Paediatric elbow fractures and public play spaces: adherence to standards for children’s playground equipment and surfacing

BackgroundSupracondylar humerus fractures (SCHF) are the most common fractures sustained following a fall onto an outstretched hand among healthy children, and one of the leading causes of hospital admission and surgical intervention. The aim of this study was to examine SCHF occurring at public play spaces—particularly to determine whether or not the playground equipment implicated in injurious falls aligned with Canadian playground safety standards.MethodsCases of children who attended the provincial paediatric orthopaedic clinic following SCHF at a public playground between April 2017 and October 2019 were included in the study. A research assistant visited each playground to measure the play structure type and dimensions, height of the equipment at the point from which the child fell and the type and depth of the surface material, and compare measurements to the 2016 safety standards. Child demographics and injury classification were also noted. Descriptive statistics were calculated and a scatterplot of fall height and surface depth was generated.ResultsForty-three sites, representing 47 SCHF cases (18 female, 29 male), were included in the final analysis. Fourteen children sustained type 1 fracture, 23 had type 2 fracture and the remaining 10 had type 3 fracture. Five children with type 2 fracture and all 10 children with type 3 fracture required surgery. The majority of sites had engineered wood fibre surfacing, with surfacing at 35 sites being less than 300 mm deep. Twenty-six play structures were upper body equipment (ie, monkey bars or similar), seven were track rides, five were rotating structures and the rest comprised a variety of classified and unclassified structures. Twenty-seven children fell from a height exceeding 2 m.ConclusionsThe majority of SCHF cases occurred at playgrounds with insufficient surface depth and/or non-compliant equipment. Upper body equipment, track rides and rotating play structures were of particular concern, as the children fell from heights exceeding the recommended standard, likely reflecting the degradation and compaction of the surfacing material over time.

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Methodological Challenges in Investigating Supracondylar Fractures of the Humerus From a Child’s Viewpoint: Evolution of Study Protocol

JMIR Research Protocols ◽

10.2196/21816 ◽

2020 ◽

Vol 9 (11) ◽

pp. e21816

Author(s):

Brittany Tara Lim ◽

Harpreet Chhina ◽

Ian Pike ◽

Mariana Brussoni ◽

Anthony Cooper

Keyword(s):

Phase 1 ◽

Healthy Children ◽

Supracondylar Fractures ◽

Severe Injuries ◽

Safety Standards ◽

Methodological Challenges ◽

Elbow Fractures ◽

Potential Risk Factors ◽

Structure Height ◽

Serious Injuries

Background Outdoor play and risk-taking behaviors, including play at heights, are important to children’s physical, social, and cognitive development. These aspects of play are important to consider when informing prevention policies for serious injuries that commonly occur on play structures. Supracondylar fractures of the humerus (SCH) are the most common type of elbow fractures that result from falls on an outstretched hand among healthy children. Despite being one of the leading causes of admission to the hospital and surgical intervention, the details surrounding the cause of these injuries are often not recorded. Previous research has correlated decreased overall playground safety with higher rates of SCH fractures. Play structure height and the type of undersurface have been identified as potential risk factors for severe injuries, including SCH fractures, in part due to low compliance with safety standards. This paper explores the challenges we encountered designing the study and the resulting insights and methodological modifications we made. Objective The aim of this paper is to discuss the challenges related specifically to clinical research in pediatrics and strategies developed to conduct a study that prioritizes the engagement and perspective of children and their families. Methods To explore the link between the severity of SCH fractures and children’s behavioral, environmental, and mechanistic factors, we conducted a mixed-methods study. Results During phase 1 (the original methodology) from April 2017 to July 2018, there were 58 eligible study participants and 17 were recruited. For phase 2 (the revised methodology) between October 2018 and October 2019, there were 116 eligible participants and 47 were recruited. Conclusions The changes in methodology made following the first phase of data collection were effective in our ability to recruit participants. By identifying and addressing challenges pertaining to recruitment and resource limitations, we were able to collect data in a concise manner while not compromising the quality of the data and make for an easily adoptable methodology for other sites interested in participating in the study. We hope that future studies that plan to employ a similar methodology can gain insight through the methodological challenges we have encountered and the way we adapted the methodology to build a more pragmatic approach. International Registered Report Identifier (IRRID) DERR1-10.2196/21816

