Exploring the 36Cl/Cl input in arid environments: New insights gained by 81Kr groundwater dating in the Negev Desert, Israel

2021 ◽  
Author(s):  
Roi Ram ◽  
Roland Purtschert ◽  
Christof Vockenhuber ◽  
Reika Yokochi ◽  
Eilon M. Adar ◽  
...  
Keyword(s):  
Land Surface ◽  
Noble Gas ◽  
Climatic Conditions ◽  
Arid Environments ◽  
Near Surface ◽  
Spatial Differences ◽  
Practical Tool ◽  
Groundwater Dating ◽  
Long Timescales

<p>   <sup>36</sup>Cl and <sup>81</sup>Kr (half-lives of 301 and 229 kyr, respectively) are among a very few age tracers with dating capabilities in the 10<sup>4</sup>–10<sup>6</sup> yr timescale. Although widely applied since the 1980s in various hydrological studies, the <sup>36</sup>Cl/Cl system has been found complex as an effective dating tool. In contrast, <sup>81</sup>Kr has become a practical tool only recently and is considered to be an ideal dating tool due to the inert properties of the noble gas. In the present study, simultaneous measurements of both radioisotopes were used to assess the <sup>36</sup>Cl/Cl input ratios and the Cl<sup>-</sup> content for paleorecharge into the deep, transboundary Nubian Sandstone Aquifer (NSA) which stretches below the hyperarid deserts of the Sinai Peninsula (Egypt) and the Negev (Israel).</p><p>   By means of <sup>81</sup>Kr data, reconstructed Cl<sup>-</sup> content of recharge that occurred during the late Pleistocene was found to be 300–400 mg/L with an initial <sup>36</sup>Cl/Cl ratio of 50 × 10<sup>-15</sup>. This latter value is in agreement with the <sup>36</sup>Cl/Cl ratio in recent local rainwater, indicating constancy over prolonged periods with possible variable climatic conditions. This similarity in values suggests a process that is rather insensitive to atmospheric <sup>36</sup>Cl fallout rates. Erosion and weathering of near-surface materials in the desert environment could dominate the hydrochemistry of rains, floods, and the consequent groundwater recharge. This near-surface Cl<sup>-</sup> reservoir integrates various sources and processes, including marine and terrestrial Cl<sup>-</sup>, cosmogenic <sup>36</sup>Cl fallout, and cosmogenic <sup>36</sup>Cl production in the shallow unsaturated zone, all of which are active over long timescales and accumulate on the land surface and in the epigene zone.  Spatial differences in the reconstructed initial <sup>36</sup>Cl/Cl ratio are attributed to differences in the mineral aerosol sources for specific recharge areas of the NSA. The results of this study highlight the potential of integrating <sup>81</sup>Kr age information in evaluating the initial <sup>36</sup>Cl/Cl and Cl<sup>-</sup> input, which is essential for the calibration of <sup>36</sup>Cl radioisotope as a long-term dating tool for a given basin.</p>

scholarly journals Spatial Relationship between Precipitation and Runoff in Africa

2018 ◽  
Author(s):  
Fidele Karamage ◽  
Yuanbo Liu ◽  
Xingwang Fan ◽  
Meta Francis Justine ◽  
Guiping Wu ◽  
...  
Keyword(s):  
Land Surface ◽  
Spatial Scales ◽  
Spatial Relationship ◽  
Resource Planning ◽  
Climatic Conditions ◽  
Runoff Coefficient ◽  
Global Precipitation Climatology Centre ◽  
High Runoff ◽  
Monthly Runoff

