ANALYSIS ON CORRELATION AND CAUSES OF MONTHLY PRECIPITATION AND DROUGHTS/FLOODS ON BOTH SIDES OF THE STRAIT FROM 1951 TO 1998

Abstract— The Manabí Hydrographic Demarcation (DHM) is characterized as the only one that does not receive input from Andes Mountains, therefore, its water network is fed exclusively by the rainfall that occurs in the rainy season and that the warm current of El Niño plays a fundamental role in its production. In order to have technical information, important for the planning, control and development of the water resources of the DHM, in this research is made a temporal analysis of the monthly precipitation for 55 years, period 1963-2017. The National Institute of Hydrology and Meteorology of Ecuador (INAMHI) in station M005, located in the Botanical Garden of the Technical University of Manabí (Universidad Técnica de Manabí) in Portoviejo, obtained these records. An analysis is made of the monthly and annual patterns, establishing that the El Niño events that occurred in 1983, 1997 and 1998, have set guidelines for the change in rainwater production at the intensity and temporal distribution levels, increasing the months of drought, while the levels of rainfall increase, concentrating in fewer months, basically in February and March. This is a situation that increases the water deficit especially when there is not enough infrastructure of hydraulic works for the storage and regulation of runoff. Index Terms— Hydrology, rainfall, monthly distribution, annually distribution, climate change, El Niño phenomenon

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Cool season precipitation projections for California and the Western United States in NA-CORDEX models

Climate Dynamics ◽

10.1007/s00382-021-05632-z ◽

2021 ◽

Author(s):

Kelly Mahoney ◽

James D. Scott ◽

Michael Alexander ◽

Rachel McCrary ◽

Mimi Hughes ◽

...

Keyword(s):

United States ◽

Climate Models ◽

Snow Water Equivalent ◽

Regional Climate ◽

Regional Climate Models ◽

Western United States ◽

Monthly Precipitation ◽

Wet Season ◽

Cool Season ◽

Projected Change

AbstractUnderstanding future precipitation changes is critical for water supply and flood risk applications in the western United States. The North American COordinated Regional Downscaling EXperiment (NA-CORDEX) matrix of global and regional climate models at multiple resolutions (~ 50-km and 25-km grid spacings) is used to evaluate mean monthly precipitation, extreme daily precipitation, and snow water equivalent (SWE) over the western United States, with a sub-regional focus on California. Results indicate significant model spread in mean monthly precipitation in several key water-sensitive areas in both historical and future projections, but suggest model agreement on increasing daily extreme precipitation magnitudes, decreasing seasonal snowpack, and a shortening of the wet season in California in particular. While the beginning and end of the California cool season are projected to dry according to most models, the core of the cool season (December, January, February) shows an overall wetter projected change pattern. Daily cool-season precipitation extremes generally increase for most models, particularly in California in the mid-winter months. Finally, a marked projected decrease in future seasonal SWE is found across all models, accompanied by earlier dates of maximum seasonal SWE, and thus a shortening of the period of snow cover as well. Results are discussed in the context of how the diverse model membership and variable resolutions offered by the NA-CORDEX ensemble can be best leveraged by stakeholders faced with future water planning challenges.

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Dry and Wet Climate Periods over Eastern South America: Identification and Characterization through the SPEI Index

Atmosphere ◽

10.3390/atmos12020155 ◽

2021 ◽

Vol 12 (2) ◽

pp. 155

Author(s):

Anita Drumond ◽

Milica Stojanovic ◽

Raquel Nieto ◽

Luis Gimeno ◽

Margarida L. R. Liberato ◽

...