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Complications and Predictors of Need for Return to the Operating Room in the Treatment of Supracondylar Humerus Fractures in Children

The Open Orthopaedics Journal ◽

10.2174/1874325001509010139 ◽

2015 ◽

Vol 9 (1) ◽

pp. 139-142 ◽

Cited By ~ 8

Author(s):

Matthew E Oetgen ◽

Gudrun E Mirick ◽

Lara Atwater ◽

John F Lovejoy

Keyword(s):

Risk Factors ◽

Operating Room ◽

Nerve Palsy ◽

Patient Age ◽

Post Operative Period ◽

Supracondylar Humerus Fractures ◽

Younger Patient ◽

Humerus Fractures ◽

Type 3

Supracondylar humerus fractures are common pediatric injuries. Little is known about the risk factors for repeat operative procedures. A retrospective chart review of 709 patients treated for a displaced supracondylar humerus fracture was performed to identify risk factors for return to the operating room during the initial post-operative period. Deviations of routine fracture care were recorded and complication rates were compared between Gartland type 2 and 3 fractures using logistic regression. Type 3 fractures were found to have a higher complication rate, and, specifically, more peri-operative nerve palsies, more likely to need to return to the operating room for hardware removal, to lose fracture reduction, and require a return to the operating room for any reason. Five risk factors which may require returning to the operating room were identified: younger patient age, left sided fractures, type 3 fractures, peri-operative nerve palsy, and post-operative infection. In conclusion, Gartland type 3 supracondylar humerus fractures are associated with more complications then type 2 fractures. Risk factors for the need to return to the operating room in the post-operative period include: younger patient age, left sided fractures, type 3 fractures, peri-operative nerve palsy, and post-operative infection. Patients with these risk factors should be considered at risk for return to the OR and fracture fixation and follow up protocols should be adjusted for this risk. Level of Evidence : Prognostic Study, Level II.

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Evaluation of the Severity and Pattern of Epistaxis In Children with a Mucocutaneous Bleeding Disorder and In Healthy Children Using a Standardized Questionnaire

Blood ◽

10.1182/blood.v116.21.713.713 ◽

2010 ◽

Vol 116 (21) ◽

pp. 713-713

Author(s):

Catherine I. Segbefia ◽

Tina T. Biss ◽

Dewi S. Clark ◽

James Riddel ◽

Paula D. James ◽

...

Keyword(s):