Abstract. Lack of sufficient and reliable hydrological information is a key hindrance to water resource planning and management in Africa. Hence, the objective of this research is to examine the relationship between precipitation and runoff at three spatial scales, including the whole continent, 25 major basins and 55 countries. For this purpose, the long-term monthly runoff coefficient (Rc) was estimated using the long-term monthly runoff data (R) calculated from the Global Runoff Data Centre (GRDC) streamflow records and Global Precipitation Climatology Centre (GPCC) precipitation datasets for the period of time spanning from 1901 to 2017. Subsequently, the observed Rc data were interpolated in order to estimate Rc over the ungauged basins under guidance of key runoff controlling factors, including the land-surface temperature (T), precipitation (P) and potential runoff coefficient (Co) inferred from the land use and land cover, slope and soil texture information. The results show that 16 % of the annual mean precipitation (672.52 mm) becomes runoff (105.72 mm), with a runoff coefficient of 0.16, and the remaining 84 % (566.80 mm) evapotranspirates over the continent during 1901–2017. Spatial analysis reveals that the precipitation–runoff relationship varies significantly among different basins and countries, mainly dependent on climatic conditions and its inter-annual variability. Generally, high runoff depths and runoff coefficients are observed over humid tropical basins and countries with high precipitation intensity compared to those located in subtropical and temperate drylands.

scholarly journals From Near-Surface to Root-Zone Soil Moisture Using Different Assimilation Techniques

2007 ◽  
Vol 8 (2) ◽  
pp. 194-206 ◽  
Author(s):  
Joaquín Muñoz Sabater ◽  
Lionel Jarlan ◽  
Jean-Christophe Calvet ◽  
François Bouyssel ◽  
Patricia De Rosnay
Keyword(s):  
Soil Moisture ◽  
Data Assimilation ◽  
Land Surface ◽  
Surface Soil ◽  
Diffusion Processes ◽  
Root Zone ◽  
Computational Cost ◽  
Climatic Conditions ◽  
Surface Soil Moisture ◽  
Near Surface

Abstract Root-zone soil moisture constitutes an important variable for hydrological and weather forecast models. Microwave radiometers like the L-band instrument on board the European Space Agency’s (ESA) future Soil Moisture and Ocean Salinity (SMOS) mission are being designed to provide estimates of near-surface soil moisture (0–5 cm). This quantity is physically related to root-zone soil moisture through diffusion processes, and both surface and root-zone soil layers are commonly simulated by land surface models (LSMs). Observed time series of surface soil moisture may be used to analyze the root-zone soil moisture using data assimilation systems. In this paper, various assimilation techniques derived from Kalman filters (KFs) and variational methods (VAR) are implemented and tested. The objective is to correct the modeled root-zone soil moisture deficiencies of the newest version of the Interaction between Soil, Biosphere, and Atmosphere scheme (ISBA) LSM, using the observations of the surface soil moisture of the Surface Monitoring of the Soil Reservoir Experiment (SMOSREX) over a 4-yr period (2001–04). This time period includes contrasting climatic conditions. Among the different algorithms, the ensemble Kalman filter (EnKF) and a simplified one-dimensional variational data assimilation (1DVAR) show the best performances. The lower computational cost of the 1DVAR is an advantage for operational root-zone soil moisture analysis based on remotely sensed surface soil moisture observations at a global scale.

scholarly journals Modeling water balance using the Budyko framework over variable timescales under diverse climates

2017 ◽  
Author(s):  
Chuanhao Wu ◽  
Pat J.-F. Yeh ◽  
Kai Xu ◽  
Bill X. Hu ◽  
Guoru Huang ◽  
...  
Keyword(s):  
Water Balance ◽  
Temporal Variability ◽  
Land Surface ◽  
Potential Evapotranspiration ◽  
Climatic Conditions ◽  
Climate Control ◽  
Temporal Scales ◽  
Control Factors ◽  
Modeling Errors

Abstract. Understanding the effects of climate and catchment characteristics on overall water balance at different temporal scales remains a challenging task due to the large spatial heterogeneity and temporal variability. Based on a long-term (1960–2008) land surface hydrologic dataset over China, this study presented a systematic examination of the applicability of the Budyko model (BM) under various climatic conditions at long-term mean annual, annual, seasonal and monthly temporal scales. The roles of water storage change (WSC, dS/dt) in water balance modeling and the dominant climate control factors on modeling errors of BM are investigated. The results indicate that BM performs well at mean annual scale and the performance in arid climates is better than humid climates. At other smaller timescales, BM is generally accurate in arid climates, but fails to capture dominant controls on water balance in humid climates due to the effects of WSC not included in BM. The accuracy of BM can be ranked from high to low as: dry seasonal, annual, monthly, and wet seasonal timescales. When WSC is incorporated into BM by replacing precipitation (P) with effective precipitation (i.e., P minus WSC), significant improvements are found in arid climates, but to a lesser extent in humid climates. The ratio of the standard deviation of WSC to that of evapotranspiration (E), which increases from arid to humid climates, is found to be the key indicator of the BM simulation errors due to the omission of the effect of WSC. The modeling errors of BM are positively correlated with the temporal variability of WSC and hence larger in humid climates, and also found to be proportional to the ratio of potential evapotranspiration (PET) to E. More sophisticated models than the BM which explicitly incorporate the effect of WSC are required to improve water balance modeling in humid climates particularly at all the annual, seasonal, and monthly timescales.

