EGSIEM is pleased to announce its latest publication:
AIUB-RL02: an improved time series of monthly gravity fields from GRACE data, which has been written by U. Meyer, A. Jäggi, Y. Jean, & G. Beutler of the Astronomical Institute, University of Bern and is published in the Geophysical Journal International
In figure 1 the typical rapid mapping workflow of ZKI during crisis situations is illustrated. After the disaster the initial mobilisation phase follows. Civil protection offices, situation centers or decision makers receive information regarding the occurrence of a crisis event and trigger ZKI activities either directly or indirectly through authorised users.
Figure 1: Rapid Mapping Workflow - from crisis events to the delivery of information
The EGSIEM project has the potential to make a real difference to people in europe and around the world, but you can’t achieve anything worthwhile without generating a certain amount of paperwork.
Colleagues at project partners Géode et Cie have produced a helpful video which accompanies the EGSIEM Plotter
Scientists from the EGSIEM consortium visited the worlds largest gathering of Earth and space scientists in San Francisco, USA, you can view the presentations given here
Here you can view our fourth Newsletter, published in January 2016, simply click on the image or links below.
We would love to hear any feedback you might have on the content, so please do contact us if you have any comments!
In spaceborne gravimetry we usually have a very high number of both observations and the unknowns we want to derive from these observations.
The GRACE satellites have now been in orbit for over 13 years. This means that we have about 87 million intersatellite range observations, 43 million GPS positions for each satellite, as well as accelerometer and attitude measurements. Considering global daily gravity field solutions we estimate about 2600 parameters per day, resulting in 13 million parameters for the whole time series. Processing such a huge amount of data in a sensible time frame (read: days) is quite challenging from two perspectives:
Snow and glacier melt from the high mountain ranges is essential for water supply of the Central Asian countries. While glaciers can store water as glacier ice over decades, snow cover is a seasonal water storage that transfers winter precipitation into the summer months by releasing it as melt water. This is particularly important in seasonally dry regions since local water supply is then dependent on meltwater availability. By assessing the mass changes of glaciers and of the seasonal snow cover at the regional scale, GRACE may provide useful complementary information for assessing the water resources in Central Asia.
Central Asian mountain ridges north of Issyk Kul. Photo: Andreas Güntner, GFZ Potsdam.
On the relative weighting between GPS and KBR measurements in GRACE data processing
The GRACE GPS data provides, besides absolute satellite positions, information on the gravity field that is lacking in the K-band ranging measurements (KBR; microwave satellite-to-satellite ranging). The sectorial coefficients, on the diagonal of the triangle of spherical harmonics coefficients, are badly sensed by the KBR instrument due to the polar orbit. The 3-D information, although not as accurate, provided by the GPS data complements the precise North-South information provided by the KBR measurements. The coefficients that are modified by the contribution of the GPS data are displayed in the plot below. They are mostly in the low degrees of the gravity field, corresponding to the longest spatial wavelengths, and along the diagonal (i.e. sectorial coefficients). The amplitudes of the coefficients are expressed in cm of equivalent water height.
The EGSIEM Project has been featured in the Geodesy section of the European Science Union website, to read more please click on the following;
or go to http://blogs.egu.eu/divisions/g/
Just returning from this year’s AGU Fall Meeting in San Francisco - a week full of intensive conversations with lots of fellow scientists.
The conferring of degrees by institutions around the world represents a cornucopia of rules, traditions and regulations. Recently, I was invited (along with Frank Flechtner from our partner GFZ) to Delft University of Technology to participate on an examination committee for a “Waarde promovendus” (or ‘worthy doctoral candidate’) who would be assisted by up to two “paranymphs” (supporters). There is something a little ‘Harry Potter’ about many of these ceremonies and Delft is no exception as you can see from the picture below.
