scholarly journals Long-term Variation of World Terrestrial Water Cycle in 20th Century

2005 ◽  
Vol 49 ◽  
pp. 409-414
Author(s):  
Yukiko HIRABAYASHI ◽  
Shinjiro KANAE ◽  
Taikan OKI
Keyword(s):  
20Th Century ◽  
Water Cycle ◽  
Term Variation ◽  
Terrestrial Water

scholarly journals Developing and Demonstrating Climate Indicators for Monitoring the Changing Water Cycle

2016 ◽  
Vol 2016 ◽  
pp. 1-18 ◽  
Author(s):  
Xia Feng ◽  
Paul Houser
Keyword(s):  
Water Cycle ◽  
Spatial Scales ◽  
Atmospheric Moisture ◽  
Spatial Correlations ◽  
Climate Indicators ◽  
Terrestrial Water ◽  
The Mean ◽  
Atmospheric Moisture Content ◽  
Daily Total

In this study, we developed a suite of spatially and temporally scalable Water Cycle Indicators (WCI) to examine the long-term changes in water cycle variability and demonstrated their use over the contiguous US (CONUS) during 1979–2013 using the MERRA reanalysis product. The WCI indicators consist of six water balance variables monitoring the mean conditions and extreme aspects of the changing water cycle. The variables include precipitation (P), evaporation (E), runoff (R), terrestrial water storage (dS/dt), moisture convergence flux (C), and atmospheric moisture content (dW/dt). Means are determined as the daily total value, while extremes include wet and dry extremes, defined as the upper and lower 10th percentile of daily distribution. Trends are assessed for annual and seasonal indicators at several different spatial scales. Our results indicate that significant changes have occurred in most of the indicators, and these changes are geographically and seasonally dependent. There are more upward trends than downward trends in all eighteen annual indicators averaged over the CONUS. The spatial correlations between the annual trends in means and extremes are statistically significant across the country and are stronger forP,E,R, andCcompared todS/dtanddW/dt.

scholarly journals The Reliability of Global Remote Sensing Evapotranspiration Products over Amazon

2020 ◽  
Vol 12 (14) ◽  
pp. 2211
Author(s):  
Jie Wu ◽  
Venkataraman Lakshmi ◽  
Dashan Wang ◽  
Peirong Lin ◽  
Ming Pan ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Water Cycle ◽  
Remotely Sensed ◽  
Observational Period ◽  
Observation Network ◽  
Terrestrial Water ◽  
Local Measurements ◽  
Long Term Trends ◽  
Scientific Significance

As a key component of terrestrial water cycle, evapotranspiration (ET), specifically over the Amazon River basin, is of high scientific significance. However, due to the sparse observation network and relatively short observational period of eddy covariance data, large uncertainties remain in the spatial-temporal characteristics of ET over the Amazon. Recently, a great number of long-term global remotely sensed ET products have been developed to fill the observation gap. However, the reliabilities of these global ET products over the Amazon are unknown. In this study, we assessed the consistency of the magnitude, trend and spatial pattern of Amazon ET among five global remotely sensed ET reconstructions. The magnitudes of these products are similar but the long-term trends from 1982 to 2011 are completely divergent. Validation from the eddy covariance data and water balance method proves a better performance of a product grounded on local measurements, highlighting the importance of local measurements in the ET reconstruction. We also examined four hypotheses dealing with the response of ET to brightening, warming, greening and deforestation, which shows that in general, these ET products respond better to warming and greening than to brightening and deforestation. This large uncertainty highlights the need for future studies focusing on ET issues over the Amazon.

scholarly journals Influence of atmospheric internal variability on the long-term Siberian water cycle during the past 2 centuries

2018 ◽  
Vol 9 (2) ◽  
pp. 497-506 ◽  
Author(s):  
Kazuhiro Oshima ◽  
Koto Ogata ◽  
Hotaek Park ◽  
Yoshihiro Tachibana
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Water Cycle ◽  
Circulation Model ◽  
Internal Variability ◽  
The Arctic ◽  
The Past ◽  
Term Variation ◽  
East West

