Synoptic Circulation Patterns and Climate Regionalization of East Africa

2020 ◽  
Author(s):  
Markos Ware ◽  
Paolo Mori ◽  
Kisten Warrach -Sagi ◽  
Mark Jury ◽  
Thomas Schiwtalla ◽  
...  
Keyword(s):  
East Africa ◽  
Principal Component ◽  
Domain Size ◽  
Optimal Number ◽  
Final Decision ◽  
Test Technique ◽  
Circulation Types ◽  
Circulation Patterns ◽  
Climate Regionalization

<p><strong>Abstract</strong>. Climate regionalization is crucial for climate studies, especially in the case of heterogeneous regions like East Africa. This paper focuses on categorizing Ethiopia into homogeneous climatic sub-regions by applying a classification of circulation patterns on precipitation. The sub-regions obtained will be applied on the verification of WRF-NOAHMP seasonal simulations performed over the Horn of Africa. We analyzed the occurrence of each circulation type per month and per year over the whole country. Then, trend analysis of temperature and precipitation over the respective sub-regions were performed. Principal Component Analysis (PCA) were applied to group daily mean Sea Level Pressure (SLP) into Circulation Types (CTs). Then, PCA coupled with k-means clustering employed to regionalize precipitation fields (distributed spatially) following CTs into homogeneous climatic sub-regions. Observational data were obtained from the National Center for Environmental Prediction (NCEP) reanalysis, Climate Hazards Group Infrared Precipitation with Stations (CHIRPS version 2), and National Meteorology Agency (NMA) of Ethiopia (gauge 1st and 2nd classes). Five principal components, which explain 98% of the total variance, were maintained using the Scree test technique. Ten CTs were obtained using positive and negative phases of each principal component scores following the extreme score values (> 2 and < −2) procedure. From ten CTs, we found that three (CT1, CT3, and CT8) were characterized by low pressure over the southwest corner of the domain, which consequently brings rainfall over the Ethiopian highlands. The number of days classified under different CTs shows different trends. CTs seasonal distribution agreed with the regional seasons. Long-term monthly mean rainfall ranges from 0-600 mm over the region. Ethiopia is clustered into four homogeneous sub-regions based on the spatial distribution of precipitation following CTs. Rainfall from CHIRPS and gauge did not have any specific trend over the sub-regions, however high standardized anomalies were observed compared to the long term mean. The temperature showed a 2 °C change for the past three decades. There was a negligible difference in the shape, size, and location of regions using data from different sources. The final decision on the optimal number of homogeneous climatic sub-regions depends upon the research objective, geographical domain size, and topographic features of the domain. This study provides an assessment and decision pathway.</p><p> </p><p><strong>Keywords: </strong>climatology, regionalization, Ethiopia, precipitation, k-means, circulation types</p>

Archetypal analysis of Southern Hemisphere extreme circulation events

2020 ◽  
Author(s):  
James Risbey ◽  
Didier Monselesan
Keyword(s):  
Principal Component Analysis ◽  
Southern Hemisphere ◽  
Principal Component ◽  
Temperature Extremes ◽  
Archetypal Analysis ◽  
Long Period ◽  
Circulation Types ◽  
Circulation Patterns ◽  
Extreme Flow ◽  
Flow States

<p>Archetypal analysis of Southern Hemisphere extreme circulation events</p><p>This work conducts an archetypal analysis (AA) of midtropospheric flow<br>in the Southern Hemisphere.  The analysis identifies the archetypical<br>extreme flow states and compares them with the leading modes of<br>variability from Principal Component Analysis (PCA) methods.  In<br>particular, we examine long-lived extreme circulation patterns and<br>events from both AA and PCA, together with their synoptic signatures<br>and surface impacts.  The long-lived circulation types are efficient at<br>generating surface temperature extremes and exhibit long period<br>variability.  Case studies of documented surface extreme events show<br>that they correspond clearly to the midtropospheric flow archetypes.</p><p> </p>

scholarly journals EXTENDING LKN CLIMATE REGIONALIZATION WITH SPATIAL REGULARIZATION: AN APPLICATION TO EPIDEMIOLOGICAL RESEARCH

2016 ◽  
Vol XLI-B8 ◽  
pp. 209-213
Author(s):  
Alexander Liss ◽  
Yulia R. Gel ◽  
Alexandra Kulinkina ◽  
Elena N. Naumova
Keyword(s):  
Spatial Distribution ◽  
Decision Support ◽  
Regional Climate ◽  
Principal Component ◽  
Critical Factor ◽  
Target Population ◽  
Public Health Research ◽  
Optimal Number ◽  
Epidemiological Research ◽  
Climate Regionalization

