Thank you for inviting me to
this wonderful celebration!
Nimbus of course
is very dear to me
because I began my professional
career here in 1966
with the Nimbus program,
and a lot of people
in the Nimbus program,
like Bill Nordberg, Harry Press,
Bill Bandeen and others
were professional
fathers to me.
I grew up with Nimbus,
and it was exciting,
and Nimbus, and NASA,
especially NASA Goddard,
as well as my own
organization, ESA,
which is not an oil company,
it was the old NOAA,
gave me lots of opportunities
as a young scientist,
so I thank everyone for that.
The... of course
the Nimbus program,
as has been mentioned earlier,
is instrumental
in flying the...
instrumental in flying
the very first instruments
for atmospheric sounding,
on the Nimbus-3 satellite,
and that, as you'll see,
has turned out to
absolutely revolutionize
weather forecasting,
as we know it today.
It began with
these instruments.
And this is sort
of a chronology
of the sounding milestones
in the Nimbus program,
but I want to point
out Nimbus-B here,
which was the one
mentioned earlier,
that fell into the drain,
it was a launch failure,
and what happened remarkably
as a result of that was
the Nimbus program,
under Harry Press,
decided that,
hey, this is so important
that we can't... we've got
to get Nimbus-B up there
as soon as we can,
and they vowed to get
a Nimbus replacement,
Nimbus-B2 up there
in less than a year
from the day that
was launched,
which was in May of 1968.
And sure enough,
this is something that
couldn't be done today,
but 11 months later,
in April of 1969,
Nimbus-B2, which became of
course in orbit Nimbus-3,
was launched successfully,
and that was the
beginning of the
satellite sounding
program in space.
And there are a
lot of pioneers
that I have on
this chart here;
I am not going to
go into all of them,
but of course
for this lecture
most notably were
these two guys;
David Wark, Dr. David Wark,
who was with this
organization, ESA;
and of course Rudolf Hanel,
who flew all these
instruments to more planets
than anybody else,
also had an instrument on
the Nimbus-3 spacecraft.
The Wark instrument was
a grating spectrometer.
It measured the radiation
at eight optimally
defined wavelengths
to observe atmospheric
temperature profiling.
And from the window region,
all the way to the center of
an absorption band due to CO2,
which allowed you to relate the
spectrovariation of radiance
to the temperature
variation in the atmosphere.
If I turn that
slide sideways
you would see the temperature
profile of the atmosphere
being warm near the surface,
going to a minimum
at the tropopause,
and then increasing again,
going higher in the atmosphere,
and that was the concept.
Rudy Hanel flew
this interferometer,
which measured many
spectro channels,
hundreds of spectro channels
compared to just those eight.
At that time we didn't
realize how valuable that was.
Today we're flying these
kinds of instruments
on our operational satellites,
as I'll show
you in a moment,
but these two gentlemen,
Rudy, who is shown here,
he is still with us,
he is at the 45th anniversary
so he didn't make
it to this one,
and his IRIS instrument;
and David Wark,
who passed away some time ago,
but with his
SIRS instrument,
which provided the very first
atmospheric temperature sounding
back in... on the launch day
of 1960... 1969, April 14,
as compared to
a balloon sound.
Now you can see
very close agreement,
which gave everybody
a lot of excitement.
Now, here's something that's
really quite interesting.
Hal Woolf worked for the
National Meteorological Center
with me on producing
the algorithm
and the software to
process the SIRS data,
and of course on launch
day Ralph Shapiro,
who was running the
ground station...
I was pestering him.
I think I was in the ground
station all the time,
watching the data come out
on the strip recorders,
couldn't wait to get
my hands on the data.
Provided us with tapes of
the data for the entire day
of that first day,
and Hal Wolf of NFC and
I stayed up all night
that very first night
and processed these data
and hand-plotted these data,
these sounding
data on a chart
and hand-analyzed them,
contoured analysis.
We got very excited
about what we saw.
So the very next morning,
about 8 o'clock in the morning,
right after the
Director of NMC
(the National Meteorological
Center) got in his office,
we were there waiting for him,
that was Fred Shuman,
and said, we have got some
exciting results to show you.
And he was kind
of a skeptic,
you know, that you could sound
the atmosphere from space.
So he says, okay, let
me call my deputies.
He called Ed Fawcett, his
deputy, and Harlan Saylor,
his Director of
Operations in,
to look at these maps
that we created.
And Harlan Saylor
was really a skeptic.
He used to needle me on
why am I wasting my
time on this business.
But he says,
let me see those charts.
So he took those charts
and took a look at them,
you know, and he looked at them
and looked, stared at them,
and he went right
to one position
and ran his finger down there
and he goes, oh my God!
And I said, oh,
what's wrong?
He says, well,
he says, we've been taking a
lot of flak from the airlines
getting calls overnight on
our bad weather forecasts;
we mis-positioned
the jet stream
and the airlines were
flying into headwinds
and had to stop
midway to refuel
and it's costing
them a lot of money.
And here I see that you...
that SIRS, the Nimbus satellite,
properly positioned
that jet stream.
And then he went
on to say, he said,
when can you make
this operational?
This is the very
first the day;
the day after the launch.
And of course my and my naivety
and youth and so on said,
oh, we can do it
in about six weeks.
And he says, great!
He says, listen,
let's do it.
So we were committed
to do that,
and through Ralph,
Ralph Shapiro,
who is running the ground
station, played a big role
in being able to get that
digital data to us from Nimbus
on a routine basis.
And we started with a
carrier transporting tapes
from the ground station
to Suitland on,
almost on an orbital basis
to make this happen.
And that started on May 22,
less than six weeks after...
after launch.