Abstract. River discharges from Siberia are a large source of freshwater into the Arctic Ocean, whereas the cause of the long-term variation in Siberian discharges is still unclear. The observed river discharges of the Lena in the east and the Ob in the west indicated different relationships in each of the epochs during the past 7 decades. The correlations between the two river discharges were negative during the 1980s to mid-1990s, positive during the mid-1950s to 1960s, and became weak after the mid-1990s. More long-term records of tree-ring-reconstructed discharges have also shown differences in the correlations in each of the epochs. It is noteworthy that the correlations obtained from the reconstructions tend to be negative during the past 2 centuries. Such tendency has also been obtained from precipitations in observations, and in simulations with an atmospheric general circulation model (AGCM) and fully coupled atmosphere–ocean GCMs conducted for the Fourth Assessment Report of the IPCC. The AGCM control simulation further demonstrated that an east–west seesaw pattern of summertime large-scale atmospheric circulation frequently emerges over Siberia as an atmospheric internal variability. This results in an opposite anomaly of precipitation over the Lena and Ob and the negative correlation. Consequently, the summertime atmospheric internal variability in the east–west seesaw pattern over Siberia is a key factor influencing the long-term variation in precipitation and river discharge, i.e., the water cycle in this region.

scholarly journals Spatial variations and long-term trends of potential evaporation in Canada

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhaoqin Li ◽  
Shusen Wang ◽  
Junhua Li
Keyword(s):  
Climate Change ◽  
Water Cycle ◽  
Climate Change Impacts ◽  
Spatial Variations ◽  
Shortwave Radiation ◽  
Potential Evaporation ◽  
Canadian Prairies ◽  
The Status ◽  
Terrestrial Water

AbstractAssessing the status and trend of potential evaporation (PE) is essential for investigating the climate change impact on the terrestrial water cycle. Despite recent advances, evaluating climate change impacts on PE using pan evaporation (Epan) data in cold regions is hindered by the unavailability of Epan measurements in cold seasons due to the freezing of water and sparse spatial distribution of sites. This study generated long-term PE datasets in Canada for 1979–2016 by integrating the dynamic evolutions of water–ice–snow processes into estimation in the Ecological Assimilation of Land and Climate Observations (EALCO) model. The datasets were compared with Epan before the spatial variations and trends were analyzed. Results show that EALCO PE and Epan measurements demonstrate similar seasonal variations and trends in warm seasons in most areas. Annual PE in Canada varied from 100 mm in the Northern Arctic to approximately 1000 mm in southern Canadian Prairies, southern Ontario, and East Coast, with about 600 mm for the entire landmass. Annual PE shows an increasing trend at a rate of 1.5–4 mm/year in the Northern Arctic, East, and West Canada. The increase is primarily associated with the elevated air temperature and downward longwave and shortwave radiation, with some regions contributed by augmented wind speed. The increase of annual PE is mainly attributed to the augmentation of PE in warm seasons.

scholarly journals Pan-European groundwater to atmosphere terrestrial systems climatology from a physically consistent simulation

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Carina Furusho-Percot ◽  
Klaus Goergen ◽  
Carl Hartick ◽  
Ketan Kulkarni ◽  
Jessica Keune ◽  
...  
Keyword(s):  
Land Surface ◽  
Climate Models ◽  
Water Cycle ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Data Set ◽  
Groundwater Dynamics ◽  
Terrestrial System ◽  
Terrestrial Water

AbstractApplying the Terrestrial Systems Modeling Platform, TSMP, this study provides the first simulated long-term (1996–2018), high-resolution (~12.5 km) terrestrial system climatology over Europe, which comprises variables from groundwater across the land surface to the top of the atmosphere (G2A). The data set offers an unprecedented opportunity to test hypotheses related to short- and long-range feedback processes in space and time between the different interacting compartments of the terrestrial system. The physical consistency of simulated states and fluxes in the terrestrial system constitutes the uniqueness of the data set: while most regional climate models (RCMs) have a tendency to simplify the soil moisture and groundwater representation, TSMP explicitly simulates a full 3D soil- and groundwater dynamics, closing the terrestrial water cycle from G2A. As anthopogenic impacts are excluded, the dataset may serve as a near-natural reference for global change simulations including human water use and climate change. The data set is available as netCDF files for the pan-European EURO-CORDEX domain.

scholarly journals Emerging Changes in Terrestrial Water Storage Variability as a Target for Future Satellite Gravity Missions

2020 ◽  
Vol 12 (23) ◽  
pp. 3898
Author(s):  
Laura Jensen ◽  
Annette Eicker ◽  
Henryk Dobslaw ◽  
Roland Pail
Keyword(s):  
Land Surface ◽  
Seasonal Cycle ◽  
Climate Model ◽  
Water Cycle ◽  
Water Storage ◽  
Phase Changes ◽  
Terrestrial Water Storage ◽  
Satellite Gravity ◽  
Terrestrial Water