Regional climate is a critical factor in public health research, adaptation studies, climate change burden analysis, and decision support frameworks. Existing climate regionalization schemes are not well suited for these tasks as they rarely take population density into account. In this work, we are extending our recently developed method for automated climate regionalization (LKN-method) to incorporate the spatial features of target population. The LKN method consists of the data limiting step (L-step) to reduce dimensionality by applying principal component analysis, a classification step (K-step) to produce hierarchical candidate regions using k-means unsupervised classification algorithm, and a nomination step (N-step) to determine the number of candidate climate regions using cluster validity indexes. LKN method uses a comprehensive set of multiple satellite data streams, arranged as time series, and allows us to define homogeneous climate regions. The proposed approach extends the LKN method to include regularization terms reflecting the spatial distribution of target population. Such tailoring allows us to determine the optimal number and spatial distribution of climate regions and thus, to ensure more uniform population coverage across selected climate categories. We demonstrate how the extended LKN method produces climate regionalization can be better tailored to epidemiological research in the context of decision support framework.

scholarly journals The influence of the circulation on surface temperature and precipitation patterns over Europe*

2009 ◽  
Vol 5 (1) ◽  
pp. 535-555 ◽  
Author(s):  
P. D. Jones ◽  
D. H. Lister
Keyword(s):  
Surface Temperature ◽  
20Th Century ◽  
Surface Pressure ◽  
Classification Scheme ◽  
Weather Types ◽  
Circulation Types ◽  
Temperature And Precipitation ◽  
Four Seasons ◽  
Circulation Patterns

Abstract. The atmospheric circulation clearly has an important influence on variations in surface temperature and precipitation. In this study we illustrate the spatial patterns of variation that occur for the principal circulation patterns across Europe in the standard four seasons. We use an existing classification scheme of surface pressure patterns, with the aim of considering whether the patterns of influence of specific weather types have changed over the course of the 20th century. We consider whether the long-term warming across Europe is associated with more favourable weather types or related to warming within some of the weather types. The results indicate that the latter is occurring, but not all circulation types show warming. The study also illustrates that certain circulation types can lead to marked differences in temperature and/or precipitation for relatively closely positioned sites when the sites are located in areas of high relief or near coasts.

scholarly journals The influence of the circulation on surface temperature and precipitation patterns over Europe

2009 ◽  
Vol 5 (2) ◽  
pp. 259-267 ◽  
Author(s):  
P. D. Jones ◽  
D. H. Lister
Keyword(s):  
Surface Temperature ◽  
20Th Century ◽  
Surface Pressure ◽  
Classification Scheme ◽  
Weather Types ◽  
Circulation Types ◽  
Temperature And Precipitation ◽  
Four Seasons ◽  
Circulation Patterns

Abstract. The atmospheric circulation clearly has an important influence on variations in surface temperature and precipitation. In this study we illustrate the spatial patterns of variation that occur for the principal circulation patterns across Europe in the standard four seasons. We use an existing classification scheme of surface pressure patterns, with the aim of considering whether the patterns of influence of specific weather types have changed over the course of the 20th century. We consider whether the long-term warming across Europe is associated with more favourable weather types or related to warming within some of the weather types. The results indicate that the latter is occurring, but not all circulation types show warming. The study also illustrates that certain circulation types can lead to marked differences in temperature and/or precipitation for relatively closely positioned sites when the sites are located in areas of high relief or near coasts.

Estimating Regional Precipitation Trends Comparison of two Methods

1997 ◽  
Vol 28 (1) ◽  
pp. 21-36 ◽  
Author(s):  
I. Hanssen-Bauer ◽  
E. J. Førland ◽  
O.E. Tveito ◽  
P.Ø Nordli
Keyword(s):  
Regional Differences ◽  
Principal Component ◽  
Distinct Region ◽  
Precipitation Trend ◽  
Homogeneous Precipitation ◽  
Precipitation Series ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Precipitation Trends

Two different methods were applied to estimate long-term precipitation trends representative for regions in Norway. A new method, comparative trend analysis (CTA), was applied on 142 homogeneous precipitation series of 70-100 years. In this way 12 precipitation trend regions were identified. Principal component analysis (PCA) was applied on a subset of 30 series during the period 1896-1994 The results from both analyses were used to estimate precipitation trend series at several locations. The estimates based upon the PCA were of same quality as the estimates based upon the CTA. However, by CTA it is possible to visualize the trend in a distinct region by using just one trend curve, while trend curves based on PCA are composed of contributions from 5 principal components. The resulting trend curves document that the annual precipitation level has increased by 8-14% throughout this century in most Norwegian regions. The increase occurred not simultaneously all over the country. The regional differences in precipitation trends and variability are probably connected to variations in the atmospheric circulation patterns.

