Monthly Webinars
The monthly webinars are a virtual seminar series in which speakers from the HEPEX community are presenting their current research. A seminar is given every month and each seminar has a maximum length of 1 hour. Details of the talks are announced on the HEPEX linkedIn pages and on this HEPEX blog.
The aim of this seminar series are: (1) to improve communication in between meetings; (2) to reach colleagues who cannot attend meeting; (3) to provide a discussion forum for topical HEPEX research; and (4) stimulate collaboration on HEPEX topics.
Anybody can participate and volunteers are very welcome. Please email Fredrik Wetterhall to coordinate time slots etc.
April 19, 2013 at 15:56
Today’s HEPEX-WEBEX is given by Will Pozzi who is talking about droughts.
Abstract:
That the monitoring technology must match the space and time scales of the phenomenon being observed is a truism in physics. As early as the late 1990s, Byun and Wilhite (1999) made the observation, that part of the difficulty of drought indices, including Standardized Precipitation Index (SPI), was its failure to take into account aggravating effects of evapotranspiration and runoff, compounded by its limited usefulness in monitoring ongoing drought, since the real-time precipitation data were entirely limited to monthly time steps. Twenty years later, this conclusion has been re-iterated again with respect to the Horn of Africa drought: ” At the same time, adequate emergency intervention is also limited by inadequate access to reliable, spatially distributed drought monitoring information available in near real-time.(Anderson et al 2012)” Benjamin Lloyd-Hughes has made a laudable effort developing the first methodology, publicly available, to monitor drought globally, using a uniform data source, the Global Precipitation Climatology Centre (GPCC) global precipitation data; however, this data source, as before, is limited to a monthly time step.
Mark Svoboda of the USA Drought Monitor coined the term “flash drought,” in analogy to flash flood, to describe events observed in August-September 2000, when intense heat waves, accompanied by windy conditions, resulted in high evapotranspiration rates, draining off soil moisture, worsening drought over very short time scales (and increasing the risk of wildfires)–analogous to conditions experienced over the Russian Federation in 2010. Such “flash droughts” do not correspond to the classical, “slow onset” stereotype of droughts, and they require a rapid response monitor for their identification.
Besides the need to providing rapid response, drought monitoring technologies capable of monitoring over short time scales, there is a need to monitor drought over very large spatial scales. Results from dendrochronology studies suggest that drought conditions prior to the instrumental era may have been more extreme, both as “megadroughts,” extending over more than a decade, and “superdroughts,” extending over an entire continental domain, in analogy to a “superstorm” which extends over an entire continental or oceanic domain.
Besides SPI, several new remote sensing-based drought monitoring technologies are being rolled out through the USA National Integrated Drought Information System (NIDIS), the North America Drought Briefing, and the USA Drought Monitor. Each of these technologies can also be extended to the global domain, and these new technologies operate at weekly time steps. NOAA NESDIS uses Vegetation Health Index (VHI) combines Vegetative Index (such as NDVI) with temperature inferred from an instantaneous satellite overpass, and has been extended from vegetation health to a drought measure. The VHI technique may possibly give spurious results in cold regions, such as northern Eurasia or Canada.
Two additional candidate global drought measures are based upon evapotranspiration; both of these latter methodologies employ reanalysis fields to monitor meteorological conditions (winds, etc) to accompany the radiation measurements taken from satellites, combined with vegetation stand density from MODIS (to separate soil and vegetation cover within a pixel). One of these methodologies uses instantaneous land surface temperature (from MODIS), while the other attempts to increase the accuracy of surface temperature measurement by using geostationary satellite coverage for taking at least two temperature observations during the morning temperature rise. There is now the capability to monitor, to some extent, groundwater, soil moisture, and snow pack (water storage), along with precipitation inputs (water supply) to begin providing global coverage of the water cycle (and the propagation of drought within it).
Global patterns of drought are surveyed, along with the abilities of these drought indicators to monitor drought events on different time scales. The ability of these new remote sensing-based drought monitoring technologies to provide reliable monitoring in African and Central Asia areas of sparse ground-based precipitation coverage is the next question to be assessed. These steps will improve drought forecasting ability.
April 19, 2013 at 16:14
Special seminar on Land surface processes
Friday, April 26, 2013 9:15 am
GMT Summer Time (London, GMT+01:00)
Program: EC training programme
Duration: 2 hours
Description: Land surface processes
Physical mechanisms regulating the interaction of the land surface and the atmosphere are presented and components of the land surface parametrization are detailed; including the representation of the surface energy and water budgets (soil moisture in particular) and parameterization of cold regions, where snow and soil water phase changes dominate. The surface carbon budget is presented, as a physical mechanism to obtain realistic vegetation phenology in the model.
Finally, land surface assimilation is presented, as a way to control long time scales in the land; data assimilation methods are presented, with their advantages and drawbacks.
About the lecturer
Gianpaolo Balsamo (PhD) is a land surface modeller and land data assimilation expert in Numerical Weather Prediction and Earth System Modelling contexts. He is responsible for the land surface model development at the European Centre for Medium-range Weather Forecast (ECMWF, UK) where he is currently employed at senior scientist. He is PI for the IMAGINE FP7 project at ECMWF and co-I for the land surface component of SPECS project at ECMWF. He is member of the Global Land Atmosphere System Study (GLASS-GEWEX) panel on data assimilation and member of Land Expert Team of the Short-Range Numerical Weather Prediction (SRNWP). His service to the science community includes project reviews (eg. for CNRS-France, CNR-Italy, NERC-UK, NSERC-Canada), and publication reviews for a number of specialized international journals (eg GRL, GMD, HESS, JGR, JHM, JoC, TELLUS).
May 13, 2013 at 15:14
4th HEPEX webinar: Extreme flash floods: the Black Swan events and the changing paradigm for flash flood risk management
Thursday 30 May at 10:00 CET it is time for the next HEPEX webinar, this time by Prof. Marco Borga from University of Padova, Italy. For more registration and more information, please follow the link: https://ecmwf.webex.com/ecmwf/onstage/g.php?t=a&d=951253876
May 29, 2013 at 17:14
Dear all,
Thye link to the webinar was previously not the correct one, the link above is now the correct one for registration. Sorry for the inconvinience!
May 30, 2013 at 09:09
Dear all, due to technical problems we have to postpone today’s 4th HEPEX webinar. New information will follow shortly.
May 31, 2013 at 17:35
Dear all,
The new time for the 4th HEPEX webinar “Extreme flash floods: the Black Swan events and the changing paradigm for flash flood risk management” is 10 June 10:00 (am) CET. Please register on the following link to not miss it:
https://ecmwf.webex.com/ecmwf/onstage/g.php?t=a&d=951253876