scholarly journals Stochastic Modeling of Daily Summertime Rainfall over the Southwestern United States. Part II: Intraseasonal Variability

2007 ◽  
Vol 8 (4) ◽  
pp. 938-951 ◽  
Author(s):  
Jingyun Wang ◽  
Bruce T. Anderson ◽  
Guido D. Salvucci
Keyword(s):  
United States ◽  
Stochastic Models ◽  
Intraseasonal Variability ◽  
Daily Rainfall ◽  
Summer Season ◽  
Southwestern United States ◽  
Rainfall Events ◽  
Seasonal Evolution ◽  
Dry Spells ◽  
Dry Spell

Abstract The intraseasonal variability of summertime precipitation over the southwestern United States is examined using stochastic daily occurrence models combined with empirical daily rainfall distributions to document 1) the seasonal evolution of the frequency and intensity of rainfall events across the summertime monsoon season and 2) the climatological evolution of wet spells, dry spells, and storm events. Study results indicate that the evolution of the North American monsoon system (NAMS) is most apparent in the occurrence of daily rainfall events, which exhibit clear time dependence across the summer season over the southwestern United States and can be principally portrayed by stochastic models. In contrast, the seasonal evolution of NAMS is largely absent in the averaged daily rainfall amount time series. There is also a significant seasonal evolution in the length of dry spells. In the central area of the domain (approximately 39 out of 78 stations) dry-spell lengths tend to increase over the course of the summer season, while on the western fringe (8 out of 78 stations) dry-spell lengths tend to decrease. In contrast, wet spells tend to exhibit constant lengths over the course of the season (44 out of 78 stations). The seasonal trend for storms indicates that the number and duration of storms tend to decrease in September; however, the storm depths tend to be more intense, particularly over the western portion of the domain. Overall, 90% of the area-averaged variance for dry-spell lengths can be explained by the random daily evolution of the stochastic model alone. For wet-spell lengths, the area-averaged variance explained by the stochastic models is 98% and for storm amounts it is 92%. These results suggest that the characteristics of most intraseasonal events over this region (i.e., spell lengths and storm amounts) can be captured by the random evolution of daily rainfall models, even with constant year-to-year statistical parameters, indicating that systematic variations in the background climatic conditions from one year to the next may contribute little to the characteristics of these events.

scholarly journals Observed Trends in Summertime Precipitation over the Southwestern United States

2010 ◽  
Vol 23 (7) ◽  
pp. 1937-1944 ◽  
Author(s):  
Bruce T. Anderson ◽  
Jingyun Wang ◽  
Guido Salvucci ◽  
Suchi Gopal ◽  
Shafiqul Islam
Keyword(s):  
United States ◽  
Daily Rainfall ◽  
Southwestern United States ◽  
Storm Activity ◽  
Rainfall Events ◽  
Precipitation Characteristics ◽  
Monsoon Area ◽  
Intense Storm ◽  
Dry Spell ◽  
Current Century

Abstract In this paper, the authors evaluate the significance of multidecadal trends in seasonal-mean summertime precipitation and precipitation characteristics over the southwestern United States using stochastic, chain-dependent daily rainfall models. Unlike annual-mean precipitation, trends during the summertime monsoon, covering the period 1931–2000, indicate an overall increase in seasonal precipitation, the number of rainfall events, and the coverage of rainfall events in peripheral regions north of the “core” monsoon area of Arizona and western New Mexico. In addition, there is an increasing trend in intense storm activity and a decreasing trend in extreme dry-spell lengths. Over other regions of the domain, there are no discernible trends found in any of the observed characteristics. These trends are robust to the choice of start dates and, in the case of seasonal-mean precipitation, appear to persist into the current century.

scholarly journals Influence of Daily Rainfall Characteristics on Regional Summertime Precipitation over the Southwestern United States

2009 ◽  
Vol 10 (5) ◽  
pp. 1218-1230 ◽  
Author(s):  
Bruce T. Anderson ◽  
Jingyun Wang ◽  
Suchi Gopal ◽  
Guido Salvucci
Keyword(s):  
United States ◽  
Large Scale ◽  
Daily Precipitation ◽  
Daily Rainfall ◽  
Southwestern United States ◽  
Regional Variability ◽  
Rainfall Frequency ◽  
Circulation Patterns ◽  
Precipitation Characteristics ◽  
Precipitation Anomalies

