انجمن ملی ژئوفیزیک ایران مجله ژئوفیزیک ایران 2008-0336 20 3 2026 07 23 Revisiting wintertime budget of local finite-amplitude wave activity in the Northern Hemisphere storm tracks Revisiting wintertime budget of local finite-amplitude wave activity in the Northern Hemisphere storm tracks 1 24 219260 10.30499/ijg.2025.494060.1655 FA Amin Fazl Kazemi Ph.D., Student of Meteorology, Institute of Geophysics, University of Tehran, Tehran, Iran Alireza Mohebalhojeh Professor, Institute of Geophysics, University of Tehran, Tehran, Iran 0000-0002-5906-8486 Mohammad Mirzaei Associate Professor, Institute of Geophysics, University of Tehran, Tehran, Iran 0000-0003-0813-3994 Farhang Ahmadi-Givi Professor, Institute of Geophysics, University of Tehran, Tehran, Iran 0000-0002-9487-4862 Journal Article 2024 12 15 <span>The climatological distribution of the local finite-amplitude wave activity (LWA) and its three-dimensional flux components are studied for boreal winter (December to February) using the JRA-55 reanalysis dataset for the period 1979–2023. The methods for extracting the Lagrangian reference state of quasigeostrophic potential vorticity and obtaining density-weighted vertical average are modified to expand the domain of validity to include highland and low-latitude regions of the Northern Hemisphere. A novel summarization method is also proposed to extract spatial scale and identify the local dominant balances within the LWA budget terms. Additionally, variations in the LWA flux divergence components are examined for the layers representing the upper, middle and lower troposphere, as well as for the vertical profiles in the selected horizontal areas with the storm tracks. The differences observed in the distribution of LWA and its flux divergence, compared to previous studies, are qualitatively consistent with the available Eulerian diagnostics for small-amplitude disturbances. The finite-amplitude Lagrangian formulation makes it possible to provide more accurate estimates of the nonconservative source/sink processes. These estimates are revised using the diagnostics related to the geostrophic states, based on a formal quasigeostrophic inversion. The main dominant balance observed for the column-averaged budget is between the near-surface baroclinicity, which generates the vertical flux of LWA, and the nonconservative processes. The results show that, while the North Atlantic and North Pacific storm tracks exhibit similar patterns with regard to the source of LWA, they behave quite differently at the regional scale in terms of the balance between the LWA budget terms. </span> <span>The climatological distribution of the local finite-amplitude wave activity (LWA) and its three-dimensional flux components are studied for boreal winter (December to February) using the JRA-55 reanalysis dataset for the period 1979–2023. The methods for extracting the Lagrangian reference state of quasigeostrophic potential vorticity and obtaining density-weighted vertical average are modified to expand the domain of validity to include highland and low-latitude regions of the Northern Hemisphere. A novel summarization method is also proposed to extract spatial scale and identify the local dominant balances within the LWA budget terms. Additionally, variations in the LWA flux divergence components are examined for the layers representing the upper, middle and lower troposphere, as well as for the vertical profiles in the selected horizontal areas with the storm tracks. The differences observed in the distribution of LWA and its flux divergence, compared to previous studies, are qualitatively consistent with the available Eulerian diagnostics for small-amplitude disturbances. The finite-amplitude Lagrangian formulation makes it possible to provide more accurate estimates of the nonconservative source/sink processes. These estimates are revised using the diagnostics related to the geostrophic states, based on a formal quasigeostrophic inversion. The main dominant balance observed for the column-averaged budget is between the near-surface baroclinicity, which generates the vertical flux of LWA, and the nonconservative processes. The results show that, while the North Atlantic and North Pacific storm tracks exhibit similar patterns with regard to the source of LWA, they behave quite differently at the regional scale in terms of the balance between the LWA budget terms. </span> https://www.ijgeophysics.ir/article_219260_b16f297821fd18ee28fe0ee442395069.pdf