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 Increase in Near-Surface Atmospheric Moisture Content due to Land Use Changes: Evidence from the Observed Dewpoint Temperature Data

2008 ◽  
Vol 136 (4) ◽  
pp. 1554-1561 ◽  
Author(s):  
Rezaul Mahmood ◽  
Kenneth G. Hubbard ◽  
Ronnie D. Leeper ◽  
Stuart A. Foster
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Moisture Content ◽  
Great Plains ◽  
Growing Season ◽  
Atmospheric Moisture ◽  
Near Surface ◽  
Dewpoint Temperature ◽  
Atmospheric Moisture Content

Abstract Land use change can significantly affect root zone soil moisture, surface energy balance, and near-surface atmospheric temperature and moisture content. During the second half of the twentieth century, portions of the North American Great Plains have experienced extensive introduction of irrigated agriculture. It is expected that land use change from natural grass to irrigated land use would significantly increase near-surface atmospheric moisture content. Modeling studies have already shown an enhanced rate of evapotranspiration from the irrigated areas. The present study analyzes observed dewpoint temperature (Td) to assess the affect of irrigated land use on near-surface atmospheric moisture content. This investigation provides a unique opportunity to use long-term (1982–2003) mesoscale Td data from the Automated Weather Data Network of the high plains. Long-term daily Td data from 6 nonirrigated and 11 irrigated locations have been analyzed. Daily time series were developed from the hourly data. The length of time series was the primary factor in selection of these stations. Results suggest increase in growing-season Td over irrigated areas. For example, average growing-season Td due to irrigation can be up to 1.56°C higher relative to nonirrigated land uses. It is also found that Td for individual growing-season month at irrigated locations can be increased up to 2.17°C by irrigation. Based on the results, it is concluded that the land use change in the Great Plains has modified near-surface moistness.

Stochastic stress-testing approach for assessing resilience of urban water systems from source to tap

2021 ◽  
Author(s):  
Dionysios Nikolopoulos ◽  
Panagiotis Kossieris ◽  
Christos Makropoulos
Keyword(s):  
Stress Testing ◽  
Water Cycle ◽  
Spatial Scales ◽  
Water System ◽  
Water Systems ◽  
Distribution Model ◽  
Generation Model ◽  
Urban Water ◽  
Urban Water Systems

<p>Urban water systems are designed with the goal of delivering their service for several decades.  The infrastructure will inevitably face long-term uncertainty in a multitude of parameters from the hydroclimatic and socioeconomic realms (e.g., climate change, limited supply of water in terms quantity and acceptable quality, population growth, shifting demand patterns, industrialization), as well as from the conceptual realm of the decision maker (e.g., changes in policy, system maintenance incentives, investment rate, expansion plans). Because urban water systems are overly complex, a holistic analysis involves the use of various models that individually pertain to a smaller sub-system and a variety of metrics to assess performance, whereas the analysis is accomplished at different temporal and spatial scales for each sub-system. In this work, we integrate a water resources management model with a water distribution model and a water demand generation model at smaller (household and district) scale, allowing us to simulate urban water systems “from source to tap”, covering the entire water cycle. We also couple a stochastic simulation module that supports the representation of uncertainty throughout the water cycle. The performance of the integrated system under long term uncertainty is assessed with the novel measure of system’s resilience i.e. the degree to which a water system continues to perform under progressively increasing disturbance. This evaluation is essentially a framework of systematic stress-testing, where the disturbance is described via stochastically changing parameters in an ensemble of scenarios that represent future world views. The framework is showcased through a synthesized case study of a medium-sized urban water system.</p><p><strong>Acknowledgement</strong></p><p>This research is carried out / funded in the context of the project “A resilience assessment framework for water supply infrastructure under long-term uncertainty: A Source-to-Tap methodology integrating state of the art computational tools” (MIS 5049174) under the call for proposals “Researchers' support with an emphasis on young researchers- 2nd Cycle”. The project is co-financed by Greece and the European Union (European Social Fund- ESF) by the Operational Programme Human Resources Development, Education and Lifelong Learning 2014-2020.”</p>

Estimates of the Global Water Budget and Its Annual Cycle Using Observational and Model Data

2007 ◽  
Vol 8 (4) ◽  
pp. 758-769 ◽  
Author(s):  
Kevin E. Trenberth ◽  
Lesley Smith ◽  
Taotao Qian ◽  
Aiguo Dai ◽  
John Fasullo
Keyword(s):  
Annual Cycle ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Atmospheric Moisture ◽  
Community Land Model ◽  
Atmospheric Forcings ◽  
Annual Means ◽  
Climate Analysis ◽  
The Tropics

