Interaction of Convective Organization and Monsoon Precipitation, Atmosphere, Surface and Sea (INCOMPASS)

Lead Research Organisation: University of Leeds
Department Name: School of Earth and Environment

Abstract

The monsoon supplies the majority of water for agriculture and industry in South Asia, and is therefore critical to the well-being of a billion people. Active and break periods in the monsoon have a major influence on the success of farming, while year-to-year variations in the rainfall have economic consequences on an international scale. The growing population and developing economy mean that understanding and predicting the monsoon is therefore vital. Despite this, our capability to model the monsoon, and to make forecasts on scales from days to the season ahead is limited by large errors that develop quickly. The relatively poor performance of weather prediction models over India is due to a very strong and complex relationship between the land, ocean and atmosphere, which are linked by the process of convection, in the form of the rain-bringing cumulonimbus clouds. Forecast errors occur primarily because the convective clouds are not accurately linked to the large-scale circulation or to the surface conditions, and these errors persist to long time scales. Worldwide, weather and climate forecast models are gaining resolution, and yet the errors in monsoon rainfall are not diminishing. A lack of detailed observations of the land, ocean and atmospheric parts of the monsoon system, on a range of temporal and spatial scales, is preventing a more thorough understanding of processes in monsoon convective clouds and at the land surface, and their interaction with the large-scale circulation.
This project will use a programme of new measurements over India and the adjacent oceans to advance monsoon forecasting capability in the Indo-UK community. The first detachment of the FAAM research aircraft to India, in combination with an intensive ground-based observation campaign, will gather new observations of the land surface, the boundary layer structure over land and ocean, and atmospheric profiles. We will institute a new long-term series of measurements of energy and water exchanges at the land surface. Research measurements from one monsoon season will be combined with long-term observations on the Indian operational networks. Observations will be focused on two transects: in the northern plains of India, covering a range of surface types from irrigated to rain-fed agriculture, and wet to dry climatic zones; and across the Western Ghats, with transitions from land to ocean and across orography. The observational analysis will represent a unique and unprecedented characterization of monsoon processes linking the land, ocean and atmospheric patterns which control the rainfall. Long-term measurements will allow the computation of statistical relationships between the various factors.
The observational analysis will feed directly into improved forecasting at the Met Office and NCMRWF. The Met Office Unified Model, which is used for weather forecasting at both institutions, will be set up in a range of different ways for the observational period. In particular, we will pioneer the test development of a new 100m-resolution atmospheric model, which we expect to greatly improve the representation of land-ocean-atmosphere interactions. Another priority will be to improve land surface modelling in monsoon forecasts. By comparing the results of the very high resolution models on small domains with lower-resolution models representing the global weather patterns, it will be possible to describe the key processes controlling monsoon rainfall, and to indicate how these need to be represented in different applications, such as weather predictions or climate predictions. Through model evaluation at a range of scales, the development of simple theoretical understanding of the rainfall processes, and working with groups responsible for operational model improvement, the project will lead directly to improvements in monsoon forecasts. By improving rainfall prediction, we expect the work to have an economic impact in India and internationally.

Planned Impact

The primary impacts of our research will be delivered through our partners, the Met Office, National Centre for Medium Range Weather Forecasting (NCMRWF) and the India Meteorological Department (IMD). The effectiveness of these public weather forecasting and climate prediction services will be enhanced by better understanding of existing and new processes affecting monsoon predictability. The primary goal of the project is to improve the performance of the weather and climate forecast models used by these centres. Furthermore, improved understanding of the key processes in the monsoon will have knock-on scientific benefits, for instance in the improved conceptual understanding which can be taught to forecasters, improved ability to give strategic advice on issues such as land management, and better-informed strategies for model development. Improved monsoon modelling and forecasting capability in the medium-to-long term will raise the profile and performance of these organisations nationally and internationally, increasing their reputation (the current status of monsoon prediction is currently regarded as poor) and saleability of their products. These organisations would also benefit from our quantitative assessment of the value of new observations demonstrated by the proposed field campaign, and generally greater awareness of the uses of such data.

Our weather-service partners will convey impacts of our research to national and state government ministries in India. These organisations will be provided with quantitative evidence to inform new policies of investment in the monsoon observing system, given the improvements to forecasting and analysis that we expect our new and additional observations will initiate. New interpretations of the effect of contrasts between different surface types on weather over India should also influence policies on agriculture and extraction of groundwater (both related to irrigation).

