scholarly journals Spatio-temporal trends in the hydroclimate of Turkey for the last decades based on two reanalysis datasets

2016 ◽  
Author(s):  
Mustafa Gokmen
Keyword(s):  
Snow Water Equivalent ◽  
Water Cycle ◽  
Eastern Mediterranean ◽  
Regional Scale ◽  
Temporal Trends ◽  
Aegean Sea ◽  
Rain Gauge ◽  
Observation Data ◽  
Spatiotemporal Trends ◽  
Snow Water

Abstract. We present a regional assessment of the spatiotemporal trends in several hydro-climate variables from 1979 to 2010 in Turkey, one of the vulnerable countries of the Eastern Mediterranean to climate change, using the two reanalysis products of ECMWF: ERA-Interim and ERA-Interim/Land, namely. The trend analysis revealed that an average warming of 1.26 °C occurred in Turkey from 1979 to 2010, with high confidence intervals (95 to 99 %) mostly. Geographically, the largest warming (up to 1.8 °C) occurred in the Western coastal areas next to Aegean Sea and in the South-East regions. The increasing trend of air temperature was confirmed by the comparisons with the measurements from several meteorological stations. With respect to the regional trends in hydrological variables, ERA-Interim and ERA-Interim/Land revealed quite different pictures: the ERA-Interim dataset indicated that there have been significant decreasing trends of precipitation, snow water equivalent and runoff in some parts of inner/South-eastern Anatolia (up to 250 mm decrease totally in the upstream of Euphrates, Kizilirmak and Seyhan basins), while ERA-Interim/Land showed none or minor trends in the same areas. Comparison of the precipitation trends by the two datasets with some rain gauge data distributed over Turkey revealed that none of the products is consistently closer to the observations. Based on the trend assessment of the hydrological trends by the two datasets and the comparisons with the observation data and other trend studies in the study area we can conclude that, except for some evapotranspiration trends over Mediterranean and Black Sea, there have not been clear and considerable trends of precipitation, snow water equivalent and runoff quantities over Turkey from 1979 to 2010, despite the considerable warming for the same period throughout the country. In this respect, we can suggest that, the impacts of global warming on the water cycle are rather unpredictable especially at regional scale.

scholarly journals Spatio-temporal trends in the hydroclimate of Turkey for the last decades based on two reanalysis datasets

2016 ◽  
Vol 20 (9) ◽  
pp. 3777-3788 ◽  
Author(s):  
Mustafa Gokmen
Keyword(s):  
Snow Water Equivalent ◽  
Water Cycle ◽  
Eastern Mediterranean ◽  
Regional Scale ◽  
Temporal Trends ◽  
Aegean Sea ◽  
In Situ Data ◽  
Spatiotemporal Trends ◽  
Spatio Temporal

Abstract. We present a regional assessment of the spatiotemporal trends in several hydro-climate variables from 1979 to 2010 in Turkey, one of the countries of the eastern Mediterranean vulnerable to climate change, using the two reanalysis products of the ECMWF: ERA-Interim and ERA-Interim/Land. The trend analysis revealed that an average warming of 1.26 °C [0.8–1.8] occurred in Turkey from 1979 to 2010, with high confidence intervals (95–99 %, mostly). Geographically, the largest warming (up to 1.8 °C) occurred in the western coastal areas next to the Aegean Sea and in the southeastern regions. The air temperature trends were generally confirmed by the in situ data from about 100 weather stations around the country, though in situ data indicated slightly higher trends ranging from 1 to 2.5°. With respect to the regional trends in hydrological variables, ERA-Interim and ERA-Interim/Land revealed quite different pictures: the ERA-Interim dataset indicated that there have been significant decreasing trends of precipitation, snow water equivalent (SWE) and runoff in some parts of inner/southeastern Anatolia (a total decrease of up to 250 mm in the upstream of the Euphrates, Kizilirmak and Seyhan basins), while ERA-Interim/Land showed no or minor trends in the same areas. Based on the extensive comparisons with precipitation and SWE gauge data, we can suggest that the hydrological trends shown by the ERA-Interim/Land dataset, which is said to be a model improvement, are relatively closer to the observations. From the hydrological trends revealed by the ERA-Interim/Land dataset, we can conclude that, despite the strong warming trends over Turkey from 1979 to 2010, there have been no widespread and strong hydrological trends for the same period throughout the country. In this regard, we can suggest that the impacts of global warming on the water cycle are not straightforward, especially at the regional scale, and future climate simulations indicating considerable reductions in precipitation along with the significant increases in temperatures throughout the Mediterranean and the Middle East by the end of the twenty-first century need to be dealt with cautiously.

