Showing papers on "Water cycle published in 1996"
TL;DR: In this article, the isotope fractionations that accompany the evaporation from the ocean and other surface waters and the reverse process of rain formation account for the most notable changes.
Abstract: Changes of the isotopic composition of water within the water cycle provide a recognizable signature, relating such water to the different phases of the cycle. The isotope fractionations that accompany the evaporation from the ocean and other surface waters and the reverse process of rain formation account for the most notable changes. As a result, meteoric waters are depleted in the heavy isotopic species of H and O relative to ocean waters, whereas waters in evaporative systems such as lakes, plants, and soilwaters are relatively enriched. During the passage through the aquifers, the isotope composition of water is essentially a conservative property at ambient temperatures, but at elevated temperatures, interaction with the rock matrix may perturb the isotope composition. These changes of the isotope composition in atmospheric waters, surface water, soil, and groundwaters, as well as in the biosphere, are applied in the characterization of hydrological system as well as indicators of paleo-climatological conditions in proxy materials in climatic archives, such as ice, lake sediments, or organic materials.
2,010 citations
TL;DR: In this paper, the authors examined the current predictive capability of general circulation models linked with macro-scale and landscape-scale hydrologic models that simulate regional and local hydrological regimes under global warming scenarios.
275 citations
TL;DR: Water flows from the land to the sea in rivers -that is the classroom picture that seems too self-evident to question as mentioned in this paper. But there is evidence that a comparable amount may flow underground directly into coastal waters.
Abstract: Water flows from the land to the sea in rivers - that is the classroom picture that seems too self–evident to question. But there is evidence that a comparable amount may flow underground directly into coastal waters.
259 citations
TL;DR: In this paper, an approach for estimation of the parameters of a macro-scale land surface hydrology model is illustrated for the Global and Water Cycle Experiment (GEWEX) Continental Scale International Project (GCIP) large-scale area southwest (LSA-SW) which essentially comprises the Arkansas-Red River basin.
Abstract: An approach for estimation of the parameters of a macroscale land surface hydrology model is illustrated for the Global and Water Cycle Experiment (GEWEX) Continental Scale International Project (GCIP) large-scale area southwest (LSA-SW) which essentially comprises the Arkansas-Red River basin. The macroscale land surface hydrology model parameters were estimated for 44 catchments within LSA-SW with areas ranging from 180 to 7100 km2 using an automated search procedure. The catchment parameters were then linearly interpolated and overlaid on a one degree grid, which was used to represent the drainage network. The macroscale grid network model was run off-line at a daily time step, forced by gridded station precipitation and potential evapotranspiration. The model-generated long-term mean streamflows were compared with observations (corrected for management effects such as reservoir storage and diversions) and were found to agree to within one percent for the Arkansas River and about two percent for the Red River. For both rivers, the model underestimates the seasonal peak streamflow in late spring, and overestimates the late summer and early fall minimum. Model-derived evapotranspiration, spatially averaged over the entire Arkansas-Red basin, was compared to evapotranspiration derived from an atmospheric moisture budget of the Arkansas-Red River basin. On an average annual basis, for the period 1973–1986, the two agree to within one percent. The mean seasonal cycles for the two estimates agree quite closely from late winter to midsummer. However, the hydrologic model estimates less evapotranspiration in the fall, and more in midwinter, than the atmospheric budget.
209 citations
TL;DR: This paper examined the processes controlling mountain glacier retreat by comparing high-altitude air-temperature measurements for the past few decades, to the temperatures predicted by a model atmosphere forced by the observed global pattern of sea surface temperature in a 19-year simulation.
Abstract: A WIDESPREAD retreat of alpine glaciers1 and melting of tropical ice-cap margins2–7 has been observed in recent decades, over which time a general climate warming at lower altitudes has been documented8. Moreover, some ice-core records provide evidence suggesting that mid-tropospheric temperatures in the tropics have been greater in recent decades than at any time during the past 2,000–3,000 years7. Here we examine the processes controlling mountain glacier retreat by comparing high-altitude air-temperature measurements for the past few decades, to the temperatures predicted by a model atmosphere forced by the observed global pattern of sea surface temperature in a 19-year simulation9. The comparison strongly indicates that the observed changes in freezing-level height (the altitude of the 0°C isotherm) are related to a long-term (over decades) increase in sea surface temperature in the tropics, and the consequent enhancement of the tropical hydrological cycle. Although changes in this cycle are likely to affect high-elevation hydrological and ecological balances worldwide10,11, tropical environments may be particularly sensitive because the changes in tropical sea surface temperature and humidity may be largest and most systematic at low latitudes.
