A three-dimensional (3D) photochemical grid model, CAMx-2.0 (1998), was employed to analyze the spatial and temporal variations of ambient ozone during ozone episodes (concentration of ozone > 120 ppbv) in the Kao-Ping airshed in 2000-2001. The sensitivity analyses of ozone concentrations to the emission reductions in volatile organic compounds (VOC) and nitrogen oxides (NOx) were performed, and the relationships between ozone concentrations and meteorological parameters were examined. Furthermore, the transport routes were studies using inverse trajectory method. Examinations of meteorological parameters and ozone trends reveal that warm temperature, sufficient sunlight, low wind, and high surface pressure are distinct parameters that tend to trigger ozone episodes in Kao-Ping area in autumn and winter seasons. Seasonal patterns of surface ozone include a summer minimum with two maxima in autumn and late winter to the middle of spring, consistent with low mixing heights in autumn and winter and large mixing height in summer. Predicted values of hourly ozone concentration agree reasonably well with measured data. The assessment of the effect of the initial and boundary conditions on the performance of the model revealed that the model can be improved by specifying an ozone concentration of 70 ppbv rather than 30 ppbv on the top boundary of the model, while separately considering the daytime and nighttime ozone concentration on the lateral boundary conditions. The sensitivity analysis shows a VOC-sensitive regime in Kaohsiung City. In addition to the locally emitted pollutants, the inverse trajectory analysis shows that most pollutants in Kaohsiung City come from Kaohsiung County, followed by Tainan County and Ping-Tung County. In autumn, the air quality is worst in Ping-Tung County and ozone episodes occur most frequently. Because the prevailing wind is north or north-east wind in autumn, most pollutants are transported from the upwind areas, including Kaohsiung City and Kaohsiung County. The sensitivity analysis shows a NOx-sensitive regime for Ping-Tung city, consistent with Sillman¡¦s results (1999), indicating that freshly emitted pollutants are typically (but not always) characterized by VOC-sensitive chemistry and evolve towards NOx-sensitive chemistry as the air parcels move downwind.

This research aims to analyze the spatial and temporal characteristics of instrument meteorological conditions (IMC) over the Southern Appalachian Region from 2008 to 2023, utilizing Meteorological Terminal Aerodrome Report (METAR) stations across six USGS-defined physiographical provinces. IMC is defined as visibility less than three statute miles and/or cloud ceiling heights less than 1,000 feet above ground. Percentage of hours reporting IMC are considered on an annual, seasonal, and hourly basis. The greatest increase in IMC over the period occurs in the Piedmont province, and the greatest decrease in the Interior Low Plateaus province. All provinces experience the greatest amount of IMC in wintertime, and the season with the fewest IMC hours varies by province. All provinces see a maximum hour of IMC within three hours following sunrise except summertime in the Interior Low Plateaus, which experiences the highest frequency of IMC within two hours prior to sunset.

Magistratūros studijų baigiamajame darbe įvertintas ir pritaikytas Botrytis spp. infekcijos prognozavimo modelis ropiniuose svogūnuose apsaugai nuo ligų vegetacijos metu. Darbo objektai – ropiniai svogūnai (Allium cepa L.); ligos sukėlėjai - kekerinis lapų dėmėtumas (Botrytis squamosa) ir lapų taškuotoji dėmėtligė (Botrytis cinerea); internetinė „iMETOS®sm“ prognozavimo sistema (Botrytis spp. infekcijos prognozavimo modelis). Tyrimo metodai: tiriamas meteorologinės stotelės „iMETOS®sm“ Botrytis spp. infekcijos prognozavimo modelių pritaikymas ropiniuose svogūnuose. Tirti dviejų Botrytis rūšių sukeliamų ligų prognozavimo modeliai: 1) Botrytis squamosa infekcijos modelis; 2) Botrytis cinerea rizikos modelis. Mikologiniams tyrimams ėminiai surinkti nuo Botrytis grybais pažeistų svogūnų vegetatyvinių dalių vystymosi tarpsniu ir tirti taikant vizualinį – simptomatinį, drėgnų kamerų, sėjimo į Petri lėkšteles, mikroskopavimo metodus. Išskirti izoliatai identifikuoti iki rūšies, remiantis kolonijų kultūrinėmis ir morfologinėmis savybėmis bei lyginant su literatūros duomenimis, naudojant apibūdintojus (Domsch ir kt., 1980, p. 859). Tyrimams pasirinktos dvi apsaugos sistemos: pagal faktinį ligos simtomų aptikimo laiką ir pagal „iMETOS®sm“ Botrytis spp. infekcijos svogūnuose modelio parodymus. Darbo rezultatai. Botrytis squamosa infekcijos prognozavimo modelis parodė, kad svogūnų kekeriniam dėmėtumui plisti palankios sąlygos abiejuose tirtuose rajonuose susidarė birželio–rugpjūčio mėn... [toliau žr. visą tekstą] / The master's degree thesis is evaluated and applied to the Botrytis spp. infection in onion forecasting model for the protection against disease during the growing season. Object of the work - onion (Allium cepa L.) pathogens - Botrytis leaf blight discoloration (Botrytis squamosa) and Botrytis leaf spot in (Botrytis cinerea), an online „iMETOS®sm” Forecasting System (Botrytis spp. infection prediction model). Methods of the work: studied meteorological station „iMETOS®sm” Botrytis spp. infection forecasting models use onion. To explore the two types of diseases caused by Botrytis forecasting models: 1) Botrytis squamosa infection model, 2) risk model Botrytis cinerea. Mycological examination of samples collected fungi Botrytis damaged vegetative parts of the onion stage of development and exploration through visual - symptomatic, moist chambers, seeding in petri dishes, microscopy techniques. Distinguish isolates identified to species based on cultural and morphological colony characteristics and comparison with literature data using apibūdintojus (Domsch et al., 1980, p. 859). For this work, the two security systems based on the actual detection of the disease symptoms at the time and under „iMETOS®sm” Botrytis spp. evidence of infection onion model. The results of work. Botrytis squamosa infection prediction model showed that the onion gray mold to spread favorable conditions in both regions studied occurred between June and August. Kaunas district. B... [to full text]