Medical Intervention ◽

Bleeding Disorder ◽

Healthy Children ◽

Clinically Significant ◽

Seasonal Correlation ◽

Bleeding History ◽

Type 3 ◽

Mucocutaneous Bleeding

Abstract Abstract 713 Epistaxis is a common symptom in children with mucocutaneous bleeding disorders such as von Willebrand disease (VWD) or a platelet function disorder (PFD), but also occurs in healthy children. Determining the features of epistaxis that suggest underlying hemostatic defects would help distinguish which children with epistaxis should undergo laboratory testing to screen for an inherited bleeding disorder. This is particularly significant in young children who may not yet have been exposed to a hemostatic challenge. However, there is no standardized approach to determine which children presenting with epistaxis should undergo testing. The aim of this study was to describe the severity and pattern of epistaxis in children with VWD or a PFD vs. healthy children using the PBQ, a standardized, validated Pediatric Bleeding Questionnaire (Bowman et al, J Thromb Haemost 2009:7;1418). PBQ epistaxis scores were assigned depending on clinical severity of the most severe episode (0: no epistaxis or trivial, ≤5/yr; 1: >5/yr or >10 min duration; 2: consultation with a healthcare professional; 3: packing, cauterization or antifibrinolytics; 4: blood transfusion, replacement therapy or desmopressin); scores of ≥2 were considered clinically significant. Epistaxis scores and features (frequency, duration, onset (spontaneous or not), site (uni- or bilateral), presence of seasonal correlation, whether cessation required medical intervention) were retrospectively reviewed in 107 questionnaires administered to patients/parents of patients with a known diagnosis of VWD (type 1, n=60 [definite, with abnormal laboratory results at least twice + a significant bleeding history, n=37; possible, with abnormal laboratory results at least once ± a significant bleeding history, n=23]; type 2, n=8; type 3, n=16) or a PFD (Glanzmann thrombasthenia, dense granule disorder, MYH9-related disorder, Noonan syndrome, Ehlers-Danlos syndrome, unspecified; n=23) and in 163 questionnaires administered to healthy children (Bowman et al, J Thromb Haemost 2009:7;1418; Biss et al, J Thromb Haemost 2010:8;950; Biss et al, J Thromb Haemost 2010:8;1416). Epistaxis was present in 66/107 patients (62%) (definite type 1 VWD: 62%; possible type 1 VWD: 48%; type 2 VWD: 38%; type 3 VWD: 75%; PFD: 74%) with a median age of 12 yrs (range: 0.6–18.3 yrs), and in 56/163 healthy children (34%), with a median age of 11.5 yrs (range: 1.5–17.0 yrs). 59% of the 66 patients with epistaxis were males, as were 50% of the 56 controls with epistaxis. The mean PBQ epistaxis score in these 66 patients with VWD or a PFD was greater, 2.1 (range: 0–4), than in the 56 controls, 0.4 (range: 0–2) (P<0.0001). The mean PBQ epistaxis score in patients varied according to underlying diagnosis and was greater in those with type 3 VWD (3.1) than in the patients with definite type 1 VWD (2.2), possible type 1 VWD (0.8), type 2 VWD (2.0) or a PFD (2.1) (P<0.05). There was no effect of age or gender on PBQ epistaxis scores within patient and control groups. 38/66 patients (58%) had a clinically significant score compared to only 5/56 (9%) of controls (P<0.0001). Epistaxis frequency (>5 episodes/yr) was greater in patients than controls, 44/66 (67%) vs. 11/56 (20%) (P<0.0001). More patients (41/66; 62%) had epistaxis lasting >10 min compared with controls (5/56; 9%) (P<0.0001). Most patients and controls reported spontaneous onset of epistaxis − 57/66 (86%) and 44/56 (79%), respectively (P=0.2316). However, a greater number of patients bled from both nostrils (51/66; 77%) than controls (15/56; 27%) (P<0.0001). Seasonal correlation of epistaxis occurred less frequently in the patient group; 14/66 patients (21%) had epistaxis only during 1 or 2 specified seasons of the year while 24/56 controls (43%) had seasonal correlation of epistaxis (P=0.0219). More patients (38/66; 58%) required medical intervention for cessation of epistaxis than controls (5/56; 9%) (P<0.0001). In conclusion, the standardized PBQ is useful in the assessment of epistaxis pattern and severity in children with a mucocutaneous bleeding disorder – VWD or a PFD. The severity score is significantly greater in patients vs. controls. Features of epistaxis suggestive of an underlying bleeding disorder include: epistaxis frequency >5 episodes/yr; duration >10 min; epistaxis occurring from both nostrils; lack of seasonal correlation; and need for medical intervention for cessation. Disclosures: No relevant conflicts of interest to declare.

