As KAUST celebrates its five-year anniversary, the community has a plethora of milestones to celebrate, not to mention more than a few memorable events to look back on. Interestingly, one of these noteworthy events, in the form of an unforeseen natural occurrence, still serves as the basis for ongoing interdisciplinary research at the University. Shortly following KAUST's Inauguration, on November 25, 2009, over 140 millimeters of rain fell over the Jeddah region within a mere eight hours, causing in excess of 100 fatalities and resulting in an economic setback of over $100M.

"All this rain coming at the same time, in a matter of few hours, meant the water had nowhere to go; so it went into the streets," said KAUST's Ibrahim Hoteit, Associate Professor of Earth Sciences and Engineering and Principal Investigator of the Earth Fluid Modeling and Prediction group. Flash floods present a particular challenge in arid areas with limited sewage systems.

"The rain doesn't get quickly absorbed in this region." As Prof. Hoteit further explains: "We're trying to reconstruct the rain event that happened during the 2009 and 2001 floods using modeling and observations." As he emphasizes, "models predict the future data and the data guide the model toward the truth."

He points to an impressive computerized model of Jeddah on his monitor, capturing over 20,000 buildings, complete with surrounding mountains and estimated paths taken by the water as it flooded the city.

Constructing Predictive Models for Jeddah Flooding

"In order to build a local model at the level of Jeddah, we downscale from global to regional MENA (Middle East & North Africa)-wide models all the way down to a few hundred meters over Jeddah," as Hoteit outlines. To obtain the MENA region data, his team used data from satellites and international sources.

As they eventually zoomed in over the Jeddah region, the local data was provided by Presidency of Meteorology and Environment (PME) and the Jeddah Municipal government. The data collected is then used to complement and guide the atmospheric and weather models employed to forecast.

"Using all available observations and state-of-the-art weather forecasting models, our simulations suggest that we could predict these devastating extreme rain events one or two days in advance. So we can greatly improve the prediction of these events and issue timely warnings," said Prof. Hoteit.

The rain is then used as input in developing very high-resolution models to simulate street flooding in the city of Jeddah.

It's important to keep in mind that environmental fluid models are not perfect, and as such their outputs can be modeled as random variabilities with some distributions. "The question of how good or certain our forecast is dependent on a complex mathematical and computational problem. We strive to compute the best possible representation of the distribution of the system state given the models and available data."

These sophisticated models, taking into account input and modeling uncertainties, are achieved through highly multidisciplinary work involving various teams at KAUST. Prof. Hoteit closely collaborates with KAUST's Prof. Omar Knio, a world expert in the field of uncertainty quantification. He also relies heavily on collaborations with the high performance computing and visualization teams. "Visualization is very important for us as a way to communicate our scientific concepts to people and users," explained Hoteit.

Ocean Modeling and the Impact of Sea Currents

In an effort to build forecasting models meant to predict extreme marine and weather events, Prof. Hoteit and his group also rely on ocean and atmospheric observations. For any environmental model to be effective, it's important to complement it with actual data collected from the whole region and locally.

Working with data sets collected from Saudi Aramco, from PME, as well as from satellite data, KAUST was able to develop a 14-year reanalysis (from the years 2000 to 2014) of atmospheric conditions over the Red Sea at a 10-kilometer resolution – one of the highest and most accurate of its kind in the region.

"Once you have the atmosphere, you can go down and simulate the ocean. … We want to trace the history of everything that happened in the Red Sea from both the oceanic and atmospheric points of view" said Prof. Hoteit.

The long-term goal is to fully couple the ocean-atmospheric models and simulate these as one system, exactly as in nature.

Understanding the variability of ocean currents is also of vital importance in order to develop a large-scale and comprehensive picture to study and predict the Red Sea's physics and even biology. By assimilating data, Prof. Hoteit's group seeks to provide real-time nowcasting and forcasting models for the Red Sea. This involves the long-term monitoring and studying of fundamental processes in the Red Sea, which is undertaken in close collaboration with Prof. Burton Jones of the KAUST Red Sea Research Center.

Due to heat and wind, the Red Sea experiences a lot of evaporation. It loses around two meters of water per year, which is actually supplied back by water from the Indian Ocean through the Bab-el-Mandeb strait. This forms a process called overturning. The group has observed and recently explained in two recently published papers, that the overturning circulation in the Red Sea reverses directions in the summer and in the winter. "This has a very important impact on the biology," as Prof. Hoteit explains, because it "regulates and changes the food supply and nutrients for the fish and corals. You cannot study the biology without understanding the large and local scales circulation and environmental conditions (i.e. physics). There is no way to understand the complete picture."

Industrial Applications

Such detailed information about the Red Sea's ocean and atmosphere circulation is not only important for purely scientific reasons; as this knowledge has very direct applications for industry. One specific example offered by Prof. Hoteit is an oil company wanting to consult real-time current circulation models in order to determine optimal drilling areas for the purpose of mitigating the risk of spill propagation in the event of an accident.

"What can be done is to form a database from simulations based on known data," as Hoteit clarifies. By assimilating known data from various sources, the simulations are made to be as accurate as possible, with an estimate of uncertainty.

Using KAUST's visualization and supercomputing resources, Prof. Hoteit can produce a real-time model of the sea currents, before the design is complete, to inform the company on where to drill. The company may have certain conditions such as water speed. Through the clicking or hovering of a mouse, the computerized model can offer various points covering the sea map offering these specific conditions together with their uncertainties, as informed by the underlying data sets.

An important project at KAUST, helmed by Prof. Burton Jones (Marine Science), is the Saudi Aramco Marine Environmental Research Center. Prof. Jones' group is developing an ocean observatory for the Red Sea. In partnership with Saudi Aramco, one of their goals is to facilitate the long-term monitoring and predictions of the Red Sea. This strategic partnership also serves to minimizing the environment impact in the areas of the Red Sea where Aramco operates and promote the sustainability of the energy industry in the Kingdom.

Prof. Hoteit's team works in the Red Sea is part of this project providing vital predictive models. Outputs from these models could for instance be used for optimizing the operation of autonomous robotic gliders deployed in the Red Sea on observational survey missions. Since these gliders operate at a specific speed, real-time data about the speed and direction of Red Sea currents is vital. If water is moving past the glider in the opposite direction it will go backwards, stalling operational progress.

"It's thanks to a combination between high performance computing, visualization and physics," said Prof. Hoteit. "Really, few institutions have access to this type of technology."

By Meres J. Weche, KAUST News

Related Links

• Earth Fluid Modeling and Prediction
• Using Regional Climate Models in the Middle East and North Africa