159 citations
TL;DR: Xue et al. as mentioned in this paper used a simple biosphere model to simulate the interactions between the Earth's land surface and the atmosphere by treating the vegetation explic- itly and realistically.
Abstract: JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 101, NO. D3, PAGES 7419-7430, MARCH 20, 1996 Impact of vegetation properties on U.S. summer weather prediction Yongkang Xue and Michael J. Fennessy Center for Ocean-Land-Atmosphere Studies, Calverton, Maryland Piers J. Sellers NASA Goddard Space Flight Center, Greenbelt, Maryland Abstract. Systematic biases in U.S. summer integrations with the Center for Ocean- Land-Atmosphere Studies (COLA) atmospheric general circulation model (GCM) have been identified and analyzed. Positive surface air temperature biases of 2°—4°K occurred over the central United States. The temperature biases were coincident with the agricultural region of the central United States, where negative precipitation biases also occurred. The biases developed in‘June and became very significant during July and August. The impact of the crop area vegetation and soil properties on the biases was investigated in a series of numerical experiments. The biases were largely caused by the erroneous prescription of crop vegetation phenology in the surface model of the GCM. The prescribed crop soil properties also contributed to the biases. On the basis of these results the crop model has been improved and the systematic errors in the U.S. summer simulations have been reduced. The numerical experiments also revealed that land surface effects on the atmospheric variables at and near the surface during the North American summer are very pronounced and persistent but are largely limited to the area of the anomalous land surface forcing. In this regard, the midlatitude land surface effects described here are similar to those previously found for tropical regions. 1. Introduction Land surface processes have been shown to have substantial effects on short-term weather predictions and long-term cli- mate projections. Changes in land surface conditions influence the atmospheric circulation by modifying the surface energy balance and hydrological cycle. For example, Rowell and Blondin [1990] showed that the 5-day weather forecast for West Africa from the European Center for Medium Range Weather Forecasts (ECMWF) operational forecasting model was sensitive to the surface moisture distribution. Xue and Shukla [1993] used the Center for Ocean-Land-Atmosphere (COLA) Studies general circulation model (GCM) to simulate one of the observed African drought anomaly patterns in re- sponse to changes in the land surface characteristics. This GCM includes a simplified version of Sellers et al.’s [1986] simple biosphere model (SSiB) [Xue et al., 1991]. The simple biosphere model (SiB) [Sellers et al., 1986] was designed to simulate the interactions between the Earth’s land surface and the atmosphere by treating the vegetation explic- itly and realistically. A comparison between simulations with the COLA GCM coupled to SiB and the same GCM coupled with a conventional hydrological model shows that the coupled biosphere-atmosphere model produces a more realistic parti- tioning of energy at the land surface [Sato et al., 1989]. Both SiB and SSiB have been validated by using observational data from many field experiments, including the Amazon tropical rainforest experiment [Sellers er al., 1989; Xue et al., 1991], the First ISLSCP International Satellite Land-Surface Climatology Copyright 1996 by the American Geophysical Union. Paper number 9SJD02169. 0l48-0227/96/95JD-02169$05.00 Project Field Experiment (FIFE) [Sellers et al., 1992; Chen et al., this issue], the Anglo—Brazilian Amazonian Climate Obser- vation Study [Xue et al., 1995a], the HAPEX-Mobilhy experi- ment on a crop—grassland site in France [Shao and Henderson- Sellers, 1995; Xue et al., 1995b]. These calibrations have provided vegetation and soil property information for some vegetation types, and have led to improvements in the surface biosphere model, resulting in more realistic simulations. How- ever, these field measurements were made at a few sites for only about one third of the SiB vegetation types. Because of differences in spatial scales, the application of data from these site studies to GCM simulations needs further investigation. For vegetation types with little or no observational data, indi- rect information on vegetation and soil properties from scien- tific literature has to be used. We will address this problem in more detail in section 2. Although land surface modeling can enhance our ability to understand land surface-atmosphere interactions, poor or inadequate representation of surface pro- cesses or land surface conditions may have a negative impact on weather prediction and climate studies. In this study, systematic errors in U.S. summer seasonal predictions with the COLA GCM have been identified. The simulated June, July, and August (JJA) mean surface temper- ature in the central U.S. was 2°—4°K higher than observations, and the JJA mean precipitation was about 1 mm d‘1 (30%) lower than observations in the same region. Similar systematic errors have been noted in other GCMs and weather forecast models. In a 10-year integration using the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM2), Bonan [1994] found large systematic warm temper- ature biases (10°—15°K) in central North America, which A. Hahmann and R. E. Dickinson (personal communication, 7419
143 citations
Book•
18 Dec 1996
TL;DR: The IMAGE 2 approach global change impacts on agriculture, forestry and soils: the programme of the global change and terrestrial ecosystems core project of IGBP global climate change and agricultural production - an assessment of current knowledge and critical gaps as mentioned in this paper.
