## 4 Conclusions  
Investigation results confirmed the proposed method's efficiency for detecting short-period geomagnetic disturbances of differing intensity and duration. Adaptivity of the wavelet model and high time resolution of the suggested approach allow us to investigate sudden small-amplitude variations of the geomagnetic field, which are of interest in space weather. The method makes it possible to process the data of different resolution and, compared to neural networks, does not require periodic rearrangement of algorithm parameters. Comparison of the proposed wavelet model with the Sq-curve method showed its advantage. The model allows one to obtain a better approximation to geomagnetic field quiet variation than the traditional approach. The method efficiency was also confirmed on the basis of the comparison of its results with the results of application of the optimal threshold suggested in the paper [45]. Comparing the processing results of raw geomagnetic data with the data preliminary processed by a magnetologist confirmed the possibility of applying the method in online mode. In the case of short low-amplitude noise (amplitude is 1-3 nT), the method makes it possible to obtain results with admissible accuracy and can be used to perform data online analysis. The result is important as long as a great and constantly growing volume of recorded geomagnetic data cannot be analyzed manually within a reasonable amount of time. Sudden high amplitude changes caused by external impacts (for example, ionosonde or earthquake effect) can generate false anomalies. In that case, preliminary processing of the data by a magnetologist is required to improve the analysis accuracy. That indicates the necessity to develop automatic detection methods and compensation of noise in geophysical data. One of the possible solutions to the problem was considered in the papers [6; 54]. An analysis of the data during disturbed periods confirmed the investigation results [31; 32] and showed the possibility of short-period geomagnetic disturbances preceding a geomagnetic storm beginning. Weak short-period increases in geomagnetic activity before storms were described in a number of papers [3; 4; 55; 5]. During the events under consideration, geomagnetic disturbance intensity increased during SWS growth and intensification of southward IMF Bz. As the storm beginning approached, disturbances were intensified. The observed correlation of the detected geomagnetic disturbances with interplanetary environment parameters indicates their external nature and relation with an oncoming magnetic storm. Summarizing the work results shows the complicated dynamics of the processes in the near-Earth space during increased solar activity and magnetic storms. Investigation of the processes requires the development of methods for data analysis and an extended observation network. The results confirmed the importance of ground observations, which, together with space data, are a valuable and informative tool for space weather monitoring. The investigation also showed the essential role of site observations, which significantly contribute to the investigation of near-Earth space processes and space weather forecast. Conceptualization, O.M. ; methodology, O.M. ; software, Y.P. ; formal analysis, O.M. and Y.P. ; resources, S.K. ; data curation, S.K. ; writing--original draft preparation, O.M., Y.P. and S.K. ; visualization, O.M., Y.P. and S.K. ; project administration, O.M. All authors have read and agreed to the published version of the manuscript. The work was carried out according to the Subject AAAA-A21-121011290003-0 <<Physical processes in the system of near space and geospheres under solar and lithospheric influences>> IKIR FEB RAS. Not applicable.