Keyword(s):

South America ◽

Potential Evapotranspiration ◽

Monthly Precipitation ◽

Economic Activities ◽

Central Brazil ◽

Moisture Analysis ◽

Dry Conditions ◽

Wet Climate ◽

Climate Events

A large part of the population and the economic activities of South America are located in eastern regions of the continent, where extreme climate events are a recurrent phenomenon. This study identifies and characterizes the dry and wet climate periods at domain-scale occurring over the eastern South America (ESA) during 1980–2018 through the multi-scalar Standardized Precipitation–Evapotranspiration Index (SPEI). For this study, the spatial extent of ESA was defined according to a Lagrangian approach for moisture analysis. It consists of the major continental sink of the moisture transported from the South Atlantic Ocean throughout the year, comprising the Amazonia, central Brazil, and the southeastern continental areas. The SPEI for 1, 3, 6, and 12 months of accumulation was calculated using monthly precipitation and potential evapotranspiration time series averaged on ESA. The analysis of the climate periods followed two different approaches: classification of the monthly SPEI values as mild, moderate, severe, and extreme; the computation of the events and their respective parameters (duration, severity, intensity, and peak). The results indicate that wet periods prevailed in the 1990s and 2000s, while dry conditions predominated in the 2010s, when the longest and more severe dry events have been identified at the four scales.

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Validation of CHIRPS Precipitation Estimates over Taiwan at Multiple Timescales

Remote Sensing ◽

10.3390/rs13020254 ◽

2021 ◽

Vol 13 (2) ◽

pp. 254 ◽

Cited By ~ 1

Author(s):

Jie Hsu ◽

Wan-Ru Huang ◽

Pin-Yi Liu ◽

Xiuzhen Li

Keyword(s):

Annual Cycle ◽

Interannual Variation ◽

Winter Precipitation ◽

Monthly Precipitation ◽

Precipitation Estimation ◽

Precipitation Estimates ◽

Precipitation Variation ◽

Global Precipitation ◽

Multiple Timescale ◽

Better Than

The Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), which incorporates satellite imagery and in situ station information, is a new high-resolution long-term precipitation dataset available since 1981. This study aims to understand the performance of the latest version of CHIRPS in depicting the multiple timescale precipitation variation over Taiwan. The analysis is focused on examining whether CHIRPS is better than another satellite precipitation product—the Integrated Multi-satellitE Retrievals for Global Precipitation Mission (GPM) final run (hereafter IMERG)—which is known to effectively capture the precipitation variation over Taiwan. We carried out the evaluations made for annual cycle, seasonal cycle, interannual variation, and daily variation during 2001–2019. Our results show that IMERG is slightly better than CHIRPS considering most of the features examined; however, CHIRPS performs better than that of IMERG in representing the (1) magnitude of the annual cycle of monthly precipitation climatology, (2) spatial distribution of the seasonal mean precipitation for all four seasons, (3) quantitative precipitation estimation of the interannual variation of area-averaged winter precipitation in Taiwan, and (4) occurrence frequency of the non-rainy grids in winter. Notably, despite the fact that CHIRPS is not better than IMERG for many examined features, CHIRPS can depict the temporal variation in precipitation over Taiwan on annual, seasonal, and interannual timescales with 95% significance. This highlights the potential use of CHIRPS in studying the multiple timescale variation in precipitation over Taiwan during the years 1981–2000, for which there are no data available in the IMERG database.

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Time Series Analysis of Climatic Variables in Peninsular Spain. Trends and Forecasting Models for Data between 20th and 21st Centuries

Climate ◽

10.3390/cli9070119 ◽

2021 ◽

Vol 9 (7) ◽

pp. 119

Author(s):

Pitshu Mulomba Mukadi ◽

Concepción González-García

Keyword(s):

Time Series ◽

Temperature Series ◽

Climatic Variables ◽

Monthly Precipitation ◽

Agricultural Crops ◽

Arima Models ◽

Cover Time ◽

Pests And Diseases ◽

Historical Series ◽

Preliminary Phase

Time series of mean monthly temperature and total monthly precipitation are two of the climatic variables most easily obtained from weather station records. There are many studies analyzing historical series of these variables, particularly in the Spanish territory. In this study, the series of these two variables in 47 stations of the provincial capitals of mainland Spain were analyzed. The series cover time periods from the 1940s to 2013; the studies reviewed in mainland Spain go up to 2008. ARIMA models were used to represent their variation. In the preliminary phase of description and identification of the model, a study to detect possible trends in the series was carried out in an isolated manner. Significant trends were found in 15 of the temperature series, and there were trends in precipitation in only five of them. The results obtained for the trends are discussed with reference to those of other, more detailed studies in the different regions, confirming whether the same trend was maintained over time. With the ARIMA models obtained, 12-month predictions were made by measuring errors with the observed data. More than 50% of the series of both were modeled. Predictions with these models could be useful in different aspects of seasonal job planning, such as wildfires, pests and diseases, and agricultural crops.