Abstract: The climate change - agricultural conundrum the effect of changes in the world hydrological cycle on availability of water resources the effects of global change on soil conditions in relation to plant growth and food production the CO2 fertilization effect: higher carbohydrate production and retention as biomass and seed yield the effects of elevated CO2 and temperature on transpiration and crop water use effects of higher day and night temperatures on growth and yields of some crop plants adverse effects of elevated levels of UV-B radiation and ozone (03) on crop growth and productivity combined effects of changing CO2 temperature, UV-B radiation and O3 on crop growth the potential effects of climate change on world food production and security climate change, global agriculture, and regional vulnerability integrating land-use change and evaluating feedbacks in global change models - the IMAGE 2 approach global change impacts on agriculture, forestry and soils: the programme of the global change and terrestrial ecosystems core project of IGBP global climate change and agricultural production - an assessment of current knowledge and critical gaps.
131 citations
TL;DR: In this article, the isotopic composition (δ18O and δD) of water from various sources was used to see whether or not specific sources of water vapor to the atmosphere could be determined.
98 citations
Journal Article•
TL;DR: In this article, three major soil erosion models, including Environmental Policy Integrated Climate (EPIC), Water Erosion Prediction Project (WEPP), and wind erosion prediction system (WEPS), are reviewed and briefly described.
Abstract: Future changes in climate and atmospheric CO2 concentration will change the hydrologic cycle, affecting important soil-plant-water interactions, which in turn affect soil erosion rates. Climate and CO2 changes can be estimated with global circulation models (GCMs). Mathematical models are also available for simulating soil erosion as affected by weather and soil-plant-water interactions.
Three major soil erosion models, including Environmental Policy Integrated Climate (EPIC) (formerly the Erosion-Productivity Impact Calculator); Water Erosion Prediction Project (WEPP); and Wind Erosion Prediction System (WEPS), are reviewed and briefly described here. The CLIGEN (Climate Generator) model, which has been refined to simulate changing climate, is also described here.
Stockle et al. (1992) modified EPIC to simulate the effects of CO2 changes on plant growth and water-use efficiency. Recently, the Stockle relationships have been added to WEPP and to the basin scale model SWAT (Soil Water Assessment Tool) (Arnold et al. 1993). These relationships are also described in this paper.
The EPIC model
The Erosion-Productivity Impact Calculator (EPIC) (Williams et al. 1984) model was originally developed to assess the effect of soil erosion on soil productivity. It was used for that purpose as part …
98 citations
TL;DR: Strontium isotope analysis of precisely dated calcite growth layers in Holocene speleothems from Barbados, West Indies, reveals high-resolution temporal variations in ground-water composition and may provide a new approach to documenting the links between climate variability andfluctuations in the hydrologic cycle such as recharge rates and flow paths as discussed by the authors.
Abstract: Strontium isotope analysis of precisely dated calcite growth layers in Holocene speleothems from Barbados, West Indies, reveals high-resolution temporal variations in ground-water composition and may provide a new approach to documenting the links between climate variability andfluctuations in the hydrologic cycle such as recharge rates andflow paths. The speleothems grew in a cave that developed in a fresh-water aquifer in upliftedPleistocenereeflimestones.Threeperiodsofground-waterSrisotopeevolutionare observed: 87 Sr/ 86 Srvaluesdecreasedfrom6to4ka,increasedfrom4to1ka,anddecreased again after 1 ka. The Sr isotope oscillations appear to record periodic variations in the relative Sr fluxes to ground water from exchangeable soil sites vs. carbonate mineral reactions,asreflectedin 87 Sr/ 86 SrvaluesofmodernBarbadosgroundwaters.Ahydrologic model that explains changes in ground-waterflow routes in karst aquifers as a function of amountofrainfallrechargecanaccountforthespeleothemSrisotoperecord.Independent Holoceneclimaterecordsthatindicateamajorperiodofaridityataround1.3‐1.1kainthe American tropics correspond with periodic variations in rainfall on Barbados that are predicted by this hydrologic model.