Abstract A brief review is given of research in the Climate Analysis Section at NCAR on the water cycle. Results are used to provide a new estimate of the global hydrological cycle for long-term annual means that includes estimates of the main reservoirs of water as well as the flows of water among them. For precipitation P over land a comparison among three datasets enables uncertainties to be estimated. In addition, results are presented for the mean annual cycle of the atmospheric hydrological cycle based on 1979–2000 data. These include monthly estimates of P, evapotranspiration E, atmospheric moisture convergence over land, and changes in atmospheric storage, for the major continental landmasses, zonal means over land, hemispheric land means, and global land means. The evapotranspiration is computed from the Community Land Model run with realistic atmospheric forcings, including precipitation that is constrained by observations for monthly means but with high-frequency information taken from atmospheric reanalyses. Results for E − P are contrasted with those from atmospheric moisture budgets based on 40-yr ECMWF Re-Analysis (ERA-40) data. The latter show physically unrealistic results, because evaporation often exceeds precipitation over land, especially in the Tropics and subtropics.

scholarly journals Use of Four Reanalysis Datasets to Assess the Terrestrial Branch of the Water Cycle over Quebec, Canada

2016 ◽  
Vol 17 (5) ◽  
pp. 1447-1466 ◽  
Author(s):  
Florent Sabarly ◽  
Gilles Essou ◽  
Philippe Lucas-Picher ◽  
Annie Poulin ◽  
François Brissette
Keyword(s):  
Water Balance ◽  
Water Cycle ◽  
Spatial Scales ◽  
The Other ◽  
Remote Areas ◽  
Time Period ◽  
Terrestrial Water ◽  
Southern Central ◽  
Closed Water ◽  
Weather Stations

Abstract Reanalyses have the potential to provide meteorological information in areas where few or no traditional observation records are available. The terrestrial branch of the water cycle of CFSR, MERRA, ERA-Interim, and NARR is examined over Quebec, Canada, for the 1979–2008 time period. Precipitation, evaporation, runoff, and water balance are studied using observed precipitation and streamflows, according to three spatial scales: 1) the entire province of Quebec, 2) five regions derived from a climate classification, and 3) 11 river basins. The results reveal that MERRA provides a relatively closed water balance, while a significant residual was found for the other three reanalyses. MERRA and ERA-Interim seem to provide the most reliable precipitation over the province. On the other hand, precipitation from CFSR and NARR do not appear to be particularly reliable, especially over southern Quebec, as they almost systematically showed the highest and the lowest values, respectively. Moreover, the partitioning of precipitation into evaporation and runoff from MERRA and NARR does not agree with what was expected, particularly over southern, central, and eastern Quebec. Despite the weaknesses identified, the ability of reanalyses to reproduce the terrestrial water cycle of the recent past (i.e., 1979–2008) remains globally satisfactory. Nonetheless, their potential to provide reliable information must be validated by comparing reanalyses directly with weather stations, especially in remote areas.

scholarly journals Closing the water cycle from observations across scales: Where do we stand?

2021 ◽  
pp. 1-95
Author(s):  
Wouter Dorigo ◽  
Stephan Dietrich ◽  
Filipe Aires ◽  
Luca Brocca ◽  
Sarah Carter ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Water Cycle ◽  
Global Climate ◽  
Spatial Scales ◽  
Spatial And Temporal Scales ◽  
Mitigation And Adaptation ◽  
Consistent Assessment ◽  
Earth’S Climate ◽  
Improved Model

AbstractLife on Earth vitally depends on the availability of water. Human pressure on freshwater resources is increasing, as is human exposure to weather-related extremes (droughts, storms, floods) caused by climate change. Understanding these changes is pivotal for developing mitigation and adaptation strategies. The Global Climate Observing System (GCOS) defines a suite of Essential Climate Variables (ECVs), many related to the water cycle, required to systematically monitor the Earth's climate system. Since long-term observations of these ECVs are derived from different observation techniques, platforms, instruments, and retrieval algorithms, they often lack the accuracy, completeness, resolution, to consistently to characterize water cycle variability at multiple spatial and temporal scales.Here, we review the capability of ground-based and remotely sensed observations of water cycle ECVs to consistently observe the hydrological cycle. We evaluate the relevant land, atmosphere, and ocean water storages and the fluxes between them, including anthropogenic water use. Particularly, we assess how well they close on multiple temporal and spatial scales. On this basis, we discuss gaps in observation systems and formulate guidelines for future water cycle observation strategies. We conclude that, while long-term water-cycle monitoring has greatly advanced in the past, many observational gaps still need to be overcome to close the water budget and enable a comprehensive and consistent assessment across scales. Trends in water cycle components can only be observed with great uncertainty, mainly due to insufficient length and homogeneity. An advanced closure of the water cycle requires improved model-data synthesis capabilities, particularly at regional to local scales.

