Mesoscale heat waves induced by orography

Abstract. This work is devoted to the analysis of an unusual and sudden thermal fluctuation that interested portions of Friuli Venezia Giulia (Italy) during the night of 27 July 1983. The whole 1983 summer was extremely warm in Europe and in particular on the Italian peninsula, from the Alps down to Sicily. Nevertheless, the day of 27 July 1983 in Friuli Venezia Giulia deserves special attention because the observed maximum temperatures did not occur during day-time but during night-time (from 23:00 up to 24:00 LT, 21:00–22:00 UTC). Peaks of 34.8°C and values of relative humidity of the order of 28% were registered by the official network of weather stations. This event interested mainly the central-eastern part of the plain of Friuli Venezia Giulia, a few kilometers far from the Slovenian border and relieves. The thermal anomalies lasted up to an hour, then temperatures decreased toward values more usual for the climate of the month. The study of this event is carried out with the aid of the AR-WRF numerical atmospheric model, initialized through the ECMWF analysis. The numerical simulations highlight the important role played by orography, jointly with the peculiar thermal structure of the atmosphere, for the enhancing of the internal wave pattern over that area. According to the sensitivity studies realized, the amplification of the internal wave pattern might represent a possible explanation for that meteorological enigma.

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Extreme Temperature Events in Serbia in Relation to Atmospheric Circulation

Atmosphere ◽

10.3390/atmos12121584 ◽

2021 ◽

Vol 12 (12) ◽

pp. 1584

Author(s):

Ivana Tošić ◽

Suzana Putniković ◽

Milica Tošić ◽

Irida Lazić

Keyword(s):

Atmospheric Circulation ◽

Heat Waves ◽

Extreme Temperature ◽

Daily Maximum ◽

Absolute Maximum ◽

Extreme Temperature Events ◽

Atmospheric Circulation Patterns ◽

Circulation Patterns ◽

Maximum Temperatures ◽

The Relationship

In this study, extremely warm and cold temperature events were examined based on daily maximum (Tx) and minimum (Tn) temperatures observed at 11 stations in Serbia during the period 1949–2018. Summer days (SU), warm days (Tx90), and heat waves (HWs) were calculated based on daily maximum temperatures, while frost days (FD) and cold nights (Tn10) were derived from daily minimum temperatures. Absolute maximum and minimum temperatures in Serbia rose but were statistically significant only for Tx in winter. Positive trends of summer and warm days, and negative trends of frost days and cold nights were found. A high number of warm events (SU, Tx90, and HWs) were recorded over the last 20 years. Multiple linear regression (MLR) models were applied to find the relationship between extreme temperature events and atmospheric circulation. Typical atmospheric circulation patterns, previously determined for Serbia, were used as predictor variables. It was found that MLR models gave the best results for Tx90, FD, and Tn10 in winter.

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Numerical Study for Experiment on Wave Pattern of Internal Wave and Surface Wave in Stratified Fluid

Journal of Ocean Engineering and Technology ◽

10.26748/ksoe.2019.008 ◽

2019 ◽

Vol 33 (3) ◽

pp. 236-244

Author(s):

Ju-Han Lee ◽

Kwan-Woo Kim ◽

Kwang-Jun Paik ◽

Won-Cheol Koo ◽

Yeong-Gyu Kim

Keyword(s):

Surface Wave ◽

Internal Wave ◽

Numerical Study ◽

Wave Pattern ◽

Stratified Fluid

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Regional Climatic Features of the Arabian Peninsula

Atmosphere ◽

10.3390/atmos10040220 ◽

2019 ◽

Vol 10 (4) ◽

pp. 220 ◽

Cited By ~ 10

Author(s):

Patlakas ◽

Stathopoulos ◽

Flocas ◽

Kalogeri ◽

Kallos

Keyword(s):