Abstract The regional variability in the summertime precipitation over the southwestern United States is studied using stochastic chain-dependent models generated from 70 yr of station-based daily precipitation observations. To begin, the spatiotemporal structure of the summertime seasonal mean precipitation over the southwestern United States is analyzed using two independent spatial cluster techniques. Four optimal clusters are identified, and their structures are robust across the techniques used. Next, regional chain-dependent models—comprising a previously dependent occurrence chain, an empirical rainfall coverage distribution, and an empirical rainfall amount distribution—are constructed over each subregime and are integrated to simulate the regional daily precipitation evolution across the summer season. Results indicate that generally less than 50% of the observed interannual variance of seasonal precipitation in a given region lies outside the regional chain-dependent models’ stochastic envelope of variability; this observed variance, which is not captured by the stochastic model, is sometimes referred to as the “potentially predictable” variance. In addition, only a small fraction of observed years (between 10% and 20% over a given subregime) contain seasonal mean precipitation anomalies that contribute to this potentially predictable variance. Further results indicate that year-to-year variations in daily rainfall coverage are the largest contributors to potentially predictable seasonal mean rainfall anomalies in most regions, whereas variations in daily rainfall frequency contribute the least. A brief analysis for one region highlights how the identification of years with potentially predictable precipitation characteristics can be used to better understand large-scale circulation patterns that modulate the underlying daily rainfall processes responsible for year-to-year variations in regional rainfall.

Impacts of the North Atlantic Subtropical High on Daily Summer Precipitation over the Conterminous United States

2021 ◽  
Author(s):  
Enrico Zorzetto ◽  
Laifang Li
Keyword(s):  
United States ◽  
North Atlantic ◽  
Daily Rainfall ◽  
Summer Precipitation ◽  
Subtropical High ◽  
Rainfall Events ◽  
North Atlantic Subtropical High ◽  
The North ◽  
The North Atlantic ◽  
The Impact

AbstractBy modulating the moisture flux from ocean to adjacent land, the North Atlantic Subtropical High (NASH) western ridge significantly influences summer-season total precipitation over the Conterminous United States (CONUS). However, its influence on the frequency and intensity of daily rainfall events over the CONUS remains unclear. Here we introduce a Bayesian statistical model to investigate the impacts of the NASH western ridge position on key statistics of daily-scale summer precipitation, including the intensity of rainfall events, the probability of precipitation occurrence, and the probability of extreme values. These statistical quantities play a key role in characterizing both the impact of wet extremes (e.g., the probability of floods) and dry extremes. By applying this model to historical rain gauge records (1948-2019) covering the entire CONUS, we find that the western ridge of the NASH influences the frequency of rainfall as well as the distribution of rainfall intensities over extended areas of the CONUS. In particular, we find that the NASH ridge also modulates the frequency of extreme rainfall, especially that over part of the Southeast and upper Midwest. Our analysis underlines the importance of including the NASH western ridge position as a predictor for key statistical rainfall properties to be used for hydrological applications. This result is especially relevant for projecting future changes in daily rainfall regimes over the CONUS based on the predicted strengthening of the NASH in a warming climate.

Dry Spells Occurrence in Tamale, Northern Ghana – Review of Available Information

2014 ◽  
Vol 9 (4) ◽  
pp. 468-474 ◽  
Author(s):  
Gordana Kranjac-Berisavljevic ◽  
◽  
Shayibu Abdul-Ghanyu ◽  
Bizoola Zinzoola Gandaa ◽  
Felix K. Abagale
Keyword(s):  
Crop Production ◽  
Crop Yields ◽  
Daily Rainfall ◽  
Northern Ghana ◽  
Growth Stages ◽  
African Region ◽  
Rainfed Rice ◽  
Dry Spells ◽  
Rain Season ◽  
Dry Spell

Sustainable crop production is important for food security in Northern Ghana, where highly variable rainfall coupled with high evaporation rates and soils prone to degradation combine to produce low crop yields of main staple crops that are vital for local people’s livelihoods. Rainfall in this region generally ranges between 800 mm and 1200 mm per annum, falling within a single rainy season from April to October, with a peak in late August-September. This amount is adequate for most arable crops such as maize, rainfed rice, soybeans, and yams. Intermittent dry spells occur, however, at critical crop growth stages, resulting in significant yield reductions. Several studies conducted in this area show that dry spells can be expected during each annual rain season, with a high level of certainty and duration fromtwo to three days up to four weeks. This paper reviews both available literature on dry spell incidence and rainfall prediction in the West African region, with a particular focus on northern Ghana. Available daily rainfall data for 52 consecutive years are analyzed to determine dry spell duration and occurrence in northern Ghana.

scholarly journals Warm Season Dry Spells in the Central and Eastern United States: Diverging Skill in Climate Model Representation