scholarly journals Simulation of Snow Water Equivalent (SWE) Using Thermodynamic Snow Models in Québec, Canada

2009 ◽  
Vol 10 (6) ◽  
pp. 1447-1463 ◽  
Author(s):  
A. Langlois ◽  
J. Kohn ◽  
A. Royer ◽  
P. Cliche ◽  
L. Brucker ◽  
...  
Keyword(s):  
Snow Cover ◽  
Snow Water Equivalent ◽  
Meteorological Data ◽  
Regional Scale ◽  
Correlation Coefficients ◽  
Reanalysis Data ◽  
Regional Variability ◽  
The North ◽  
Snow Water ◽  
Regional Reanalysis

Abstract Snow cover plays a key role in the climate system by influencing the transfer of energy and mass between the soil and the atmosphere. In particular, snow water equivalent (SWE) is of primary importance for climatological and hydrological processes and is a good indicator of climate variability and change. Efforts to quantify SWE over land from spaceborne passive microwave measurements have been conducted since the 1980s, but a more suitable method has yet to be developed for hemispheric-scale studies. Tools such as snow thermodynamic models allow for a better understanding of the snow cover and can potentially significantly improve existing snow products at the regional scale. In this study, the use of three snow models [SNOWPACK, CROCUS, and Snow Thermal Model (SNTHERM)] driven by local and reanalysis meteorological data for the simulation of SWE is investigated temporally through three winter seasons and spatially over intensively sampled sites across northern Québec. Results show that the SWE simulations are in agreement with ground measurements through three complete winter seasons (2004/05, 2005/06, and 2007/08) in southern Québec, with higher error for 2007/08. The correlation coefficients between measured and predicted SWE values ranged between 0.72 and 0.99 for the three models and three seasons evaluated in southern Québec. In subarctic regions, predicted SWE driven with the North American Regional Reanalysis (NARR) data fall within the range of measured regional variability. NARR data allow snow models to be used regionally, and this paper represents a first step for the regionalization of thermodynamic multilayered snow models driven by reanalysis data for improved global SWE evolution retrievals.

scholarly journals Climate change impacts on maritime mountain snowpack in the Oregon Cascades

2012 ◽  
Vol 9 (11) ◽  
pp. 13037-13081 ◽  
Author(s):  
E. Sproles ◽  
A. Nolin ◽  
K. Rittger ◽  
T. Painter
Keyword(s):  
Climate Change ◽  
Snow Water Equivalent ◽  
Regional Scale ◽  
Climate Change Impacts ◽  
Snow Accumulation ◽  
Distributed Model ◽  
Modeling Framework ◽  
Highly Sensitive ◽  
Snow Cover Extent ◽  
Snow Water

