Climatic trends in Israel during the period 1970-2002 were studied in detail on the basis of three parameters: average annual temperature, annual precipitation and the annual aridity (humidity) index P/PET (P = Precipitation; PET = Potential Evapotranspiration). Significant warming is evident in all 12 evaluated meteorological stations, situated in different parts of Israel. Along the Mediterranean coast, the average annual precipitation and P/PET values remained more or less at the same level. However, more inland, both eastward and southward, precipitation and P/PET trends are declining, indicating increased aridity. Eilat, Beer Sheva and Sedom Pans, situated in the desert, showed the most significant increase in aridity among the 12 meteorological stations we investigated. The relationship between changes in temperature and precipitation showed a negative correlation in all cases except for Eilat, the southernmost and driest part of Israel. The negative correlations for Negba, Kefar Blum, Har Kena'an, Beer Sheva and Sedom Pans are statistically significant. In conclusion, the climate in Israel has become more arid in most regions, except for the coastal plain.
Recent and potential future increases in global temperature are likely to be associated with impacts on the hydrological cycle, including changes to precipitation and increases in extreme events such as droughts. This study has investigated the spatial and temporal changes in drought occurrence in far and mid-western regions of Nepal. Quantification of the severity and frequency of drought within different physiographical regions have been worked out with the help of Standardized Reconnaissance Drought Index (RDIst). Time series analyses of mean annual rainfall and annual temperature datasets of 16 meteorological stations covering far and mid western development regions from 1982-2012 have been used. It has been revealed that all the three kinds (moderate, severe and extreme) of droughts occurred in the study area. Extreme drought was recorded in four stations (Dadeldhura, Patan, Tikapur and Silgadhi) of far west region and five stations (Musikot, Dailekh, Surkhet, Tulsipur and Khajura) of mid western region. These events occurred when precipitation recorded its lowest range. Most frequent droughts were observed in Dhangadhi, Dadeldhura and Jumla. There were higher number of droughts in far western region but more extreme events occurred in mid western region. No clear correlation was found between temperature and precipitation trends in five selected stations except in Dhangadi that lies in Terai region.DOI: http://dx.doi.org/njst.v15i2.12118Nepal Journal of Science and Technology Vol. 15, No.2 (2014) 65-76
Abstract:Spatial distribution of evapotranspiration (ET) over a complex terrain is estimated using a new approach of the conventional two-source energy balance (TSEB) model by considering the effect of topography (difference in slope and aspect). We name this approach topography considered two-source energy balance (T 2 SEB) model. The novelty of this model is the estimation of incoming shortwave solar radiation considering slope, aspect, altitude, latitude, longitude, and the day of calculation in the TSEB model, so that the new model should have wider applicability than existing models over topographically complex areas. In this study, high spatial resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and meteorological data are used. ET over a complex terrain of Nagoya, Japan, on three different dates, 4 November 2005, 25 May 2004 and 30 October 2003, is estimated using both TSEB and T 2 SEB models. To validate both models, estimated results are compared with ground observation data at the flux tower site. Moreover, estimated results from TSEB and T 2 SEB models are compared in five different locations of different topography within the study area. Variation of net radiation absorbed by the surface (R n ) with topographical variables is also studied with the help of scatter plots. Estimated results for all three dates agreed within š75 W m 2 with calculated values from both models at the flux tower site. TSEB underestimated/overestimated ET in sunlit/shaded areas in hilly areas. The T 2 SEB model estimated ET in hilly areas better than the TSEB model.
Every year, South Asian countries suffer from declining agricultural outputs due to climate extremes such as floods and droughts. Recurrent droughts have depressed rural economies and enhanced widespread hunger and human migration to South Asian cities (Miyan, 2015). Due to climatic changes, the region is projected to experience rising temperatures and more frequent extreme weather events in the long term (Trenberth et al., 2014). Accurate predictions of drought, its impact, and early detection facilities are not present in most South Asian countries due to a lack of sufficient hydro-meteorological datasets, poor access to satellite products, and shortages of well-trained staff. This study seeks to address these deficiencies scientifically by analysing historical drought conditions on a regional scale using open-access satellite products. The Drought Severity Index (DSI) has been employed to assess meteorological droughts from 2000 to 2020 and to prepare drought severity maps for the South Asian region. Results from DSI were further compared with the Standardised Precipitation Index (SPI) in Nepal and Bangladesh. The results identified pre-monsoon months as the driest period in South Asian countries experiencing severe to moderate drought.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.