2016 ◽  
Vol 29 (15) ◽  
pp. 5617-5624 ◽  
Author(s):  
Siyu Zhao ◽  
Yi Deng ◽  
Robert X. Black
Keyword(s):  
United States ◽  
Large Scale ◽  
Climate Model ◽  
Warm Season ◽  
Hierarchical Cluster ◽  
Model Representation ◽  
Cmip5 Models ◽  
Eastern United States ◽  
Dry Spells ◽  
Dry Spell

Abstract Warm season dry spells over the central and eastern United States are classified into three canonical types via a hierarchical cluster analysis for the period 1950–2005. Four CMIP5 models exhibit diverging skill in representing the observed behavior, ranging from southern Great Plains dry spells that are reasonably simulated by all four models to southeastern U.S. dry spells that are only accurately captured by one model. A model’s skill in representing a particular dry spell cluster is positively correlated with the model’s ability to simulate the large-scale meteorological patterns (LMPs) accompanying the dry spell. The interannual variability and overall observed decreasing trend in dry spell days are represented with varying degrees of accuracy by the four models. The results 1) highlight existing shortcomings in the climate model representation of regional dry spells and 2) illustrate the importance of properly simulating the observed spectrum of LMPs in minimizing these shortcomings.

scholarly journals Stochastic Modeling of Daily Summertime Rainfall over the Southwestern United States. Part I: Interannual Variability

2006 ◽  
Vol 7 (4) ◽  
pp. 739-754 ◽  
Author(s):  
Jingyun Wang ◽  
Bruce T. Anderson ◽  
Guido D. Salvucci
Keyword(s):  
United States ◽  
Interannual Variability ◽  
Daily Precipitation ◽  
Temporal Structure ◽  
Daily Rainfall ◽  
Second Order ◽  
Precipitation Process ◽  
Total Precipitation ◽  
Southwestern United States ◽  
Dependent Model

Abstract The interannual variability of summertime daily precipitation at 78 stations in the southwestern United States is studied using chain-dependent models and nonparametric empirical distributions of daily rainfall amounts. Modeling results suggest that a second-order chain-dependent model can optimally portray the temporal structure of the summertime daily precipitation process over the southwestern United States. The unconditioned second-order chain-dependent model, in turn, can explain approximately 75% of the interannual variance in the seasonal total wet days over the region and 83% of the interannual variance in the seasonal total precipitation. In addition, only a small fraction (generally smaller than 20%) of the observed years at any given station show statistically significant changes in the occurrence and intensity characteristics, related to either the number of seasonal total wet days or the distributions of daily rainfall amounts. Investigations of the year-to-year variations in the occurrence and intensity characteristics indicate that both variations are random (on interannual time scales), and they display similar significance in explaining the remaining 17% of interannual variance of seasonal total precipitation over the region. However, numerical tests suggest that the interannual variations of the two are not independent for the summertime monsoon precipitation, and that complex covariability that cannot be described with simple stochastic statistical models may exist between them.

scholarly journals Two Simple Metrics for Quantifying Rainfall Intermittency: The Burstiness and Memory of Interamount Times

2015 ◽  
Vol 17 (1) ◽  
pp. 421-436 ◽  
Author(s):  
Marc Schleiss ◽  
James A. Smith
Keyword(s):  
United States ◽  
Daily Rainfall ◽  
The United States ◽  
Precipitation Patterns ◽  
Rain Gauges ◽  
The United Kingdom ◽  
Regional Trends ◽  
Dry Spells ◽  
Wide Range ◽  
Dry Climates

Abstract Precipitation displays a remarkable variability in space and time. An important yet poorly documented aspect of this variability is intermittency. In this paper, a new way of quantifying intermittency based on the burstiness B and memory M of interamount times is proposed. The method is applied to a unique dataset of 325 high-resolution rain gauges in the United States and Europe. Results show that the M–B diagram provides useful insight into local precipitation patterns and can be used to study intermittency over a wide range of temporal scales. It is found that precipitation tends to be more intermittent in warm and dry climates with the largest observed values in the southwest of the United States (i.e., California, Nevada, Arizona, and Texas). Low-to-moderate values are reported for the northeastern United States, the United Kingdom, the Netherlands, and Germany. In the second half of the paper, the new metrics are applied to daily rainfall data for 1954–2013 to investigate regional trends in intermittency due to climate variability and global warming. No evidence is found of a global shift in intermittency but a weak trend toward burstier precipitation patterns and longer dry spells in the south of Europe (i.e., Portugal, Spain, and Italy) and an opposite trend toward steadier and more correlated precipitation patterns in Norway, Sweden, and Finland is observed.

