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A Climate Fluctuation That Could Improve Forecasts Remains a Mystery

What keeps people awake at night? For baseball players, it might be a late-breaking fastball. It looks like you could hit it right out of the park until it curves.

For meteorologists, an equivalent problem is called the Madden-Julian oscillation, or the MJO. It consists of patterns identified by two scientists in 1971 that suggested a connection between far-flung weather extremes, like monsoons in India and hurricanes in the North Atlantic, and a large blob of warming water in the Indian Ocean.

The discovery made Roland Madden and Paul Julian at the National Center for Atmospheric Research famous. And for good reason. Calculated from air pressure information gathered by weather balloons, the patterns seemed to offer a step toward solving a global problem: the inability to forecast major weather events more than a few days before they occur.

That home run hasn’t happened yet.

Almost four decades later, meteorologists are armed with more information than ever before: from space satellites, sensor-packed ocean buoys and data projections made with the help of supercomputers.

But they still don’t fully understand the complexities of the Madden-Julian oscillation, or whether the warm ocean blob can help predict major weather events in the future.

Meanwhile, accumulating heat from climate change has doubled the size of the blob and increased the number and strength of extreme weather events.

What is going on?

“The impact of this warming on the MJO life cycle is largely unknown,” is how a study published by six scientists in the journal Nature described the phenomenon in November 2019.

“This is a big challenge, and there could be huge rewards,” explained Michael McPhaden, one of the authors of the study.

A senior scientist at NOAA, he put it this way: “There has been some progress, but like all great challenges, the progress on it has been slow. We’re making small steps, but there’s still a long way to go.”

The rewards could be massive. The Nature paper estimates the inability to predict weather extremes beyond more than a few days may cost the global economy as much as $2 trillion annually. U.S. damage alone amounts to $700 billion a year.

‘Pineapple Express’

What we know about the MJO is that it starts with water vapor rising out of the hot spot in the Indian Ocean. That creates major ocean storms through a progression of clouds, rainfall, winds and fluctuating air pressures moving eastward as it begins to circle the equator. The trip can last 30 to 60 days.

The MJO’s reach is extraordinary. The power of its thunderstorms raging at an altitude of 40,000 feet begins to tamper with the jet stream over the North Pacific. Among the results is the “Pineapple Express,” an airborne river of tropical moisture that crosses the Hawaiian Islands on its way to the West Coast. There it can cause heavy snows, high winds and major flooding, depending on where it lands in a given year.

That is just the beginning of the MJO’s jet stream manipulations. Over North America, impacts can include unusually cold outbreaks, heat waves, flooding and droughts.

Unlike other well-known weather shapers, such as the El Niño-Southern Oscillation (ENSO)—which is relatively stationary in a given area—the MJO tries to keep moving around the world. It has two alternate phases during its voyage. One is stormy and wet, marked by upward movement of winds. The other is sunny and dry, driven by downward winds.

Just where they might be expected to be in a given month, though, remains one of the many mysteries of the MJO. Sometimes during the summer, the MJO can stall or even disappear.

According to one NOAA paper, the MJO’s activities are so broad that they fall into a gap between weather predictions, which can be accurate up to 10 days, and climate predictions, which begin around 90 days. Whatever the MJO is doing on a given day can affect both.

The ideal goal, McPhaden explained in an interview, is to extend accurate weather predictions out to four weeks.

“It’s a big target for us to try to understand and forecast better. Because if we can do that, then all these parts of the world that are affected by the MJO and all the impacts it has will be better prepared,” he said.

“More accurate computer models,” McPhaden added, “would be a step in the right direction.”

But the MJO seems to go out of its way to avoid being observed.

Changes in the heated blob of water working underneath the MJO’s atmospheric gyrations are hard to track. Officially, the blob is called the “Indo-Pacific warm pool,” which is now estimated to be the largest body of distinctly warmer water on Earth.

According to the Nature study, it expands every year by an area the size of California.

Buoys gone missing

The blob is also shifting course. The MJO has begun spending less time in the Indian Ocean and lingering five more days in an area scientists call the Maritime Continent in the West Pacific.

The Maritime Continent consists of thousands of islands and peninsulas that make up Indonesia, Malaysia, Australia, New Guinea, the Philippines and Southeast Asia. The thousands of weather interactions between the MJO, the area’s islands, mountains, wide swaths of water and seasonal pollutants from agricultural burning can confuse even the world’s best computer models.

One of the many papers describing the MJO says meteorologists familiar with the models’ weaknesses have learned “when to trust the models” and when not to. Sometimes weather is simply chaos, explains McPhaden, “but there are influences that have fingerprints, and MJO is one of them. There are times when those [fingerprints] are active and you can see their effects.”

All this has made the MJO one of the biggest targets for meteorological research around the world. Chidong Zhang, a climate research division leader at NOAA’s Pacific Marine Environmental Laboratory in Seattle, spends most of his time trying to decipher the quirky behavior of the MJO in the Maritime Continent.

Forty percent to 50% of the time, the MJO simply disappears in the area. “If none of them made it through, the problem would be simpler, but some can get through” and continue their journey around the Earth, Zhang explained in an interview.

The problem is compounded by human factors. Some nations in the area regularly report their weather data, but some, such as Malaysia, don’t. Meteorologists are working with countries in the region to get them to report data more regularly.

“We have to engage them, to invite them to join us. That’s what we’re doing now,” Zhang said, noting that computer models have to be fed with better data. Of the world’s 20 best computer models, fewer than five reliably predict the MJO’s workings in a way that jibes with actual observations.

“The rest are off the table,” Zhang explained.

The problem is particularly frustrating in the Maritime Continent, where nations are installing sensor-equipped buoys in remote areas where human weather observations are limited. Their mission is to feed more comprehensive weather data into the computer models—and improve predictions.

Some buoys are also equipped to track the subsurface ocean temperatures of the blob. Not only do the signals sometimes disappear, but the buoys do, as well.

“They have a very active fishing industry. You put any surface buoy out there and they will just grab it. That’s still a challenge,” Zhang added.

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.

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