Climate change will affect the terrestrial water cycle during the next decades by impacting the seasonal cycle, interannual variations, and long-term linear trends of water stored at or beyond the surface. Since 2002, terrestrial water storage (TWS) has been globally observed by the Gravity Recovery and Climate Experiment (GRACE) and its follow-on mission (GRACE-FO). Next Generation Gravity Missions (NGGMs) are planned to extend this record in the near future. Based on a multi-model ensemble of climate model output provided by the Coupled Model Intercomparison Project Phase 6 (CMIP6) covering the years 2002–2100, we assess possible changes in TWS variability with respect to present-day conditions to help defining scientific requirements for NGGMs. We find that present-day GRACE accuracies are sufficient to detect amplitude and phase changes in the seasonal cycle in a third of the land surface, whereas a five times more accurate double-pair mission could resolve such changes almost everywhere outside the most arid landscapes of our planet. We also select one individual model experiment out of the CMIP6 ensemble that closely matches both GRACE observations and the multi-model median of all CMIP6 realizations, which might serve as basis for satellite mission performance studies extending over many decades to demonstrate the suitability of NGGM satellite missions to monitor long-term climate variations in the terrestrial water cycle.

scholarly journals Influence of atmospheric internal variability on the long-term Siberian water cycle during the past two centuries

2017 ◽  
Author(s):  
Kazuhiro Oshima ◽  
Koto Ogata ◽  
Hotaek Park ◽  
Yoshihiro Tachibana
Keyword(s):  
General Circulation ◽  
Water Cycle ◽  
Circulation Model ◽  
Internal Variability ◽  
The Arctic ◽  
Coupled Models ◽  
The Past ◽  
Term Variation ◽  
East West

Abstract. River discharges from Siberia are a large source of freshwater into the Arctic Ocean, although the cause of the long-term variation in discharge is still unclear. The observed river discharges of the Lena in the east and the Ob in the west indicated different relationships in each of the epochs during the past seven decades. The correlations between the two river discharges were negative during the 1980s to mid-1990s, positive during the mid-1950s to 1960s, and became weak after the mid-1990s. Long-term records of tree-ring-reconstructed discharges during the past two centuries have also shown differences in the correlations in each epoch. However, it is noteworthy that the correlations obtained from the reconstructions tend to be negative. Such negative correlations have also been obtained from precipitations over the Lena and Ob in observation, and in simulations with an atmospheric general circulation model (AGCM) and multi-coupled models conducted for the Fourth Assessment Report of the IPCC. The AGCM control simulation further demonstrated that an east–west seesaw pattern of summertime atmospheric large-scale circulation frequently emerges over Siberia as an atmospheric internal variability, resulting in the negative correlation between the Lena and Ob. Consequently, the summertime atmospheric internal variability of east–west seesaw pattern over Siberia is a key factor influencing the long-term variation in precipitation and river discharge, i.e., the water cycle in this region.

scholarly journals Multiple Data Products Reveal Long-Term Variation Characteristics of Terrestrial Water Storage and Its Dominant Factors in Data-Scarce Alpine Regions

2021 ◽  
Vol 13 (12) ◽  
pp. 2356
Author(s):  
Xuanxuan Wang ◽  
Liu Liu ◽  
Qiankun Niu ◽  
Hao Li ◽  
Zongxue Xu
Keyword(s):  
Abrupt Change ◽  
Water Storage ◽  
Terrestrial Water Storage ◽  
Alpine Regions ◽  
Increasing Trend ◽  
Term Variation ◽  
Terrestrial Water ◽  
Variation Characteristics ◽  
Spatio Temporal