91 citations
Book•
01 Jan 1996
TL;DR: Water and life unusual properties of usual water the behaviour of water at rest and in motion invisible flow - the ideas of groundwater hydrology the earth's water envelope, its circulation and resources fresh water resources and the hydrologic cycle as mentioned in this paper.
Abstract: Water and life unusual properties of usual water the behaviour of water at the rest and in motion invisible flow - the ideas of groundwater hydrology the earth's water envelope, its circulation and resources fresh water resources and the hydrologic cycle.
TL;DR: In this paper, large flood channels, valley networks, and a variety of features attributed to the action of ground ice indicate that Mars emerged from heavy bombardment around 3.8 Gyr ago, with an inventory of water at the surface equivalent to at least a few hundred meters spread over the whole planet, compared with 3 km for the Earth.
TL;DR: In this paper, the authors present an accurate simulation of soil moisture content at any time of the year is important to agriculture in dry regions due to the vital role soil moisture plays in crop production.
Abstract: Accurate simulation of soil moisture content at any time of the year is important to agriculture in dry regions due to the vital role soil moisture plays in crop production. In certain applications...
TL;DR: Using rain gauge data, an independent and direct measure of the precipitation trends in the Pacific corroborates previous results based on satellite measurements, estimates of oceanic evaporation from shipboard meteorological observations, and results from numerical models.
Abstract: Analysis of recently compiled tropical Pacific rain gauge measurements shows a trend toward increased precipitation in the central tropical Pacific during the period 1971-90. Previous studies of precipitation trends in this region have used satellite data and shipboard measurements, which have been demonstrated to contain a variety of known and unknown biases that could artificially produce a trend. Using rain gauge data, an independent and direct measure of the precipitation trends in the Pacific corroborates previous results based on satellite measurements, estimates of oceanic evaporation from shipboard meteorological observations, and results from numerical models. Furthermore, the result is consistent with suggestions that an enhancement of the tropical hydrologic cycle has been responsible for the increases in globally averaged tropospheric temperatures during the past two decades. 34 refs., 5 figs., 1 tab.
TL;DR: The broadscale aspects of the annual cycle of monthly mean global water vapor flux, flux divergence, evaporation, and precipitation derived from the National Meteorological Center (NMC) global analysis and forecast products were examined with two objectives in mind.
Abstract: The broadscale aspects of the annual cycle of monthly mean global water vapor flux, flux divergence, evaporation, and precipitation derived from the National Meteorological Center (NMC) global analysis and forecast products were examined with two objectives in mind: 1) a critical evaluation of the usefulness of recent NMC products for descriptive and diagnostic studies of the global hydrological cycle and in the process and 2) to provide additional information on the behavior of the annual cycle of selected hydrological parameters over the globe in general and over the United States in particular. The 2-year period August 1991–July 1993, was chosen for study. The global-scale characteristics of the NMC vertically integrated vapor flux fields are described in terms of the rotational and divergent components of the stationary and transient parts of the vapor flux field. Values of the zonally averaged meridional vapor flux derived from the NMC analyses are broadly similar to those presented by Peixo...
Book•
07 Nov 1996
TL;DR: In this paper, what is environmental science? environmental interactions, cycles and systems ecology and environmentalism history of environmental science changing attitudes to the natural world, including the formation and structure of the earth the formation of rocks, minerals, and geologic structures weathering the evolution of landforms coasts, estuaries, sea levels energy from the sun albedo and heat capacity the greenhouse effect the evolution, composition, and structure, general circulation of the atmosphere oceans, gyres, currents weather and climate glacials, interglacials, and interstadials dating methods climate change
Abstract: Part 1 Introduction: what is environmental science? environmental interactions, cycles and systems ecology and environmentalism history of environmental science changing attitudes to the natural world. Part 2 Earth sciences: formation and structure of the earth the formation of rocks, minerals, and geologic structures weathering the evolution of landforms coasts, estuaries, sea levels energy from the sun albedo and heat capacity the greenhouse effect the evolution, composition, and structure of the atmosphere general circulation of the atmosphere oceans, gyres, currents weather and climate glacials, interglacials, and interstadials dating methods climate change climatic regions and floristic regions. Part 3 Physical resources: fresh water and the hydrological cycle eutrophication and the life cycles of lakes salt water, brackish water, and desalination irrigation, waterlogging, and salinization soil formation, ageing, and taxonomy transport by water and wind soil, climate, and land use soil erosion and its control mining and processing of fuels mining and processing of minerals. Part 4 Biosphere: biosphere, biomes, biogeography nutrient cycles respiration and photosynthesis trophic relationships energy, numbers, biomass ecosystems succession and climax arrested successions colonization stability, instability, and reproductive strategies simplicity and diversity homeostasis, feedback, regulation limits of tolerance. Part 5 Biological resources: evolution evolutionary strategies and game theory adaption dispersal mechanisms wildlife species and habitats biodiversity fisheries forests farming for food and fibre human populations and demographic change genetic engineering. Part 6 Environmental management: wildlife conservation 57: Zoos, nature reserves, wilderness pest control restoration ecology world conservation strategies pollution control transnational pollution.
