Amnon Stupp

Angular and Energy-dependent Neutron Emission from Solar Flare Magnetic Loops

We have developed new neutron production kinematics and thoroughly updated the neutron production cross sections, and we have included ion pitch-angle scattering and magnetic mirroring in our Monte Carlo simulation programs, to make new calculations of anisotropic neutron emission produced in the solar flare magnetic loop models. The anisotropy in these models arises from the combined effects of converging magnetic field lines and a rapidly increasing ambient density in the portion of the loop below the chromosphere-corona transition. We have carried out new calculations of the depth, time, angle, and energy dependences of the neutron production, the angle distributions and energy spectra of the escaping neutrons, and the energy spectrum of the surviving neutrons at the distance 1 AU from the Sun. These new calculations will now allow much more reliable and detailed analyses of the various solar flare neutron spectral observations.

Synoptic classification of lower troposphere profiles for dust days

[1] The goal of this research is to identify meteorological characteristics distinguishing dust storm days from no-dust days. During this pioneering research, the vertical profiles of temperature, wind components, and humidity for days with dust and with no dust were compared and analyzed in order to identify features accompanying dusty conditions. Three data sets, all for the 49 year period of 1958-2006, were used. The first was the daily dust observations at Tel Aviv, Israel. The second was the eastern Mediterranean daily surface synoptic classification. The third was the vertical data over the eastern Mediterranean grid point closest to Tel Aviv at 32.5°N, 35°E. The two latter data sets were based on the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis. The meteorological parameters were averaged over the 49 year period by season, pressure level, synoptic-type, and dust and no-dust days. Prominent differences between dust and no-dust days were found for relative humidity and wind components during fall, winter, and spring at 700, 600, and 500 hPa levels. Relative humidity was found to be higher during dust episodes. This result, linking dust and humidity, looks promising for future research on connection between desert dust, ice nuclei, and precipitation. The governing eastern Mediterranean synoptic systems are low-pressure systems. For these systems, vertical velocity (Omega) values are negative. It was found that absolute Omega values were higher on dust days than on days with no dust. Southerly and westerly components of wind were found to have higher values during dust days. It was found that for most synoptic systems, temperature below the 700 hPa level was equal or higher during dust days. Thus, during dust days the lower troposphere is unstable.

Temporal fluctuations of mineral concentrations as related to the physiological status of the lichen Ramalina lacera (With.) J.R. Laund.

The present review deals with alterations in Ca, K, Mg, Na, and P content and chlorophyll integrity of the epiphytic fruticose lichen Ramalina lacera in a forested rural area in Israel over an extended period. In the years 1978-2002, Ca was found to accumulate in significant amounts whereas the P content decreased. The K content did not change significantly in this period. The Mg and Na content measured in the years 1993-2002 did not show a clear pattern of change, either. The accumulation of Ca coincided with a significant increase of dust storms, originating in the Sahara Desert, in terms of dust-stormy days. The source of the above-mentioned elements is discussed.

Spectrum of gamma‐ray lines from SN1987A

847 Kev and 1238 Kev gamma lines from SN1987A were observed to be approximately ±2500 km/sec wide with small central Doppler shifts. I present a non‐symmetric model of the SNR which reproduces these features by assuming the density changes as 1/R3(θ), R(θ) being the dimension of the SNR in direction θ.