determined with ISEE data are summarized

Assessing electron heat flux dropouts as signatures of magnetic field line disconnection from the Sun

Suprathermal electrons focused along magnetic field lines, called the strahl, carry heat flux away from the Sun. Various factors can cause heat flux dropouts (HFDs), including times when the strahl almost vanishes. HFDs are a necessary but insufficient condition for detecting magnetic flux disconnected from the Sun. To quantitatively assess the fraction of HFDs which might be due to disconnected fields, we use four years of suprathermal electron data from the Wind spacecraft to perform a comprehensive survey of heat flux dropouts with durations greater than an hour. Eliminating periods within interplanetary coronal mass ejections or containing counterstreaming electrons, we find that only ∼10% of HFDs have signatures consistent with disconnected flux

Alternative Approaches to Incorporating the Opportunity Cost of Time in Recreation Demand Models

The importance of accounting for a respondent’s travel time in recreation demand models is well established. In practice, most analysts use a fixed fraction of the respondent’s wage rate to value travel time. However, other approaches have been suggested in the literature. In this paper revealed and stated preference data on Iowa wetland usage is used to explore various specifications of travel time. It is shown that the choice of a particular specification has a direct impact on welfare estimates as well as the consistency between revealed and stated preference data.

Tuning alloy disorder in diluted magnetic semiconductors in high fields to 89 T

Alloy disorder in II-VI diluted magnetic semiconductors (DMS) is typically reduced when the local magnetic spins align in an applied magnetic field. An important and untested expectation of current models of alloy disorder, however, is that alloy fluctuations in many DMS compounds should increase again in very large magnetic fields of order 100 tesla. Here we measure the disorder potential in a Zn$_{.70}$Cd$_{.22}$Mn$_{.08}$Se quantum well via the low temperature photoluminescence linewidth, using a new magnet system to 89 T. Above 70 T, the linewidth is observed to increase again, in accord with a simple model of alloy disorder.Comment: 4 pages, 3 figure

Investigation of the magnetospheric boundary plasma and magnetic field data from Explorers 33, 43, and 50

Understanding of the plasma depletion process in the dayside magnetosheath, the nature of magnetotail boundary motion, and the geometry of the magnetospheric boundary layers was examined. A model of the dayside boundary layers, based on the hypothesis that merging occurs only for strictly anitparallel fields was developed which provides a qualitative solution to the problem of the half-wave rectifier response of the magnetosphere to the solar wind electric field. Regarding magnetotail boundary motion, consideration of the data led to the conclusion that at lunar distance, substorms are associated with very large amplitude compressional wave motion of the sausage type. A study of IMF orientation for depletion and nondepletion cases suggests that depletion is most likely to occur for angles between the IMF and the normal to the magnetopause at the measurement location near 90 deg, in agreement with predictions. Observations of the heat flux in the dayside magnetosheath plasma suggest that the energized plasma ions have their source along a given flux tube at that intersection with the bow shock where the magnetic field is most compressed

Exploring Respondent’s Perception of Bid Precision in Non-Market Valuation

Bid design is an important component of the nonmarket valuation process. To date, no research has been done on the possible effects of using round dollar amounts. It seems reasonable to believe that respondents may respond to round dollar amounts differently than they would respond to bids that include both dollar and cent amounts. One possibility is that the respondent may infer that the dollar/cent bids are more precise estimates of the true cost than the round dollar amount, and therefore put more thought into their response to survey questions. In order to explore this idea, we test whether the use of a precise versus imprecise bid design influences respondent’s willingness to pay. In particular, our sample of survey recipients was stratified into two groups based on whether they were presented with imprecise or precise bids (round dollar bids or dollar/cent bids). Precise bids were generated by adding or subtracting a randomly-drawn number of cents (between -200 and +200 cents) to each of the imprecise bid levels. We explore this issue in the context of a valuation project concerned with The Battle of Lexington State Historic Site in Lexington, MO.