[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.10,0:00:15.75,Default,,0000,0000,0000,,{\i1}34C3 preroll music{\i0}
Dialogue: 0,0:00:15.75,0:00:22.16,Default,,0000,0000,0000,,Herald: Hello everybody to the next talk,\Nhere at stage Clarke. The next talk will
Dialogue: 0,0:00:22.16,0:00:26.91,Default,,0000,0000,0000,,be held in English. And here is a quick\Nannouncement in German for the
Dialogue: 0,0:00:26.91,0:00:32.83,Default,,0000,0000,0000,,translation. Der nächste Vortrag wird in\NEnglisch sein. Und wir haben eine deutsche
Dialogue: 0,0:00:32.83,0:00:42.24,Default,,0000,0000,0000,,Übersetzung unter streaming.c3lingo.org.\NUnd wir haben das auch auf einer Folie.
Dialogue: 0,0:00:42.24,0:00:48.76,Default,,0000,0000,0000,,Und es wird auch eine französische\NÜbersetzung geben für diesen Vortrag.
Dialogue: 0,0:00:48.76,0:00:55.57,Default,,0000,0000,0000,,There will also be a french translation,\Nas well as an German translation for the
Dialogue: 0,0:00:55.57,0:01:04.24,Default,,0000,0000,0000,,next talk. And you can find everything\Nunder streaming.c3lingo.org. And, I hope,
Dialogue: 0,0:01:04.24,0:01:18.14,Default,,0000,0000,0000,,displayed behind me. The next talk is\Ncalled "Watching the changing Earth".
Dialogue: 0,0:01:18.14,0:01:23.89,Default,,0000,0000,0000,,Satellite data and change in the\Ngravitational field of the earth can tell
Dialogue: 0,0:01:23.89,0:01:29.94,Default,,0000,0000,0000,,us a lot, especially when there's so much\Npublic domain satelite data coming in from
Dialogue: 0,0:01:29.94,0:01:36.11,Default,,0000,0000,0000,,different projects or maybe CC-BY\Nsatellite data. And how this is done, this
Dialogue: 0,0:01:36.11,0:01:43.54,Default,,0000,0000,0000,,new knowledge finding out of this big\Nheap of data, this will be explained by
Dialogue: 0,0:01:43.54,0:01:50.40,Default,,0000,0000,0000,,Manuel in the talk. He dropped stuff to\Nsee if gravity still works, or, in fancy
Dialogue: 0,0:01:50.40,0:02:00.04,Default,,0000,0000,0000,,words, he does gravimetric methods and\Nsensory in geodesy. Is that pronounced
Dialogue: 0,0:02:00.04,0:02:06.21,Default,,0000,0000,0000,,right? I'm not sure, but give a big hand\Nand a round of applause for our speaker
Dialogue: 0,0:02:06.21,0:02:09.86,Default,,0000,0000,0000,,Manuel.\N{\i1}Applause{\i0}
Dialogue: 0,0:02:09.86,0:02:26.33,Default,,0000,0000,0000,,{\i1}No Audio{\i0}\NManuel: Geiler Scheiß. Oh, das war Sound.
Dialogue: 0,0:02:26.33,0:02:29.86,Default,,0000,0000,0000,,So again, so hello and welcome to my\Npresentation on watching the changing
Dialogue: 0,0:02:29.86,0:02:35.54,Default,,0000,0000,0000,,earth. This year's call for papers for the\NCongress offered me the opportunity to
Dialogue: 0,0:02:35.54,0:02:42.19,Default,,0000,0000,0000,,talk about my work in the related fields,\Nwhich is gravity. As far as Congress is
Dialogue: 0,0:02:42.19,0:02:46.87,Default,,0000,0000,0000,,concerned, a misunderstood force of\Nnature. So in the following couple of
Dialogue: 0,0:02:46.87,0:02:53.20,Default,,0000,0000,0000,,minutes, I want to talk about gravity,\Ngravitation, about the GRACE satellite
Dialogue: 0,0:02:53.20,0:02:59.18,Default,,0000,0000,0000,,mission, which maps the earth gravity\Nfield every month, about the gravity
Dialogue: 0,0:02:59.18,0:03:03.79,Default,,0000,0000,0000,,fields, and I will show good results and\Nthen we will go forward into the future.
Dialogue: 0,0:03:03.79,0:03:11.08,Default,,0000,0000,0000,,That's nice. So it's actually called,\Nactually called geodesy. Let me give you a
Dialogue: 0,0:03:11.08,0:03:16.48,Default,,0000,0000,0000,,short introduction on geodesy. Friedrich\NRobert Helmert defined it in 1880 at as
Dialogue: 0,0:03:16.48,0:03:21.32,Default,,0000,0000,0000,,the science of mapping and measuring the\Nearth on its surface, and this still holds
Dialogue: 0,0:03:21.32,0:03:29.75,Default,,0000,0000,0000,,up today. It depends on your methods and\Napplications, but he was correct. The most
Dialogue: 0,0:03:29.75,0:03:34.61,Default,,0000,0000,0000,,known profession is probably land\Nsurveying, people with colorful
Dialogue: 0,0:03:34.61,0:03:39.53,Default,,0000,0000,0000,,instruments and traffic cones. You find\Nthem on construction sites, on the side of
Dialogue: 0,0:03:39.53,0:03:44.61,Default,,0000,0000,0000,,the road, but we actually have a lot of\Napplications not only in geodesy but in
Dialogue: 0,0:03:44.61,0:03:49.59,Default,,0000,0000,0000,,related fields like geophysics,\Nfundamental physics, if you want to build
Dialogue: 0,0:03:49.59,0:03:57.01,Default,,0000,0000,0000,,an autonomous car you need geodesists,\Nmetrology. This talk is specifically about
Dialogue: 0,0:03:57.01,0:04:02.04,Default,,0000,0000,0000,,physical geodesy, which is the mapping of\Nthe gravitational field of the earth, and
Dialogue: 0,0:04:02.04,0:04:07.65,Default,,0000,0000,0000,,in this case specifically with satellites.\NSo I drop stuff on the earth, which is
Dialogue: 0,0:04:07.65,0:04:15.30,Default,,0000,0000,0000,,terrestrial gravimetry, this talk is about\Nsatellite gravimetry. Now gravity and
Dialogue: 0,0:04:15.30,0:04:19.94,Default,,0000,0000,0000,,gravitation, we usually talk about\Ngravitational potential. This is a scalar
Dialogue: 0,0:04:19.94,0:04:25.85,Default,,0000,0000,0000,,field. Gravitational acceleration is the\Ngradient of the gravitational potential
Dialogue: 0,0:04:25.85,0:04:31.84,Default,,0000,0000,0000,,and when we talk about gravity in geodesy,\Nit's usually the combination of attraction