And that was in time for the
National Meteorological Center
to get these data into
their final analysis,
which was used for
weather forecasting.
And it was quite
an achievement.
And this just shows an
example of one test
of how these data were improving
weather forecasts for the US.
This is data over the Pacific,
the mid-Pacific,
where the Nimbus data
showed a cut-off low.
You see this low up here and
then another low to the South.
This was cut-off from
the one to the North,
whereas the analysis
without the satellite data
didn't show that at all.
It was just a
diffused straw.
And that made a
huge difference...
oops, I lost a slide there,
that made a huge difference
for the forecast
for the western United States
three days later.
This was a three-day forecast
and you see that this is
the verifying analysis
and you can see that
with the Nimbus data
correctly forecast
the shortwave ridge
over the western
United States,
which was not forecast
without the Nimbus data,
and in fact the areas were...
were more than twice as great
without the data than with the
data in the forecast there.
Of course, that leads to
precipitation forecast there
and everything else.
But the satellite data
wasn't perfect by any means.
These instruments, SIRS and IRIS
had large fields of use,
so a lot of cloud contamination
and the cloudy soundings,
quite frankly,
were pretty poor
compared to the
clearer soundings.
So that problem had
to be dealt with.
So on Nimbus-5 and Nimbus-6
we flew different
kind of instruments.
They were multispectral
radiometers
rather than these grating and
interferometer spectrometers,
but they had the
characteristic of being
very high spatial resolution;
20 kms compared to a 150 kms.
And that pretty much solved the
cloud problem in the infrared.
We were able to look
through breaks in the clouds
and see lots of
clear... clear sky
and so the yield and the
accuracy of the soundings
got much, much better
with these instruments.
And then we also flew
microwave instruments
on Nimbus-5 and Nimbus-6,
which were able to
go through cloud.
The other thing that
happened was in 1998,
we flew an Advanced
Microwave Sounding Unit
which added a lot of
spectral channels
of temperature and water
vapor in the microwave,
and this really advanced
sounding accuracy
quite a bit as well.
And so we see here
where the temperature accuracy
is getting down to...
in the one and-a-half
degree level here
from two and-a-half to
3 degrees before that,
and the problem though
with these soundings,
with the early Nimbus soundings
and even these soundings,
with the Advanced
Microwave system
is the lack of
vertical resolution
because the energy comes
from such a deep layer
of the atmosphere
the soundings from the
satellite were very smooth
compared to the detailed
structure that exists
due to fronts and the
tropopause and so on
that's measured
by our balloons.
So something had to be done
to alleviate this vertical
resolution deficiency.
So that began in the 1980s
supported by the EOS Program,
and I will give Shelby Telford
a lot of credit
for supporting
our work in this area.
We developed the methodology
of hyperspectral sounding
instead of having just
couple of dozen of channels
for sounding the atmosphere
we observed the whole spectrum
with high resolution,
very high resolution
like shown here;
thousands of
spectral channels
which together with the
large number of channels
together with the
details of the spectrum
that are measured here led to
a big increase improvement
in vertical resolving power.
It wasn't that the
waiting functions
or the resolution of
a single measurement
was all that much better
than the older instruments,
in fact, that you have
thousands of these channels
and when you put it in
the retrieval system
you had very high
signal-to-noise ratio
for this de-convolution process
of transforming radiance
in the atmospheric profiles,
and this led to a factor of
three to four improvement
in the vertical resolution
of these soundings.
In fact, the hyperspectral
sounding information content
is shown from real data
once we start to flying
these, these instruments
like the AIRS instrument,
on the Aqua satellite,
on the IASI instrument,
on the MetOp satellite,
and now the CrIS instrument
on the SNPP satellite
showed this much
greater improvement,
three to four times higher
information content
than these old
multispectral instruments
and almost as much information
as the radio song,
and so this has led to
a dramatic improvement
in weather forecasting.
As shown here by ECMWF
which is the European Centre
for Medium-Range
Weather prediction
where they show that the
satellite sounding systems,
the microwave and
the hyperspectral infrared
are the biggest contributors
to the weather forecast now,
much greater than
say the radio song.
In other words the forecast
accuracy degrades the most
if you exclude these...
these instruments from it.
And to go on further
that when you look at
single instruments,
individual microwave and
hyperspectral instruments,
the hyperspectral
infrared instruments
are way beyond the capability
of the other data sources
for improving the
weather forecast,
in fact the single-most
important instrument
in today's operation
is the MetOp IASI
which has almost 9,000
spectral channels to it.
And practical
example of this
was the superstorm
Hurricane Sandy prediction,
you would remember
that October of 2012
which land fall in New Jersey
and just devastated
the North-East Coast.
And this was a 5-day forecast
by the European Center
using all the data,
including all the
hyperspectral sounding data
and of course every
other observation
that goes into the
Global Observing System.
And that forecast
was spot on at 5-days out
with what actually occurred
which is this
verifying analysis,
when they took out the
satellite sounding data
this is what's the forecast,
it never even made landfall
and so you can see
that the satellite data
playing a very
dramatic role
for improving not only
weather prediction
but severe storm prediction
such as this Hurricane forecast.
And the next
observing system
with the WMO caused the
space component for 2025,
it's going to have at least
nine of these hyperspectral
sounders in orbit.
It's going to
have 6 of them,
at least 6 on geostationary
satellites around the globe
and we are going to have at
least 3 of these in the orbits
and complementary orbital
planes and the polar system.
And so, thank you
for your attention
and bearing
through the...
the problem with the
PowerPoint slides
but I hope the presentation
gave you a... the sense
that the Nimbus
Satellite Program
really did initiate
the revolutionary advances
achieve the weather forecast
that we enjoy today.
Thank you very much
for your attention!
[Applause]