scholarly journals Assessing the Added Value of Dynamical Downscaling Using the Standardized Precipitation Index

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Jared H. Bowden ◽  
Kevin D. Talgo ◽  
Tanya L. Spero ◽  
Christopher G. Nolte
Keyword(s):  
Climate Model ◽  
Dynamical Downscaling ◽  
Regional Climate ◽  
Standardized Precipitation Index ◽  
Precipitation Index ◽  
Added Value ◽  
Tropical Storms ◽  
The Standardized Precipitation Index ◽  
The Impact ◽  
Resources Planning

In this study, the Standardized Precipitation Index (SPI) is used to ascertain the added value of dynamical downscaling over the contiguous United States. WRF is used as a regional climate model (RCM) to dynamically downscale reanalysis fields to compare values of SPI over drought timescales that have implications for agriculture and water resources planning. The regional climate generated by WRF has the largest improvement over reanalysis for SPI correlation with observations as the drought timescale increases. This suggests that dynamically downscaled fields may be more reliable than larger-scale fields for water resource applications (e.g., water storage within reservoirs). WRF improves the timing and intensity of moderate to extreme wet and dry periods, even in regions with homogenous terrain. This study also examines changes in SPI from the extreme drought of 1988 and three “drought busting” tropical storms. Each of those events illustrates the importance of using downscaling to resolve the spatial extent of droughts. The analysis of the “drought busting” tropical storms demonstrates that while the impact of these storms on ending prolonged droughts is improved by the RCM relative to the reanalysis, it remains underestimated. These results illustrate the importance and some limitations of using RCMs to project drought.

scholarly journals Past and future drought in Northwestern Algeria: the Beni Bahdel Dam catchment

2020 ◽  
Vol 383 ◽  
pp. 315-318
Author(s):  
Senna Bouabdelli ◽  
Ayoub Zeroual ◽  
Mohamed Meddi ◽  
Fateh Djelloul ◽  
Ramdane Alkama
Keyword(s):  
Climate Model ◽  
Regional Climate ◽  
Standardized Precipitation Index ◽  
Circulation Model ◽  
Global Circulation Model ◽  
Drought Duration ◽  
Global Circulation ◽  
Drought Characteristics ◽  
The Standardized Precipitation Index ◽  
The Impact

Abstract. In last decades, the impact of climate change started to appear in the semi-arid regions of the Mediterranean Basin. The severity and frequency of drought events in Northwestern Algeria have affected water resources availability and agriculture. This study aims to evaluate the temporal evolution of drought events characteristics, such as drought duration, frequency and severity, of the Beni Bahdel Dam catchment, Northwestern Algeria. Drought characteristics have been derived from the Standardized precipitation index (SPI) computed for the period from 1941 to 2100 using precipitation data from observations and simulations of the regional climate model RCA4 (Rossby Centre Atmosphere model, version 4). The RCA4 model was forced by the global circulation model MPI-ESM-LR under two Representative Concentration Pathways (RCPs) scenarios. The ability of the model simulations was firstly assessed to reproduce the drought characteristics from observed data (1951–2005). Then, future changes in drought characteristics over the twenty-first century were investigated under the two scenarios (RCP4.5 and RCP8.5). Results show an amplification of drought frequencies and durations in the future under the RCP8.5 scenario.

scholarly journals Climate Change Impact on the Frequency of Hydrometeorological Extremes in the Island of Crete

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 587 ◽  
Author(s):  
Evdokia Tapoglou ◽  
Anthi Vozinaki ◽  
Ioannis Tsanis
Keyword(s):  
Climate Change ◽  
Frequency Analysis ◽  
Extreme Precipitation ◽  
Climate Model ◽  
Regional Climate ◽  
Standardized Precipitation Index ◽  
Hydrological Drought ◽  
Drought Indices ◽  
Rcp Scenarios ◽  
The Impact

Frequency analysis on extreme hydrological and meteorological events under the effect of climate change is performed in the island of Crete. Data from Regional Climate Model simulations (RCMs) that follow three Representative Concentration Pathways (RCP2.6, RCP4.5, RCP8.5) are used in the analysis. The analysis was performed for the 1985–2100 time period, divided into three equal-duration time slices (1985–2010, 2025–2050, and 2075–2100). Comparison between the results from the three time slices for the different RCMs under different RCP scenarios indicate that drought events are expected to increase in the future. The meteorological and hydrological drought indices, relative Standardized Precipitation Index (SPI) and Standardized Runoff index (SRI), are used to identify the number of drought events for each RCM. Results from extreme precipitation, extreme flow, meteorological and hydrological drought frequency analysis over Crete show that the impact of climate change on the magnitude of 100 years return period extreme events will also increase, along with the magnitude of extreme precipitation and flow events.

