The garden hose angle is the angle at which the water flows out of the hose. This angle is usually measured in degrees, but there are also several other units of measurement. It is important to understand how these units are measured, and the differences between the units, so that you can use the correct unit to measure the angle.
Increasing heliocentric distance
A garden hose angle is an angle between the sunward radial and tangential fields. It’s the tiniest of details, but this little tidbit may have a large impact on the radial component of the overall magnetic field strength.
The best way to measure this is with the aid of the latest and greatest heliospheric simulations. In the present paper we take a look at the sun’s radial velocity, heliocentric distance, and the corresponding deflected field lines. This combination of factors makes for a very granular dataset – one which is both robust and statistically sound.
As the heliocentric distance is reduced, the effect of path length dependent scattering is diminished, allowing for an enhanced radial component. At the same time, more complex forms of radial flux are present, owing to local inversions of the HMF, a topic on which we’ll explore in a later article.
What is the most important thing to learn from all this is that the heliospheric magnetic field is much larger than previously thought.
The gardenhose angle is the angle between the tangential and radial fields. In the Parker-spiral theory, the angle is predicted to be tangential to the solar rotation and opposite radially toward the Sun. It is a function of the heliocentric distance (r) and the solar-wind speed V.
Parker-spiral theory explains the orientation of the HMF. It predicts that the HMF will become stronger at higher heliocentric distances. This is because the HMF is more likely to lie in a direction orthogonal to the average Parker-spiral direction. On the other hand, the HMF will be weaker at low heliocentric distances.
An observational study of the solar wind shows that a large fraction of the ortho-Parker orientations are not consistent with the Parker model. These observations suggest that magnetic reversals at lower altitudes are possible. A proposed concept, termed’magnetically braiding,’ has been described by Borovsky (2010). However, it has been found that the magnitude of the HMF varies with V, but the direction of the deflection does not.
The Gaussian distributions of garden hose angle th, ft, r and m are not new. In fact, this research has gone so far as to model them. To do this, we took a statistical sample of the data, rescaled to an averaging time of 30 seconds, and then fitted the results to a regression equation to determine the true astrophysical origin of each measurement. We found that the unsigned radial th axis was the best correlated to the actual garden hose emitted, while the true astrophysical origin of ft was inversely related to r.
This isn’t to say that the garden hose has a fixed position in the heliosphere, it’s simply that there are a finite number of reconnection sites and the resulting outflow-exhaust regions are likely to be Alfvenic structures. Hence, the relative strengths of these regions may change with time and space. As such, this is an important topic for study in the long term.
Effects of averaging
Averaging can change the garden hose angle distribution. This study uses data from the ACE and WIND spacecraft and the IMF to examine the effects of averaging on the HMF gardenhose angle. The results show that the distribution of the th-angle is affected by averaging on the timescale of one minute. However, the effects of averaging on the OGH and GH sectors are different. It has been shown that the OGH and GH sector can be affected by reconnection outside the corona. These differences can be associated with changes in the Class-A and Class-B OGH flux.
As a result of reconnection outside the corona, the probability of inflow decreases with r. In addition, the strength of Alfvenic structures decreases with r. Because of this, there are small differences in the gardenhose angle at the Sun. Therefore, averaging the data can be used to calculate the distributions of the garden hose angle for a given r. Using the Gaussian distributions, a regression fit is performed on the data.