Search

We analyzed dose rate data of space neutron and gamma radiation during several flight with various destinations, i.e. Jakarta – Kupang, Kupang – Jakarta, Jakarta – Pontianak, and Pontianak – Jakarta. Data were collected using personal radiation dosimeter (RadEye for neutron and Dosicard for gamma radiation) during flights from take off until landing at the destination airports. As expected, the higher the aircraft from sea level, the radiation received are higher also, but the behaviour of the neutron and gamma radiation are different. The neutron radiation received are more erratic compared with that of the gamma radiation. We found the correlation between the height of the aircraft and neutron and gamma radiation dose rates with correlation coeficient values of 0.89, 0.86, 0.90, 0.87 respectively for neutron radiation and 0.91, 0.95, 0.84, 0.88 respectively for gamma radiation. We found the empirical relations between latitude and dose rates of neutron and gamma radiation in the height of 35.000 feet from the sea level as Dn = −0.034 Lat + 1.036 for neutron dose rates and Dg = −0.027 Lat + 0.636 for gamma radiation dose rates. [ABSTRACT FROM AUTHOR]

This paper show our preliminary results on solar acitivty effect to the low-latitude Sq field. We analyzed one solar cycle of geomagnetic data observed at Biak station Indonesia during 1992-2004 to show the dependence of Sq field amplitude to solar activity. In this paper, the monthly sunspot number has been used to represent the solar activity. We found that the amplitude of Sq field following the trend of sunspot number. Also, we analyzed the seasonal variation of Sq field and found that the amplitude of Sq field during equinoxes are larger than solstices. This results show that low latitude Sq field are influenced by the solar radiation. [ABSTRACT FROM AUTHOR]

The geomagnetic disturbance is one of the effects of space weather which is expressed by the Dst index. The Dst index is an indication of geomagnetic field activity at middle and low latitudes. In this paper, predictions of the Dst index are carried out using an artificial neural network using the NARX method (Nonlinear Autoregressive Network with exogenous input) with the input parameters consisting of the width angle of the coronal mass ejection, the position center angle of the coronal mass ejection, the coronal mass ejection velocity, the coronal hole area, solar wind velocity, solar wind density, and interplanetary magnetic field. The data used for learning, validation, and testing with the 7 exogenous input parameters above are from 1997 to 2019. The Dst index obtained is quite good with a regression between output and target of more than 98%. This model can predict the hourly Dst index one to five days ahead. From the 8 events that occurred in 2020, we found the average RMSE error is 11.41 nT. The Dst index prediction can be used as a guide in forecasting geomagnetic disturbances in providing space weather information. [ABSTRACT FROM AUTHOR]