January, 1998, I dug out my old cutoff shorts, dusted off my bicycle and
went for a relaxing ride around a neighborhood that at that time of year
is normally buried under two feet of snow and where a winter day above
30 degrees is considered balmy. It was 85 degrees that day in Canada.
Later this year, on the Pacific Coast Highway in Southern California,
I watched the driver of a Miata frantically attempt to keep the water
level in his car from reaching the dashboard, using only a takeout coffee
cup. Through the torrential downpour, the driver tried to follow a 4X4
through a very large puddle and lost. The Paita sailors, who frequently
navigate along the coast in small craft... name this countercurrent the
current of "El Nino" (the child Jesus) because it has been observed to
appear immediately after Christmas. As this countercurrent has been noticed
on different occasions, and its appearance along the Peruvian coast has
been concurrent with rains in latitudes where it seldom if ever rains
to any great extent, I wish, on the present occasion, to call the attention
of the distinguished geographers here assembled to this phenomenon, which
exercises, undoubtedly, a very great influence on the climatic conditions
of that part of the world.
Dr. Luis Carranza
President of the Lima Geographical Society, 1895
If these occurrences seem strange, they are by no means unusual. They
are simply part and parcel of a global weather phenomenon that we have
come to know as "El Nino".
Due to the severe weather conditions that have recently affected many
parts of the planet, El Nino has become a household name. Forest fires
in Florida, tornadoes in California and floods in Manitoba, are just a
few El Nino events that made the headlines this past year.
For most people El Nino, the harbinger of unusual weather, was a temporaray
inconvenience expected to depart with the arrival of summer. And to a
large extent, the weather has returned to normal. What very few people
don't realize is that El Nino has not actually gone away. Or perhaps more
accurately, it has gone away but it will soon return. Despite what most
of us may think, this is not the first El Nino and it is not likely to
be the last. The reality is that El Nino is not a one time freak phenomenon;
it is just another part of the earth's natural weather pattern.
What we must keep in mind is that the severity of the floods, tornadoes,
and droughts of the past year may not be entirely attributable to El Nino.
There is a possibility that the global climate pattern is actually shifting.
If this is the case the weather events of the past year need to be taken
very seriously, as the future of global food production may potentially
be in jeopardy. For now, continued study of the earth's weather systems
will allow countries to better prepare and mitigate the effects of floods
With El Nino wreaking havoc on the world's seasonal weather predictions,
scientists have recognized the need for more advanced forecasting models.
Currently, operational responsibility for weather forecasting is the jurisdiction
of the National Oceanographic and Atmospheric Administration (NOAA). However,
since El Nino has global impact, weather observations networks have come
to include satellite monitoring. In the US, this has occurred with the
help of NASA.
ABILITY Magazine recently spoke to NASA scientist, Dr. Tony Bassalachi
about NASA's role in the study of El Nino and how satellite monitoring
may help improve the future predictability of El Nino events.
Chet Cooper: What is El Nino?
Tony Bassalachi: The first thing to realize about the El Nino phenomenon
is that it doesn't exist in the ocean by itself and it doesn't exist in
the atmosphere by itself. It is a result of the two being coupled, beginning
in the tropical Pacific. This coupling point is an area that spans one
third the circumference of the globe. Because of its magnitude, we now
know that it affects world weather patterns.
CC: How are El Nino and La Nina related?
TB: El Nino and La Nina are basically one in the same. They are
part of the same process. You can basically think of it as the flip-side
or opposite of El Nino. That's very simplistic, but whereas the tropical
Pacific is warm during El Nino, it's colder than normal during La Nina.
Now, why doesn't every El Nino have a La Nina that follows it? We really
don't know. But we do understand the fundamental cyclical processes that
give rise to El Nino, then to La Nina and back to El Nino again on these
three to seven year time scales.
CC: How is NASA involved?
TB: One of the things that the 1997-98 El Nino really brought home
was that you can't just focus your attention on the tropical Pacific Ocean.
You really need to also take into account the contributions from the water
temperatures in the tropical Atlantic and the tropical Indian oceans.
To monitor El Nino and increase our overall understanding of the interaction
between the ocean and the atmosphere helps improve our forecasting ability
and is the real reason that we really need the satellites. The satellites
provide us with a sort of global overview. From NASA's perspective, there
is a need for global coverage that some of the satellites provide. However,
in the future it will be a blend of the sort of satellites NASA is putting
up and instruments that NOAA is putting in the ocean that will really
offer the hope of improving our forecast field and predictions, for the
betterment of societies around the world. I don't just mean for developing
countries in the tropics, but also for developed countries such as North
America as well.