Correction of Inhomogeneities in Observed Land Surface Temperatures over China

2020 ◽  
Vol 33 (20) ◽  
pp. 8885-8902
Author(s):  
Jizeng Du ◽  
Kaicun Wang ◽  
Baoshan Cui ◽  
Shaojing Jiang
Keyword(s):  
Climate Change ◽  
Land Surface ◽  
Surface Air Temperature ◽  
Warming Trend ◽  
Cmip5 Models ◽  
Near Surface ◽  
Land Surface Temperatures ◽  
Long Term Trends ◽  
The Difference

AbstractLand surface temperature Ts and near-surface air temperature Ta are two main metrics that reflect climate change. Recently, based on in situ observations, several studies found that Ts warmed much faster than Ta in China, especially after 2000. However, we found abnormal jumps in the Ts time series during 2003–05, mainly caused by the transformation from manual to automatic measurements due to snow cover. We explore the physical mechanism of the differences between automatic and manual observations and develop a model to correct the automatic observations on snowy days in the observed records of Ts. Furthermore, the nonclimatic shifts in the observed Ts were detected and corrected using the RHtest method. After corrections, the warming rates for Ts-max, Ts-min, and Ts-mean were 0.21°, 0.34°, and 0.25°C decade−1, respectively, during the 1960–2014 period. The abnormal jump in the difference between Ts and Ta over China after 2003, which was mentioned in existing studies, was mainly caused by inhomogeneities rather than climate change. Through a combined analysis using reanalyses and CMIP5 models, we found that Ts was consistent with Ta both in terms of interannual variability and long-term trends over China during 1960–2014. The Ts minus Ta (Ts − Ta) trend is from −0.004° to 0.009°C decade−1, accounting for from −3.19% to 5.93% (from −3.09% to 6.39%) of the absolute warming trend of Ts (Ta).

Development of a 50-Year High-Resolution Global Dataset of Meteorological Forcings for Land Surface Modeling

2006 ◽  
Vol 19 (13) ◽  
pp. 3088-3111 ◽  
Author(s):  
Justin Sheffield ◽  
Gopi Goteti ◽  
Eric F. Wood
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Hydrologic Cycle ◽  
Surface Fluxes ◽  
Specific Humidity ◽  
Meteorological Variables ◽  
Coupled Models ◽  
Near Surface ◽  
Solid Precipitation

Abstract Understanding the variability of the terrestrial hydrologic cycle is central to determining the potential for extreme events and susceptibility to future change. In the absence of long-term, large-scale observations of the components of the hydrologic cycle, modeling can provide consistent fields of land surface fluxes and states. This paper describes the creation of a global, 50-yr, 3-hourly, 1.0° dataset of meteorological forcings that can be used to drive models of land surface hydrology. The dataset is constructed by combining a suite of global observation-based datasets with the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis. Known biases in the reanalysis precipitation and near-surface meteorology have been shown to exert an erroneous effect on modeled land surface water and energy budgets and are thus corrected using observation-based datasets of precipitation, air temperature, and radiation. Corrections are also made to the rain day statistics of the reanalysis precipitation, which have been found to exhibit a spurious wavelike pattern in high-latitude wintertime. Wind-induced undercatch of solid precipitation is removed using the results from the World Meteorological Organization (WMO) Solid Precipitation Measurement Intercomparison. Precipitation is disaggregated in space to 1.0° by statistical downscaling using relationships developed with the Global Precipitation Climatology Project (GPCP) daily product. Disaggregation in time from daily to 3 hourly is accomplished similarly, using the Tropical Rainfall Measuring Mission (TRMM) 3-hourly real-time dataset. Other meteorological variables (downward short- and longwave radiation, specific humidity, surface air pressure, and wind speed) are downscaled in space while accounting for changes in elevation. The dataset is evaluated against the bias-corrected forcing dataset of the second Global Soil Wetness Project (GSWP2). The final product provides a long-term, globally consistent dataset of near-surface meteorological variables that can be used to drive models of the terrestrial hydrologic and ecological processes for the study of seasonal and interannual variability and for the evaluation of coupled models and other land surface prediction schemes.

