Research

Unravelling cloud/precipitation variability over land 

　Earth is a water planet. Water exists in three phases—solid, liquid, and gas (ice, liquid water, and water vapor)—and continuously transitions among them through the atmosphere, hydrosphere, and Earth’s surface. These phase changes drive highly dynamic variations in the Earth’s atmosphere. Clouds and precipitation arise from this water cycle and play a crucial role in supplying freshwater essential for life. At the same time, variability in clouds and precipitation can lead to severe disasters, such as droughts and floods, that threaten human societies. The temporal scales of cloud and precipitation variability range from hours to decades, while their spatial scales span from kilometers to thousands of kilometers. Moreover, the impacts of climate change associated with global warming further amplify these variations. Understanding cloud and precipitation variability and its underlying mechanisms across multiple temporal and spatial scales—from regional to global—is therefore essential. Such studies also provide vital observational evidence for evaluating numerical models, which are indispensable for reliable future projections.

Cloud and precipitation variability over land is particularly important for water resources and disaster management. Asia, where we live, generally experiences a distinct rainy season driven by the Asian monsoon. This abundant precipitation sustains the lives of approximately 60% of the world’s population residing in Asia. However, precipitation systems and the mechanisms that produce rainfall vary substantially across the region. Even within the same region, seasonal precipitation is modulated on an annual basis, resulting in pronounced year-to-year variability, such as wetter or drier years. Understanding the mechanisms underlying these variations remains a significant scientific challenge. Furthermore, feedbacks between the land surface—including surface conditions and topography—and terrestrial ecosystems, such as vegetation, play a critical role in shaping cloud and precipitation processes over land. How these surface characteristics influence water cycle variability across a wide range of spatial and temporal scales is therefore a key research question.

Our laboratory adopts an integrated approach that combines data analysis and field observations with both regional and global modeling to advance our understanding of the Earth’s climate system through the study of precipitation. To address these challenges, we actively pursue collaborative research across fields such as cryosphere, plant ecology, and animal ecology, primarily using meteorological, climatic, hydrometeorological, and hydroclimatic approaches.

Research Time Scales:

Diurnal variation (1-day cycle), synoptic-scale disturbances (3-7 day cycles), intraseasonal variability (10-60 day cycles), seasonal variation (several months to 1-year cycles), interannual variability (1-several year cycles), decadal-scale variability, climate change (including warming), and the multi-scale structure between these different spatiotemporal scales.

Specific Case Studies:

Cumulonimbus clouds, mesoscale precipitation systems, tropical disturbances (typhoons, cyclones, monsoon lows), Meiyu/Baiu front, interseasonal variations (QBW, BSISO, MJO), seasonal precipitation patterns, long-term change

Analysis Areas (Land and Coastal Regions):

Tibetan Plateau, Himalayas, Eastern Chinese Plains, Japan, Bangladesh, India, Myanmar, Thailand, Bay of Bengal, Maritime Continent (Borneo, Sumatra, etc.), Mongolia, Siberia, Arctic Ocean, East China Sea, etc.

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