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The Caucasus Region has been affected by an increasing number of heat waves during the last decades, which have had serious impacts on human health, agriculture and natural ecosystems. A dataset of 22 homogenized, daily maximum (Tmax) and minimum (Tmin) air temperature series is developed to quantify climatology and summer heat wave changes for Georgia and Tbilisi station between 1961 and 2010 using the extreme heat factor (EHF) as heat wave index. The EHF is studied with respect to eight heat wave aspects: event number, duration, participating heat wave days, peak and mean magnitude, number of heat wave days, severe and extreme heat wave days. A severity threshold for each station was determined by the climatological distribution of heat wave intensity. Moreover, heat wave series of two indices focusing on the 90th percentile of daily minimum temperature (CTN90p) and the 90th percentile of daily maximum temperature (CTX90p) were compared. The spatial distribution of heat wave characteristics over Georgia showed a concentration of high heat wave amplitudes and mean magnitudes in the Southwest. The longest and most frequently occurring heat wave events were observed in the Southeast of Georgia. Most severe heat wave events were found in both regions. Regarding the monthly distribution of heat waves, the largest proportion of severe events and highest intensities are measured during May. Trends for all Georgia-averaged heat wave aspects demonstrate significant increases in the number, intensity and duration of low- and high-intensity heat waves. However, for the heat wave mean magnitude no change was observed. Heat wave trend magnitudes for Tbilisi mainly exceed the Georgia-averages and its surrounding stations, implying urban heat island (UHI) effects and synergistic interactions between heat waves and UHIs. Comparing heat wave aspects for CTN90p and CTX90p, all trend magnitudes for CTN90p were larger, while the correlation between the annual time-series was very high among all heat wave indices analyzed. This finding reflects the importance of integrating the most suitable heat wave index into a sector-specific impact analysis.
Ina Keggenhoff; Mariam Elizbarashvili; Lorenz King. Heat Wave Events over Georgia Since 1961: Climatology, Changes and Severity. Climate 2015, 3, 308 -328.
AMA StyleIna Keggenhoff, Mariam Elizbarashvili, Lorenz King. Heat Wave Events over Georgia Since 1961: Climatology, Changes and Severity. Climate. 2015; 3 (2):308-328.
Chicago/Turabian StyleIna Keggenhoff; Mariam Elizbarashvili; Lorenz King. 2015. "Heat Wave Events over Georgia Since 1961: Climatology, Changes and Severity." Climate 3, no. 2: 308-328.
Sixteen temperature minimum and maximum series are used to quantify annual and seasonal changes in temperature means and extremes over Georgia (Southern Caucasus) during the period 1961 and 2010. Along with trends in mean minimum and maximum temperature, eight indices are selected from the list of climate extreme indices as defined by the Expert Team on Climate Change Detection and Indices (ETCCDI) of the Commission for Climatology of the World Meteorological Organization (WMO), for studying trends in temperature extremes. Between the analysis periods 1961–2010, 1971–2010 and 1981–2010 pronounced warming trends are determined for all Georgia-averaged trends in temperature means and extremes, while all magnitudes of trends increase towards the most recent period. During 1981 and 2010, significant warming trends for annual minimum and maximum temperature at a rate of 0.39 °C (0.47 °C) days/decade and particularly for the warm temperature extremes, summer days, warm days and nights and the warm spell duration index are evident, whereas warm extremes show larger trends than cold extremes. The most pronounced trends are determined for summer days 6.2 days/decade, while the warm spell duration index indicates an increase in the occurrence of warm spells by 5.4 days/decade during 1981 and 2010. In the comparison of seasonal changes in temperature means and extremes, the largest magnitudes of warming trends can be observed for temperature maximum in summer and temperature minimum in fall. Between 1981 and 2010, summer maximum temperature shows a significant warming at a rate of 0.84 °C/decade, increasing almost twice as fast as its annual trend (0.47 °C/decade). The Georgia-averaged trends for temperature minimum in fall increase by 0.59 °C/decade. Strongest significant trends in temperature extremes are identified during 1981 and 2010 for warm nights (4.6 days/decade) in summer and fall as well as for warm days (5.6 days/decade) in summer. Analyses demonstrate that there have been increasing warming trends since the 1960s, particularly for warm extremes during summer and fall season, accompanied by a constant warming of temperature means in Georgia.
I. Keggenhoff; M. Elizbarashvili; L. King. Recent changes in Georgia׳s temperature means and extremes: Annual and seasonal trends between 1961 and 2010. Weather and Climate Extremes 2015, 8, 34 -45.
AMA StyleI. Keggenhoff, M. Elizbarashvili, L. King. Recent changes in Georgia׳s temperature means and extremes: Annual and seasonal trends between 1961 and 2010. Weather and Climate Extremes. 2015; 8 ():34-45.
Chicago/Turabian StyleI. Keggenhoff; M. Elizbarashvili; L. King. 2015. "Recent changes in Georgia׳s temperature means and extremes: Annual and seasonal trends between 1961 and 2010." Weather and Climate Extremes 8, no. : 34-45.
