Publications by Year: 2011

2011
Price C, Yair Y, Mugnai A, Lagouvardos K, Llasat MC, Michaelides S, Dayan U, Dietrich S, Galanti E, Garrote L, et al. The FLASH Project : using lightning data to better understand and predict flash floods. Environmental Science & Policy [Internet]. 2011;14 :898–911. Publisher's VersionAbstract
The FLASH project was implemented from 2006 to 2010 under the EU FP6 framework. The project focused on using lightning observations to better understand and predict convective storms that result in flash floods. As part of the project 23 case studies of flash floods in the Mediterranean region were examined. For the analysis of these storms lightning data from the ZEUS network were used together with satellite derived rainfall estimates in order to understand the storm development and electrification. In addition, these case studies were simulated using mesoscale meteorological models to better understand the meteorological and synoptic conditions leading up to these intense storms. As part of this project tools for short term predictions (nowcasts) of intense convection across the Mediterranean and Europe, and long term forecasts (a few days) of the likelihood of intense convection were developed. The project also focused on educational outreach through our website http:// flashproject.org supplying real time lightning observations, real time experimental now- casts, forecasts and educational materials. While flash floods and intense thunderstorms cannot be prevented as the climate changes, long-range regional lightning networks can supply valuable data, in real time, for warning end-users and stakeholders of imminent intense rainfall and possible flash floods.
Yakir H, Morin E. Hydrologic response of a semi-arid watershed to spatial and temporal characteristics of convective rain cells. Hydrology and Earth System Sciences [Internet]. 2011;15 :393–404. Publisher's VersionAbstract
Antibodies directed to citrullinated proteins (anti-cyclic citrullinated peptide) are highly specific for rheumatoid arthritis (RA). Recent data suggest that the antibodies may be involved in the disease process of RA and that several RA-associated genetic factors might be functionally linked to RA via modulation of the production of anti-cyclic citrullinated peptide antibodies or citrullinated antigens.
Sheffer NA, Cohen M, Morin E, Grodek T, Gimburg A, Magal E, Gvirtzman H, Nied M, Isele D, Frumkin A. Integrated cave drip monitoring for epikarst recharge estimation in a dry Mediterranean area, Sif Cave, Israel. Hydrological Processes [Internet]. 2011;25 :2837–2845. Publisher's VersionAbstract
Abstract Understanding recharge mechanisms and controls in karst regions is extremely important for managing water resources because of the dynamic nature of the system. The objective of this study was to evaluate water percolation through epikarst by monitoring water flow into a cave and conducting artificial irrigation and tracer experiments, at Sif Cave in Wadi Sussi, Israel from 2005 through 2007. The research is based on continuous high-resolution direct measurements of both rainfall and water percolation in the cave chamber collected by three large PVC sheets which integrate drips from three different areas (17, 46, and 52 m2). Barrels equipped with pressure transducers record drip rate and volume for each of the three areas. The combined measured rainfall and cave data enables estimation of recharge into the epikarst and to better understand the relationship of rainfall-recharge. Three distinct types of flow regimes were identified: (1) ‘Quick flow' through preferential flow paths (large fractures and conduits); (2) ‘Intermediate flow' through a secondary crack system; and (3) ‘Slow flow' through the matrix. A threshold of ∼100 mm of rain at the beginning of the rainy season is required to increase soil water content allowing later rainfall events to percolate deeper through the soil and to initiate dripping in the cave. During winter, as the soil water content rises, the lag time between a rain event and cave drip response decreases. Annual recharge (140–160 mm in different areas in the cave) measured represents 30–35% of annual rainfall (460 mm). Copyright © 2011 John Wiley & Sons, Ltd.
Morin E. To know what we cannot know: Global mapping of minimal detectable absolute trends in annual precipitation. Water Resources Research [Internet]. 2011;47 :1–9. Publisher's VersionAbstract
Fresh water resources, human societies, and ecosystems are expected to be strongly impacted by climate change, with precipitation trends being one of the most important elements that will be closely monitored. However, the natural variability of precipitation data can often mask existing trends such that the results appear as statistically insignificant. Information on the limitations of trend detection is important for risk assessment and for decision making related to adaption strategies under inherent uncertainties. This paper reports on an effort to quantify and map minimal detectable absolute trends in annual precipitation data series on a global scale. Monte Carlo simulations were conducted to generate realizations of trended precipitation data for different precipitation means and coefficients of variance, and the MannKendall method was applied for detecting the trend significance. Global Precipitation Climatology Centre (GPCC) VASClimO data was used to compute the mean and coefficient of variance of annual precipitation over land and to map minimal detectable absolute trends. It was found that relatively high magnitude trends (positive or negative) have a low chance of being detected as a result of high natural variance of the precipitation data. The largest undetectable trends were found for the tropics. Arid and semiarid regions also present high relative values in terms of percent change from the mean annual precipitation. Although the present analysis is based on several simplified assumptions, the goal was to point out an inherent problem of potentially undetectable high absolute trends that must be considered in analyzing precipitation data series and assessing risks in adaption strategies to climate change.