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Methodological Challenges in Investigating Supracondylar Fractures of the Humerus From a Child’s Viewpoint: Evolution of Study Protocol (Preprint)

10.2196/preprints.21816 ◽

2020 ◽

Author(s):

Brittany Tara Lim ◽

Harpreet Chhina ◽

Ian Pike ◽

Mariana Brussoni ◽

Anthony Cooper

Keyword(s):

Phase 1 ◽

Healthy Children ◽

Supracondylar Fractures ◽

Severe Injuries ◽

Safety Standards ◽

Methodological Challenges ◽

Elbow Fractures ◽

Potential Risk Factors ◽

Structure Height ◽

Serious Injuries

BACKGROUND Outdoor play and risk-taking behaviors, including play at heights, are important to children’s physical, social, and cognitive development. These aspects of play are important to consider when informing prevention policies for serious injuries that commonly occur on play structures. Supracondylar fractures of the humerus (SCH) are the most common type of elbow fractures that result from falls on an outstretched hand among healthy children. Despite being one of the leading causes of admission to the hospital and surgical intervention, the details surrounding the cause of these injuries are often not recorded. Previous research has correlated decreased overall playground safety with higher rates of SCH fractures. Play structure height and the type of undersurface have been identified as potential risk factors for severe injuries, including SCH fractures, in part due to low compliance with safety standards. This paper explores the challenges we encountered designing the study and the resulting insights and methodological modifications we made. OBJECTIVE The aim of this paper is to discuss the challenges related specifically to clinical research in pediatrics and strategies developed to conduct a study that prioritizes the engagement and perspective of children and their families. METHODS To explore the link between the severity of SCH fractures and children’s behavioral, environmental, and mechanistic factors, we conducted a mixed-methods study. RESULTS During phase 1 (the original methodology) from April 2017 to July 2018, there were 58 eligible study participants and 17 were recruited. For phase 2 (the revised methodology) between October 2018 and October 2019, there were 116 eligible participants and 47 were recruited. CONCLUSIONS The changes in methodology made following the first phase of data collection were effective in our ability to recruit participants. By identifying and addressing challenges pertaining to recruitment and resource limitations, we were able to collect data in a concise manner while not compromising the quality of the data and make for an easily adoptable methodology for other sites interested in participating in the study. We hope that future studies that plan to employ a similar methodology can gain insight through the methodological challenges we have encountered and the way we adapted the methodology to build a more pragmatic approach. INTERNATIONAL REGISTERED REPORT DERR1-10.2196/21816

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A comparison of fluoroscopic exposure and operative time during treatment of displaced supracondylar elbow fractures in children

Trauma ◽

10.1177/1460408617742676 ◽

2017 ◽

Vol 21 (1) ◽

pp. 40-44

Author(s):

Cameron Hand ◽

James J Bresnahan ◽

William L Hennrikus

Keyword(s):

Closed Reduction ◽

Operative Time ◽

Cumulative Risk ◽

Fluoroscopy Time ◽

Percutaneous Pinning ◽

Supracondylar Fractures ◽

Fractures In Children ◽

Elbow Fractures ◽

Type 3

Background Intraoperative fluoroscopy can potentially expose the surgeon to levels of radiation beyond the recommended limits. This study aimed to assess the intraoperative differences between the fixation of types 2 and 3 supracondylar fractures for fluoroscopy time, operative time, direction of displacement, and potential cumulative risk of radiation to the surgeon. Methods Retrospective chart analysis was used to review 74 consecutive subjects with type 2 or 3 extension supracondylar fractures over a six-year period. Closed reduction and percutaneous pinning with fluoroscopy was used in all cases. Fluoroscopy time and operative time were analyzed based on the fracture type, direction of initial displacement, and the number of K-wires used. Results Type 2 supracondylar fractures require less fluoroscopy (mean: 16.8 s) and are shorter operations (mean: 19.2 min) when compared to type 3 (26.2 s and 25.1 min; p<0.05). The direction of displacement (posteromedial vs. posterolateral) did not influence operative (23.8 vs. 26.5 min) or fluoroscopy times (27.6 vs. 24.9 s; p>0.05). Conclusions Type 3 supracondylar fractures utilize more fluoroscopy time and operative time than type 2 fractures. The direction of displacement did not affect fluoroscopy time or operative time. Surgeons who perform large numbers of closed reduction and percutaneous pinning may be exposed to excess amounts of radiation.