scholarly journals Regularities of soil temperature changes during the period with snow cover in modern climatic conditions of the Eurasian Subarctic

2021 ◽  
pp. 13-22
Author(s):  
Lev M. Kitaev
Keyword(s):  
Standard Deviation ◽  
Soil Temperature ◽  
Snow Cover ◽  
Air Temperature ◽  
Land Surface ◽  
Environmental Changes ◽  
Surface Air Temperature ◽  
Climatic Conditions ◽  
Winter Period

The influence of snow cover on the dynamics of soil temperature in the modern climatic conditions of the Eurasian Subarctic was investigated through a quantitative assessment of the features of the seasonal and long-term variation of parameters. Seasonal and long-term values of soil temperature for stable snow period decrease from west to east: a decrease of snow thickness and air temperature from west to east of Eurasia leads to a weakening of the heat-insulating properties of the snow cover with a significant decrease in regional air temperatures. With the emergence of a stable snow cover, the soil temperature seasonal and long-term standard deviation sharply decreases compared to the autumn and spring periods. With the appearance of snow cover, the soil temperature standard deviation drops sharply compared to the autumn and spring periods. An exception is the northeast of Siberia: here, a relatively small thickness of snow determines a noticeable dependence of the course of soil temperature on the dynamics of surface air temperature. There are no significant long-term trends in soil temperature due to its low variability during winter period. Analysis of the course of the studied characteristics anomalies showed an insignificant and non-systematic number of their coincidences. Currently, we have not found similar research results for large regions. The revealed patterns can be used in the analysis of the results of monitoring the state of the land surface, in the development of remote sensing algorithms, in the refinement of predictive scenarios of environmental changes.

scholarly journals Drought Model DISS Based on the Fusion of Satellite and Meteorological Data under Variable Climatic Conditions

2020 ◽  
Vol 12 (18) ◽  
pp. 2944
Author(s):  
Katarzyna Dabrowska-Zielinska ◽  
Alicja Malinska ◽  
Zbigniew Bochenek ◽  
Maciej Bartold ◽  
Radoslaw Gurdak ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Land Surface ◽  
Drought Index ◽  
Extreme Values ◽  
Meteorological Data ◽  
Climatic Conditions ◽  
Agricultural Drought ◽  
Drought Monitoring ◽  
Large Area

The use of effective methods for large-area drought monitoring is an important issue; hence, there have been many attempts to solve this problem. In this study, the Drought Information Satellite System (DISS) index is presented, based on the synergistic use of meteorological data and information derived from satellite images. The index allows us to monitor drought phenomena in various climatic and environmental conditions. The approach utilizes two indices for constructing a drought index: (1) the hydrothermal coefficient (HTC), which characterizes meteorological conditions across the study area over a long-term period; and (2) the temperature condition index (TCI) derived from Moderate-resolution Imaging Spectroradiometer (MODIS) data, which refers instantaneous land surface temperature (LST) to long-term extreme values. The model for drought assessment based on the DISS index was applied for generating drought index maps for Poland for the 2001–2019 vegetation seasons. The performance of the index was verified through comparison of the extent of agricultural drought to the reduction in cereal and maize yield. Analysis of variance revealed a significant relationship between the area of drought determined by the drought index and the decrease in cereal yield due to unfavorable growth conditions. The presented study proves that the proposed drought index can be an effective tool for large-area drought monitoring under variable environmental conditions.