scholarly journals Contact Heat Evoked Potentials in China: Normal Values and Reproducibility

2022 ◽  
Vol 15 ◽  
Author(s):  
Bo Sun ◽  
Hongfen Wang ◽  
Zhaohui Chen ◽  
Fang Cui ◽  
Fei Yang ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Normal Values ◽  
Visual Analog Scale Score ◽  
Optimal Number ◽  
Chinese Adults ◽  
Contact Heat ◽  
Test Technique ◽  
Contact Heat Evoked Potentials ◽  
Baseline Temperature

Background: Contact heat evoked potentials (CHEPs) is used to diagnose small fiber neuropathy (SFN). We established the normal values of CHEPs parameters in Chinese adults, optimized the test technique, and determined its reproducibility.Methods: We recruited 151 healthy adults (80 men; mean age, 37 ± 14 years). CHEPs was performed on the right forearm to determine the optimal number of stimuli, and then conducted at different sites to establish normal values, determine the effects of demographic characteristics and baseline temperature, and assess the short- (30 min) and long-term (1 year) reproducibility. N2 latency/height varied with age and sex, while P2 latency/height and N2–P2 amplitude varied with age. The optimal number of stimuli was three.Results: N2 latency/height (t = 5.45, P < 0.001) and P2 latency/height (χ2 = −4.06, P < 0.001) decreased and N2–P2 amplitude (t = −5.01, P < 0.001) and visual analog scale score (χ2 = −5.84, P < 0.001) increased with increased baseline temperature (35 vs. 32°C). CHEPs parameters did not differ with time (baseline vs. 30 min vs. 1 year).Conclusion: We established normal CHEPs values in Chinese adults. We found that CHEPs parameters changed with baseline temperature and that the short- and long-term test reproducibility were satisfactory.

scholarly journals EXTENDING LKN CLIMATE REGIONALIZATION WITH SPATIAL REGULARIZATION: AN APPLICATION TO EPIDEMIOLOGICAL RESEARCH

2016 ◽  
Vol XLI-B8 ◽  
pp. 209-213
Author(s):  
Alexander Liss ◽  
Yulia R. Gel ◽  
Alexandra Kulinkina ◽  
Elena N. Naumova
Keyword(s):  
Spatial Distribution ◽  
Decision Support ◽  
Regional Climate ◽  
Principal Component ◽  
Critical Factor ◽  
Target Population ◽  
Public Health Research ◽  
Optimal Number ◽  
Epidemiological Research ◽  
Climate Regionalization

Regional climate is a critical factor in public health research, adaptation studies, climate change burden analysis, and decision support frameworks. Existing climate regionalization schemes are not well suited for these tasks as they rarely take population density into account. In this work, we are extending our recently developed method for automated climate regionalization (LKN-method) to incorporate the spatial features of target population. The LKN method consists of the data limiting step (L-step) to reduce dimensionality by applying principal component analysis, a classification step (K-step) to produce hierarchical candidate regions using k-means unsupervised classification algorithm, and a nomination step (N-step) to determine the number of candidate climate regions using cluster validity indexes. LKN method uses a comprehensive set of multiple satellite data streams, arranged as time series, and allows us to define homogeneous climate regions. The proposed approach extends the LKN method to include regularization terms reflecting the spatial distribution of target population. Such tailoring allows us to determine the optimal number and spatial distribution of climate regions and thus, to ensure more uniform population coverage across selected climate categories. We demonstrate how the extended LKN method produces climate regionalization can be better tailored to epidemiological research in the context of decision support framework.

scholarly journals Can synoptic patterns influence the track and formation of tropical cyclones in the Mozambique Channel?