scholarly journals Evaluation of wet troposphere path delays from atmospheric reanalyses and radiometers and their impact on the altimeter sea level

2014 ◽  
Vol 11 (3) ◽  
pp. 1613-1642 ◽  
Author(s):  
J.-F. Legeais ◽  
M. Ablain ◽  
S. Thao
Keyword(s):  
Sea Level ◽  
Spatial Scales ◽  
Weather Forecast ◽  
Atmospheric Model ◽  
Path Delay ◽  
Medium Range Weather Forecast ◽  
The Mean ◽  
Microwave Radiometers

Abstract. The assessment of long-term errors in altimeter sea level measurements is essential for studies related to the mean sea level (MSL) evolution. One of the main contributors to the long-term sea level uncertainties is the correction of the altimeter range from the wet troposphere path delay, which is provided by onboard microwave radiometers for the main altimeter missions. The wet troposphere correction (WTC) derived from the operational European Centre for Medium-Range Weather Forecast (ECMWF) atmospheric model is usually used as a reference for comparison with the radiometer WTC. However, due to several improvements of the processing, this model is not homogenous over the altimetry period (from 1993 onwards), preventing the detection of errors in the radiometer WTC, especially in the first altimetry decade. In this study, we determine the quality of WTC provided by the operational ECMWF atmospheric model in comparison with the fields derived from the ERA Interim (ECMWF) and the National Centers for Environmental Predictions/National Center for Atmospheric Research (NCEP/NCAR) reanalyses. Separating our analyses on several temporal and spatial scales, we demonstrate that ERA Interim provides the best modeled WTC for the altimeter sea level at climate scales. This allows us to better evaluate the radiometer WTC errors, especially for the first altimetry decade (1993–2002), and thus to improve the altimeter MSL error budget. This work also demonstrates the relevance of the feed-backs that the "altimetry" and "atmosphere" communities can bring to each other.

scholarly journals The relevance of glacier melt in the water cycle of the Alps: the example of Austria

2011 ◽  
Vol 15 (6) ◽  
pp. 2039-2048 ◽  
Author(s):  
G. R. Koboltschnig ◽  
W. Schöner
Keyword(s):  
River Runoff ◽  
Water Cycle ◽  
Point Of View ◽  
Statistical Interpretation ◽  
Study Region ◽  
Ice Melt ◽  
Glacier Melt ◽  
Precipitation Increase ◽  
The Mean

Abstract. This paper quantifies the contribution of glacier melt to river runoff from compilation and statistical interpretation of data from available studies based on observations or glacio- hydrological modelling for the region of Austria (Austrian Salzach and Inn river basin). A logarithmic fit between the glacier melt contribution and the relative glacierized area was found not only for the long-term mean glacier contributions but also for the glacier melt contribution during the extreme hot an dry summer of 2003. Interestingly, the mean contributions of glacier melt to river runoff do not exceed 15 % for both river catchments and are uncorrelated to glacierization for glacierization values >10 %. This finding, however, has to be seen in the light of the general precipitation increase with altitude for the study region which levels out the increase of absolute melt with glacierization thus resulting in the rather constant value of glacier melt contribution. In order to qualitatively proof this finding another approach has been applied by calculating the quotient qA03 of the mean monthly August runoff in 2003 and the long-term mean August runoff for 38 gauging stations in Austria. The extreme summer 2003 was worth to be analysed as from the meteorological and glaciological point of view an extraordinary situation was observed. During June and July nearly the entire snow-cover melted and during August mainly bare ice melt of glaciers contributed to runoff. The qA03 quotients were calculated between 0.32 for a non-glacierized and 2.0 for a highly glacierized catchment. Using the results of this study the mean and maximum possible glacier melt contribution of catchments can be estimated based on the relative glacierized area. It can also be shown that the found correlation of glacierized area and glacier melt contribution is applicable for the Drau basin where yet no results of modelled glacier melt contributions are available.

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 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 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.

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