TL;DR: In this article, the authors compared three different land surface schemes used in general circulation models (GCM) to simulate evaporation, runoff, and soil moisture, and found that the surface resistance and field capacity were essential parameters in determining the annual cycle of evapse and that a representation of subgrid-scale variability of soil moisture had an important impact on runoff.
01 Jan 1996
TL;DR: In this article, the impact of Global Warming on the hydrological cycle of the world is discussed. But the authors focus on the effect of climate change on the water resources in the world.
Abstract: 1. Predicting the Hydrological Effects of Climate Change J.A.A. Jones. Section I: Sensitivity of the Global Hydrosphere. 2. An Introduction to Global Water Dynamics I. Kayane. 3. Biospheric Aspects of the Hydrological Cycle: Approaches to Upscaling and Downscaling B. Bass, et al. 4. Trends in Historical Streamflow Data F.H.S. Chiew, T.A. McMahon. Section II: Regional Implications of Global Warming. 5. Hydrology of Northern North America Under Global Warming M.-K. Woo. 6. Current Evidence on the Likely Impact of Global Warming on Hydrological Regimes in Europe J.A.A. Jones. 7. The Impact of Climatic Warming on Hydrological Regimes in China: An Overview C. Liu, G. Fu. Section III: Precipitation: Change and Variability. 8. The Influence of Topography, Season and Circulation on Spatial Patterns of Daily Precipitation P.J. Robinson. 9. The Use of Artificial Neural Networks to Predict Temporal Precipitation Patterns H. Kung, et al. 10. Generation of Sequences of Air Temperature and Precipitation for Estimation of the Hydrological Cycle in Changing Climatic Conditions over Poland M. Gutry-Korycka, P. Wetner. 11. Some Aspects of Climatic Fluctuation at Four Stations on the Tibetan Plateau During the last 40 Years M. Yoshino. 12. The Influence of the North Atlantic Oscillation, the El Nino/Southern Oscillation and the Quasi-Biennial Oscillation on Winter Precipitation in Ireland S. Daultrey. Section IV: Impacts on Snow, Ice and Meltwaters. 13. Runoff Formation and Discharge Modelling for a Glacierized Basin E. Kang, et al. 14. Impact of Eventual Climatic Change on Glacier Runoff and the Possibilities of Artificial Increases in the Aral Sea Basin A.N. Krenke, G.N. Kravchenko. 15. Glaciers and Snow Cover of Central Asia as Indicators of Climatic Changes V. Aizen, E.M. Aizen. 16. Global Warming and the Trend Toward Dryness in the Frigid High Mountains and Plateau of Western China L.-S. Zhang. Section V: The Water Balance and Changing Regional Resources. 17. A Method to Assess the Effects of Climatic Warming on the Water Balance of Mountainous Regions C. Liu, M.-K. Woo. 18. Sensitivity and Analyses for the Impact of Global Warming on Water Resources in Wales C.P. Holt, J.A.A. Jones. 19. Potential Hydrological Responses to Climate Change in Australia F.H.S. Chiew, et al. 20. Dynamics of Stage Fluctuation in Yangzhouyongcuo Lake, Tibet T. Liu. 21. Use of Satellite Data for Modelling Regional Climatic Change: A Case Study - Surface Temperature, Albedo and Heat Budget over the Tibetan Plateau L. Shi. 22. Climatic Warming and Its Impact on the Water Resources of the Yalong River, Sichuan, China Y. Deng, Y. Hou. 23. The Probable Impact of Global Change on the Water Resources of Patagonia, Argentina R.M. Quintela, et al. 24. A Long Term Trend in the Water Balance in Japan K. Mori. Conclusions. 25. The Impact of Global Warming on Regional Hydrology and Future Research Priorities J.A.A. Jones.