Large Scale ◽

Arabian Peninsula ◽

Regional Climate ◽

Atmospheric Model ◽

Temporal Variations ◽

Spatial And Temporal Variations ◽

Spatial Distance ◽

Temperature Extremes ◽

Mean Temperature ◽

Maximum Temperatures

The climate of the Arabian Peninsula is characterized by significant spatial and temporal variations, due to its complex topography and the large-scale atmospheric circulation. Furthermore, the role of dust in the formation of regional climate is considered to be crucial. In this work, the regional climatology for the Arabian Peninsula has been studied by employing a high resolution state of the art atmospheric model that included sophisticated physical parameterization schemes and online treatment of natural aerosol particles. The simulations covered a 30-year period (1986–2015) with a temporal resolution of 3 h and a spatial distance of 9 km. The main focus was given to the spatial and temporal variations of mean temperature and temperature extremes, wind speed and direction, and relative humidity. The results were evaluated using in situ measurements indicating a good agreement. An examination of possible climatic changes during the present climate was also performed through a comprehensive analysis of the trends of mean temperature and temperature extremes. The statistical significant trend values were overall positive and increased over the northwestern parts of the examined area. Similar spatial distributions were found for the daily minimum and maximum temperatures. Higher positive values emerged for the daily maxima.

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REMOTE SENSING AND NIGHT TIME URBAN HEAT ISLAND

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xliii-b3-2021-15-2021 ◽

2021 ◽

Vol XLIII-B3-2021 ◽

pp. 15-22

Author(s):

B. Arellano ◽

J. Roca

Keyword(s):

Heat Waves ◽

Urban Climate ◽

Construction Materials ◽

Thermal Inertia ◽

Cooling Capacity ◽

Night Time ◽

Urban Heat ◽

Materials Used ◽

Significant Health

Abstract. The urban climate literature has highlighted the remarkable prominence of nighttime UHI phenomenon. During nighttime the UHI effects become more evident due to the greater thermal inertia of the materials used in urban fabric. It is during the night when the heat accumulated in urban materials, especially in contexts of heat waves, can generate significant health risks. The low cooling capacity of urban construction materials negatively affects the comfort and the health of urban dwellers. However, and despite the great importance of night stress due to heat, the study of night UHIs is still underdeveloped. In this context, this paper aims to determine nighttime LST contrasting Landsat's very limited nighttime images with daytime ones. The example developed refers to heat wave situations during the summer 2015. The case study is the Metropolitan Area of Barcelona (35 municipalities, 636 km2, 3.3 million inhabitants).

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Geostationary Sensor Based Forest Fire Detection and Monitoring: An Improved Version of the SFIDE Algorithm

10.20944/preprints201801.0007.v1 ◽

2018 ◽

Author(s):

Valeria Di Biase ◽

Giovanni Laneve

Keyword(s):

Forest Fires ◽

Elevation Angle ◽

Fire Detection ◽

High Sensitivity ◽

Low Earth Orbit ◽

False Alarms ◽

Commission Error ◽

Night Time ◽

Thermal Anomalies ◽

Mediterranean Countries

The paper aims at presenting the results obtained in the development of a system allowing the detection and monitoring of forest fires and the continuous comparison of their intensity when several events occur simultaneously, as usually happens in the European Mediterranean countries during the summer season. The system, called SFIDE (Satellite FIre DEtection), exploits a geostationary satellite sensor (SEVIRI on board of MSG satellite series). The algorithm was developed several years ago in the framework of a project (SIGRI) funded by the Italian Space Agency (ASI). This algorithm has been completely reviewed in order to enhance its efficiency by reducing false alarms rate preserving a high sensitivity. Due to the very low spatial resolution of SEVIRI images (4x4 km2 at Mediterranean latitude) the sensitivity of the algorithm should be very high to detect even small fires. The improvement of the algorithm has been obtained by: introducing the sun elevation angle in the computation of the preliminary thresholds to identify potential thermal anomalies (hot spots), introducing a contextual analysis in the detection of clouds and in the detection of night-time fires. The results of the algorithm have been validated in the Sardinia region by using ground true data provided by the regional Corpo Forestale e di Vigilanza Ambientale (CFVA). A significant reduction of the commission error (less than 10%) has been obtained with respect to the previous version of the algorithm and also with respect to fire-detection algorithms based on low earth orbit satellites.