Dialogue: 0,0:04:31.84,0:04:37.49,Default,,0000,0000,0000,,of the masses, gravitation, and the\Ncentrifugal acceleration, but here we talk
Dialogue: 0,0:04:37.49,0:04:42.36,Default,,0000,0000,0000,,mostly about gravitation. And the\Npotential can easily be calculated, at
Dialogue: 0,0:04:42.36,0:04:47.85,Default,,0000,0000,0000,,least according to this very short\Nequation. We have G, which is the
Dialogue: 0,0:04:47.85,0:04:52.87,Default,,0000,0000,0000,,gravitational constant of the earth, or\Nother planets if you want to do. We have
Dialogue: 0,0:04:52.87,0:04:58.27,Default,,0000,0000,0000,,an ugly triple integral about the whole\Nearth, and this is basically what breaks
Dialogue: 0,0:04:58.27,0:05:04.33,Default,,0000,0000,0000,,the neck. We have to integrate about the\Nwhole mass of the earth, we divide up into
Dialogue: 0,0:05:04.33,0:05:11.02,Default,,0000,0000,0000,,small parts and we need to know the\Ndensity of these parts. So, density times
Dialogue: 0,0:05:11.02,0:05:16.17,Default,,0000,0000,0000,,small volume, you have the mass of the\Nearth if you integrate over it. So what,
Dialogue: 0,0:05:16.17,0:05:19.68,Default,,0000,0000,0000,,the density of the whole earth is not\Nknown. So if you want to calculate the
Dialogue: 0,0:05:19.68,0:05:25.12,Default,,0000,0000,0000,,potential sufficiently, you would need the\Ndensity of a penguin on the other side of
Dialogue: 0,0:05:25.12,0:05:29.21,Default,,0000,0000,0000,,the world. We don't know that. So, what\Ndo you do if you cannot calculate the
Dialogue: 0,0:05:29.21,0:05:35.78,Default,,0000,0000,0000,,quantity? You write a proposal and get all\Nthe funding. This is what happened about,
Dialogue: 0,0:05:35.78,0:05:40.47,Default,,0000,0000,0000,,let's say, twenty years ago, and the\Nresult was the gravity recovery and
Dialogue: 0,0:05:40.47,0:05:46.78,Default,,0000,0000,0000,,climate experiment, or GRACE for short. In\Nthis talk, we will only cover gravity
Dialogue: 0,0:05:46.78,0:05:54.53,Default,,0000,0000,0000,,recovery, so gravity field of the Earth.\NAs we can see, these are two satellites.
Dialogue: 0,0:05:54.53,0:05:59.28,Default,,0000,0000,0000,,They are flying in the same orbit, and the\Nmain instrument is distance measurement
Dialogue: 0,0:05:59.28,0:06:06.40,Default,,0000,0000,0000,,between these two satellites, Here we see\Nthe two satellites prior to its launch in
Dialogue: 0,0:06:06.40,0:06:12.00,Default,,0000,0000,0000,,2002, and this K-Band Microwave ranging,\Nwhich is the instrument, gives us a high
Dialogue: 0,0:06:12.00,0:06:17.33,Default,,0000,0000,0000,,resolution gravity field of the Earth.\NThis is spatial resolution of around 200
Dialogue: 0,0:06:17.33,0:06:23.15,Default,,0000,0000,0000,,kilometers (km). You might think 200 km is\Nnot really high resolution, but we have it
Dialogue: 0,0:06:23.15,0:06:29.30,Default,,0000,0000,0000,,for the whole planet and not, let's say,\Nfor Germany. And also we got the temporal
Dialogue: 0,0:06:29.30,0:06:35.04,Default,,0000,0000,0000,,variations. So for 15 years now, we have\Neach month, with only a few exceptions, a
Dialogue: 0,0:06:35.04,0:06:41.32,Default,,0000,0000,0000,,picture of the gravitational field of the\Nearth. The satellites fly in height of
Dialogue: 0,0:06:41.32,0:06:49.29,Default,,0000,0000,0000,,about 450 km, 220 km apart, and we see\Nhere the orbits of a single day. So 15
Dialogue: 0,0:06:49.29,0:06:55.77,Default,,0000,0000,0000,,orbits per day, and we take one month of\Ndata to generate one gravity field. The
Dialogue: 0,0:06:55.77,0:06:59.99,Default,,0000,0000,0000,,working principle is quite simple: The\Ndistance between the two satellites is
Dialogue: 0,0:06:59.99,0:07:05.70,Default,,0000,0000,0000,,affected by gravity, so we measure the\Ndistance and then we calculate gravity. In
Dialogue: 0,0:07:05.70,0:07:10.27,Default,,0000,0000,0000,,a homogenous gravity field, this is quite\Nsimple: Let's say we take a spherical
Dialogue: 0,0:07:10.27,0:07:16.99,Default,,0000,0000,0000,,earth, it has only a single density, the\Nsatellites fly along, and the distance
Dialogue: 0,0:07:16.99,0:07:21.42,Default,,0000,0000,0000,,between the two satellites does not\Nchange. There is nothing to pull one or
Dialogue: 0,0:07:21.42,0:07:27.68,Default,,0000,0000,0000,,another, they just move along, not\Nchanging the distance. Now we introduce a
Dialogue: 0,0:07:27.68,0:07:33.81,Default,,0000,0000,0000,,mass, let's say a mountain, this can be\Nany mass change or density change
Dialogue: 0,0:07:33.81,0:07:38.94,Default,,0000,0000,0000,,somewhere inside the earth, and the\Nleading satellite experiences a
Dialogue: 0,0:07:38.94,0:07:44.74,Default,,0000,0000,0000,,gravitational pull by this mass. And as\Ngravitation falls off with distance, it is
Dialogue: 0,0:07:44.74,0:07:49.33,Default,,0000,0000,0000,,a stronger than the pull experienced by\Nthe trailing satellite. So the distance
Dialogue: 0,0:07:49.33,0:07:58.81,Default,,0000,0000,0000,,between the two satellites increases. Now,\Nthe satellite, the trailing the leading
Dialogue: 0,0:07:58.81,0:08:05.01,Default,,0000,0000,0000,,satellite has passed the mass, and it is\Nstill feeling its gravitational pull, but
Dialogue: 0,0:08:05.01,0:08:10.56,Default,,0000,0000,0000,,now it is being decelerated because the\Nmass is behind. And the trailing satellite
Dialogue: 0,0:08:10.56,0:08:16.45,Default,,0000,0000,0000,,is still being accelerated towards the\Nmass. This means the distance between the