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FUNCTIONAL STATUS AND ADAPTIVE POTENTIAL IN FOREIGN STUDENTS WITH DIFFERENT TYPES OF VEGETATIVE REGULATION DURING TUITION

Ulyanovsk Medico-biological Journal ◽

10.34014/2227-1848-2020-1-118-126 ◽

2020 ◽

pp. 118-126

Author(s):

A.M. Satarkulova

Keyword(s):

Heart Rate ◽

Foreign Students ◽

Autonomic Regulation ◽

The Body ◽

Functional Changes ◽

Different Types ◽

Type 3 ◽

Adaptive Abilities

The assessment and dynamic control over students’ status is a very important task. It allows timely detection of prenosological status prior to pathology and health maintenance in students. The objective of the paper is to assess the adaptive abilities of the body, to analyze changes in heart rate variability indicators in students with various types of autonomic regulation, to identify prenosological status and precursory pathological symptoms. Materials and Methods. The study enrolled 302 students from India, aged 21.54±1.43. Programming complex «Psychophysiologist» was used to register the main HRV parameters within 5 minutes. Health status was evaluated according to the index of functional changes and the scale of functional states. Results. N.I. Shlyk (2009) distinguished two groups of students with different types of autonomic regulation: type 1 (53 %) with moderate and type 2 (5 %) with marked characteristics of central regulation profile, type 3 (35 %) with moderate and type 4 (7 %) with marked characteristics of autonomous regulation profile. Main parameters of HRV and adaptation potential were defined for each student.All the parameters characterized functional and health status. Conclusions. It was shown that 82 % of trial subjects (type 1), 53 % (type 2), 94 % (type 3) and 95 % (type 4) demonstrated satisfactory adaptation and their physiological processes were at an optimal level. 18 % of students (type 1) demonstrated reduced adaptive abilities of the body. Moreover, they were under moderate stress. 47 % of subjects (type 2) were also under a significant stress, which was proven by excessively high SI, low SDNN and TP, and an increased index of functional changes. 5 % of students (type 4) revealed dysfunctional characteristics in the heart rhythm, peculiar to pathology. Keywords: foreign students, heart rate variability, types of autonomic regulation, adaptation potential, functional status. Оценка состояния студентов и динамический контроль за ним является важной задачей, поскольку позволяет своевременно выявлять у студентов донозологические состояния, предшествующие патологии, и способствовать сохранению здоровья. Цель. Оценка адаптивных возможностей организма, анализ изменений показателей вариабельности сердечного ритма у студентов с различными типами вегетативной регуляции, выявление донозологических состояний и ранних признаков патологии. Материалы и методы. В исследовании участвовало 302 студента в возрасте 21,54+1,43 года из Индии. Регистрировались основные параметры ВСР в течение 5 мин с использованием программно-аппаратного комплекса «Психофизиолог». Состояние и уровень здоровья оценивались по индексу функциональных изменений и шкале функциональных состояний. Результаты. По способу, предложенному Н.И. Шлык, выделены группы студентов с различными типами вегетативной регуляции: I (53 %) и II типы (5 %) – с умеренным и выраженным преобладанием центрального контура регуляции соответственно, III (35 %) и IV типы (7 %) – с умеренным и выраженным преобладанием автономного контура регуляции соответственно. У каждого из студентов определены основные параметры ВСР и адаптационного потенциала, характеризующие функциональное состояние и уровень здоровья. Выводы. Показано, что для 82 % обследуемых с I типом, 53 % со II типом, 94 % c III типом и 95 % с IV типом регуляции характерно состояние удовлетворительной адаптации, физиологические процессы сохраняются на оптимальном уровне. В группе студентов I типа у 18 % студентов адаптивные возможности организма снижены, выявлено состояние умеренного напряжения. У 47 % обследуемых II типа также зафиксировано состояние резко выраженного напряжения, индикатором которого является чрезмерно высокое значение SI, низкие величины SDNN и ТP, повышенное значение индекса функциональных изменений. В группе студентов с IV типом у 5 % учащихсяв регуляции ритма сердца выявлены дисфункциональные признаки, характерные для патологии. Ключевые слова: иностранные студенты, вариабельность сердечного ритма, типы вегетативной регуляции, адаптационный потенциал, функциональное состояние.