Abstract. Globally maritime snow comprises 10% of seasonal snow and is considered highly sensitive to changes in temperature. This study investigates the effect of climate change on maritime mountain snowpack in the McKenzie River Basin (MRB) in the Cascades Mountains of Oregon, USA. Melt water from the MRB's snowpack provides critical water supply for agriculture, ecosystems, and municipalities throughout the region especially in summer when water demand is high. Because maritime snow commonly falls at temperatures close to 0 °C, accumulation of snow versus rainfall is highly sensitive to temperature increases. Analyses of current climate and projected climate change impacts show rising temperatures in the region. To better understand the sensitivity of snow accumulation to increased temperatures, we modeled the spatial distribution of snow water equivalent (SWE) in the MRB for the period of 1989–2009 with the SnowModel spatially distributed model. Simulations were evaluated using point-based measurements of SWE, precipitation, and temperature that showed Nash-Sutcliffe Efficiency coefficients of 0.83, 0.97, and 0.80, respectively. Spatial accuracy was shown to be 82% using snow cover extent from the Landsat Thematic Mapper. The validated model was used to evaluate the sensitivity of snowpack to projected temperature increases and variability in precipitation, and how changes were expressed in the spatial and temporal distribution of SWE. Results show that a 2 °C increase in temperature would shift peak snowpack 12 days earlier and decrease basin-wide volumetric snow water storage by 56%. Snowpack between the elevations of 1000 and 1800 m is the most sensitive to increases in temperature. Upper elevations were also affected, but to a lesser degree. Temperature increases are the primary driver of diminished snowpack accumulation, however variability in precipitation produce discernible changes in the timing and volumetric storage of snowpack. This regional scale study serves as a case study, providing a modeling framework to better understand the impacts of climate change in similar maritime regions of the world.

scholarly journals Long-Term Records of Snow Cover Water Equivalent in the Swiss Alps

1994 ◽  
Vol 25 (1-2) ◽  
pp. 53-64 ◽  
Author(s):  
M. B. Rohrer ◽  
L. N. Braun ◽  
H. Lang
Keyword(s):  
Snow Cover ◽  
Snow Water Equivalent ◽  
Water Cycle ◽  
Swiss Alps ◽  
Special Investigation ◽  
Quality Aspects ◽  
Snow Water ◽  
Ranking Order ◽  
Seasonal Discharge

The snow-water equivalent (SWE) of the seasonal snow cover is an important component of the water cycle in the Swiss Alps. It is used for predicting seasonal discharge, for short-range discharge forecasts and also for assessing water quality aspects. The SWE has been measured every two weeks at about 50 stations located between 860 and 2,540 m a.s.l. for more than 30 years. In addition there are special investigation areas with stations located between 600 m and 2,900 m a.s.l. where SWE is measured once per winter. The main characteristics of temporal and spatial SWE distributions are analyzed. The variations of SWE values depend in ranking order on elevation, on the year-to-year variations, on the region and on the exposition. The standardized SWE-values depend mostly on the year-to-year variations and on the region.

scholarly journals Forest Phenology Shifts in Response to Climate Change over China–Mongolia–Russia International Economic Corridor

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 757
Author(s):  
Lingxue Yu ◽  
Zhuoran Yan ◽  
Shuwen Zhang
Keyword(s):  
Climate Change ◽  
International Economic ◽  
Forest Ecosystem ◽  
Vegetation Index ◽  
Snow Water Equivalent ◽  
Global Climate ◽  
Growing Season ◽  
Observation Data ◽  
Single Temperature ◽  
Snow Water

Vegetation phenology is a sensitive indicator of climate change. With the intensification of global warming, the changes in growing seasons of various vegetation types have been widely documented across the world. However, as one of the most vulnerable regions in response to the global climate change, the phenological responses and associated mechanisms in mid–high latitude forests are still not fully understood. In this study, long-term changes in forest phenology and the associated relationship with the temperature and snow water equivalent in the China–Mongolia–Russia International Economic Corridor were examined by analyzing the satellite-measured normalized difference vegetation index and the meteorological observation data during 1982 to 2015. The average start date of the growing season (SOS) of the forest ecosystem in our study area advanced at a rate of 2.5 days/decade, while the end date of the growing season (EOS) was delayed at a rate of 2.3 days/decade, contributing to a growing season that was approximately 15 days longer in the 2010s compared to that in 1980s. A higher April temperature is beneficial to the advance in the SOS, and a higher summer temperature has the potential to extend the EOS in the forest ecosystem. However, our results also suggest that a single temperature cannot fully explain the advance of the SOS, as well as the delay in the EOS. The preseason Snow Water Equivalent (SWE) is also an essential factor in influencing the growing season. A higher SWE in February and March and lower SWE in April tend to advance the SOS, while higher SWE in pre-year December and lower SWE in current year October are beneficial to the extension of the EOS.