Dialogue: 0,0:08:16.45,0:08:24.71,Default,,0000,0000,0000,,satellites decreases. And finally, the\Nsecond satellite passes the mass and it
Dialogue: 0,0:08:24.71,0:08:30.67,Default,,0000,0000,0000,,now also feels the gravitational pull\Ndecelerating the satellite. The leading
Dialogue: 0,0:08:30.67,0:08:34.66,Default,,0000,0000,0000,,satellite is feeling less and less\Ngravitational pull and once both
Dialogue: 0,0:08:34.66,0:08:39.39,Default,,0000,0000,0000,,satellites left the gravitational\Ninfluence of this mass, we will have the
Dialogue: 0,0:08:39.39,0:08:44.24,Default,,0000,0000,0000,,same distance as prior to encountering the\Nmass. So the gravitational acceleration is
Dialogue: 0,0:08:44.24,0:08:51.01,Default,,0000,0000,0000,,a zero sum at this point. So of course,\Nthe Earth is a little more complex than a
Dialogue: 0,0:08:51.01,0:08:56.80,Default,,0000,0000,0000,,single mountain or a single density\Nanomaly in the ground, but this is the
Dialogue: 0,0:08:56.80,0:09:04.48,Default,,0000,0000,0000,,basic concept. Now, how do we come from\Nthese measurements to the actual
Dialogue: 0,0:09:04.48,0:09:14.29,Default,,0000,0000,0000,,potential? The formula is basically the\Nsame as a couple of slides earlier. We are
Dialogue: 0,0:09:14.29,0:09:21.18,Default,,0000,0000,0000,,still calculating the potential. It looks\Nmore complicated, but we don't have triple
Dialogue: 0,0:09:21.18,0:09:24.93,Default,,0000,0000,0000,,integrals anymore, and all these\Nquantities in here are basically easily
Dialogue: 0,0:09:24.93,0:09:30.95,Default,,0000,0000,0000,,calculated. We start with the\Ngravitational constant and the mass of the
Dialogue: 0,0:09:30.95,0:09:35.47,Default,,0000,0000,0000,,earth, which we can get from a physics\Nbook, if we like. And then we have a
Dialogue: 0,0:09:35.47,0:09:42.52,Default,,0000,0000,0000,,couple of geometric quantities, a and r\Nare basically the size of my earth
Dialogue: 0,0:09:42.52,0:09:48.71,Default,,0000,0000,0000,,ellipsoid, the major axes and r is the\Ndistance from a calculating point, let's
Dialogue: 0,0:09:48.71,0:09:53.22,Default,,0000,0000,0000,,say this podium, for which I want to know\Nthe potential value to the center of the
Dialogue: 0,0:09:53.22,0:09:57.40,Default,,0000,0000,0000,,ellipsoid. And then we have lambda and\Ntheta at the end, these are the
Dialogue: 0,0:09:57.40,0:10:06.03,Default,,0000,0000,0000,,geographical coordinates of this podium. P\Nis short for the associated Legendre
Dialogue: 0,0:10:06.03,0:10:11.73,Default,,0000,0000,0000,,functions, also depending solely on\Ngeometry, not on the mass of the earth,
Dialogue: 0,0:10:11.73,0:10:16.77,Default,,0000,0000,0000,,depending on the software where you want\Nto implement this formula, it probably has
Dialogue: 0,0:10:16.77,0:10:22.11,Default,,0000,0000,0000,,already a function to calculate this, and\Nif not, it is easily done by yourself as
Dialogue: 0,0:10:22.11,0:10:28.43,Default,,0000,0000,0000,,the formulas look very long, but they are\Nquite simple. The interesting part are the
Dialogue: 0,0:10:28.43,0:10:34.98,Default,,0000,0000,0000,,two parameters C and S, these are\Nspherical harmonic coefficients. They
Dialogue: 0,0:10:34.98,0:10:38.79,Default,,0000,0000,0000,,include all the information about the\Nmass of the earth, as measured by the
Dialogue: 0,0:10:38.79,0:10:44.73,Default,,0000,0000,0000,,satellites. So we have the satellites in\Nspace, and the user gets just the C and S
Dialogue: 0,0:10:44.73,0:10:51.28,Default,,0000,0000,0000,,coefficients, which are a couple of\Nthousand for the gravity field. Implements
Dialogue: 0,0:10:51.28,0:10:56.76,Default,,0000,0000,0000,,this formula and has a potential value.\NSo, these spherical harmonic coefficients
Dialogue: 0,0:10:56.76,0:11:01.19,Default,,0000,0000,0000,,are calculated from the GRACE Level 1B\Nproducts. These are the actual
Dialogue: 0,0:11:01.19,0:11:04.50,Default,,0000,0000,0000,,measurements done by the satellites. This\Nis the ranging information, the distance
Dialogue: 0,0:11:04.50,0:11:11.12,Default,,0000,0000,0000,,between satellites, satellite orbits, star\Ncamera data, and so on. You add a couple
Dialogue: 0,0:11:11.12,0:11:14.31,Default,,0000,0000,0000,,of additional models for earth's gravity,\Nwhich you do not want to include in your
Dialogue: 0,0:11:14.31,0:11:19.55,Default,,0000,0000,0000,,satellite gravity field, and then you do\Nyour processing. This is done by a couple
Dialogue: 0,0:11:19.55,0:11:27.17,Default,,0000,0000,0000,,of different groups JPL and GFZ, which is\Na German research center for the
Dialogue: 0,0:11:27.17,0:11:33.33,Default,,0000,0000,0000,,geosciences. CSR is the center for space\Nresearch at university Austin. These three
Dialogue: 0,0:11:33.33,0:11:39.81,Default,,0000,0000,0000,,institutes also provides these GRACE Level\N1B data. So they take the raw satellite
Dialogue: 0,0:11:39.81,0:11:47.53,Default,,0000,0000,0000,,data, process it to theGRACE Level 1B\Nproducts, which are accessible for all
Dialogue: 0,0:11:47.53,0:11:54.42,Default,,0000,0000,0000,,users, and then calculate further these\Ncoefficients, C and S. But there are also
Dialogue: 0,0:11:54.42,0:11:59.75,Default,,0000,0000,0000,,additional groups who provide gravity\Nfields who calculate these coefficients,
Dialogue: 0,0:11:59.75,0:12:04.35,Default,,0000,0000,0000,,for example, Institute for Geodesy of the\NUniversity of Graz, or the Astronomical
Dialogue: 0,0:12:04.35,0:12:11.66,Default,,0000,0000,0000,,Institute of the University of Bern. They\Nall have slightly different approaches to