CC: Before El Nino actually arrived there was considerable warning
and evidence that something big was happening. What's the history of tracking
this type of phenomenon?
TB: The last El Nino event of the century was in 1982-83. That
El Nino event really caught the scientific community off-guard in that
we didn't know that an event was underway until several months after the
fact, because we just didn't have the observation capability we have today.
So, as a result of getting caught unaware, the international scientific
community really mobilized and focused effort on improving prediction
models, putting more observation into the ocean and more satellites in
orbit. It was called the TOGA program, Tropical Ocean Global Atmosphere
program, which was part of the World Climate Research Program, within
the World Meteorological Organization. That was about a ten year program
from 1985 to 1994. The sort of ability we have now to monitor El Nino
in real time and the predictive skill that we have today is a direct result
of the intense international effort during that decade.
CC: How is NASA involved in forecasting global weather patterns?
TB: The operational responsibility for weather forecasting in this
country is NOAA's responsibility. So, they have the operational forecast
model. They also have the operational observational network for weather
At NASA, we don't do operational forecasts. What we are doing is developing
new satellites, using them in a monitoring mode and assessing the extent
to which new satellite observations advance forecast skill, so that in
the future, provided we can make them affordable, these observations satellite
systems can be transferred to NOAA. If a satellite platform is shown to
advance forecast skill, then NASA's responsibility is to make it affordable,
demonstrate how one can develop the models to utilize and exploit this
observational information, and then hand the systems to NOAA for them
to use in an observational sense. So, in that regard, NASA is looking
to develop new satellite based measurement platforms and models for the
ocean and atmosphere that can assimilate those observations.
CC: Where are we in terms of the technology used for tracking?
Have there been many advances in technology in the US since the TOGA program
TB: No, and that's a potential problem in the US right now. Our
colleagues, overseas, have access to computer platforms that we don't
have access to here in the US. Basically, since the end of the Cold War
the market just isn't there anymore for super computers in this country.
So, the Japanese are building computer platforms, which countries outside
the US have access to, but for whatever reasons, we really don't. So,
it's going to be interesting to see how this super computing problem plays
out in the years ahead.
CC: Is global warming in some way linked to El Nino and are humans
contributing to the increased severity of El Nino events?
TB: Obviously researchers are looking at the extent to which global
warming is anthrogenic [human caused]. There is already natural variability
going on and there is a suspicion, but we don't know for certain, that
if you put more energy into the system, you have a warmer climate that
these natural modes of oscillation like El Nino would intensify.
CC: Do we know why the 1997 El Nino event was so much more severe
than the 1982-83 event?
TB: No, we don't understand why this event was as large as it was.
Was it a result of global warming? We don't know. But there are signs
that the warming in the Indian Ocean and the warming in the Atlantic Ocean
was related to El Nino.
CC: With the information gathered to date, is there an emerging
explanation for the changing and unseasonable temperatures of the oceans?
TB: There are some ideas. Again, nothing is one hundred percent
certain, but there's some suggestions that this El Nino event changed
the major heat sources to the atmosphere. What I mean by heat sources
are these areas where we have a lot of rising moist air, called convection
zones. So, for example, normally we have a lot of warm, moist air rising
over Indonesia, which sinks over Ecuador and Peru. That explains why there
is a lot of rainfall in Indonesia and dry conditions over Ecuador and
Peru. During El Nino that heat source shifts eastward, which means that
the rising air is further to the east, which also means the descending
air is further east, not in its normal location. There's some thinking
that as a result of this heat source being moved away from Indonesia,
it has changed the circulation patterns for both the atmosphere and the
ocean currents of the Indian Ocean.
CC: But what causes the rising air to shift?
TB: El Nino. Normally the warmest water of the world's oceans is
in the far west tropical Pacific. It's about eighty six degrees Fahrenheit
and it's kept in place by the trade winds. During El Nino that system
breaks down, the trade winds weaken, and the winds that brought the cold
water to the surface in the eastern equatorial Pacific are no longer there.
So, the warm water essentially begins to migrate eastward.
CC: From what you can tell, is El Nino an indicator of a large
shift in the global climate, or is it just another part of the earth's
TB: I would say that it is premature to speak of shifts. Clearly,
we have seen a tendency towards more severe events...floods, droughts,
tornadoes. That's been documented. However, the ultimate cause of that
is still under debate.
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