scholarly journals Recent Evidence of Large-Scale Receding Snow Water Equivalents in the European Alps

2017 ◽  
Vol 18 (4) ◽  
pp. 1021-1031 ◽  
Author(s):  
Christoph Marty ◽  
Anna-Maria Tilg ◽  
Tobias Jonas
Keyword(s):  
Time Series ◽  
Large Scale ◽  
Snow Water Equivalent ◽  
Water Cycle ◽  
Critical Role ◽  
European Alps ◽  
Measurement Series ◽  
Snow Water ◽  
Snow Mass

Abstract Snow plays a critical role in the water cycle of many mountain regions and heavily populated areas downstream. In this study, changes of snow water equivalent (SWE) time series from long-term stations in five Alpine countries are analyzed. The sites are located between 500 and 3000 m above mean sea level, and the analysis is mainly based on measurement series from 1 February (winter) and 1 April (spring). The investigation was performed over different time periods, including the last six decades. The large majority of the SWE time series demonstrate a reduction in snow mass, which is more pronounced for spring than for winter. The observed SWE decrease is independent of latitude or longitude, despite the different climate regions in the Alpine domain. In contrast to measurement series from other mountain ranges, even the highest sites revealed a decline in spring SWE. A comparison with a 100-yr mass balance series from a glacier in the central Alps demonstrates that the peak SWEs have been on a record-low level since around the beginning of the twenty-first century at high Alpine sites. In the long term, clearly increasing temperatures and a coincident weak reduction in precipitation are the main drivers for the pronounced snow mass loss in the past.

scholarly journals Modelling the water budget and the riverflows of the Maritsa basin in Bulgaria

2007 ◽  
Vol 4 (2) ◽  
pp. 475-521 ◽  
Author(s):  
E. Artinyan ◽  
F. Habets ◽  
J. Noilhan ◽  
E. Ledoux ◽  
D. Dimitrov ◽  
...  
Keyword(s):  
Water Budget ◽  
Snow Water Equivalent ◽  
Water Cycle ◽  
Slow Component ◽  
First Year ◽  
Transfer Model ◽  
Distributed Hydrological Model ◽  
Snow Water ◽  
High Level ◽  
The Impact

Abstract. A soil-vegetation-atmosphere transfer model coupled with a macroscale distributed hydrological model was used in order to simulate the water cycle for a large region in Bulgaria. To do so, an atmospheric forcing was built for two hydrological years (1 October 1995 to 30 September 1997), at an eight km resolution. It was based on the data available at the National Institute of Meteorology and Hydrology (NIMH) of Bulgaria. Atmospheric parameters were carefully checked and interpolated with a high level of detail in space and time (3-h step). Comparing computed Penman evapotranspiration versus observed pan evaporation validated the quality of the implemented forcing. The impact of the human activities on the rivers (especially hydropower or irrigation) was taken into account. Some improvements of the hydrometeorological model were made: for better simulation of summer riverflow, two additional reservoirs were added to simulate the slow component of the runoff. Those reservoirs were calibrated using the observed data of the 1st year, while the 2nd year was used for validation. 56 hydrologic stations and 12 dams were used for the model calibration while 41 rivergages were used for the validation of the model. The results compare well with the daily-observed discharges, with good results obtained over more than 25% of the rivergages. The simulated snow depth was compared to daily measurements at 174 stations and the evolution of the snow water equivalent was validated at 5 sites. The process of melting and refreezing of snow was found to be important on this region. The comparison of the normalized values of simulated versus measured soil moisture showed good correlation. The surface water budget shows large spatial variations due to the elevation influence on the precipitations, soil properties and vegetation variability. An inter annual difference was observed in the water cycle as the first year was more influenced by Mediterranean climate, while the second year was characterised by continental influence. Energy budget shows a dominating sensible heat component in summer, due to the fact that the water stress limits the evaporation. This study is a first step for the implementation of an operational hydrometeorological model that could be used for real time monitoring and forecast the water budget and the riverflow of Bulgaria.

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