Dialogue: 0,0:12:11.66,0:12:16.16,Default,,0000,0000,0000,,topic and come to more or less the same\Nconclusions. There are countless papers,
Dialogue: 0,0:12:16.16,0:12:20.69,Default,,0000,0000,0000,,comparing these different gravity fields\Nwith each other, but the user usually
Dialogue: 0,0:12:20.69,0:12:25.83,Default,,0000,0000,0000,,starts with the coefficients C and S, and\Nthen it takes a formula like the one on
Dialogue: 0,0:12:25.83,0:12:31.64,Default,,0000,0000,0000,,top of this slide and calculates your\Ngravity value or whatever you want. Now,
Dialogue: 0,0:12:31.64,0:12:36.75,Default,,0000,0000,0000,,I'm talking about potential, I'm talking\Nabout accelaration. These are not really
Dialogue: 0,0:12:36.75,0:12:42.77,Default,,0000,0000,0000,,useful quantities in day to day life. If\Nsomeone told to you in Greenland gravity
Dialogue: 0,0:12:42.77,0:12:48.44,Default,,0000,0000,0000,,decrease by 50 microGal, you have two\Nchoices, you can say "wow, awesome" or you
Dialogue: 0,0:12:48.44,0:12:53.91,Default,,0000,0000,0000,,can say "oh no, we're all gonna die" It's\Na 50:50 chance you'd say the correct
Dialogue: 0,0:12:53.91,0:13:01.35,Default,,0000,0000,0000,,thing. So we are looking for a more useful\Nrepresentation of the changes in
Dialogue: 0,0:13:01.35,0:13:07.33,Default,,0000,0000,0000,,gravity field. Now gravity field reflects\Nmass redistributions and the most dynamic
Dialogue: 0,0:13:07.33,0:13:15.87,Default,,0000,0000,0000,,redistribution we have is water storage,\Nsummer/winter, more snow, more rain, less
Dialogue: 0,0:13:15.87,0:13:25.60,Default,,0000,0000,0000,,water in summer, so we express our gravity\Nchange in a unit called equivalent water
Dialogue: 0,0:13:25.60,0:13:31.95,Default,,0000,0000,0000,,height. This is the layer of water on the\Nsurface with a thickness, equivalent to
Dialogue: 0,0:13:31.95,0:13:39.94,Default,,0000,0000,0000,,the mass change measured with the\Nsatellites. This is also easily
Dialogue: 0,0:13:39.94,0:13:47.18,Default,,0000,0000,0000,,calculated. This is my last equation, I\Npromise, but this looks familiar. The
Dialogue: 0,0:13:47.18,0:13:55.48,Default,,0000,0000,0000,,second half of this equation, is basically\Nthe same we saw one slide prior and the
Dialogue: 0,0:13:55.48,0:14:02.53,Default,,0000,0000,0000,,parameters in front of the sum is the\Naverage density of earth, which is around
Dialogue: 0,0:14:02.53,0:14:13.71,Default,,0000,0000,0000,,5500 kg/m^3. We need the density or water,\Nlet's say it 1000 kg/m^3. And in this
Dialogue: 0,0:14:13.71,0:14:19.43,Default,,0000,0000,0000,,fraction in the middle, we need to\Nparameter K, which are the so-called Love
Dialogue: 0,0:14:19.43,0:14:26.15,Default,,0000,0000,0000,,numbers. Now, this is not a numerical\Nrepresentation of mutual attraction, but
Dialogue: 0,0:14:26.15,0:14:33.79,Default,,0000,0000,0000,,was put forward by, I think, Albert Love\Nin 1911, and they are parameters
Dialogue: 0,0:14:33.79,0:14:37.67,Default,,0000,0000,0000,,concerning the elastic response of the\Nearth to forces. So, if you put a lot of
Dialogue: 0,0:14:37.67,0:14:44.33,Default,,0000,0000,0000,,weight on a part of the earth, the earth\Ndeforms and these parameters, describe the
Dialogue: 0,0:14:44.33,0:14:51.77,Default,,0000,0000,0000,,elastic response of the earth to such\Nloading. Now we have calculated our
Dialogue: 0,0:14:51.77,0:14:59.12,Default,,0000,0000,0000,,equivalent water height, let's say for two\Nmonths, let's say, in May 2002 and 15
Dialogue: 0,0:14:59.12,0:15:04.79,Default,,0000,0000,0000,,years later in May 2017 and we just\Nsubtract these two gravity fields, these
Dialogue: 0,0:15:04.79,0:15:11.11,Default,,0000,0000,0000,,two equivalent waterheights, from these\Ntwo epoches. What we have left is the
Dialogue: 0,0:15:11.11,0:15:17.90,Default,,0000,0000,0000,,change in gravity between these 2 epochs, \N15 years apart, expressed in water layer
Dialogue: 0,0:15:17.90,0:15:23.07,Default,,0000,0000,0000,,equivalent to the change in gravity\Nmeasured. And we can see a couple of
Dialogue: 0,0:15:23.07,0:15:28.19,Default,,0000,0000,0000,,features here. There should not be any\Nseasonal variations because it's the same
Dialogue: 0,0:15:28.19,0:15:35.48,Default,,0000,0000,0000,,month, just 15 years apart. So we see long\Nterm gravity change between these two
Dialogue: 0,0:15:35.48,0:15:40.13,Default,,0000,0000,0000,,epochs. And what we see is, for example,\Nmass loss in the northern and southern ice
Dialogue: 0,0:15:40.13,0:15:46.38,Default,,0000,0000,0000,,shields, and we see two red blobs, one in\Nnorthern canada and one in northern
Dialogue: 0,0:15:46.38,0:15:53.01,Default,,0000,0000,0000,,europe, which are geophysical processes.\NSo this is glacial isostastic adjustment
Dialogue: 0,0:15:53.01,0:15:58.80,Default,,0000,0000,0000,,and during the last ice age the ice\Nshields deformed the earth downward.
Dialogue: 0,0:15:58.80,0:16:04.58,Default,,0000,0000,0000,,The material in the "Mantel" had to flow\Naside, and now that the ice is gone, the
Dialogue: 0,0:16:04.58,0:16:10.06,Default,,0000,0000,0000,,lead is uplifting and the material in the\N"Mantel" is flowing back. So it's flowing
Dialogue: 0,0:16:10.06,0:16:14.46,Default,,0000,0000,0000,,back and the earth is uplifting. This\Nprocess has been going on for 10000 years
Dialogue: 0,0:16:14.46,0:16:23.28,Default,,0000,0000,0000,,and will probably a couple of years\Nlonger. Now how do you get your data?