Price C, Yair Y, Mugnai A, Lagouvardos K, Llasat MC, Michaelides S, Dayan U, Dietrich S, Di Paola FD, Galanti E, et al. Using Lightning Data to Better Understand and Predict Flash Floods in the Mediterranean. Surveys in Geophysics [Internet]. 2011;32 :733–751. Publisher's VersionAbstract
The FLASH project was implemented from 2006 to 2010 under the EU FP6 framework. The project focused on using lightning observations to better understand and predict convective storms that result in flash floods. As part of the project 23 case studies of flash floods in the Mediterranean region were examined. For the analysis of these storms lightning data from the ZEUS network were used together with satellite derived rainfall estimates in order to understand the storm development and electrification. In addition, these case studies were simulated using mesoscale meteorological models to better understand the meteorological and synoptic conditions leading up to these intense storms. As part of this project tools for short term predictions (nowcasts) of intense convection across the Mediterranean and Europe, and long term forecasts (a few days) of the likelihood of intense convection were developed. The project also focused on educational outreach through our website http://flashproject.org supplying real time lightning observations, real time experimental nowcasts, forecasts and educational materials. While flash floods and intense thunderstorms cannot be prevented as the climate changes, long-range regional lightning networks can supply valuable data, in real time, for warning end-users and stakeholders of imminent intense rainfall and possible flash floods. ?? 2011 Elsevier Ltd.
Gabella M, Morin E, Notarpietro R. Using TRMM spaceborne radar as a reference for compensating ground-based radar range degradation: Methodology verification based on rain gauges in Israel. Journal of Geophysical Research [Internet]. 2011;116 :D02114. Publisher's VersionAbstract
While intense scientific efforts have focused on radar precipitation estimation in temperate climatic regimes, relatively few studies have examined dry climatic regions. This paper examines rain depth estimation for a 19 day rainfall period in Israel, where the gauge spatial distribution is particularly nonhomogeneous. This fact exacerbates the main drawback of rain gauge observations, which is undersampling. Meteorological ground‐ based radar (GR) can supplement the desired information on precipitation distribution. However, especially in a complex orographic region, radar scientists are faced with beam broadening with distance, nonhomogeneous beam filling, and partial‐beam occultation, together with changes in the vertical reflectivity profile. This paper presents an improvement of GR precipitation estimates thanks to a range adjustment based on spaceborne meteorological radar. In the past, the Tropical Rainfall Measuring Mission (TRMM) satellite radar was used for checking the GR mean field bias around the world. To our knowledge, however, it is the first time that GR‐derived cumulative rainfall amounts show a better agreement with gauges, thanks to the mean field bias and range‐ dependent compensation derived using the well‐calibrated Ku band TRMM radar as a reference. The average bias improves from +1.0 dB to −0.3 dB; more interesting and difficult to obtain is a reduction of the dispersion of the error. Using TRMM‐based range compensation, the scatter decreases from 2.21 dB to 1.93 dB. We conclude that it is well worth trying to compensate for the GR range degradation.
Shohami D, Dayan U, Morin E. Warming and drying of the eastern Mediterranean: Additional evidence from trend analysis. Journal of Geophysical Research Atmospheres [Internet]. 2011;116 :1–12. Publisher's VersionAbstract
The climate of the eastern Mediterranean (EM), at the transition zone between the Mediterranean climate and the semi‐arid/arid climate, has been studied for a 39‐year period to determine whether climate changes have taken place. A thorough trend analysis using the nonparametric Mann‐Kendall test with Sen's slope estimator has been applied to ground station measurements, atmospheric reanalysis data, synoptic classification data and global data sets for the years 1964–2003. In addition, changes in atmospheric regional patterns between the first and last twenty years were determined by visual comparisons of their composite mean. The main findings of the analysis are: 1) changes of atmospheric conditions during summer and the transitional seasons (mainly autumn) support a warmer climate over the EM and this change is already statistically evident in surface temperatures having exhibited positive trends of 0.2–1°C/decade; 2) changes of atmospheric conditions during winter and the transitional seasons support drier conditions due to reduction in cyclogenesis and specific humidity over the EM, but this change is not yet statistically evident in surface station rain data, presumably because of the high natural precipitation variance masking such a change. The overall conclusion of this study is that the EM region is under climate change leading to warmer and drier conditions.