About Wuhan Institute of Heavy Rain, China Meteorological Administration

Wuhan Institute of Heavy Rain, China Meteorological Administration

The Wuhan Institute of Heavy Rain, China Meteorological Administration — WIHR, also abbreviated IHR — is one of the eight specialised research institutes of the China Meteorological Administration, based in Wuhan, Hubei, with the postal code 430205 on its publications. According to the CMA, WIHR conducts basic and applied research on heavy rain in China, and technological development. That short brief conceals a large problem: heavy rainfall is China's most frequent meteorological disaster, driving the Yangtze floods, urban waterlogging and landslides that recur every summer, and Wuhan sits in the middle reaches of the Yangtze in the heart of the mei-yu rain belt. The institute hosts the Hubei Key Laboratory for Heavy Rain Monitoring and Warning Research, and its best-known achievement is a purpose-built observing system and a pair of international field campaigns devoted to a single phenomenon — the frontal rainstorms of the East Asian summer monsoon.

Place in the CMA system

The CMA lists the Wuhan Institute of Heavy Rain among its nine national meteorological research institutions — the Chinese Academy of Meteorological Sciences and eight specialised institutes — that pursue scientific and technological innovation in meteorology. Where the Shanghai institute owns typhoons and the Guangzhou institute owns tropical systems, Wuhan owns non-typhoon heavy rain: the mei-yu fronts, mesoscale convective systems and basin-scale rainstorms of central China. Its later publications also carry the name China Meteorological Administration Basin Heavy Rainfall Key Laboratory in author affiliations, reflecting the institute's evolution towards a basin-wide framing of its subject — the Yangtze basin as a single heavy-rainfall system. Wuhan itself, a metropolis at the confluence of the Yangtze and Han rivers with average annual rainfall of approximately 1,200 millimetres, mainly concentrated in the flood season, is both the institute's home and one of its case studies.

The mei-yu problem

The institute's central scientific target is the mei-yu, the early-summer rainy season of the East Asian summer monsoon — baiu in Japanese — when a quasi-stationary elongated rainband settles over the Yangtze-Huai River Valley from mid-June to mid-July. The mei-yu season contributes on average about 32 percent of annual precipitation over the valley — around 32 percent in Hubei, reaching 50 percent in certain years — and is one of the three heavy-rainfall periods of China. Its rain is produced by multiscale frontal systems whose observations, in the words of the institute's campaign review, are seriously lacking for a system of such tremendous scientific and societal importance. Institute-linked statistical work has identified three canonical synoptic patterns driving extreme mei-yu rainfall, centred on strengthened southerly flow meeting anomalous northerly flow, and established the importance of low-level jets: 79 percent of low-level jets are accompanied by rainstorms during the mei-yu period, while 83 percent of rainstorms are accompanied by low-level jets. Understanding which patterns, jets and moisture transports turn a wet week into a flood is the institute's core business.

MHROS: an observing system built for rainstorms

To observe those systems the institute built the Mesoscale Heavy Rainfall Observing System, MHROS, over the middle region of the Yangtze River, documented in a 2015 paper by Cui Guode and colleagues in the Journal of Geophysical Research: Atmospheres. MHROS combines ground-based remote sensing instruments of different wavelengths — radars including an S-band precipitation radar, a 35-GHz cloud radar and a 24-GHz micro rain radar, microwave radiometers and disdrometers — arranged so that a rainstorm's structure can be followed from cloud droplets to rainfall at the ground. Its central facility is at Xianning in southeastern Hubei, at 29.51 degrees north, 114.22 degrees east. A permanent, multi-instrument site of this kind is what separates an institute from a modelling group: models of mei-yu microphysics can be tested against MHROS observations of real storms, season after season, and the system was designed from the start as the backbone for field campaigns rather than as a single experiment's kit.