Dialogue: 0,0:16:23.28,0:16:27.01,Default,,0000,0000,0000,,Everyone can get the GRACE Level 1B data,\Nwhich are the observations by the
Dialogue: 0,0:16:27.01,0:16:32.40,Default,,0000,0000,0000,,satellite, like again, ranging information\Nbetween the satelite, orbits,
Dialogue: 0,0:16:32.40,0:16:39.95,Default,,0000,0000,0000,,accelerometer data, star camera data and\Nso on. You can get them without hurdles at
Dialogue: 0,0:16:39.95,0:16:44.92,Default,,0000,0000,0000,,the ISDC, which is the information system,\Na data center at the Geoforschungszentrum
Dialogue: 0,0:16:44.92,0:16:53.74,Default,,0000,0000,0000,,Potsdam, or at the Physical Oceanography \NDistributed Active Archive Center run by
Dialogue: 0,0:16:53.74,0:16:59.88,Default,,0000,0000,0000,,JPL. And if you'd like, you can calculate\Nyour own spherical harmonic coefficients
Dialogue: 0,0:16:59.88,0:17:06.27,Default,,0000,0000,0000,,for gravity fields. Or you can compare for\Nexample, satelite orbits they give you
Dialogue: 0,0:17:06.27,0:17:11.20,Default,,0000,0000,0000,,with one you integrated yourself using\Nyour own gravity field, to see if they fit
Dialogue: 0,0:17:11.20,0:17:19.91,Default,,0000,0000,0000,,together or not. You can get gravity field\Nmodels, if you'd like. A large collection
Dialogue: 0,0:17:19.91,0:17:25.61,Default,,0000,0000,0000,,is at the International Centre for Global\NEarth Models. They have recent and
Dialogue: 0,0:17:25.61,0:17:30.79,Default,,0000,0000,0000,,historic gravity models all in the same\Ndata format. So you only need to implement
Dialogue: 0,0:17:30.79,0:17:36.64,Default,,0000,0000,0000,,your software once from the 1970s to\Ntoday. They also have the proper
Dialogue: 0,0:17:36.64,0:17:43.07,Default,,0000,0000,0000,,references, the papers you want to read to\Nwork with them. These are so-called Level
Dialogue: 0,0:17:43.07,0:17:47.51,Default,,0000,0000,0000,,2 Products. So, you can take a gravity\Nfield from there, use the equation, I
Dialogue: 0,0:17:47.51,0:17:51.53,Default,,0000,0000,0000,,showed you earlier and calculate your\Nequivalent water height, if you'd like.
Dialogue: 0,0:17:51.53,0:17:56.53,Default,,0000,0000,0000,,If you don't want to do this, there is\Nsomeone to help you, a service called
Dialogue: 0,0:17:56.53,0:18:01.81,Default,,0000,0000,0000,,"TELLUS", which is a play on words I\Ndon't want to go into detail about. They
Dialogue: 0,0:18:01.81,0:18:08.33,Default,,0000,0000,0000,,offer equivalent water heights calculated\Nfor each monthly solution from the GRACE
Dialogue: 0,0:18:08.33,0:18:13.87,Default,,0000,0000,0000,,satellites. This tells us a lot about the\Nearth, if you look closer into it. In the
Dialogue: 0,0:18:13.87,0:18:20.50,Default,,0000,0000,0000,,following, I will use the monthly\Nsolutions from the ITSG-GRACE 2016,
Dialogue: 0,0:18:20.50,0:18:25.86,Default,,0000,0000,0000,,provided by Institute for Geodesy at\NUniversity of Graz. The previous graph I
Dialogue: 0,0:18:25.86,0:18:32.29,Default,,0000,0000,0000,,showed you was also created with that\Ngravity model. I will not go into detail
Dialogue: 0,0:18:32.29,0:18:40.14,Default,,0000,0000,0000,,about further processing like filtering\Nand gravity reductions done to this, not
Dialogue: 0,0:18:40.14,0:18:47.12,Default,,0000,0000,0000,,enough time. So here are some results,\Nlet's start with the most obvious one, the
Dialogue: 0,0:18:47.12,0:18:54.92,Default,,0000,0000,0000,,greenland ice shield, which has, as we saw\Nearlier, the greatest loss of mass
Dialogue: 0,0:18:54.92,0:19:04.46,Default,,0000,0000,0000,,according to the gravity field and we see\Nhere, a water layer on the whole landmass,
Dialogue: 0,0:19:04.46,0:19:10.14,Default,,0000,0000,0000,,describing the loss of mass expressed as a\Nwater layer of a certain thickness.
Dialogue: 0,0:19:10.14,0:19:15.34,Default,,0000,0000,0000,,So let's say in the southern tip, you have\None meter water layer. This would be
Dialogue: 0,0:19:15.34,0:19:23.70,Default,,0000,0000,0000,,equvalent in gravity to the actual mass\Nlost in Greenland. But we also see, that
Dialogue: 0,0:19:23.70,0:19:28.95,Default,,0000,0000,0000,,the signal is not very localized. So it's\Nnot bound to the land mass. It's also in
Dialogue: 0,0:19:28.95,0:19:34.91,Default,,0000,0000,0000,,the ocean. This effect is called leakage.\NIf you do signal processing you will know
Dialogue: 0,0:19:34.91,0:19:45.47,Default,,0000,0000,0000,,this. There are methods to reduce leakage.\NMy next slide will show such a result, but
Dialogue: 0,0:19:45.47,0:19:49.11,Default,,0000,0000,0000,,I have done no reduction to this. So if\Nyou use my formula I showed you, you will
Dialogue: 0,0:19:49.11,0:19:55.71,Default,,0000,0000,0000,,pretty much get a result like this. This\Ngives you a trend of around 280 gigatons
Dialogue: 0,0:19:55.71,0:20:01.68,Default,,0000,0000,0000,,per year in mass loss over the whole land\Nmass of greenland. And now gigatons is
Dialogue: 0,0:20:01.68,0:20:08.47,Default,,0000,0000,0000,,also not very useful an expression. One\Ncubic meter of water has a weight of a
Dialogue: 0,0:20:08.47,0:20:15.85,Default,,0000,0000,0000,,1000 kilos; one tonne, 1 gigatonne is\N10^9 tonne, if you are familiar with ball
Dialogue: 0,0:20:15.85,0:20:23.79,Default,,0000,0000,0000,,sports, 1 soccer field with the 140 km\Nhigh water column has the weight of
Dialogue: 0,0:20:23.79,0:20:33.49,Default,,0000,0000,0000,,1 gigatonne, or if you are not fan of sports\Nball, if you're more of a plane guy or girl
Dialogue: 0,0:20:33.49,0:20:42.69,Default,,0000,0000,0000,,the A380-800 has a maximum takeoff weight\Nof 575 tonne, so we need 1.7 mio of these
Dialogue: 0,0:20:42.69,0:20:52.95,Default,,0000,0000,0000,,airplanes for one gigatonne. So this is a more\Nbeautiful representation of the process in
Dialogue: 0,0:20:52.95,0:20:58.93,Default,,0000,0000,0000,,greenland, done by NASA JPL. If you go to\Nthe website of the GRACE project, they
Dialogue: 0,0:20:58.93,0:21:06.44,Default,,0000,0000,0000,,have a couple of these illustrations, they\Nobviously worked hard on the leakage.