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Evaluating the Spatiotemporal Characteristics of Agricultural Drought in Bangladesh Using Effective Drought Index

Water ◽

10.3390/w11122437 ◽

2019 ◽

Vol 11 (12) ◽

pp. 2437 ◽

Cited By ~ 1

Author(s):

Mohammad Kamruzzaman ◽

Syewoon Hwang ◽

Jaepil Cho ◽

Min-Won Jang ◽

Hanseok Jeong

Keyword(s):

Central Region ◽

Drought Index ◽

Regional Analysis ◽

Mitigation Strategies ◽

Agricultural Drought ◽

Monthly Precipitation ◽

Effective Drought Index ◽

Spatiotemporal Characteristics ◽

North Western

This study aims to assess the spatiotemporal characteristics of agricultural droughts in Bangladesh during 1981–2015 using the Effective Drought Index (EDI). Monthly precipitation data for 36 years (1980–2015) obtained from 27 metrological stations, were used in this study. The EDI performance was evaluated for four sub-regions over the country through comparisons with historical drought records identified by regional analysis. Analysis at a regional level showed that EDI could reasonably detect the drought years/events during the study period. The study also presented that the overall drought severity had increased during the past 35 years. The characteristics (severity and duration) of drought were also analyzed in terms of the spatiotemporal evolution of the frequency of drought events. It was found that the western and central regions of the country are comparatively more vulnerable to drought. Moreover, the southwestern region is more prone to extreme drought, whereas the central region is more prone to severe droughts. Besides, the central region was more prone to extra-long-term droughts, while the coastal areas in the southwestern as well as in the central and north-western regions were more prone to long-term droughts. The frequency of droughts in all categories significantly increased during the last quinquennial period (2011 to 2015). The seasonal analysis showed that the north-western areas were prone to extreme droughts during the Kharif (wet) and Rabi (dry) seasons. The central and northern regions were affected by recurring severe droughts in all cropping seasons. Further, the most significant increasing trend of the drought-affected area was observed within the central region, especially during the pre-monsoon (March–May) season. The results of this study can aid policymakers in the development of drought mitigation strategies in the future.

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Numerical simulations of spreading of the Persian Gulf outflow into the Oman Sea

Ocean Science ◽

10.5194/os-6-887-2010 ◽

2010 ◽

Vol 6 (4) ◽

pp. 887-900 ◽

Cited By ~ 15

Author(s):

M. Ezam ◽

A. A. Bidokhti ◽

A. H. Javid

Keyword(s):

Persian Gulf ◽

Bottom Topography ◽

World Ocean ◽

Monthly Precipitation ◽

Boundary Current ◽

Surface Salinity ◽

Data Set ◽

Open Boundaries ◽

The Mean ◽

The Persian Gulf

Abstract. A three dimensional numerical model namely POM (Princeton Ocean Model) and observational data are used to study the Persian Gulf outflow structure and its spreading pathways during 1992. In the model, the monthly wind speed data were taken from ICOADS (International Comprehensive Ocean-Atmosphere Data Set) and the monthly SST (sea surface temperatures) were taken from AVHRR (Advanced Very High Resolution Radiometer) with the addition of monthly net shortwave radiations from NCEP (National Center for Environmental Prediction). The mean monthly precipitation rates from NCEP data and the calculated evaporation rates are used to impose the surface salinity fluxes. At the open boundaries the temperature and salinity were prescribed from the mean monthly climatological values from WOA05 (World Ocean Atlas 2005). Also the four major components of the tide were prescribed at the open boundaries. The results show that the outflow mainly originates from two branches at different depths in the Persian Gulf. The permanent branch exists during the whole year deeper than 40 m along the Gulf axis and originates from the inner parts of the Persian Gulf. The other seasonal branch forms in the vicinity of the shallow southern coasts due to high evaporation rates during winter. Near the Strait of Hormuz the two branches join and form the main outflow source water. The results of simulations reveal that during the winter the outflow boundary current mainly detaches from the coast well before Ras Al Hamra Cape, however during summer the outflow seems to follow the coast even after this Cape. This is due to a higher density of the colder outflow that leads to more sinking near the coast in winter. Thus, the outflow moves to a deeper depth of about 500 m (for which some explanations are given) while the main part detaches and spreads at a depth of about 300 m. However in summer it all moves at a depth of about 200–250 m. During winter, the deeper, stronger and wider outflow is more affected by the steep topography, leading to separation from the coast. While during summer, the weaker and shallower outflow is less influenced by bottom topography and so continues along the boundary.

