Abstract <p>Tropopause-level jet streams are an integral part of the atmospheric general circulation and play a certain role in the formation of the Earth’s weather and climate, they are also an object of continuous monitoring by aviation weather services worldwide. The initial and important stage of exploration of jet streams includes reliable determination of their characteristics, the main ones being their latitudinal position and intensity. A simple and universal method for identifying the jet stream core in three-dimensional space containing wind data at nodes with a regular grid is proposed. The algorithm for locating wind speed maxima related to the core of the jet stream takes into account areas where the flow deviates from the west-east orientation through the ratio of the zonal component of the wind speed to its absolute value. Using reanalysis fields, the position of the Northern Hemisphere jet stream cores is given at one of the synoptic hour together with estimates of the intensity of individual segments of the jet. To analyze and identify differences in jet stream regimes, latitude-longitude and latitude-height frequency distributions were constructed for December 2010 and 2020. It is shown that a three-dimensional analysis, in particular, identifying cores in strongly curved segments of jet streams, allows for a more detailed determination of characteristics such as branching, merging, degree of meandering, and intensity.</p>