Dialogue: 0,0:21:06.44,0:21:12.46,Default,,0000,0000,0000,,You can see localized where most of the\Ngravity, most of the mass is lost on the
Dialogue: 0,0:21:12.46,0:21:20.49,Default,,0000,0000,0000,,left and on the right you see accumulated\Nover time, the mass which is lost, and
Dialogue: 0,0:21:20.49,0:21:26.54,Default,,0000,0000,0000,,which trend it gives you. Also, if look\Nclosely in the center of greenland, you
Dialogue: 0,0:21:26.54,0:21:36.58,Default,,0000,0000,0000,,see black lines, these are the ice flow,\Nas determined by radar interferometry.
Dialogue: 0,0:21:36.58,0:21:43.00,Default,,0000,0000,0000,,So now pretty much know where ice is lost,\Nwhere mass is lost. This goes into the
Dialogue: 0,0:21:43.00,0:21:52.03,Default,,0000,0000,0000,,ocean, and this would be a good idea to\Nsee, to check our GRACE results, the mass
Dialogue: 0,0:21:52.03,0:21:56.80,Default,,0000,0000,0000,,we find missing on earth, so the melted\Nice, and the additional mass in the ocean,
Dialogue: 0,0:21:56.80,0:22:03.70,Default,,0000,0000,0000,,does this agree with other methods who\Ndetermine the sea level rise. One of these
Dialogue: 0,0:22:03.70,0:22:09.29,Default,,0000,0000,0000,,methods is satellite radar altimetry, that\Nstarted in the 70's, but since 1991, we
Dialogue: 0,0:22:09.29,0:22:15.27,Default,,0000,0000,0000,,have lots of dedicated satellite missions,\Nwhich only job is basically mapping the
Dialogue: 0,0:22:15.27,0:22:21.54,Default,,0000,0000,0000,,global sea surface. So, they send down a\Nradar pulse, which is reflected at the sea
Dialogue: 0,0:22:21.54,0:22:27.05,Default,,0000,0000,0000,,surface. They measure the run time and\Nthen they have a geometric representation
Dialogue: 0,0:22:27.05,0:22:35.48,Default,,0000,0000,0000,,of the global sea surface. Now, if we\Ncompare this with the mass we calculated
Dialogue: 0,0:22:35.48,0:22:41.33,Default,,0000,0000,0000,,or we got from the GRACE result, calculate\Na sea level rise rise from this additional
Dialogue: 0,0:22:41.33,0:22:46.58,Default,,0000,0000,0000,,mass in the ocean than these two systems\Nwould not add up. The geometric sea level
Dialogue: 0,0:22:46.58,0:22:51.82,Default,,0000,0000,0000,,rise is higher than just the additional\Nmass. So there is the second process which
Dialogue: 0,0:22:51.82,0:22:58.76,Default,,0000,0000,0000,,is thermal expansion of the water. If\Nwater gets warm it needs more space.
Dialogue: 0,0:22:58.76,0:23:07.16,Default,,0000,0000,0000,,In 2000 the deployment of so-called ARGO\Nfloats started. These are free-floating
Dialogue: 0,0:23:07.16,0:23:13.39,Default,,0000,0000,0000,,devices in the ocean. Currently, there are\Nover 3000 and they measure temperature and
Dialogue: 0,0:23:13.39,0:23:20.68,Default,,0000,0000,0000,,salinity between sea surface and a depth\Nof 2000 meters. These are globally
Dialogue: 0,0:23:20.68,0:23:28.87,Default,,0000,0000,0000,,distributed. So, we have at least for the\Nupper layer of the ocean, how much thermal
Dialogue: 0,0:23:28.87,0:23:36.71,Default,,0000,0000,0000,,expansion there is. And what we want to\Nsee is, do these components of additional
Dialogue: 0,0:23:36.71,0:23:41.45,Default,,0000,0000,0000,,mass in the ocean as determined by GRACE\Nand thermal expansion of the upper ocean
Dialogue: 0,0:23:41.45,0:23:47.46,Default,,0000,0000,0000,,layer come to the same result as\Ngeometrical measurements done by satellite
Dialogue: 0,0:23:47.46,0:23:52.90,Default,,0000,0000,0000,,altimetry? On the left we see an image\Ntaken from the last IPCC report on climate
Dialogue: 0,0:23:52.90,0:23:59.77,Default,,0000,0000,0000,,change from 2013. In green we see the\Nsealevel rise as measured with satellite
Dialogue: 0,0:23:59.77,0:24:06.28,Default,,0000,0000,0000,,altimetry in the time span 2005 to 2012\Nand in orange we see the combination of
Dialogue: 0,0:24:06.28,0:24:13.20,Default,,0000,0000,0000,,additional mass, as measured by GRACE, and\Nthermal extension as determined with ARGO
Dialogue: 0,0:24:13.20,0:24:21.72,Default,,0000,0000,0000,,inside the ocean. And these 2 graphs follow\Neach other quite well. On the right. We
Dialogue: 0,0:24:21.72,0:24:27.80,Default,,0000,0000,0000,,see a recent publication by Chen, Wilson\Nand Tapley, the latter one being one of
Dialogue: 0,0:24:27.80,0:24:34.46,Default,,0000,0000,0000,,the PIs of the GRACE mission, who\Naccumulated the data from 2005 to 2011. We
Dialogue: 0,0:24:34.46,0:24:41.35,Default,,0000,0000,0000,,basically come to the same conclusion. So\Nnow if you really don't want to do the
Dialogue: 0,0:24:41.35,0:24:48.87,Default,,0000,0000,0000,,math, there are online services who make\Nthe graphs for you. One of those is
Dialogue: 0,0:24:48.87,0:24:55.22,Default,,0000,0000,0000,,EGSIEM European Gravity Service for\NImproved Emergency Control. If we can
Dialogue: 0,0:24:55.22,0:25:00.66,Default,,0000,0000,0000,,measure how much water is stored in a certain\Narea, we know that this amount of water