As a result of improved weather and climate predictions, there is an opportunity for planners and governors at the state and district level to benefit from improved protection against extremes, and associated impact reductions (of flooding, drought, delayed monsoon onset), if the intended improvements to understanding of monsoon variability and forecasting can be effectively communicated to society. For instance, the IMD are already communicating forecast information to millions of farmers via new electronic media.

Technical staff undertaking in situ measurements in India will benefit from improved skills and knowledge in measurement of surface fluxes, the relative merits of the different techniques involved and improvement in their quality control procedures. This will make their data products more reliable and useful.

Finally, the public will benefit through greater awareness of monsoon forecasting and its inherent limitations, and its effect on society. The public will also become engaged more directly with the process of science.

Publications

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Barton E (2019) A casestudy of land-atmosphere coupling during monsoon onset in northern India in Quarterly Journal of the Royal Meteorological Society

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Fletcher J (2019) The dynamic and thermodynamic structure of the monsoon over southern India: New observations from the INCOMPASS IOP in Quarterly Journal of the Royal Meteorological Society

 
Description We have for the first time, presented an explanation for the movement of the onset of monsoon rains over India.

The monsoon rains commence around 1 June over South India every year, and progress northward and finally to the northwest, reaching Pakistan some 6 weeks later. This progression is against the direction of the mean winds, and the mean moisture transport. Therefore, it has always been a puzzle how the monsoon rains can progress in a direction contrary to the moisture flows.

We find that the onset of the rains is controlled by mid-level dry air which suppresses rainfall. This air originates in the mountainous desert regions to the North-West of India, and covers the whole of India in the pre-monsoon season, so although the monsoon winds become significant in May, there is relatively little rainfall. The effects of increasing monsoon flow at low levels, and small cumulus clouds over India, are to gradually humidify and erode the mid-level dry layer, so that deep rain-bringing storms can develop. The dry air originates in the north-west and moves towards the southeast, being eroded by clouds as it moves, so the first location for monsoon rains is in the south. As the monsoon onset proceeds, the dry air is more efficiently eroded, and retreats to the northwest of the subcontinent.
Exploitation Route These results are useful for Indian weather forecasters, in understanding the day to day controls on the monsoon rains.

They are also useful for researchers trying to understand the physical controls on monsoon onset, and the possible causes of errors and biases in models.
Sectors Agriculture, Food and Drink,Energy,Environment

URL http://dx.doi.org/10.1002/qj.2815
 
Description CEH-Leeds 
Organisation Natural Environment Research Council
Department Centre for Ecology & Hydrology (CEH)
Country United Kingdom 
Sector Academic/University 
PI Contribution My team in Leeds conduct atmospheric studies using observations, models and theoretical ideas. I have also led a number of projects and field experiements in which we have collaborated with CEH.
Collaborator Contribution Expertise in land-surface processes. Expertise in land-atmosphere interactions. Expertise in land-atmosphere climate dynamics. Data analysis, especially remote sensing of rainfall and land surface state. Leadership of projects. Co-supervision of PhD students.
Impact This is a multidisciplinary partnership in the area of land-atmosphere interaction. It has resulted in a large number of high-impact papers, successful jointly-supervised PhD studentships, and successful impacts, especially in Africa.
 
Description Met Office 
Organisation Meteorological Office UK
Country United Kingdom 
Sector Public 
PI Contribution Our research group analyses atmospheric processes in order to better represent them in the Met Office's forecast models. We also use those forecast models in our research, and evaluate their performance in order to identify the best strategies to improve the models.
Collaborator Contribution The Met Office brings its models and its datasets to the partnership, in addition to the considerable expertise of its staff. The Met Office also represent a conduit to the impact of our research for society, through its provision of operational weather and climate forecasts.
Impact Our research has influenced the Met Office strategy for model development, especially in regard to high-resolution models, and the convective parametrisation scheme. We have jointly influenced international strategy for atmospheric research and measurements.
 
Description AGU2017 - Title: Interaction of Convective Organization and Monsoon Precipitation, Atmosphere, Surface and Sea (INCOMPASS) (Andrew Turner) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Academic conf presentation
Year(s) Of Engagement Activity 2016
 
Description EGU 2017 - Moist convection and its upscale effects in simulations of the Indian summer monsoon with explicit and parametrised convection (Peter Willetts et al) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Academic conf presentation
Year(s) Of Engagement Activity 2017