Regional crop water use assessment using Landsat-derived evapotranspiration     

Arun Bawa  Gabriel B. Senay  Sandeep Kumar 《水文研究》2021,35(1):e14015

Reliable information on water use and availability at basin and field scales are important to ensure the optimized constructive uses of available water resources. This study was conducted with the specific objective to estimate Landsat-based actual evapotranspiration (ETa) using the Operational Simplified Surface Energy Balance (SSEBop) model across the state of South Dakota (SD), USA for the 1986–2018 (33-year) period. Validated ETa estimations (r² = 0.91, PBIAS = −4%, and %RMSE = 11.8%) were further used to understand the crop water-use characteristics and existing historic mono-directional (increasing/decreasing) trends over the eastern (ESD) and western (WSD) regions of SD. The crop water-use characteristics indicated that the annual cropland water uses across the ESD and WSD were more or less met by the precipitation amounts in the area. The ample water supply and distribution have led to high rainfed and low percentage of irrigated cropland (~2.5%) in the state. The WSD faced greater crop-water use reductions than the ESD during drought periods. The landscape ETa responses across the state were found to be more sensitive than precipitation for the drought impact assessments. The Mann Kendall trend analysis revealed the absence of a significant trend (p > 0.05) in annual ETa at a regional scale due to the varying weather conditions in the state. However, about 12% and 9% cropland areas in the ESD and WSD, respectively, revealed a significant mono-directional trend at pixel scale ETa. Most of the pixels under significant trend showed an increasing trend that can be explained by the shift in agricultural practices, increased irrigated cropland area, higher productions, moisture regime shifts, and decreased risk of farming in the dry areas. The decreasing trend pixels were clustered in mid-eastern SD and could be the result of dynamic conversion of wetlands to croplands and decreased irrigation practices in the region. This study also demonstrates the tremendous potential and robustness of the SSEBop model, Landsat imagery, and remote sensing-based ETa modelling approaches in estimating consistent spatially distributed evapotranspiration.  相似文献   

The Multiscale TROPIcal CatchmentS critical zone observatory M-TROPICS dataset III: Hydro-geochemical monitoring of the Mule Hole catchment,south India     

Jean Riotte  Laurent Ruiz  Stéphane Audry  Benjamin Baud  Jean-Pierre Bedimo Bedimo  Laurie Boithias  Jean-Jacques Braun  Bernard Dupré  Jean-Louis Duprey  Mikael Faucheux  Christelle Lagane  Jean-Christophe Marechal  Hemanth Moger  Mandalagiri Subbarayappa Mohan Kumar  Harshad Parate  Olivier Ribolzi  Emma Rochelle-Newall  Buvaneshwari Sriramulu  Murari Varma  Muddu Sekhar 《水文研究》2021,35(5):e14196

Despite the importance of tropical ecosystems for climate regulation, biodiversity, water and nutrient cycles, only a few Critical Zone Observatories (CZOs) are located in the tropics. Among these, most are in humid climates, while very few data exist for semi-arid and sub-humid climates, due to the difficulty of estimating hydro-geochemical balances in catchments with ephemeral streams. We contribute to fill this gap by presenting a meteorological and hydro-geochemical dataset acquired at the Mule Hole catchment (4.1 km²), a pristine dry deciduous forest located in a biosphere reserve in south India. The dataset consists of time series of variables related to (i) meteorology, including rainfall, air temperature, relative humidity, wind speed and direction, and global radiation, (ii) hydrology, including water level and discharge at the catchment outlet, (iii) hydrogeology, including manual (monthly) and/or automated (from 15 min to hourly) groundwater levels in nine piezometers and (iv) geochemistry, including suspended sediment content in the stream and chemical composition of rainfall (event based), groundwater (monthly sampling) and stream water (storm events, 15 min to hourly frequency with an automatic sampler). The time series extend from 2003 to 2019. Measurement errors are minimized by frequent calibration of sensors and quality checks, both in the field and in the laboratory. Despite these precautions, several data gaps exist, due to occasional access restriction to the site and instrument destruction by wildlife. Results show that large seasonal and interannual variations of climatic conditions were reflected in the large variations of stream flow and groundwater recharge, as well as in water chemical composition. Notably, they reveal a long-term evolution of groundwater storage, suggesting hydrogeological cycles on a decadal scale. This dataset, alone or in combination with other data, has already allowed to better understand water and element cycling in tropical dry forests, and the role of forest diversity on biogeochemical cycles. As tropical ecosystems are underrepresented by Critical Zone Observatories, we expect this data note to be valuable for the global scientific community.  相似文献   