Dialogue: 0,0:25:00.66,0:25:04.93,Default,,0000,0000,0000,,has sooner or later to be removed from\Nthis area. This can be a flood, for
Dialogue: 0,0:25:04.93,0:25:08.84,Default,,0000,0000,0000,,example, and with a mission like GRACE, we\Ncan determine how much mass, how much
Dialogue: 0,0:25:08.84,0:25:15.29,Default,,0000,0000,0000,,water is there and are the rivers large\Nenough to allow for this water to be
Dialogue: 0,0:25:15.29,0:25:22.97,Default,,0000,0000,0000,,flowing away. That was the intention\Nbehind this service. Oops, no, this is not
Dialogue: 0,0:25:22.97,0:25:39.30,Default,,0000,0000,0000,,the future. So, I wanted to do the life\Ndemo but. So, yeah, the live demo did not
Dialogue: 0,0:25:39.30,0:25:46.91,Default,,0000,0000,0000,,work as expected. So, you will be greeted\Nwith this graphic. You can plot for all
Dialogue: 0,0:25:46.91,0:25:50.65,Default,,0000,0000,0000,,areas in the world. The first thing you\Nhave to do is you change your gravity
Dialogue: 0,0:25:50.65,0:25:56.99,Default,,0000,0000,0000,,functional, we want water heights. This is\Nwhat I talked about in this talk. Then you
Dialogue: 0,0:25:56.99,0:26:03.20,Default,,0000,0000,0000,,want to look at the data set and at the\Nbottom you see a large list of GRACE
Dialogue: 0,0:26:03.20,0:26:07.19,Default,,0000,0000,0000,,gravity fields. These are different\Ngroups, I mentioned, providing these
Dialogue: 0,0:26:07.19,0:26:15.44,Default,,0000,0000,0000,,monthly solutions. And so we choose one of\Nthese groups. Then we choose an area which
Dialogue: 0,0:26:15.44,0:26:21.81,Default,,0000,0000,0000,,we are interested in. You can freely\Nchoose one area like here Finno-Scandia,
Dialogue: 0,0:26:21.81,0:26:29.07,Default,,0000,0000,0000,,or you can use pre-determined areas, for\Nexample, the Amazon river basin or Elbe
Dialogue: 0,0:26:29.07,0:26:35.57,Default,,0000,0000,0000,,river or something like that. These areas\Nall over the world and you can see the
Dialogue: 0,0:26:35.57,0:26:41.06,Default,,0000,0000,0000,,gravity change in this area. So let's look\Nhere at Finno-Scandia, and then you are
Dialogue: 0,0:26:41.06,0:26:47.25,Default,,0000,0000,0000,,greeted with a plot like this. This is\Nequivalent water height, even though this
Dialogue: 0,0:26:47.25,0:26:51.74,Default,,0000,0000,0000,,is a geophysical process. So we see here\Nthe layer of water, which would have been
Dialogue: 0,0:26:51.74,0:27:01.58,Default,,0000,0000,0000,,added to the region as selected, and we\Nsee a clear trend upward. Again, this is a
Dialogue: 0,0:27:01.58,0:27:08.75,Default,,0000,0000,0000,,geophysical process. This is not\Nadditional ice or water or anything. Can I
Dialogue: 0,0:27:08.75,0:27:20.24,Default,,0000,0000,0000,,return to my...? No, I cannot. So, yeah,\Nlive demo did not work. If you want to do
Dialogue: 0,0:27:20.24,0:27:26.71,Default,,0000,0000,0000,,this yourself. I have uploaded to the\NFahrplan all my resources, all my links.
Dialogue: 0,0:27:26.71,0:27:31.51,Default,,0000,0000,0000,,And the EGSIEM page also includes the\Ndescription of what is done in the backend
Dialogue: 0,0:27:31.51,0:27:37.65,Default,,0000,0000,0000,,and were the data comes from and what you\Ncan see in the various fields. Now I want
Dialogue: 0,0:27:37.65,0:27:42.29,Default,,0000,0000,0000,,to give a last impression on the future,\Nbecause unfortunately while I was
Dialogue: 0,0:27:42.29,0:27:46.73,Default,,0000,0000,0000,,preparing my abstract for this conference,\None of the GRACE satellites was turned off
Dialogue: 0,0:27:46.73,0:27:51.75,Default,,0000,0000,0000,,due to age. It was launched in 2002,\Nplanned for a five mission year; it
Dialogue: 0,0:27:51.75,0:27:56.97,Default,,0000,0000,0000,,survived 15 years, which is quite good,\Nbut now we have no more ranging
Dialogue: 0,0:27:56.97,0:28:01.25,Default,,0000,0000,0000,,information between these satellites. We\Nhad ranging information in micrometer
Dialogue: 0,0:28:01.25,0:28:09.05,Default,,0000,0000,0000,,accuracy, a couple of micrometer, and now\Nwe cannot rely on these information
Dialogue: 0,0:28:09.05,0:28:14.32,Default,,0000,0000,0000,,anymore. And this means mo more gravity\Nfields with high spatial resolution, and
Dialogue: 0,0:28:14.32,0:28:17.80,Default,,0000,0000,0000,,I'm not sure about the temporal\Nresolution. So, the current work which is
Dialogue: 0,0:28:17.80,0:28:23.27,Default,,0000,0000,0000,,done is taking all satellites which are in\Nthe low-enough orbits and calculate the
Dialogue: 0,0:28:23.27,0:28:26.80,Default,,0000,0000,0000,,gravity field from their positions,\Nbecause everything which is in low-earth
Dialogue: 0,0:28:26.80,0:28:32.87,Default,,0000,0000,0000,,orbit is affected by the Earth's gravity\Nfield. So, if I take the satellite orbits,
Dialogue: 0,0:28:32.87,0:28:38.69,Default,,0000,0000,0000,,look "how does this orbit change" and the\Nreason is gravity, then I can calculate
Dialogue: 0,0:28:38.69,0:28:46.11,Default,,0000,0000,0000,,the gravity field. Unfortunately, not in\Nthis higher resolution we are used to.