scholarly journals Influência de veranico na produção agrícola no município de Santa Filomena, Piauí, Brasil

2015 ◽  
Vol 10 (5) ◽  
pp. 21
Author(s):  
H. E. A. Menezes ◽  
R. M. de Medeiros ◽  
J. L. G. Santos ◽  
T. S. Lima ◽  
T. A. Pimenta
Keyword(s):  
Agricultural Production ◽  
Broad Bean ◽  
Daily Rainfall ◽  
Precipitation Series ◽  
Banana Production ◽  
Rainfall Station ◽  
Dry Spells ◽  
Dry Spell ◽  
Proportional Relationship ◽  
The Relationship

<p>O objetivo deste estudo foi verificar a relação entre a duração, em dias, dos maiores veranicos, e as produções de arroz, cana-de-açúcar, fava, feijão, mandioca, milho, banana e laranja para Santa Filomena – PI. Os dados utilizados consistem de séries diárias de precipitação do posto pluviométrico localizado em Santa Filomena – PI e gentilmente cedido pela empresa de assistência técnica e extensão rural do estado do Piauí (EMATER) para o período de dezembro de 1992 a março de 2010 e de produção agrícola anual das referidas culturas disponibilizadas pelo Instituto Brasileiro de Geografia e Estatística (IBGE) para o período de 1993 a 2010. Considerou-se veranico como sendo o número de dias consecutivos sem chuva ou com chuva abaixo de 2,0 mm/dia. E o mais longo período de veranico da estação chuvosa (dezembro a março), não havendo quebra entre os meses. Resultou-se que as produções de milho e banana no município de Santa Filomena – PI apresentaram relações diretamente proporcionais aos maiores veranicos ocorridos no período estudado. A produção de laranja foi inversamente proporcional aos maiores veranicos e as produções de arroz, cana-de-açúcar, fava, feijão e mandioca foram independentes da duração de veranicos.</p><p> </p><p align="center"><strong><em>Influence of veranico in agricultural production in the Santa Filomena city, Piauí state, Brazil</em></strong></p><p>The objective of this study was to investigate the relationship between the duration in days, the biggest dry spells, and the production of rice, sugarcane, broad bean, bean, cassava, corn, banana and orange for Santa Filomena – PI city. The data used consist of daily rainfall station precipitation series located in Santa Filomena – PI city and kindly provided by the service company and extension of the Piauí state (EMATER) for the period December 1992 to March 2010 and production annual agricultural cultures of those offered by the Brazilian Institute of Geography and Statistics (IBGE) for the period 1993 to 2010. It was considered dry spells as the number of consecutive days without rain or rain below 2.0 mm/day. And the longest dry spell period of the rainy season (December to March), with no breaks between the months. It resulted that the corn and banana production in Santa Filomena – PI city presented directly proportional relationship to the larger dry spells occurred during the study period. The orange production was inversely proportional to dry spells higher productions and rice, sugarcane, broad bean, bean and cassava were independent of the duration dry spells.</p><p align="center"><strong><em><br /></em></strong></p>

scholarly journals A study on effective monsoon and dry spells of short return periods The Indian mountain ranges during monsoon months in two north Bengal districts

MAUSAM ◽  
2021 ◽  
Vol 47 (2) ◽  
pp. 145-148
Author(s):  
A. D. DAS ◽  
S. K. MUKHOPADHYAY
Keyword(s):  
Monsoon Season ◽  
Daily Rainfall ◽  
Return Periods ◽  
Mountain Ranges ◽  
Dry Spells ◽  
Rainfed Farming ◽  
Dry Spell ◽  
Expected Length ◽  
The Mean ◽  
North Bengal

This article uses daily rainfall data (April-October) of Cooch Behar (1971-90) and Jalpaiguri (1972-90), the two predominantly rainfed farming districts of Terai zone of West Bengal, to study the, nature of different rainfall parameters of this area. It was observed that the mean date of Onset of Effective Monsoon (OEM) of this region is about one month in advance from the normal occurrence of monsoon over Kerala. However, the monsoon rains, here, retreat at about the same time with those of  Kerala. Distribution of the duration of dry spell has been studied to have some idea of the nature of critical dry spells during the monsoon season. The article also examines how prolonged, on the average, are the monsoon breaks for different return periods. Expected length of dry spell (in days) for 2, 5, 10 and 20 years return periods have been estimated with the help of suitably fitted curves for each location.

Sign in / Sign up

Export Citation Format

Share Document