TL;DR: The Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite is able to retrieve water vapor concentration in the upper troposphere with good sensitivity and nearly global coverage.
Abstract: Water vapor in the upper troposphere has a significant impact on the climate system. Difficulties in making accurate global measurements have led to uncertainty in understanding water vapor's coupling to the hydrologic cycle in the lower troposphere and its role in radiative energy balance. The Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite is able to retrieve water vapor concentration in the upper troposphere with good sensitivity and nearly global coverage. An analysis of these preliminary retrievals based on 3 years of observations shows the water vapor distribution to be similar to that measured by other techniques and to model results. The primary MLS water vapor measurements were made in the stratosphere, where this species acts as a conserved tracer under certain conditions. As is the case for the upper troposphere, most of the stratospheric discussion focuses on the time evolution of the zonal mean and zonally varying water vapor. Stratospheric results span a 19-month period and tropospheric results a 36-month period, both beginning in October of 1991. Comparisons with stratospheric model calculations show general agreement, with some differences in the amplitude and phase of long-term variations. At certain times and places, the evolution of water vapor distributions in the lower stratosphere suggests the presence of meridional transport.
TL;DR: In this paper, the authors investigated the relationship among the large-scale hydrological cycle, Asian summer monsoon and Indian Ocean sea-surface temperature (SST) anomalies in a series of numerical experiments.
Abstract: Relationships among the large-scale hydrological cycle, Asian summer monsoon and Indian Ocean sea-surface temperature (SST) anomalies are investigated in a series of numerical experiments. Ensembles of integrations with the National Center for Atmospheric Research community climate model, CCM 1, focusing on the summer months (June, July, and August) provide the basic information for analysis. Impacts of SST anomalies in the southern Indian Ocean are evaluated by intercomparison of experiments with and without these anomalies. Systematic changes in the hydrological cycle and monsoon circulation are demonstrated and summarized in the context of a three-dimensional framework consisting of the basic elements of the Asian summer monsoon system. In the negative SST anomaly case, both the hydrological cycle and circulation processes are enhanced by virtue of their close relationship and especially the inherent coupling between the large-scale water vapour transport and the low-level monsoon flow. The overall intensity of the broad-scale monsoon, in this case, is enhanced. In the positive SST anomaly case, the model response is essentially opposite to that of the negative case and the intensity of the broad-scale monsoon is reduced. These enhanced/weakened monsoon scenarios share many similar features to observed interannual variations of the Asian summer monsoon.
01 Dec 1996
TL;DR: In this paper, an evaluation of the moisture fields, the precipitation P and evaporation E, and the moisture transport and divergence in the atmosphere from the global atmospheric National Centers for Environmental Prediction (NCEP) reanalyses produced with four-dimensional-data assimilation is carried out.
Abstract: An evaluation is carried out of the moisture fields, the precipitation P and evaporation E, and the moisture transport and divergence in the atmosphere from the global atmospheric National Centers for Environmental Prediction (NCEP) reanalyses produced with four-dimensional-data assimilation. The moisture fields are summarized by the precipitable water which is compared with analyzed fields from NVAP based primarily on Special Sensor Microwave Imager (SSM/I) over the oceans and rawinsonde measurements over land, plus TIROS Operational Vertical Sounder (TOVS). The moisture budgets are evaluated through computation of the freshwater flux at the surface E - P using residual techniques from the divergence of the total moisture transport, and this is compared with the reanalysis E - P that is based upon a 6-hour integration of the assimilating model and thus depends on the model parameterizations. The P field is evaluated using Xie-Arkin Global Precipitation Climatology Project (GPCP) estimates. An atlas presents climatological means for the period 1979 1995 (17 years) and standard deviations for annual, seasonal and monthly values, and the differences between estimates.
TL;DR: In this paper, the atmospheric components of the water cycle over the Baltic Sea and its catchment area are calculated using the regional numerical weather prediction model REMO and daily as well as monthly mean values of precipitation, evapotranspiration, horizontal water transport, and change of atmospheric water content are presented.