scholarly journals Impacts of Dynamical Downscaling on Circulation type Statistics: Potential added Value in the Euro-CORDEX Ensemble

2021 ◽  
Author(s):  
Julie Røste ◽  
Oskar A Landgren
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Dynamical Downscaling ◽  
Regional Climate ◽  
Circulation Type ◽  
Global Model ◽  
Added Value ◽  
Classification Methods ◽  
Circulation Types ◽  
Climate Model Simulations

Abstract Atmospheric circulation type classification methods were applied to an ensemble of 57 regional climate model simulations from Euro-CORDEX, their 11 boundary models from CMIP5 and the ERA5 reanalysis. We compared frequencies of the different circulation types in the simulations with ERA5 and found that the regional models add value especially in the summer season. We applied three different classification methods (the subjective Grosswettertypes and the two optimisation algorithms SANDRA and distributed k-means clustering) from the cost733class software and found that the results are not particularly sensitive to choice of circulation classification method. There are large differences between models. Simulations based on MIROC-MIROC5 and CNRM-CERFACS-CNRM-CM5 show an over-representation of easterly flow and an under-representation of westerly. The downscaled results retain the large-scale circulation from the global model most days, but especially the regional model IPSL-WRF381P changes the circulation more often, which increases the error relative to ERA5. Simulations based on ICHEC-EC-EARTH and MPI-M-MPI-ESM-LR show consistently smaller errors relative to ERA5 in all seasons. The ensemble spread is largest in the summer and smallest in the winter. Under the future RCP8.5 scenario, more than half of the ensemble shows an increase in frequency of north-easterly flow and decrease in the Central-Eastern European high and south-easterly flow. There is in general a strong agreement in the sign of the change between the regional simulations and the data from the corresponding global model.

scholarly journals Added Value of Atmosphere-Ocean Coupling in a Century-Long Regional Climate Simulation

Atmosphere ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 537 ◽  
Author(s):  
Fanni Dóra Kelemen ◽  
Cristina Primo ◽  
Hendrik Feldmann ◽  
Bodo Ahrens
Keyword(s):  
Climate Model ◽  
Regional Climate ◽  
Added Value ◽  
Climate Simulation ◽  
Climatic Research Unit ◽  
Small Scale ◽  
Limited Area ◽  
Regional Climate Simulation ◽  
Marginal Seas ◽  
The Impact

A twentieth century-long coupled atmosphere-ocean regional climate simulation with COSMO-CLM (Consortium for Small-Scale Modeling, Climate Limited-area Model) and NEMO (Nucleus for European Modelling of the Ocean) is studied here to evaluate the added value of coupled marginal seas over continental regions. The interactive coupling of the marginal seas, namely the Mediterranean, the North and the Baltic Seas, to the atmosphere in the European region gives a comprehensive modelling system. It is expected to be able to describe the climatological features of this geographically complex area even more precisely than an atmosphere-only climate model. The investigated variables are precipitation and 2 m temperature. Sensitivity studies are used to assess the impact of SST (sea surface temperature) changes over land areas. The different SST values affect the continental precipitation more than the 2 m temperature. The simulated variables are compared to the CRU (Climatic Research Unit) observational data, and also to the HOAPS/GPCC (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data, Global Precipitation Climatology Centre) data. In the coupled simulation, added skill is found primarily during winter over the eastern part of Europe. Our analysis shows that, over this region, the coupled system is dryer than the uncoupled system, both in terms of precipitation and soil moisture, which means a decrease in the bias of the system. Thus, the coupling improves the simulation of precipitation over the eastern part of Europe, due to cooler SST values and in consequence, drier soil.

scholarly journals Dynamical Downscaling with Reinitializations: A Method to Generate Finescale Climate Datasets Suitable for Impact Studies

2013 ◽  
Vol 14 (4) ◽  
pp. 1159-1174 ◽  
Author(s):  
Philippe Lucas-Picher ◽  
Fredrik Boberg ◽  
Jens H. Christensen ◽  
Peter Berg
Keyword(s):  
Climate Model ◽  
Dynamical Downscaling ◽  
Regional Climate ◽  
Temporal Correlation ◽  
Systematic Errors ◽  
Added Value ◽  
Driving Field ◽  
Continuous Simulation ◽  
Impact Studies ◽  
Sequence Of Events

