Professor sees clouds as key to better weather forecast, climate predictions

Zhien Wang makes no bones about it. He believes meteorologists could do a better job of predicting the weather. To do so, he believes the clues are in the clouds.

"With a weather forecast, we talk about tomorrow, the day after tomorrow, (what's going to happen) within a week," says the University of Wyoming associate professor of atmospheric science. "For a climate forecast, we are looking at what the climate will be like in Wyoming over a longer time period, such as 400 years later. We're trying to build the blocks to forecast better. Clouds are so important."

To build an accurate forecast for precipitation, you need to know how clouds are created, how they change and how precipitation is generated, Wang says. In other words, meteorologists cannot take a "one cloud fits all" approach to weather forecasting.

Wang hopes that his use of the National Center for Atmospheric Research (NCAR)-Wyoming Supercomputing Center (NWSC) this winter will provide improved weather models that meteorologists will be able to use. His project is titled "Understanding Tropical Convection and Mid-Level Stratiform Cloud Formation by Combining Cloud-Resolving Model Simulations and Remote Sensing Measurements."

"We have a lot of (cloud) data from aircraft and satellites. Just that data is not enough to study what's happening inside clouds," says Wang, who has been a NASA satellite science team member for 13 years. "This (supercomputing) project allows us to run high-resolution models. We will be able to compare model simulations and observed clouds, and combine them to understand the process."

He stresses one has to be able to input accurate cloud processes—through observation and understanding of clouds—into the computer model for the information to be relevant. That means forecasting the type and number of clouds in a particular area or region; the amount of water in each cloud; the descent rate of raindrops, etc.

Wang says these data are crucial because, during the summer months, rain often falls only in small areas, making such storms more difficult for meteorologists to pinpoint for the public. Weather forecasters typically use Doppler radar to issue thunderstorm and tornado warnings, but are not able to rely as much on model-predicted dynamics and microphysics now, Wang says.

"There is knowledge we have to know first if we can tell it (the computer) the kinds of clouds you can expect to be in your (computer) grid box," he says. "It will help provide better forecasting, and earlier and quicker storm warnings."

Most current climate models have 200-kilometer grids, roughly the distance from Laramie to Denver, Wang says. However, most clouds are smaller than that, but their impact still has to be measured within that larger grid. With the supercomputer, individual clouds can be analyzed by using models with smaller grids. This could lead to improved accuracy and details of cloud behavior in climate models.

"The more computer power we have, we'll be able to simulate better clouds," Wang says. "If we can simulate better clouds, we can provide better forecasting."

Weather and climate affect daily life

Short-range climate affects so many aspects of the public's daily lives that it's sometimes easy to overlook its overall impact, Wang says.

For example, he says seasonal climate predictions can be useful for farmers when planting crops, and help them predict corn or soybean futures based on rain or drought conditions, Wang says. If drought is predicted, corn or soybean production will be lower than normal, meaning their prices would be higher based on lack of supply, which affects many aspects of the public's lives.

In addition, energy companies can use seasonal climate predictions to better understand future consumer demand for natural gas and electricity based on how warm or cold the weather will be. Hydrologic power companies can manage or gauge how much water they release to communities based on available water reserves and how much precipitation is forecast in the next three months to a year, Wang says.

"Weather or climate is essential to our daily lives," Wang says. "It's not just pulling out an umbrella."

NWSC is the result of a partnership among the University Corporation for Atmospheric Research (UCAR), the operating entity for NCAR; the University of Wyoming; the state of Wyoming; Cheyenne LEADS; the Wyoming Business Council; and Cheyenne Light, Fuel & Power. The NWSC is operated by NCAR under sponsorship of the National Science Foundation (NSF).

The NWSC contains one of the world's most powerful supercomputers (1.5 petaflops, which is equal to 1.5 quadrillion mathematical operations per second) dedicated to improving scientific understanding of climate change, severe weather, air quality and other vital atmospheric science and geo-science topics. The center also houses a premier data storage (11 petabytes) and archival facility that holds historical climate records and other information.

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