Abstract: The atmospheric components of the water cycle over the Baltic Sea and its catchment area are calculated using the regional numerical weather prediction model REMO. Daily as well as monthly mean values of precipitation, evapotranspiration, horizontal water transport, and change of atmospheric water content are presented. As a first attempt of validation, precipitation data provided by several national meteorological services (5898 stations) are compared with the model results. The areal averages of daily precipitation over the whole catchment area agree well with the measurements but on some days there is a mismatch in the geographical distribution between observations and model results. A comparison of evaporation and precipitation with measured data of June 1993 as well as with climatological values shows that the model reflects the relatively wet character of this month. DOI: 10.1034/j.1600-0870.1996.t01-4-00007.x
TL;DR: For each kilogram of water on Earth, only 1 mg is stored as soil moisture as discussed by the authors. Yet this miniscule amount of water exerts significant control over various hydrological, ecological, and meteorological processes ranging from boundary layer dynamics to the global water cycle.
Abstract: For each kilogram of water on Earth, only 1 mg is stored as soil moisture. Yet this miniscule amount of water exerts significant control over various hydrological, ecological, and meteorological processes ranging from boundary layer dynamics to the global water cycle. The 1993 Mississippi River flood illustrated the power of 0.0001% of Earth's water to dictate the fate and evolution of regional weather and climate.
The space-time distribution of soil moisture is a key component in describing transfer and distribution of mass and energy between the land and the atmosphere. It is a fundamental variable in biosphere-atmosphere transfer, biogeochemistry, ecosystem process, and rainfall-runoff models. There is a growing consensus that a unified approach is necessary to monitor, characterize, and model soil moisture over a range of scales, but such an approach has yet to be defined.
TL;DR: In this article, the water balance in two small neighbouring catchments, namely Honryu (HN) and Shozawa (SH) in the Takaragawa Forest Watershed Experiment Station, Japan, was analyzed by analysing records of precipitation in rainfall seasons and snow water equivalent (SWE) in snowfall seasons.
Book•
01 Jan 1996
TL;DR: In this article, an evaluation of the moisture fields, the precipitation P and evaporation E, and the moisture transport and divergence in the atmosphere from the global atmospheric National Centers for Environmental Prediction (NCEP) reanalyses produced with four-dimensional-data assimilation is carried out.
Abstract: An evaluation is carried out of the moisture fields, the precipitation P and evaporation E, and the moisture transport and divergence in the atmosphere from the global atmospheric National Centers for Environmental Prediction (NCEP) reanalyses produced with four-dimensional-data assimilation. The moisture fields are summarized by the precipitable water which is compared with analyzed fields from NVAP based primarily on Special Sensor Microwave Imager (SSM/I) over the oceans and rawinsonde measurements over land, plus TIROS Operational Vertical Sounder (TOVS). The moisture budgets are evaluated through computation of the freshwater flux at the surface E - P using residual techniques from the divergence of the total moisture transport, and this is compared with the reanalysis E - P that is based upon a 6-hour integration of the assimilating model and thus depends on the model parameterizations. The P field is evaluated using Xie-Arkin Global Precipitation Climatology Project (GPCP) estimates. An atlas presents climatological means for the period 1979 1995 (17 years) and standard deviations for annual, seasonal and monthly values, and the differences between estimates.
TL;DR: In this article, the authors compare the performance of the National Center for Atmospheric Research global atmospheric general circulation model (GCM) or community climate model (CCM1), coupled to a mixed layer model, compared to available global hydrologic observations.
Abstract: To better understand the global hydrologic cycle, climatological simulations with the National Center for Atmospheric Research global atmospheric general circulation model (GCM) or community climate model (CCM1), coupled to a mixed layer model, are compared to available global hydrologic observations. We find that CCM1 simulates, reasonably well, the large-scale precipitable water, moisture flux convergence, precipitation, and evaporation potentials. Regional discrepancies are noticeable, though, especially in the eastern tropical Pacific. Smaller-scale moisture flux convergence, precipitation, and evaporation also compare less well since effects of resolution can be discerned between low-resolution simulations and higher-resolution global observations. Sensitivity experiments to changed CO2 show that the CCM1 hydrologic response is similar to other GCMs. Precipitable water, evaporation, and precipitation increase while snow decreases with increasing CO2. Soil moisture changes are seasonally and regionally dependent. In middle latitudes, soil moisture increases during the winter and decreases during the summer with increasing CO2. Changes in moisture transport between land and ocean are also seasonally dependent. Increased CO2 induces increased moisture divergence over the central equatorial Pacific during December, January, February (DJF). This water is transported to the rest of the northern hemisphere land and ocean where precipitation is much greater than evaporation over the climatologically cold land surface. During June, July, August (JJA), water is preferentially converged over the western Pacific Ocean.