Abstract To retain the sequence of events of a regional climate model (RCM) simulation driven by a reanalysis, a method that has not been widely adopted uses an RCM with frequent reinitializations toward its driving field. In this regard, this study highlights the benefits of an RCM simulation with frequent (daily) reinitializations compared to a standard continuous RCM simulation. Both simulations are carried out with the RCM HIRHAM5, driven with the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-Analysis (ERA-Interim) data, over the 12-km-resolution European Coordinated Regional Climate Downscaling Experiment (CORDEX) domain covering the period 1989–2009. The analysis of daily precipitation shows improvements in the sequence of events and the maintenance of the added value from the standard continuous RCM simulation. The validation of the two RCM simulations with observations reveals that the simulation with reinitializations indeed improves the temporal correlation. Furthermore, the RCM simulation with reinitializations has lower systematic errors compared to the continuous simulation, which has a tendency to be too wet. A comparison of the distribution of wet day precipitation intensities shows similar added value in the continuous and reinitialized simulations with higher variability and extremes compared to the driving field ERA-Interim. Overall, the results suggest that the finescale climate dataset of the RCM simulation with reinitializations better suits the needs of impact studies by providing a sequence of events matching closely the observations, while limiting systematic errors and generating reliable added value. Downsides of the method with reinitializations are increased computational costs and the introduction of temporal discontinuities that are similar to those of a reanalysis.

scholarly journals INDEKS KEKERINGAN SPI (STANDARDIZED PRECIPITATION INDEX) DAN PENGARUHNYA TERHADAP PRODUKTIVITAS HORTIKULTURA TAHUNAN DI KABUPATEN JEMBER

2019 ◽  
Vol 2 (4) ◽  
pp. 149
Author(s):  
Arzaky Ardi Surya Nugroho ◽  
Cahyoadi Bowo ◽  
Joko Sudibya
Keyword(s):  
Standardized Precipitation Index ◽  
Correlation Method ◽  
Precipitation Index ◽  
World Meteorological Organization ◽  
Rainfall Data ◽  
Climate Fluctuations ◽  
Productivity Data ◽  
The Standardized Precipitation Index ◽  
The Impact ◽  
The Relationship

ABSTRACT Perennial tropical horticulture is a superior product whose productivity is affected by water availability. The impact of climate fluctuations due to global warming affects the availability of ground water. This study aims to determine the effect of the Standardized Precipitation Index (SPI) drought index derived from rainfall data on the productivity of perennial horticulture (durian, avocado and rambutan). The study was conducted from July 2016 - November 2018 in 9 sub-districts in Jember Regency where has the highest production. Rainfall data is proceed into SPI data according to the guidelines of the WMO (World Meteorological Organization). Productivity data derived from production data divided by the number of plants. The results of 12 monthly SPI calculations compared with the perennial horticultural productivity data. To find out the relationship between productivity and SPI, the correlation method is used. The results showed that the appropriate SPI value for observing annual horticultural productivity was SPI 9 and 12 monthly. The value of SPI greatly influences the correlation of productivity of durian, avocado and rambutan. Keywords: SPI, productivity, annual horticulture. ABSTRAK Tanaman hortikultura tropis tahunan adalah produk unggulan yang produktivitasnya dipengaruhi oleh ketersediaan air. Dampak fluktuasi iklim akibat pemanasan global mempengaruhi ketersediaan air tanah. Penelitian ini bertujuan untuk mengetahui pengaruh index kekeringan SPI yang berasal dari data curah hujan terhadap produktivitas hotikultura tahunan (durian, alpukat dan rambutan). Penelitian dilakukan mulai bulan Juli 2016 – November 2018 pada 9 Kecamatan dengan produksi tertinggi di Kabupaten Jember. Data curah hujan diolah menjadi data SPI sesuai pedoman WMO (World Meteorological Organization) dan data produktivitas berasal dari data produksi dibagi jumlah tanaman kemudian hasil perhitungan SPI 12 bulanan dibandingkan dengan data produktifitas hortikultura t ahunan. Untuk mengetahui hubungan produktivitas dan SPI digunkan metode korelasi. Hasil penelitian menunjukkan nilai SPI yang sesuai untuk mengamati produktivitas hortikultura tahunan adalah SPI 9 dan 12 bulanan. Nilai SPI sangat berpengaruh terhadap korelasi produktivitas durian, alpukat dan rambutan. Nilai SPI yang semakin tinggi menaikkan produktivitas durian, tetapi menurunkan produktivitas alpukat dan rambutan. Kata Kunci : SPI, produktifitas, hortikuktura tahunan

scholarly journals The Assessment of Climate Change Impact on Meteorological Draught Susceptability on Sampean Watershed

2021 ◽  
Vol 9 (4) ◽  
pp. 146
Author(s):  
Masita Ratih ◽  
Gusfan Halik ◽  
Retno Utami Agung Wiyono
Keyword(s):  
Climate Change ◽  
Atmospheric Circulation ◽  
Drought Index ◽  
Standardized Precipitation Index ◽  
Assessment Method ◽  
Precipitation Index ◽  
Climate Change Scenarios ◽  
Change Impact ◽  
The Standardized Precipitation Index ◽  
The Impact