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Internal wave-induced changes in the chemical stratification in relation to the thermal structure in Lake Kinneret

SIL Proceedings 1922-2010 ◽

10.1080/03680770.2001.11901859 ◽

2002 ◽

Vol 28 (2) ◽

pp. 962-966

Author(s):

Werner Eckert ◽

K. David Hambright ◽

Yosef Z. Yacobi ◽

Ilia Ostrovsky ◽

Assaf Sukenik

Keyword(s):

Internal Wave ◽

Thermal Structure ◽

Lake Kinneret ◽

Chemical Stratification ◽

Induced Changes ◽

Wave Induced

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Investigating marine heat waves with a coupled atmosphere-ocean regional climate model

10.5194/egusphere-egu21-4006 ◽

2021 ◽

Author(s):

Marie Pontoppidan ◽

Priscilla Mooney ◽

Jerry Tjiputra

Keyword(s):

Climate Model ◽

Heat Waves ◽

Human Life ◽

Regional Climate ◽

Atmospheric Model ◽

Ocean Model ◽

Environmental Drivers ◽

Climate Simulation ◽

Substantial Impact ◽

Spatio Temporal

Marine heat waves (MHW&#8217;s) exert a substantial impact on human life and ecosystems in the ocean. In the western part of the tropical Atlantic basin, coral reefs are impacted by such events, resulting in coral bleaching and subsequently loss of biodiversity. To mitigate future changes in MHW&#8217;s it is detrimental to increase our mechanistic understanding of these events, and this must be investigated on a local scale to understand the smaller scale driving processes of the heat waves, e.g. air-sea interactions, and the spatio-temporal extent on environmental drivers essential for the ecosystem processes.Here we use a coupled ocean-atmosphere modelling system (COAWST), which includes the atmospheric model WRF and the ocean model ROMS (including the Fennel ecosystem module), to dynamically downscale an area consisting of the Caribbean Sea and the Gulf of Mexico. Our 12 km grid spacing resolves (at least partly) smaller scale phenomena and in combination with the coupling of the ocean and the atmospheric model, it ensures a skilled representation of the air-sea interactions which are important for MHW&#8217;s. We will show the results of this decadal climate simulation with regards to generation, evolution and persistence of the MHW&#8217;s.

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Extreme temperatures analysis: A study for Campinas, Brazil

10.5194/egusphere-egu21-13403 ◽

2021 ◽

Author(s):

Guilherme Correia ◽

Ana Maria Ávila

Keyword(s):

Minimum Temperature ◽

Temperature Increase ◽

Heat Waves ◽

Vulnerable Groups ◽

Maximum Temperature ◽

Daily Maximum ◽

P Value ◽

Significance Level ◽

Historical Series ◽

Maximum Temperatures

Extreme events such as heat waves have adverse effects on human health, especially on vulnerable groups, which can lead to deaths, thus they must be faced as a huge threat. Many studies show general mean temperature increase, notably, minimum temperatures. The scope of this work was to assess daily data of a historical series (1890-2018) available on the Instituto Agron&#244;mico de Campinas (IAC), in Campinas, using a suite of indices derived from daily temperature and formulated by the Expert Team on Climate Change Detection and Indices (ETCCDI) and evaluate trends. To compute the extreme indices RClimDex 1.1 was used. The significance test is based on a t &#160;test, with a significance level of 95% (p-value<0,05). Temperature increase is undoubtedly through many indices, especially from 1980, as there is a continuous rise of the temperature. Annual mean maximum temperature rose from 26&#176;C to 29&#176;C, whereas many years consistently have more than 50 days with maximum temperatures as high as 31&#176;C and more than 20% of the days within a year are beyond the 90th percentile of the daily maximum temperatures. Annual mean minimum temperature rose from 14&#176;C to 18&#176;C, whereas many years consistently have more than 150 days with minimum temperatures as high as 18&#176;C and more than 30% of the days within a year are beyond the 90th percentile of the daily minimum temperatures. Therefore, results indicate the increase of minimum temperature is greater than the increase of maximum temperatures.

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An insight on the polyphase thermal history of the Ghomarides and Upper Sebtides in the Internal Rif (North Morocco) by means of Raman spectroscopy on organic matter

10.5194/egusphere-egu21-7459 ◽

2021 ◽

Author(s):

Andrea Schito ◽

Achraf Atouabat ◽

Rocco Calcagni ◽

Sveva Corrado ◽

David Muirhead ◽

...

