Hokkaido University · Environmental Science
Professor Shoshiro Minobe's research lab specializes in climate dynamics, with a focus on interdecadal climate variability, atmospheric-oceanic interactions, and the mechanisms behind climatic regime shifts. The lab investigates long-term climate oscillations—particularly the pentadecadal and bidecadal variations—using observational data, reanalysis, and advanced signal processing techniques such as wavelet analysis and optimal interpolation. Key research directions include the role of sea surface temperature anomalies (e.g., in the Gulf Stream and tropical oceans) in driving atmospheric responses, and the dynamics of western boundary currents and sea level changes. The lab also develops innovative methods like the Maximal Wavelet Filter to extract evolving patterns in climate oscillations.
Figures are computed from collected data and may differ slightly.
The chronology of interdecadal climatic regime shifts is examined, using instrumental data over the North Pacific, North America and the tropical oceans, and reconstructed climate records for North America. In the North Pacific and North America, climatic regime shifts around 1890 and in the 1920s with alternating polarities are detected, whose spatial structure is similar to that of the previously‐known climatic shifts observed in the 1940s and 1970s. Sea‐surface temperatures in the tropical In
The roles of interdecadal oscillations in climatic regime shifts, which are observed as rapid strength changes in the Aleutian low in winter and spring seasons, have been analyzed. A regime shift results from simultaneous phase reversals between pentadecadal and bidecadal variations, which synchronize with one another at a relative period of three. The pentadecadal variation, which is observed in both winter and spring seasons, provides the basic timescale of regime shifts, while the bidecadal v
Abstract The atmospheric response to the Gulf Stream front in sea surface temperature is investigated using high-resolution data from satellite observations and operational analysis and forecast. Two types of atmospheric response are observed with different seasonality and spatial distribution. In winter, surface wind convergence is strong over the Gulf Stream proper between Cape Hatteras and the Great Banks, consistent with atmospheric pressure adjustments to sea surface temperature gradients.
Abstract A new gridded water temperature dataset of upper 400-m depths (0, 50, 100, 200, 300, and 400 m) for the Japan Sea (or East Sea) is produced by using an optimal interpolation technique from 1930 to 1996, based on oceanographic observations collected in the World Ocean Database 1998. The temperature data are analyzed by a complex empirical orthogonal function (CEOF) with six levels combined using the data for a period from 1957 to 1996, during which most of gridded data are available. Bef
Abstract To better understand coastal sea level variability and changes, a theory that predicts sea levels along a curved western boundary using interior ocean sea level information is proposed. The western boundary sea level at a particular latitude is expressed by the sum of contributions from interior sea levels propagating onto the western boundary by long Rossby waves between that latitude and a higher latitude, and from the western boundary sea level at the higher latitude. This theory is
Based on a wavelet transform, a new method referred to as maximal wavelet filter (MWF) is proposed to extract temporal structure changes of a climatic oscillation, which varies its pattern corresponding to the changes of the oscillation period. The MWF is a bandpass filter having a narrow pass band, the central frequency of which temporally varies according to the periods of maximal wavelet amplitudes for a specific region. MWF is applied to wintertime sea level pressures (SLPs) in the Northern
Abstract Using surface marine data collected in International Comprehensive Ocean Atmosphere Data Set (ICOADS) release 2.1, a gridded SST dataset on a monthly, 1° × 1° grid is produced from 1850 to 2002. Some unrealistic features, which are commonly found in the gridded SSTs of ICOADS, are removed by a subjective quality control. Based on the gridded SST data, SST variability associated with the oceanic fronts is investigated for the North Atlantic and North Pacific. Year‐to‐year SST variability
Abstract Diurnal cycles of precipitation and lightning are investigated by analyzing rain rates of the TRMM3G68 dataset, consisting of Precipitation Radar and Microwave Imager data only; rain rates of Global Satellite Mapping of Precipitation (GSMaP), for which infrared (IR) data are also used; lightning flash rates observed by TRMM Lightning Imaging Sensor (LIS); and lightning stroke rates of World Wide Lightning Location Network (WWLLN) over the tropics. Diurnal amplitudes relative to averages
Abstract Regional-scale precipitation responses over Indonesia to major climate modes in the tropical Indo–Pacific Oceans, namely canonical El Niño, El Niño Modoki, and the Indian Ocean dipole (IOD), and how the responses are related to large-scale moisture convergences are investigated. The precipitation responses, analyzed using a high-spatial-resolution (0.5° × 0.5°) terrestrial precipitation dataset for the period 1960–2007, exhibit differences between the dry (July–September) and wet (Novem
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