Annual changes to climate extreme indices in Georgia (Southern Caucasus) from 1971 to 2010 are studied using homogenized daily minimum and maximum temperature and precipitation series. Fourteen extreme temperature and 11 extreme precipitation indices are selected from the list of core climate extreme indices recommended by the World Meteorological Organization – Commission for Climatology (WMO-CCL) and the research project on Climate Variability and Predictability (CLIVAR) of the World Climate Research Programme (WCRP). Trends in the extreme indices are studied for 10 minimum and 11 maximum temperature and 24 precipitation series for the period 1971–2010. Between 1971 and 2010 most of the temperature extremes show significant warming trends. In 2010 there are 13.3 fewer frost days than in 1971. Within the same time frame there are 13.6 more summer days and 7.0 more tropical nights. A large number of stations show significant warming trends for monthly minimum and maximum temperature as well as for cold and warm days and nights throughout the study area, whereas warm extremes and night-time based temperature indices show greater trends than cold extremes and daytime indices. Additionally, the warm spell duration indicator indicates a significant increase in the frequency of warm spells between 1971 and 2010. Cold spells show an insignificant increase with low spatial coherence. Maximum 1-day and 5-day precipitation, the number of very heavy precipitation days, very wet and extremely wet days as well as the simple daily intensity index all show an increase in Georgia, although all trends manifest a low spatial coherence. The contribution of very heavy and extremely heavy precipitation to total precipitation increased between 1971 and 2010, whereas the number of wet days decreases.
I. Keggenhoff; M. Elizbarashvili; A. Amiri-Farahani; L. King. Trends in daily temperature and precipitation extremes over Georgia, 1971–2010. Weather and Climate Extremes 2014, 4, 75 -85.
AMA StyleI. Keggenhoff, M. Elizbarashvili, A. Amiri-Farahani, L. King. Trends in daily temperature and precipitation extremes over Georgia, 1971–2010. Weather and Climate Extremes. 2014; 4 ():75-85.
Chicago/Turabian StyleI. Keggenhoff; M. Elizbarashvili; A. Amiri-Farahani; L. King. 2014. "Trends in daily temperature and precipitation extremes over Georgia, 1971–2010." Weather and Climate Extremes 4, no. : 75-85.
Semarang is one of the biggest cities in Indonesia and nowadays suffering from extended land subsidence, which is due to groundwater withdrawal, to natural consolidation of alluvium soil and to the load of constructions. Land subsidence causes damages to infrastructure, buildings, and results in tides moving into low-lying areas. Up to the present, there has been no comprehensive information about the land subsidence and its monitoring in Semarang. This paper examines digital elevation model (DEM) and benchmark data in Geographic Information System (GIS) raster operation for the monitoring of the land subsidence in Semarang. This method will predict and quantify the extent of subsidence in future years. The future land subsidence prediction is generated from the expected future DEM in GIS environment using ILWIS package. The procedure is useful especially in areas with scarce data. The resulting maps designate the area of land subsidence that increases rapidly and it is predicted that in 2020, an area of 27.5 ha will be situated 1.5–2.0 m below sea level. This calculation is based on the assumption that the rate of land subsidence is linear and no action is taken to protect the area from subsidence.
Muh Aris Marfai; Lorenz King. Monitoring land subsidence in Semarang, Indonesia. Environmental Earth Sciences 2007, 53, 651 -659.
AMA StyleMuh Aris Marfai, Lorenz King. Monitoring land subsidence in Semarang, Indonesia. Environmental Earth Sciences. 2007; 53 (3):651-659.
Chicago/Turabian StyleMuh Aris Marfai; Lorenz King. 2007. "Monitoring land subsidence in Semarang, Indonesia." Environmental Earth Sciences 53, no. 3: 651-659.
Permafrost has been identified as one of six cryospheric indicators for global climate change within the monitoring framework of the World Meteorological Organisations Global Climate Observing System (GCOS). Vast areas of the Tibetan Plateau are underlain by predominantly warm permafrost, which is actually degrading due to a rise in mean surface temperatures caused by global warming. Because of the important role of surface temperature variations on the Tibetan Plateau for the onset and characteristic of the monsoon circulation over south-east Asia, it becomes evident that a consistent climate monitoring strategy in the region is urgently required. As permafrost reacts sensitively to changes in surface temperature, it is considered as a key variable in such a regional climate monitoring system. The Permafrost and Climate in Europe (PACE) project developed standardised methods for the monitoring of permafrost temperatures and distribution in European mountains, which are in good agreement with the site selection criteria of the GCOS Global Terrestrial Network-Permafrost (GTN-P). Following the PACE monitoring strategy, an international project “Permafrost and Climate in Tibet” is proposed.
L. King; T. Herz; H. Hartmann; R. Hof; T. Jiang; C. Ke; Z. Wei; J. Liu; C. Yi. The PACE monitoring strategy: A concept for permafrost research in Qinghai–Tibet. Quaternary International 2006, 154-155, 149 -157.
AMA StyleL. King, T. Herz, H. Hartmann, R. Hof, T. Jiang, C. Ke, Z. Wei, J. Liu, C. Yi. The PACE monitoring strategy: A concept for permafrost research in Qinghai–Tibet. Quaternary International. 2006; 154-155 ():149-157.
Chicago/Turabian StyleL. King; T. Herz; H. Hartmann; R. Hof; T. Jiang; C. Ke; Z. Wei; J. Liu; C. Yi. 2006. "The PACE monitoring strategy: A concept for permafrost research in Qinghai–Tibet." Quaternary International 154-155, no. : 149-157.