TL;DR: In this article, the authors compare the relative impact of land and sea surface anomalies on Sahel rainfall and describe the associated anomalies in the atmospheric general circulation, showing the importance of land surface parameterization in climate change modelling.
Abstract: The aim of this work is to compare the relative impact of land and sea surface anomalies on Sahel rainfall and to describe the associated anomalies in the atmospheric general circulation. This sensitivity study was done with the Meteo-France climate model: ARPEGE. The sensitivity to land surface conditions consists of changes in the management of water and heat exchanges by vegetation cover and bare soil. The sensitivity to ocean surfaces consists in forcing the lower boundary of the model with worldwide composite sea surface temperature (SST) anomalies obtained from the difference between 4 dry Sahel years and 4 wet Sahel years observed since 1970. For each case, the spatiotemporal variability of the simulated rainfall anomaly and changes in the modelled tropical easterly jet (TEJ) and African easterly jet (AEJ) are discussed. The global changes in land surface evaporation have caused a rainfall deficit over the Sahel and over the Guinea Coast. No significant changes in the simulated TEJ and an enhancement of the AEJ are found; at the surface, the energy budget and the hydrological cycle are substantially modified. On the other hand, SST anomalies induce a negative rainfall anomaly over the Sahel and a positive rainfall anomaly to the south of this area. The rainfall deficit due to those anomalies is consistent with previous diagnostic and sensitivity studies. The TEJ is weaker and the AEJ is stronger than in the reference. The composite impact of SST and land surfaces anomalies is also analyzed: the simulated rainfall anomaly is similar to the observed mean African drought patterns. This work suggests that large-scale variations of surface conditions may have a substantial influence on Sahel rainfall and shows the importance of land surface parameterization in climate change modelling. In addition, it points out the interest in accurately considering the land and sea surfaces conditions in sensitivity studies on Sahel rainfall.
TL;DR: In this article, the frequency of threshold precipitation events is discussed from the perspective of ground-water recharge in arid and semi-arid environments of the Nevada Test Site (NTS).
Abstract: In this paper, the frequency of threshold precipitation events is discussed from the perspective of ground-water recharge in arid and semiarid environments of the Nevada Test Site (NTS). The terminology threshold precipitation refers to precipitation events resulting in the penetration of moisture approximately 1 m into the unsaturated zone at study sites on NTS. While it is not proved that this type of moisture penetration results in ground-water recharge, it is suggested that deep penetration does remove moisture from the atmospheric and surface components of the hydrologic cycle. Estimates of the frequency of episodic recharge events are important from the viewpoint of regional contaminant transport models and provide perspective on the length of precipitation record required to estimate recharge.
TL;DR: In this article, the authors analyzed the annual variation of global-mean precipitable water and associated hydrological cycle with the upper-air data generated by the Global Data Assimilation System of the National Meteorological Center for 1981-1991 and the European Centre for Medium Range Weather Forecasts from 1983-1991.
Abstract: The annual variation of the global-mean precipitable water 〈W〉and the associated hydrological cycle were analyzed with the upper-air data generated by the Global Data Assimilation System of the National Meteorological Center for 1981–1991 and the European Centre for Medium Range Weather Forecasts from 1983–1991. It was found that the annual variation of 〈W〉 coincides with that of the Northern Hemisphere precipitable water [W]NH. The hemispheric-mean ([ ]) water budget analysis shows that water vapor is transported from the winter to the summer hemisphere across the equator by the Hadley circulation, and that the annual variations in the water vapor sink [P – E] for both hemispheres also follow the same seasonal march. The amplitudes of the annual variations in these two hydrological processes are comparable in both hemispheres. Thus, the annual variations of [W]NH and [W]SH are the result of slight imbalances between the cross-equator water vapor transport and the water vapor sink, particularly in the spring and fall. The climatological hemispheric-mean water budgets reveal that the Southern Hemisphere is a water vapor source and the Northern Hemisphere is a water vapor sink. The cross-equator water vapor transport constitutes a major source acting to maintain [W]NH, and in turn 〈W〉. The hydrological mechanism maintaining the observed 〈W〉 annual variation is consistent with that obtained from the hydrological cycle in a 10-year (1979–1988) climate simulation done at the Goddard Laboratory for Atmospheres as part of their participation in the Atmospheric Model Intercomparison Project (AMIP). DOI: 10.1034/j.1600-0870.1996.00001.x
TL;DR: In this paper, a physical-mathematical model is proposed to describe hourly dynamics of water and heat transfers in a forested watershed which is conceptually divided into seven sub-compartments.