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Downscaling of precipitation on a lake basin: evaluation of rule and decision tree induction algorithms

Hydrology Research ◽

10.2166/nh.2012.040 ◽

2012 ◽

Vol 43 (3) ◽

pp. 215-230 ◽

Cited By ~ 22

Author(s):

Manish Kumar Goyal ◽

C. S. P. Ojha

Keyword(s):

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Lake Basin ◽

Monthly Precipitation ◽

M5 Model Tree ◽

Reanalysis Dataset ◽

Model Tree ◽

Basin Scale ◽

M5 Model

We investigate the performance of existing state-of-the-art rule induction and tree algorithms, namely Single Conjunctive Rule Learner, Decision Table, M5 Model Tree, Decision Stump and REPTree. Downscaling models are developed using these algorithms to obtain projections of mean monthly precipitation to lake-basin scale in an arid region in India. The effectiveness of these algorithms is evaluated through application to downscale the predictand for the Lake Pichola region in Rajasthan state in India, which is considered to be a climatically sensitive region. The predictor variables are extracted from (1) the National Centre for Environmental Prediction (NCEP) reanalysis dataset for the period 1948–2000 and (2) the simulations from the third-generation Canadian Coupled Global Climate Model (CGCM3) for emission scenarios A1B, A2, B1 and COMMIT for the period 2001–2100. M5 Model Tree algorithm was found to yield better performance among all other learning techniques explored in the present study. The precipitation is projected to increase in future for A2 and A1B scenarios, whereas it is least for B1 and COMMIT scenarios using predictors.

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The Application of Box–Cox Transformation to Determine the Standardised Precipitation Index (SPI), the Standardised Discharge Index (SDI) and to Identify Drought Events: Case Study in Eastern Kujawy (Central Poland)

Journal of Water and Land Development ◽

10.2478/jwld-2014-0017 ◽

2014 ◽

Vol 22 (1) ◽

pp. 3-15 ◽

Cited By ~ 4

Author(s):

Arkadiusz Bartczak ◽

Ryszard Glazik ◽

Sebastian Tyszkowski

Keyword(s):

Normal Distribution ◽

Meteorological Data ◽

Precipitation Index ◽

Low Flow ◽

Monthly Precipitation ◽

Discharge Data ◽

Central Poland ◽

Winter Half ◽

Bartlett’S Test ◽

Standardised Precipitation Index

Abstract The article presents the results of research into the transformation of series of hydro-meteorological data for determining dry periods with the Standardised Precipitation Index (SPI) and the Standardised Discharge Index (SDI). Time series from eight precipitation stations and five series of river discharge data in Eastern Kujawy (central Poland) were analysed for 1951–2010. The frequency distribution of the series for their convergence with the normal distribution was tested with the Shapiro–Wilk test and homogeneity with the Bartlett's test. The transformation of the series was done with the Box–Cox technique, which made it possible to homogenise the series in terms of variance. In Poland, the technique has never been used to determine the SPI. After the transformation the distributions of virtually all series complied with the normal distribution and were homogeneous. Moreover, a statistically significant correlation between the δ transformation parameter and the skewness of the series of monthly precipitation was observed. It was similar for the series of mean monthly discharges in the winter half-year and the hydrological year. The analysis indicates an alternate occurrence of dry and wet periods both in case of precipitation and run-offs. Drought periods coincided with low flow periods. Thus, the fluctuations tend to affect the development of agriculture more than long-term ones.

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