As the “Water Tower of Asia” and “The Third Pole” of the world, the Qinghai–Tibet Plateau (QTP) shows great sensitivity to global climate change, and the change in its terrestrial water storage has become a focus of attention globally. Differences in multi-source data and different calculation methods have caused great uncertainty in the accurate estimation of terrestrial water storage. In this study, the Yarlung Zangbo River Basin (YZRB), located in the southeast of the QTP, was selected as the study area, with the aim of investigating the spatio-temporal variation characteristics of terrestrial water storage change (TWSC). Gravity Recovery and Climate Experiment (GRACE) data from 2003 to 2017, combined with the fifth-generation reanalysis product of the European Centre for Medium-Range Weather Forecasts (ERA5) data and Global Land Data Assimilation System (GLDAS) data, were adopted for the performance evaluation of TWSC estimation. Based on ERA5 and GLDAS, the terrestrial water balance method (PER) and the summation method (SS) were used to estimate terrestrial water storage, obtaining four sets of TWSC, which were compared with TWSC derived from GRACE. The results show that the TWSC estimated by the SS method based on GLDAS is most consistent with the results of GRACE. The time-lag effect was identified in the TWSC estimated by the PER method based on ERA5 and GLDAS, respectively, with 2-month and 3-month lags. Therefore, based on the GLDAS, the SS method was used to further explore the long-term temporal and spatial evolution of TWSC in the YZRB. During the period of 1948–2017, TWSC showed a significantly increasing trend; however, an abrupt change in TWSC was detected around 2002. That is, TWSC showed a significantly increasing trend before 2002 (slope = 0.0236 mm/month, p < 0.01) but a significantly decreasing trend (slope = −0.397 mm/month, p < 0.01) after 2002. Additional attribution analysis on the abrupt change in TWSC before and after 2002 was conducted, indicating that, compared with the snow water equivalent, the soil moisture dominated the long-term variation of TWSC. In terms of spatial distribution, TWSC showed a large spatial heterogeneity, mainly in the middle reaches with a high intensity of human activities and the Parlung Zangbo River Basin, distributed with great glaciers. The results obtained in this study can provide reliable data support and technical means for exploring the spatio-temporal evolution mechanism of terrestrial water storage in data-scarce alpine regions.

Water cycle changes in the headwater regions of the Yangtze River and Yellow River basins during the past three decades

2020 ◽  
Author(s):  
Zhicheng Xu ◽  
Lei Cheng ◽  
Pan Liu
Keyword(s):  
Yangtze River ◽  
Water Cycle ◽  
Yellow River ◽  
Water Storage ◽  
Total Water ◽  
Atmospheric Water ◽  
Water Budgets ◽  
Terrestrial Water ◽  
Rr Variability

&lt;p&gt;Yangtze River and Yellow River are the two most important rivers in China. Long-term observation shows that runoff ratio (i.e., runoff/precipitation, denoted as RR) in the headwater of both Yangtze River (HYZR) and Yellow River (HYER) has experienced significant decrease and then increase trend (referred as V-change) during the period 1980-2015. Over the whole period, RR of the HYER shows significant decreasing trend (-0.02/10a, p &lt; 0.05), while it is not significant for the HYZR. Changes in RR in both HYZR and HYER pose great challenge on runoff predication and water management in the downstream. However, driven mechanisms underlying the V-change of RR are still unclear. Here, based on ground-based and remote sensing datasets, both terrestrial and atmospheric water budgets are investigated to understand the evolution of RR in the headwater regions of Yangtze River and Yellow River. Terrestrial water budgets are for evaporation estimation and water cycle analysis. Atmospheric water budgets are used to calibrate the estimated evaporation. Results show that TWS-REC agrees well with observed total water storage (TWS-GRACE) in both HYZR (r = 0.94, NSE = 0.83) and HYER (r = 0.93, NSE = 0.83) over the period of 2003-2012. Estimated evaporation from both terrestrial water balance and atmospheric water balance method also agree well with each other in the HYZR (r = 0.89, NSE = 0.80) and in the HYER (r = 0.88, NSE = 0.79) over the period of 2000-2015. It suggests that reconstructed TWS and estimated evaporation are reliable for analyzing long-term water cycle in the study areas. Both the ratio of the estimated evaporation to precipitation (ER) in two basin increase first and then decreased during the study period. The correlation coefficients between ER and RR in the HYZR and HYER are -0.63 and -0.79, respectively, presenting that RR variability could be mainly caused by the evolution ER. Meanwhile it also indicates the nonignored role of total water storage (TWS) changes in RR variability in the two basin. TWS-REC in both regions have experienced significant increasing with rate of 26 mm/10a (HYZR, p &lt; 0.05) and 17mm/10a (HYER, p &lt; 0.05), later of which is the main reason of downward trend of RR in HYER. Further analysis indicates that changes in ER are resulted from comprehensive effects of precipitation variability (26.4mm/10a, p &lt; 0.05 in HYZR and 3.5mm/10a p &gt; 0.1 in HYER) and of dramatic climate warming (0.6&amp;#8451;/10a, p &lt; 0.05 in HYZR and 0.5&amp;#8451;/10a, p &lt; 0.05 in HYER). TWS changes in both basin are positively related with dramatic temperature rising and significant vegetation greening. It means that annual fluctuation of precipitation-runoff process (i.e., V-change RR) has affected negatively by climate warming and vegetation greening in the HYZR and HYER. These findings can advance our understanding of the runoff ratio evolution and water cycle in the headwater of Yangtze River and Yellow River and it is also important for ecological conservation strategy and downstream water resources management.&lt;/p&gt;

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