Environmental ocean ultra low frequency pressure fields generalized data limits estimate

Physical analysis of processes responsible for ultra low frequency (ULF) pressure field formation in the ocean is made. Estimates of natural background ULF pressure spectrum levels observed by bottom installed transducer in frequency band 0.0001-0.1 Hz are obtained. To derive such estimates two types of results are used-results of direct pressure measurements in the frequency range (2-80) mHz obtained by the authors in a coastal regions of the former USSR (the Black Sea, the Sea of Japan, the Barents Sea) during multiyear observation cycles, results of pressure measurements fulfilled by other authors, as well as materials of indirect long period gravity waves parameters measurements made at the sea surface. The latter results were obtained by specialists in oceanology in the form of surface wave oscillations spectra and were transformed by authors in bottom pressure variations by recalculation. On the basis of a multilayer pressure measurement statistical treatment an important conclusion is obtained, that pressure fields observed at the ocean bottom in frequency range below 30 mHz are formed presumably by pressure pulsations produced by long period ocean gravity waves