2021 ◽  
Author(s):  
Chibuike Chiedozie Ibebuchi
Keyword(s):  
Tropical Cyclones ◽  
Large Scale ◽  
Principal Component ◽  
Large Scale Circulation ◽  
Modes Of Variability ◽  
Mozambique Channel ◽  
Circulation Types ◽  
Mascarene High ◽  
Circulation Patterns ◽  
Grid Points

Abstract The influence of large-scale circulation patterns on the track and formation of tropical cyclones (TCs) in the Mozambique Channel is investigated in this paper. The output of the hourly classification of circulation types (CTs), in Africa, south of the equator, using rotated principal component analysis on the T-mode matrix (variable is time series and observation is grid points) of sea level pressure (SLP) from ERA5 reanalysis from 2010 to 2019 was used to investigate the time development of the CTs at a sub-daily scale. The result showed that at specific seasons, certain CTs can persist for a longer time so that their features overlap with other CTs. CTs with synoptic features favorable for the development of TC in the Mozambique Channel were noted. The 2019 TC season in the Mozambique Channel characterized by TC Idai in March and TC Kenneth afterward in April was used in evaluating how the CTs designated to have TC characteristics played role in the formation and track of the TCs towards their maximum intensity. The results were discussed and it generally showed that large-scale circulation patterns might influence the formation and track of the TCs in the Mozambique Channel especially through the different modes of variability associated with the western branch of the Mascarene high.

scholarly journals Can synoptic patterns influence the track and formation of tropical cyclones in the Mozambique Channel?

2022 ◽  
Vol 8 (1) ◽  
pp. 33-51
Author(s):  
Chibuike Chiedozie Ibebuchi ◽  
Keyword(s):  
Tropical Cyclones ◽  
Large Scale ◽  
Principal Component ◽  
Precipitable Water ◽  
Cyclonic Activity ◽  
Large Scale Circulation ◽  
Mozambique Channel ◽  
Circulation Types ◽  
Mascarene High ◽  
Circulation Patterns

<abstract> <p>The influence of large-scale circulation patterns on the track and formation of tropical cyclones (TCs) in the Mozambique Channel is investigated in this paper. The output of the hourly classification of circulation types (CTs), in Africa, south of the equator, using rotated principal component analysis on the T-mode matrix (variable is time series and observation is grid points) of sea level pressure (SLP) from ERA5 reanalysis from 2010 to 2019 was used to investigate the time development of the CTs at a sub-daily scale. The result showed that at specific seasons, certain CTs are dominant so that their features overlap with other CTs. CTs with synoptic features, such as enhanced precipitable water and cyclonic activity in the Mozambique Channel that can be favorable for the development of TC in the Channel were noted. The 2019 TC season in the Mozambique Channel characterized by TC Idai in March and TC Kenneth afterward in April were used in evaluating how the CTs designated to have TC characteristics played role in the formation and track of the TCs towards their maximum intensity. The results were discussed and it generally showed that large-scale circulation patterns can influence the formation and track of the TCs in the Mozambique Channel especially through (ⅰ) variations in the position and strength of the anticyclonic circulation at the western branch of the Mascarene high; (ⅱ) modulation of wind speed and wind direction; hence influencing convergence in the Channel; (ⅲ) and modulation of the intensity of cyclonic activity in the Channel that can influence large-scale convection.</p> </abstract>

Adherence to RCS recommendations for extraction of first permanent molars in a teaching hospital: To compensate or not to compensate?

2021 ◽  
pp. 146531252199183
Author(s):  
Jed Lee ◽  
Joanna Johnson ◽  
Dirk Bister ◽  
Mohsin Chaudhary ◽  
Golfam Khoshkhounejad
Keyword(s):  
Teaching Hospital ◽  
Poor Prognosis ◽  
Service Evaluation ◽  
Good Prognosis ◽  
Final Decision ◽  
National Guidelines ◽  
High Quality Research ◽  
Permanent Molars ◽  
First Permanent Molars

Objective: To observe whether paediatric dentists and orthodontists balance and compensate the extraction of first permanent molars (FPMs) in children aged 7–11 years. Design: Service evaluation. Setting: UK dental teaching hospital. Methods: Retrospective analysis of FPM extraction patterns in patients aged 7–11 years that attended for extraction of FPMs from 1 January 2019 to 31 January 2020 (13-month period). Results: A total of 194 patients were included and they collectively had 435 FPMs extracted. No balancing extractions to prevent dental centreline shifts and no lower FPM compensatory extractions were performed. Compensatory extraction of good prognosis upper FPMs were performed in 64% (94/146) of cases to avoid overeruption. Orthodontic input was sought for poor prognosis lower FPMs in 76% of cases compared to 51% for poor prognosis upper FPMs. Conclusion: Compensatory extraction of good prognosis upper FPMs to avoid overeruption appears to be a common practice at Guy’s and St Thomas’ Hospitals. There was also higher demand for orthodontic advice for cases presenting with poor prognosis lower FPMs compared to poor prognosis upper FPMs, which suggests that paediatric dentists may prefer for the final decision on upper FPM compensatory extractions to be made by an orthodontist, even with national guidelines available. More high-quality research on the topic is required to determine the necessity of this practice for achieving optimal long-term oral health in children.

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