Future trends in global water vs. energy-controlled evaporative regimes

2021 ◽  
Author(s):  
Jasper Denissen ◽  
Adriaan Teuling ◽  
Wantong Li ◽  
Markus Reichstein ◽  
Andy Pitman ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Climate Model ◽  
Global Climate ◽  
Coupled Model ◽  
Energy Availability ◽  
Water Control ◽  
Near Surface ◽  
Global Patterns

<p>Water and energy availability govern the exchange of carbon, energy and water between the land surface and the atmosphere and therefore exert influence on near-surface weather. Roughly one can distinguish between two evaporative regimes: One limited by available energy (under wet conditions) and one limited by available soil moisture (under dry conditions). The transition between these evaporative regimes has been studied on local to global scales using observational and modelled datasets. This revealed the complexity of defining this transition, as it varies both in space and time and is sensitive to climate, soil and vegetation characteristics.</p><p>In this study, we characterized this transition by comparing the correlations of evaporation anomalies with (i) soil moisture anomalies (proxy for strength of water control) and (ii) temperature anomalies (proxy for strength of energy control). In the first step, we use observation-based data to derive global patterns of evaporative regimes and establish that the regime transition is sensitive to not only long-term average soil moisture, but also long-term average temperature. Analyzing historical and future climate model simulations from the Coupled Model Intercomparison Project (CMIP6), we found that the ensemble mean of the CMIP6 models produces similar global patterns and sensitivities to energy and water availability. However, there is ample disagreement between results of individual models, with the largest spread around the transition zones. Further, the disagreement between individual models on the total area of water-limited regions increases gradually in time from historical to future experiments. In the next step, we attribute trends in evaporative regimes to trends in water and energy availability, CO<sub>2</sub> and vapor pressure deficit. This research reveals how global climate change translates into regional-global scale trends in water- vs. energy-controlled evaporative regimes. Our observational results can constrain modelled global evaporative regimes and inform future model development to decrease the substantial spread across the present model ensemble.</p>

scholarly journals Dispersion of Smoke Plumes over South America

2021 ◽  
Vol 25 (1) ◽  
pp. 1-14
Author(s):  
Mark R. Jury ◽  
América R. Gaviria Pabón
Keyword(s):  
South America ◽  
Biomass Burning ◽  
Land Surface ◽  
Trace Gases ◽  
Climatic Conditions ◽  
Atmospheric Environment ◽  
Plume Dispersion ◽  
Near Surface ◽  
Fire Emissions ◽  
Smoke Plumes

AbstractSatellite and reanalysis products are used to study the atmospheric environment, aerosols, and trace gases in smoke plumes over South America in the period 2000–18. Climatic conditions and fire density maps provide context to link biomass burning across the southern Amazon region (5°–15°S, 50°–70°W) to thick near-surface plumes of trace gases and fine aerosols. Intraseasonal weather patterns that underpin greater fire emissions in the dry season (July–October) are exacerbated by high pressure over a cool eastern Pacific Ocean, for example in September 2007. Smoke-plume dispersion simulated with HYSPLIT reveals a slowing of westward transport between sources in eastern Brazil and the Andes Mountains. During cases of thick smoke plumes over southern Amazon, an upper ridge and sinking motions confine trace gases and fine aerosols below 4 km. Long-term warming, which tends to coincide with the zone of biomass burning, is +0.03°C yr−1 in the air and +0.1°C yr−1 at the land surface. Our study suggests that weather conditions promoting fire emissions also tend to limit dispersion.

Modelling of Moisture Movement in Wood during Outdoor Storage

2001 ◽  
Vol 6 (2) ◽  
pp. 3-14 ◽  
Author(s):  
R. Baronas ◽  
F. Ivanauskas ◽  
I. Juodeikienė ◽  
A. Kajalavičius
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
Climatic Conditions ◽  
Two Dimensional ◽  
Moisture Movement ◽  
Finite Difference Technique ◽  
Long Term Storage ◽  
Space Formulation ◽  
Term Storage

A model of moisture movement in wood is presented in this paper in a two-dimensional-in-space formulation. The finite-difference technique has been used in order to obtain the solution of the problem. The model was applied to predict the moisture content in sawn boards from pine during long term storage under outdoor climatic conditions. The satisfactory agreement between the numerical solution and experimental data was obtained.

Sign in / Sign up

Export Citation Format

Share Document