IMFRE: the integrative monsoon frontal rainfall experiments

On that backbone the institute organised the Integrative Monsoon Frontal Rainfall Experiment, IMFRE. Phase one, IMFRE-I, ran from 10 June to 10 July 2018 in the middle reaches of the Yangtze-Huai valley, organised by the Wuhan Institute of Heavy Rain with primary support from the National Natural Science Foundation of China, maximising the observational capacity of MHROS and its ground-based and remote sensing instruments. Phase two, IMFRE-II, ran from 16 June to 19 July 2020 and was the first field campaign in China to use ground-based, airborne and spaceborne platforms together for comprehensive observation over the middle and lower Yangtze. The 2020 mei-yu season justified the effort: the Yangtze basin experienced ten precipitation events, including a three-hour fall of 178.5 millimetres and a 24-hour fall of 502 millimetres at Jingzhou, 309.4 millimetres in six hours and 436 millimetres in 24 hours at Wuhan, and 993.9 millimetres in 24 hours at Huanggang. The campaigns' stated aims were to build warm- and cold-rain conceptual models of cloud-to-rain conversion, improve cloud and precipitation retrieval algorithms, understand the formation and dissipation of mei-yu frontal systems, and improve cloud microphysics parameterisation schemes and model simulations.

Findings: fronts, heating and microphysics

The published yield of this programme is concrete. Studies from the institute found that condensation heating plays a significant role in mei-yu frontogenesis, primarily through its thermodynamic effect and additionally through dynamic feedback — the rain itself helps maintain the front that produces it. Earlier institute work, including a case study of the continuous rainstorms of 5 to 8 June 2006 in northern Fujian under a quasi-stationary mei-yu front, used potential vorticity analysis and inversion to show how the front's formation and persistence depended on high-pressure systems to its south and north, and on lower-tropospheric potential vorticity. More recent work evaluates and improves microphysical parameterisation for heavy mei-yu rainfall in numerical models, comparing dual-polarisation radar observations of real storms with model behaviour. This chain — observe with MHROS, campaign with IMFRE, diagnose the physics, fix the model schemes — is the institute's method, and it is why a small specialised institute can influence national forecasting practice for China's costliest weather.

Urban waterlogging and warning research

The institute's applied side reaches the city street. Researchers at the Institute of Heavy Rain in Wuhan, with university and municipal partners, analysed waterlogging monitoring and rainfall observations in Wuhan from 2011 to 2016 to build rainfall thresholds and a waterlogging risk map for the city. They found that rainstorm waterlogging occurred in summer, mostly in June and July, accounting for 90 percent of the total; that it clustered along rivers and lakes in low-lying areas; that the longest continuous waterlogging exceeded ten hours and the deepest water reached two metres; and that severity rose with cumulative rainfall over 24, 12, 6 and 3 hours. The thresholds they derived — 24-hour rainfall of 123, 163 and 196 millimetres for mild, moderate and severe waterlogging, with corresponding shorter-period values — are exactly the kind of numbers a city's drainage and emergency services need, and the authors note the thresholds must be revised as drainage capacity improves. The Hubei Key Laboratory for Heavy Rain Monitoring and Warning Research, hosted at the institute, is the platform named on this line of work: monitoring and warning, not only understanding.

Collaboration and continuity

WIHR's campaigns and papers are collaborative by design. IMFRE brought together the National Climate Center and other CMA bodies with the institute in Wuhan; its reviews appear in Advances in Atmospheric Sciences, the journal of the Institute of Atmospheric Physics, Chinese Academy of Sciences; its waterlogging work partners with China University of Geosciences, Wuhan and the Wuhan Meteorological Bureau. A funding line in a 2000s paper — the Heavy Rain Opening Fund of IHR, CMA — shows the institute operating an open fund to draw outside researchers into heavy-rain problems, a standard key-laboratory mechanism. Across two decades the bylines change but the affiliation is constant: Institute of Heavy Rain, China Meteorological Administration, Wuhan, working on the same frontal rainstorms with steadily better instruments, from potential-vorticity case studies in the 2000s to a three-platform national field campaign in 2020.

Why the institute matters

Rainstorms are the major meteorological disaster in China, as the institute's own authors state, because heavy rainfall leads to flooding, urban waterlogging, landslides and derivative disasters. The Wuhan Institute of Heavy Rain is the CMA's dedicated answer: a specialised institute that built its own mesoscale observing system over the middle Yangtze, led China's integrative mei-yu field campaigns in 2018 and 2020, hosts Hubei's key laboratory for heavy rain monitoring and warning, and turns its physics into thresholds and model improvements that forecasters and city governments can use. In a country where a single 24-hour fall can approach a metre of rain, an institute that studies nothing else is not a luxury; it is the point of the specialised-institute system.

Official website: not recorded; institute listed by the China Meteorological Administration among its specialised research institutes.