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POLIOMYELITIS IN CANADIAN ESKIMOS: LABORATORY STUDIES. V. TYPE 1 AND TYPE 3 POLIOMYELITIS ANTIBODY LEVELS IN BAFFIN ISLAND ESKIMOS

Canadian Journal of Biochemistry and Physiology ◽

10.1139/y54-013 ◽

1954 ◽

Vol 32 (1) ◽

pp. 119-125

Author(s):

W. Wood ◽

Eina M. Clark ◽

F. T. Shimada ◽

A. J. Rhodes

Keyword(s):

Medical Records ◽

Baffin Island ◽

Tissue Cultures ◽

Laboratory Studies ◽

Poliomyelitis Virus ◽

Antibody Titers ◽

Antibody Levels ◽

Type 3

Studies on the basic immunology of poliomyelitis in Canadian Eskimos have been continued. Some 87 sera collected from Eskimos at Pangnirtung, Baffin Island, have been examined for the presence of Type 1 and Type 3 poliomyelitis antibody by quantitative tests in tissue cultures. The same sera were previously examined for Type 2 antibody by quantitative tests in mice. The results of the three determinations are now presented together for comparison. These sera came from Eskimos aged 2 to 72 years of age. None of the Eskimos showed any evidence of paralysis. Examination of the medical records did not suggest that any paralytic disease had been present in this part of Baffin Island. Very few of the sera showed the presence of poliomyelitis antibody; thus, Type 1 antibody was demonstrated in the sera of 8%, Type 2 antibody in the sera of 9%, and Type 3 antibody in the sera of 14%. No significant number of Eskimos below the age of 45 years had acquired poliomyelitis antibody. The antibody titers mostly ranged between 10−1.0 and 10−2.0, and were significantly lower than the titers customarily found in recently paralyzed cases. These findings suggest that poliomyelitis infection occurred in Pangnirtung Eskimos many years before the date on which the samples were taken (1951). These results point to the worldwide prevalence of the three types of poliomyelitis virus.

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A determination of excitability changes in dorsal spinocerebellar tract neurons from spike-train analysis

Journal of Neurophysiology ◽

10.1152/jn.1977.40.3.626 ◽

1977 ◽

Vol 40 (3) ◽

pp. 626-646 ◽

Cited By ~ 19

Author(s):

C. K. Knox ◽

S. Kubota ◽

R. E. Poppele

Keyword(s):

Spike Train ◽

Afferent Input ◽

Complex Interactions ◽

Group I ◽

Long Latency ◽

Cross Correlation Analysis ◽

Output Spike ◽

Type 3 ◽

Stimulation Of

1. Responses of DSCT neurons to random electrical stimulation of peripheral nerves of the hindleg at group I intensity were studied using cross-correlation analysis of the output spike train with the stimulus. Three types of response were found: type 1 was due to monosynaptic activation of DSCT cells, type 2 resulted from inhibition of those cells, and type 3 was due to a long-latency excitation that was probably polysynaptic. 2. Most of the units studied responded to stimulation of both proximal and distal flexor and extensor nerves. The extensive convergence of afferent input on DSCT cells is much greater than has been observed previously, with type 2 and type 3 responses totaling 80% of the observed responses. We attribute this to the sensitivity of the analysis in detecting small changes in postsynaptic excitability. 3. The results of the study, particularly the derivation of postsynaptic excitability changes, generally confirm those of earlier work employing intracellular recording. 4. By varying stimulus rate and stimulus intensity in the group 1 range and simulating the resulting correlations, we conclude that excitability changes in DSCT cells are the net result of complex interactions involving excitation and inhibition. A summary of these findings is presented as a model for the minimum circuitry necessary to account for the observed behavior.