Keyword(s):

Raman Spectroscopy ◽

Thermal Structure ◽

Carbonaceous Material ◽

Stability Field ◽

Lower Paleozoic ◽

Suitable Alternative ◽

History Of ◽

Maximum Temperatures ◽

Paleozoic Rocks ◽

Metamorphic Core

The correct assessment of maximum temperatures experienced by rocks is an essential tool to unravel the evolution of the thermal structure of the crust during the main phases of an orogenesis. Given to broad P-T stability field of classical metamorphic mineralogical indicators, maximum temperatures derived from the analyses of carbonaceous material dispersed in rocks by means of Raman spectroscopy has shown to be a suitable alternative to classical geothermometer. Initially developed for high metamorphic rocks the use of this tools has recently been extended also at lower metamorphic degree and diagenesis. This allowed us to extend the analyses of paleotemperatures experienced by rocks from Ghomarides and Sebtides from the Internal Rif in North Morocco with respect to previous works. Ghomaride and Sebtides in this portion of the Rif-Betic-Tell chain, represent respectively the upper and lower plates of a metamorphic core complex&#160; and are composed, the first, by Paleozoic rocks with a partially preserved Mesozoic-Cenozoic cover and the second by lower Paleozoic to Triassic deep-crustal mica-schists, migmatites and granulites associated with peridotites (Beni Bousera complex).Our data suggest that the uppermost Tiszgarine Unit of the Upper Sebtides experienced warmer condition than previously observed. Moreover, we calculate the maximum temperatures experienced by the Ghomarides&#160; during both the Eo and Late Variscan cycles showing that differences in temperature exist among the vary units that compose the complex. Finally, in the southern area our data suggest a less severe alpine heating related to the emplacement of the Beni Bousera peridotite, than previously calculated.

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A Pyrenean-like model for the Variscan belt in NW Africa : insights from thermometry-based Raman spectroscopy study in the Khenifra Basin

10.5194/egusphere-egu2020-20672 ◽

2020 ◽

Author(s):

Rémi Leprêtre ◽

Andrea Schito ◽

Rachid Ouchaou ◽

Mohamed El Houicha ◽

Francis Chopin

Keyword(s):

Raman Spectroscopy ◽

Thermal Structure ◽

Early Carboniferous ◽

Variscan Orogeny ◽

Time Interval ◽

Short Time Interval ◽

Variscan Belt ◽

Single Event ◽

Maximum Temperatures ◽

Short Time

The Variscan belt in NW Africa is an intracontinental belt, resulting from far-field compressional stress during the closure of the Rheic Ocean between the Late Carboniferous and the Early Permian. In the classical view, this orogen building was preceded by a pre-orogenic stage, namely the Eo-variscan stage, suggested to have occurred at the Late Devonian-Early Carboniferous transition.This view is now questioned, for multiple reasons. A first structural reason aims at re-interpreting the so-called Eovariscan features as extensional ones. Indeed, although many structures have been described, their integration into a compressional setting is not straightforward. A second reason is geodynamical, since this peculiar stage is bracketed between two general extensional phases recorded at the scale of NW Africa, and this leaves a very short time interval to proceed to a compressional phase that is geodynamically not integrated until today. At last, a third reason stems from early findings from metamorphic works in the Western Meseta that demonstrated the occurrences of previously unnoticed high geothermal gradients inside numerous Early Carboniferous basins (Chopin et al., 2014&#160;; Wernert et al., 2016&#160;; Delchini et al., 2018&#160;; Lahfid et al., 2019).In this work, we sampled the Khenifra Basin within the easternmost part of the Western Meseta, where the Eovariscan deformation was defined (Allary et al., 1972). We carried on structural observations into the basement and sampled both the Ordovician basement and the Middle(?)-Late Visean series of the basin, which is thought the be extensional. Maximum temperatures reached by the 77 sampled rocks were obtained from the analysis of organic matter with the use of the Raman spectroscopy. The examination of this new dataset demonstrates that the Ordovician series acquired temperatures through a single event, consistently with their common record of the Eovariscan deformation. Instead, the unconformable Visean series on top of the basement show a pronounced basinal asymmetry, from low temperatures (< 160&#176;C) to temperatures equivalent to the Ordovician ones (> 250&#176;C). The Visean series do not record the Eovariscan deformation, and their thermal structure was acquired before the Variscan event, regarding their repartition within the basin. The examination of the different hypotheses for the timing of the maximal temperature acquisition (Variscan, compressional Eovariscan and extensional Eovariscan) leads to a single option only compatible with an extensional Eovariscan context.The renewal on the knowledge about the early stages of the Variscan orogeny in NW Africa allows us to consider a Pyrenean-like model for the formation of this intraplate belt, resulting from the inversion of hot Early Carboniferous rifted basins.

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