Drought disasters that occur in the Sampean watershed from time to time have increased, both the intensity of events and the area affected by drought. The general objective of this research is to develop an assessment method for the impact of climate chan ge on vulnerability to drought disasters based on atmospheric circulation data. The specific objectives of this study are to model rainfall predictions based on atmospheric circulation data, predict rainfall in various climate change scenarios (Intergovernm ental Panel on Climate Change, IPCC – AR5), and assess vulnerability to drought disasters using a meteorological approach. The Standardized Precipitation Index (SPI) is one way to analyze the drought index in an area which was developed previous researcher. The Standardized Precipitation Index (SPI) is designed to quantitatively determine the rainfall deficit with various time scales. The advantage of the Standardized Precipitation Index (SPI) is that it is enough to use monthly rainfall data to compare drou ght levels between regions even with different climate types. To facilitate the presentation of the data base on the identification of d rought susceptibility, we need a system that can assist in building, storing, managing and displaying geographically ref erenced information in the form of spatial mapping. This research facilitates monitoring of the area of drought-prone areas, predicts drought levels, prevents future drought disasters, and prepares plans for rebuilding drought-prone areas in the Sampean watershed.

scholarly journals The impact of regional climate model formulation and resolution on simulated precipitation in Africa

2020 ◽  
Vol 11 (2) ◽  
pp. 377-394 ◽  
Author(s):  
Minchao Wu ◽  
Grigory Nikulin ◽  
Erik Kjellström ◽  
Danijel Belušić ◽  
Colin Jones ◽  
...  
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
Horizontal Resolution ◽  
Added Value ◽  
Primary Control ◽  
Model Formulation ◽  
Simulated Precipitation ◽  
Mean Climate ◽  
The Impact

Abstract. We investigate the impact of model formulation and horizontal resolution on the ability of Regional Climate Models (RCMs) to simulate precipitation in Africa. Two RCMs (SMHI-RCA4 and HCLIM38-ALADIN) are utilized for downscaling the ERA-Interim reanalysis over Africa at four different resolutions: 25, 50, 100, and 200 km. In addition to the two RCMs, two different parameter settings (configurations) of the same RCA4 are used. By contrasting different downscaling experiments, it is found that model formulation has the primary control over many aspects of the precipitation climatology in Africa. Patterns of spatial biases in seasonal mean precipitation are mostly defined by model formulation, while the magnitude of the biases is controlled by resolution. In a similar way, the phase of the diurnal cycle in precipitation is completely controlled by model formulation (convection scheme), while its amplitude is a function of resolution. However, the impact of higher resolution on the time-mean climate is mixed. An improvement in one region/season (e.g. reduction in dry biases) often corresponds to a deterioration in another region/season (e.g. amplification of wet biases). At the same time, higher resolution leads to a more realistic distribution of daily precipitation. Consequently, even if the time-mean climate is not always greatly sensitive to resolution, the realism of the simulated precipitation increases as resolution increases. Our results show that improvements in the ability of RCMs to simulate precipitation in Africa compared to their driving reanalysis in many cases are simply related to model formulation and not necessarily to higher resolution. Such model formulation related improvements are strongly model dependent and can, in general, not be considered as an added value of downscaling.

scholarly journals Inconsistencies between observed, reconstructed, and simulated precipitation indices for England since the year 1650 CE

2019 ◽  
Vol 15 (1) ◽  
pp. 307-334 ◽  
Author(s):  
Oliver Bothe ◽  
Sebastian Wagner ◽  
Eduardo Zorita
Keyword(s):  
Regional Climate ◽  
Standardized Precipitation Index ◽  
Climate Simulation ◽  
Sources Of Information ◽  
Internal Climate Variability ◽  
Simulated Precipitation ◽  
Regional Simulation ◽  
The Standardized Precipitation Index ◽  
Instrumental Records ◽  
The Impact

Abstract. The scarcity of long instrumental records, uncertainty in reconstructions, and insufficient skill in model simulations hamper assessing how regional precipitation changed over past centuries. Here, we use standardized precipitation data to compare a regional climate simulation, reconstructions, and long observational records of seasonal (March to July) mean precipitation in England and Wales over the past 350 years. The Standardized Precipitation Index is a valuable tool for assessing agreement between the different sources of information, as it allows for a comparison of the temporal evolution of percentiles of the precipitation distributions. These evolutions are not consistent among reconstructions, a regional simulation, and instrumental observations for severe and extreme dry and wet conditions. The lack of consistency between the different data sets may be due to the dominance of internal climate variability over the impact of natural exogenous forcing conditions on multi-decadal timescales. The disagreement between sources of information reduces our confidence in inferences about the origins of hydroclimate variability for small regions. However, it is encouraging that there is still some agreement between a regional simulation and observations. Our results emphasize the complexity of hydroclimate changes during the recent centuries and stress the necessity of a thorough understanding of the processes affecting forced and unforced precipitation variability.

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