On the Application of Cluster Analysis to Growing Season Precipitation Data in North America East of the Rockies

Gong, Xiaofeng; Richman, Michael B.

doi:10.1175/1520-0442(1995)008<0897:otaoca>2.0.co;2

Cited by 297 publications

(211 citation statements)

References 54 publications

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“…Les données utilisées sont les précipitations mensuelles de 1961 à 2000 d'un réseau de trente quatre stations réparties dans le bassin et à proximité, provenant de la base de données de l'ASECNA de Cotonou (Bénin), de la Météorologie Nationale de Lomé (Togo), du Centre de Recherches de Climatologie (Dijon) et du Global Historical Climate Network (Vose et al 1992 (Fichet 1987), considéré comme le plus pertinent au sein des méthodes agrégatives (Gong et Richman 1995 (Fig. 2(a)).…”

Section: Donnees Et Methodesunclassified

Impact de la variabilité climatique et du barrage Nangbéto sur l'hydrologie du système Mono-Couffo (Afrique de l'Ouest)

Amoussou

Camberlin

Mahé³

2012

Hydrological Sciences Journal

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Section: Donnees Et Methodesunclassified

Impact de la variabilité climatique et du barrage Nangbéto sur l'hydrologie du système Mono-Couffo (Afrique de l'Ouest)

Amoussou

Camberlin

Mahé³

2012

Hydrological Sciences Journal

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“…The analysed area extends from 35°N to 65°N and from 40°W to 40°E. The classification method is based on principal component analysis (PCA) in a T-mode (Bartzokas and Metaxas, 1996;Huth, 1996a;Compagnucci and Salles, 1997) combined with the k-means method of cluster analysis (Gong and Richman, 1995) with Euclidean distance used as a dissimilarity measure. It was decided to employ the T-mode PCA because it is very efficient at uncovering the underlying structure of data (it best reproduces the circulation types known in advance), whereas the major advantage of the k-means method consists in its ability to provide well-separated clusters (Huth, 1996b).…”

Section: Data and Analysis Methodsmentioning

confidence: 99%

“…It was decided to employ the T-mode PCA because it is very efficient at uncovering the underlying structure of data (it best reproduces the circulation types known in advance), whereas the major advantage of the k-means method consists in its ability to provide well-separated clusters (Huth, 1996b). The connection of the two methods, which is briefly described below, relieves the drawbacks of either of them: a difficult application of T-mode PCA to very large datasets and a dependence of the output of k-means clustering on the initial selection of grid-points (Gong and Richman, 1995;Huth, 1996b).…”

Section: Data and Analysis Methodsmentioning

confidence: 99%

Disaggregating climatic trends by classification of circulation patterns

Huth

2001

Intl Journal of Climatology

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The trends in occurrence frequencies of circulation types over Europe and in nine climate variables in the Czech Republic conditioned by the types are examined for period . The circulation types are determined by an objective procedure from daily 500 hPa heights. Both in summer and winter, anticyclonic types have become more frequent at the expense of cyclonic types. The circulation changes are shown to be unrelated to the trends in surface climate elements in summer, whereas in winter, trends in circulation explain a part of the observed warming and strengthening of southerly winds.The trends in climate elements are not uniform among circulation types. In summer, the trend pattern consisting of decreasing maximum and daily mean temperatures, daily temperature range (DTR) and sunshine duration, and increasing cloudiness and relative humidity is observed under the cyclonic types and the types with a well-pronounced jet, but is missing under types with a blocking anticyclone over Europe. Two possible mechanisms causing this trend pattern are proposed: increasing cloudiness, and a process responsible for the reduction of sunshine without a concurrent increase of cloudiness. The latter mechanism can possibly be identified with increasing aerosol concentrations. In winter, the degree of warming is governed by changes in zonal wind. The mechanism of change in DTR seems to vary with elevation: at the lowland station (Prague-Klementinum), the increase in DTR is related to the warming trend, and consequently with zonal wind changes, while at the mountain station (Milešovka), the increase in DTR reflects the increase in precipitating clouds.The changes in DTR are related much more to mid-tropospheric circulation than to cloud cover in summer, whereas in winter, cloud cover plays a more important role in affecting DTR trends.

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“…Hierarchical cluster methods, such as the Ward's method, have been used frequently for distinguishing precipitation regimes (Gong and Richman, 1995;Ramos, 2001) and other environmental patterns (Allen and Walsh, 1996). The events are clustered based on their morning (06:00 LST) convective triggering potential and low-level humidity (e.g.…”

Section: Atmospheric Conditionsmentioning

confidence: 99%

Soil moisture–precipitation coupling: observations from the Oklahoma Mesonet and underlying physical mechanisms

Ford

Rapp

Quiring

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract.Interactions between soil moisture and the atmosphere are driven by the partitioning of sensible and latent heating, through which soil moisture has been connected to atmospheric modifications that could potentially lead to the initiation of convective precipitation. The majority of previous studies linking the land surface to subsequent precipitation have used atmospheric reanalysis or model data sets. In this study, we link in situ observations of soil moisture from more than 100 stations in Oklahoma to subsequent unorganized afternoon convective precipitation. We use hourly next generation (NEXRAD) radar-derived precipitation to identify convective events, and then compare the location of precipitation initiation to underlying soil moisture anomalies in the morning. Overall we find a statistically significant preference for convective precipitation initiation over drier than normal soils, with over 70 % of events initiating over soil moisture below the long-term median. The significant preference for precipitation initiation over drier than normal soils is in contrast with previous studies using satellite-based precipitation to identify the region of maximum precipitation accumulation. We evaluated 19 convective events occurring near Lamont, Oklahoma, where soundings of the atmospheric profile at 06:00 and 12:00 LST are also available. For these events, soil moisture has strong negative correlations with the level of free convection (LFC), planetary boundary layer (PBL) height, and surface temperature changes between 06:00 and 12:00 LST. We also find strong positive correlations between morning soil moisture and morning-toafternoon changes in convective available potential energy and convective inhibition. In general, the results of this study demonstrate that both positive and negative soil moisture feedbacks are important in this region of the USA.

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On the Application of Cluster Analysis to Growing Season Precipitation Data in North America East of the Rockies

Cited by 297 publications

References 54 publications

Impact de la variabilité climatique et du barrage Nangbéto sur l'hydrologie du système Mono-Couffo (Afrique de l'Ouest)

Impact de la variabilité climatique et du barrage Nangbéto sur l'hydrologie du système Mono-Couffo (Afrique de l'Ouest)

Disaggregating climatic trends by classification of circulation patterns

Soil moisture–precipitation coupling: observations from the Oklahoma Mesonet and underlying physical mechanisms

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