Spectral analysis of wind and temperature components during lightning in pre-monsoon season over Ranchi     

Arun K. Dwivedi  Sagarika Chandra  Manoj Kumar  Sanjay Kumar  N. V. P. Kiran Kumar 《Meteorology and Atmospheric Physics》2015,127(1):95-105

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Variability in aerosol optical properties and radiative forcing over Gorongosa (18.97oS, 34.35oE) in Mozambique     

A. Joseph Adesina  K. Raghavendra Kumar  V. Sivakumar 《Meteorology and Atmospheric Physics》2015,127(2):217-228

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Stability evaluation of hill cut slopes along national highway-13 near Hospet,Karnataka, India     

Ravi Kumar Umrao  T. N. Singh 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2015,9(3):158-170

The road networks are backbone of a nation for the economic growth and safe communication. A shortest road design shall always be encouraged, but in hilly terrain, railway crossings and road crossings are constraints for the highway designers. The same problem was faced while planning a new design of National Highway-13 near the Hospet city in Karnataka, India. To resolve that problem, a twin tunnel was proposed to overcome steep gradient, sharp curve and a railway crossing. The field investigation was carried out to measure the joint parameters, lithology and ground water condition to establish the tunnel and tunnel portal stability along with hill cuttings. In the present study, the basic rock mass rating (RMR_Basic) and continuous slope mass rating (CSMR) of the slope outside tunnel portal were computed based on the field investigation for different rocks of Sandur schist belt viz. metabasics, phyllite/chlorite schist and banded iron formation. The support measures were proposed based on the computed CSMR.  相似文献   

Source and seasonal variation in the major ion chemistry of two eastern Himalayan high altitude lakes,India     

Jyoti Prakash Deka  Goman Tayeng  Sangeeta Singh  Raza Rafiqul Hoque  Amit Prakash  Manish Kumar 《Arabian Journal of Geosciences》2015,8(12):10597-10610

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Projecting date palm distribution in Iran under climate change using topography,physicochemical soil properties,soil taxonomy,land use,and climate data     

Farzin Shabani  Lalit Kumar  Subhashni Taylor 《Theoretical and Applied Climatology》2014,118(3):553-567

This study set out to model potential date palm distribution under current and future climate scenarios using an emission scenario, in conjunction with two different global climate models (GCMs): CSIRO-Mk3.0 (CS), and MIROC-H (MR), and to refine results based on suitability under four nonclimatic parameters. Areas containing suitable physicochemical soil properties and suitable soil taxonomy, together with land slopes of less than 10° and suitable land uses for date palm (Phoenix dactylifera) were selected as appropriate refining tools to ensure the CLIMEX results were accurate and robust. Results showed that large regions of Iran are projected as likely to become climatically suitable for date palm cultivation based on the projected scenarios for the years 2030, 2050, 2070, and 2100. The study also showed CLIMEX outputs merit refinement by nonclimatic parameters and that the incremental introduction of each additional parameter decreased the disagreement between GCMs. Furthermore, the study indicated that the least amount of disagreement in terms of areas conducive to date palm cultivation resulted from CS and MR GCMs when the locations of suitable physicochemical soil properties and soil taxonomy were used as refinement tools.  相似文献   

SST and ENSO variability and change simulated in historical experiments of CMIP5 models   总被引：1，自引：1，他引：0  