Dialogue: 0,0:28:46.11,0:28:50.02,Default,,0000,0000,0000,,And... But fortunately, there already is a\Nnext-generation gravity field mission on
Dialogue: 0,0:28:50.02,0:28:58.41,Default,,0000,0000,0000,,its way. It arrived last week in the US,\Nwhere it will be launched in late March,
Dialogue: 0,0:28:58.41,0:29:05.33,Default,,0000,0000,0000,,early April by SpaceX. You might look at\Nthis image and think, "I just saw this
Dialogue: 0,0:29:05.33,0:29:10.99,Default,,0000,0000,0000,,earlier" and you are quite correct: The\Nmission called "Grace Follow On" is a copy
Dialogue: 0,0:29:10.99,0:29:16.42,Default,,0000,0000,0000,,of Grace, which improved components, of\Ncourse, and now with lasers. We see not
Dialogue: 0,0:29:16.42,0:29:21.50,Default,,0000,0000,0000,,only the microwave ranging between the two\Nsatellites, but additionally a laser
Dialogue: 0,0:29:21.50,0:29:26.29,Default,,0000,0000,0000,,interferometer. So, from micrometer\Naccuracy in the distance measurements we
Dialogue: 0,0:29:26.29,0:29:33.32,Default,,0000,0000,0000,,go to nanometer accuracy, hopefully. But\Nthe main instrument will be the
Dialogue: 0,0:29:33.32,0:29:36.67,Default,,0000,0000,0000,,microwave ranging. So, in conclusion,
Dialogue: 0,0:29:36.67,0:29:42.13,Default,,0000,0000,0000,,I hope I showed you that the gravity field\Ncan show mass transport on the surface and
Dialogue: 0,0:29:42.13,0:29:47.89,Default,,0000,0000,0000,,inside the Earth; that this offers, in\Ncombination with other methods, new
Dialogue: 0,0:29:47.89,0:29:54.18,Default,,0000,0000,0000,,insights and also some kind of mutual\Nverification. If several different types
Dialogue: 0,0:29:54.18,0:29:57.96,Default,,0000,0000,0000,,of observations coming to the same\Nconclusion, none of them can be awfully
Dialogue: 0,0:29:57.96,0:30:03.70,Default,,0000,0000,0000,,wrong; and that the access to these\Nmethods are relatively easy: the data is
Dialogue: 0,0:30:03.70,0:30:09.48,Default,,0000,0000,0000,,available, all the methods are described\Nin geodesy textbooks and the technical
Dialogue: 0,0:30:09.48,0:30:14.60,Default,,0000,0000,0000,,documentation; and there are other\Napplications, other than, let's say,
Dialogue: 0,0:30:14.60,0:30:22.03,Default,,0000,0000,0000,,climate change; you can look into drought\Nand flood prediction; the El Niño–Southern
Dialogue: 0,0:30:22.03,0:30:29.99,Default,,0000,0000,0000,,Oscillation you can predict from Grace's\Ngravity field data. So, lot's of work to do.
Dialogue: 0,0:30:29.99,0:30:35.93,Default,,0000,0000,0000,,So, this would be the end for my talk.\NI thank you for your interest in the topic.
Dialogue: 0,0:30:35.93,0:30:46.78,Default,,0000,0000,0000,,{\i1}applause{\i0}
Dialogue: 0,0:30:46.78,0:30:51.25,Default,,0000,0000,0000,,Herald: Thank you, Manuel, for the talk.\NAnd I think we have time for one or two,
Dialogue: 0,0:30:51.25,0:30:57.35,Default,,0000,0000,0000,,maybe two very short questions. Please be\Nseated during the Q&A session. Is there
Dialogue: 0,0:30:57.35,0:31:02.25,Default,,0000,0000,0000,,some questions? Okay, microphone 3,\Nplease.
Dialogue: 0,0:31:02.25,0:31:05.74,Default,,0000,0000,0000,,Mic 3: Yeah, hi. {\i1}In a quiet voice{\i0}\NHi, hello? Can you hear me? {\i1}Now loud{\i0}
Dialogue: 0,0:31:05.74,0:31:07.86,Default,,0000,0000,0000,,Herald: Yeah.\NMic 3: Okay. Hey. So, my question is
Dialogue: 0,0:31:07.86,0:31:12.94,Default,,0000,0000,0000,,regarding acceleration. What's the\Ninfluence of Earth atmosphere and all the
Dialogue: 0,0:31:12.94,0:31:18.68,Default,,0000,0000,0000,,planetary bodies, like the moon, and does\Nit need to be accounted for?
Dialogue: 0,0:31:18.68,0:31:22.24,Default,,0000,0000,0000,,Manuel: The external gravity needs to be\Naccounted for, so the tidal effects of sun
Dialogue: 0,0:31:22.24,0:31:26.98,Default,,0000,0000,0000,,and moon would be one of those additional\Nmodels you put into the processing of the
Dialogue: 0,0:31:26.98,0:31:32.34,Default,,0000,0000,0000,,satellite data. The Earth's atmosphere has\Nan effect on the satellites themselves,
Dialogue: 0,0:31:32.34,0:31:37.16,Default,,0000,0000,0000,,which is measured onboard by\Naccelerometers and then reduced. And the
Dialogue: 0,0:31:37.16,0:31:43.29,Default,,0000,0000,0000,,gravitational effect of the atmosphere:\NPart of this is averaged out, because we
Dialogue: 0,0:31:43.29,0:31:48.37,Default,,0000,0000,0000,,take a month of time series, and the rest\Nare also inclu... provide as extra
Dialogue: 0,0:31:48.37,0:31:54.28,Default,,0000,0000,0000,,products; at least by the Institute for\NGeodesy in Graz. So atmosphere... the mass
Dialogue: 0,0:31:54.28,0:31:58.90,Default,,0000,0000,0000,,of the atmosphere is... has to be\Naccounted for, yes.
Dialogue: 0,0:31:58.90,0:32:04.28,Default,,0000,0000,0000,,Herald: Okay. Microphone 2 has vanished\Nall of a sudden. Then, microphone 1,
Dialogue: 0,0:32:04.28,0:32:08.70,Default,,0000,0000,0000,,please.\NMic 1: Hi. Is it possible to measure
Dialogue: 0,0:32:08.70,0:32:16.21,Default,,0000,0000,0000,,changes in the temperature of the oceans\Nor of the ocean streams, like... Can you
Dialogue: 0,0:32:16.21,0:32:25.36,Default,,0000,0000,0000,,see if El Niño is active by just measuring\Nthe gravity... change in gravity fields?
Dialogue: 0,0:32:25.36,0:32:29.100,Default,,0000,0000,0000,,Manuel: As a precursor tool, El Niño, as I\Nunderstand it... certain regions of the
Dialogue: 0,0:32:29.100,0:32:35.69,Default,,0000,0000,0000,,ocean get warmer; it's a density change;\Nand, of course, this would be measured as
Dialogue: 0,0:32:35.69,0:32:42.07,Default,,0000,0000,0000,,part of ARGO and it's also in the GRACE\Ngravity field. There are probably papers
Dialogue: 0,0:32:42.07,0:32:47.80,Default,,0000,0000,0000,,on it. So, the last... the extend of the\Nlast El Niño was predicted by GRACE. I
Dialogue: 0,0:32:47.80,0:32:51.66,Default,,0000,0000,0000,,don't know to what extend this was\Ncorrect, but...
Dialogue: 0,0:32:51.66,0:32:55.36,Default,,0000,0000,0000,,Mic 1: Okay, then.\NHerald: Good. Then, that's all the time we
Dialogue: 0,0:32:55.36,0:32:57.92,Default,,0000,0000,0000,,have. A big round of applause for Manuel\Nand his talk, please.
Dialogue: 0,0:32:57.92,0:33:00.69,Default,,0000,0000,0000,,{\i1}Applause{\i0}
Dialogue: 0,0:33:00.69,0:33:07.79,Default,,0000,0000,0000,,{\i1}34C3 Music{\i0}
Dialogue: 0,0:33:07.79,0:33:22.00,Default,,0000,0000,0000,,subtitles created by c3subtitles.de\Nin the year 2020. Join, and help us!