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Toward Personalized Treatment for Patients with Low von Willebrand Factor and Quantitative von Willebrand Disease

Seminars in Thrombosis and Hemostasis ◽

10.1055/s-0041-1722864 ◽

2021 ◽

Vol 47 (02) ◽

pp. 192-200

Author(s):

James S. O'Donnell

Keyword(s):

Von Willebrand Factor ◽

Bleeding Risk ◽

Von Willebrand Disease ◽

Personalized Treatment ◽

Treatment Plans ◽

Type 3 ◽

Von Willebrand ◽

Willebrand Factor

AbstractThe biological mechanisms involved in the pathogenesis of type 2 and type 3 von Willebrand disease (VWD) have been studied extensively. In contrast, although accounting for the majority of VWD cases, the pathobiology underlying partial quantitative VWD has remained somewhat elusive. However, important insights have been attained following several recent cohort studies that have investigated mechanisms in patients with type 1 VWD and low von Willebrand factor (VWF), respectively. These studies have demonstrated that reduced plasma VWF levels may result from either (1) decreased VWF biosynthesis and/or secretion in endothelial cells and (2) pathological increased VWF clearance. In addition, it has become clear that some patients with only mild to moderate reductions in plasma VWF levels in the 30 to 50 IU/dL range may have significant bleeding phenotypes. Importantly in these low VWF patients, bleeding risk fails to correlate with plasma VWF levels and inheritance is typically independent of the VWF gene. Although plasma VWF levels may increase to > 50 IU/dL with progressive aging or pregnancy in these subjects, emerging data suggest that this apparent normalization in VWF levels does not necessarily equate to a complete correction in bleeding phenotype in patients with partial quantitative VWD. In this review, these recent advances in our understanding of quantitative VWD pathogenesis are discussed. Furthermore, the translational implications of these emerging findings are considered, particularly with respect to designing personalized treatment plans for VWD patients undergoing elective procedures.

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Optimally growing initial errors of El Niño events in the CESM

Climate Dynamics ◽

10.1007/s00382-021-05668-1 ◽

2021 ◽

Author(s):

Hui Xu ◽

Lei Chen ◽

Wansuo Duan

Keyword(s):

El Niño ◽

El Nino ◽

Equatorial Pacific ◽

Initial Error ◽

Initial Errors ◽

El Niño Events ◽

Type 3 ◽

El Nino Events

AbstractThe optimally growing initial errors (OGEs) of El Niño events are found in the Community Earth System Model (CESM) by the conditional nonlinear optimal perturbation (CNOP) method. Based on the characteristics of low-dimensional attractors for ENSO (El Niño Southern Oscillation) systems, we apply singular vector decomposition (SVD) to reduce the dimensions of optimization problems and calculate the CNOP in a truncated phase space by the differential evolution (DE) algorithm. In the CESM, we obtain three types of OGEs of El Niño events with different intensities and diversities and call them type-1, type-2 and type-3 initial errors. Among them, the type-1 initial error is characterized by negative SSTA errors in the equatorial Pacific accompanied by a negative west–east slope of subsurface temperature from the subsurface to the surface in the equatorial central-eastern Pacific. The type-2 initial error is similar to the type-1 initial error but with the opposite sign. The type-3 initial error behaves as a basin-wide dipolar pattern of tropical sea temperature errors from the sea surface to the subsurface, with positive errors in the upper layers of the equatorial eastern Pacific and negative errors in the lower layers of the equatorial western Pacific. For the type-1 (type-2) initial error, the negative (positive) temperature errors in the eastern equatorial Pacific develop locally into a mature La Niña (El Niño)-like mode. For the type-3 initial error, the negative errors in the lower layers of the western equatorial Pacific propagate eastward with Kelvin waves and are intensified in the eastern equatorial Pacific. Although the type-1 and type-3 initial errors have different spatial patterns and dynamic growing mechanisms, both cause El Niño events to be underpredicted as neutral states or La Niña events. However, the type-2 initial error makes a moderate El Niño event to be predicted as an extremely strong event.

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