Bhaskar Jha  Zeng-Zhen Hu  Arun Kumar 《Climate Dynamics》2014,42(7-8):2113-2124

This work documents the diversity in Coupled Model Inter-comparison Project Phase 5 (CMIP5) models in simulating different aspects of sea surface temperature (SST) variability, particularly those associated with the El Niño–Southern Oscillation (ENSO), as well as the impact of low-frequency variations on the ENSO variability and its global teleconnection. The historical simulations (1870–2005) include 10 models with ensemble member ranging from 3 to 10 that are forced with observed atmospheric composition changes reflecting both natural and anthropogenic forcings. It is shown that the majority of the CMIP5 models capture the relative large SST anomaly variance in the tropical central and eastern Pacific, as well as in North Pacific and North Atlantic. The frequency of ENSO is not well captured by almost all models, particularly for the period of 5–6 years. The low-frequency variations in SST caused by external forcings affect the SST variability and also modify the global teleconnection of ENSO. The models reproduce the global averaged SST low-frequency variations, particularly since 1970s. However, majority of the models are unable to correctly simulate the spatial pattern of the observed SST trends. These results suggest that it is still a challenge to reproduce the features of global historical SST variations with the state-of-the-art coupled general circulation model.  相似文献   

Attribution of SST variability in global oceans and the role of ENSO     

Arun Kumar  Bhaskar Jha  Hui Wang 《Climate Dynamics》2014,43(1-2):209-220

Based on a novel design of coupled model simulations where sea surface temperature (SST) variability in the equatorial tropical Pacific was constrained to follow the observed El Niño—Southern Oscillation (ENSO) variability, while rest of the global oceans were free to evolve, the ENSO response in SSTs over the other ocean basins was analyzed. Conceptually the experimental setup was similar to discerning the contribution of ENSO variability to interannual variations in atmospheric anomalies. A unique feature of the analysis was that it was not constrained by a priori assumptions on the nature of the teleconnected response in SSTs. The analysis demonstrated that the time lag between ENSO SST and SSTs in other ocean basins was about 6 months. A signal-to-noise analysis indicated that between 25 and 50 % of monthly mean SST variance over certain ocean basins can be attributed to SST variability over the equatorial tropical Pacific. The experimental setup provides a basis for (a) attribution of SST variability in global oceans to ENSO variability, (b) a method for separating the ENSO influence in SST variations, and (c) understanding the contribution from other external factors responsible for variations in SSTs, for example, changes in atmospheric composition, volcanic aerosols, etc.  相似文献   

Imprint of the Atlantic multi-decadal oscillation and Pacific decadal oscillation on southwestern US climate: past,present, and future     

Petr Chylek  Manvendra K. Dubey  Glen Lesins  Jiangnan Li  Nicolas Hengartner 《Climate Dynamics》2014,43(1-2):119-129

The surface air temperature increase in the southwestern United States was much larger during the last few decades than the increase in the global mean. While the global temperature increased by about 0.5 °C from 1975 to 2000, the southwestern US temperature increased by about 2 °C. If such an enhanced warming persisted for the next few decades, the southwestern US would suffer devastating consequences. To identify major drivers of southwestern climate change we perform a multiple-linear regression of the past 100 years of the southwestern US temperature and precipitation. We find that in the early twentieth century the warming was dominated by a positive phase of the Atlantic multi-decadal oscillation (AMO) with minor contributions from increasing solar irradiance and concentration of greenhouse gases. The late twentieth century warming was about equally influenced by increasing concentration of atmospheric greenhouse gases (GHGs) and a positive phase of the AMO. The current southwestern US drought is associated with a near maximum AMO index occurring nearly simultaneously with a minimum in the Pacific decadal oscillation (PDO) index. A similar situation occurred in mid-1950s when precipitation reached its minimum within the instrumental records. If future atmospheric concentrations of GHGs increase according to the IPCC scenarios (Solomon et al. in Climate change 2007: working group I. The Physical Science Basis, Cambridge, 996 pp, 2007), climate models project a fast rate of southwestern warming accompanied by devastating droughts (Seager et al. in Science 316:1181–1184, 2007; Williams et al. in Nat Clim Chang, 2012). However, the current climate models have not been able to predict the behavior of the AMO and PDO indices. The regression model does support the climate models (CMIP3 and CMIP5 AOGCMs) projections of a much warmer and drier southwestern US only if the AMO changes its 1,000 years cyclic behavior and instead continues to rise close to its 1975–2000 rate. If the AMO continues its quasi-cyclic behavior the US SW temperature should remain stable and the precipitation should significantly increase during the next few decades.  相似文献