Mechanisms controlling the productivity, abundançe and taxonomic composition of phytoplankton in tropical Lake Malawi were examined by monitoring phytoplankton dynamics in 8 regions covering the length of the lake (560 km) over a 10-12 month period, and relating these dynamics to spatio-temporal changes in thermal structure, nutrient availability, and meteorological conditions. In addition, nearshore benthic photosynthetic rates were measured in 7 different months.Spatial and temporal changes in areal photosynthetic rates were due almost entirely to changes in the efficiency of light utilization by the phyroplankton community. An evaluation of potential factors which might influence tight utilization indicates that nutrient availabitity is the most important. Most of the photosynthetic N and P demand is met by internal recycling within the upper 200 m, and therefore spatio-temporal variation of phytoplankton photosynthetic rate is closely related to changes in mixing regime. It is shown that the dominant meteorological factors responsible for changes in the mixing regime were solar radiation and windspeed. A comparison with previous photosynthesis data for Lake Malawi indicates that windspeed is a dominant factor controlling interannual variability. Shallow areas of the lake were more productive than deep areas, due to more intense upwelling and more efficient internal nutrient recycling in shallow waters. Within the littoral zone, benthic photosynthetic rates were very high, accounting for 14% to 28% of total net photosynthesis within the shallow southeast arm. Phytoplankton biomass was not correlated with photosynthetic rate, indicating that biomass loss processes were important in controlling biomass variability. Changes in phytoplankton taxonomic composition were related to changes in mixing regime. Cyanobacteria and chlorophytes were dominant throughout much of the study period, but diatoms made up a significant proportion of total biomass during periods of increased turbulence and nutrient availability. An analysis of phytoplankton surface area : volume ratios revealed that organism shape and size are important determinants in species succession. Previous studies have emphasized the low variability of phytoplankton biomass and photosynthetic rates in tropical lakes, relative to temperate lakes. An inter-lake comparison reveals that this tenet does not apply to large lakes. Fluctuations in the mixing regime of large tropical lakes have an effect on phytoplankton variability similar in magnitude to the effect of fluctuating solar irradiance in large temperate lakes.

Magistrantūros studijų baigiamajame darbe pateikiami internetinės prognozavimo „iMETOS®sm“ sistema atlikti bakterinės degligės rizikos faktorių analizė bei prognozavimo galimybes Lietuvos versliniuose soduose Darbo objektas –. obelys (Malus); ligos sukėlėja - bakterinė degligė (Erwinia amylovora Burr.). Darbo metodai: tiriamas meteorologinės stotelės Pessl Instruments „iMETOS®sm“ Erwinia amylovora Burr. infekcijos rizikos prognozavimo modelio pritaikymas Lietuvos versliniuose soduose. Darbo rezultatai. 2011 m. Lietuvos agrarinių ir miškų mokslų centro filialo Sodininkystės ir daržininkystės institute atlikti tyrimai prognuozuojant bakterinės degligės (Erwinia amylovora Burr.) pasireiškimo galimybes Lietuvos versliniuose soduose taikant internetinę „iMETOS®sm‘‘prognozavimo sistemą. Bakterinės degligės prognozavimo modelis numato skirtingus ligos pasireiškimo fonus (PETΣ): 1) paskutinius du sezonus degligės nebuvo; 2) paskutinius du sezonus degligė pasireiškė atskirose vietose; 3) praeitą sezoną degligė pasireiškė atskirose vietose; 4) bakterinė degligė aptikta šalia sodo; 5) netoliese dabar aktyvios degligės žaizdos. Visuose stebėtuose ūkiuose per 2011 m. vegetacijos periodą bakterinės degligės prognozavimo modelis apskaičiavo iš viso 310 dienų, kai bakterinės degligės infekcijos rizikos indeksas DIV rodė didžiausią E. amylovora pasireiškimo galimybę pagal PETΣ. Stebėtuose obelų soduose, kai paskutinius du sezonus degligės sode nebuvo, nustatyta, kad didžiausia patogeno... [toliau žr. visą tekstą] / Master’s thesis submitted to the online prediction "sand'' iMETOS ® forecasting system to perform fire blight risk factor analysis and the predictive ability of Lithuanian business orchards. Object of the work- apple (Malus) to cause disease - a fire blight (Erwinia amylovora Burr.). Method of the work: working methods studied meteorological station Pessl Instruments iMETOS ® sm 'Erwinia amylovora Burr. infection risk prediction model for Lithuanian business orchards. The results of work. In 2011. Lithuanian Institute of Agrarian and Forest Sciences Centre branch of the Institute of Horticulture forecasting studies of fire blight (Erwinia amylovora Burr.) The possibility of a Lithuanian business orchards using an online "sand'' iMETOS ® forecasting system. Fire blight forecasting model for the different disease backgrounds (PETΣ): 1) the last two seasons were not fire blight, 2) the last two seasons fire blight occurred in different places, and 3) last season fire blight occurred in different places, 4) fire blight found near the orchards, 5) nearby is now active fire blight wounds. All the observed farms in 2011. fire blight vegetation period forecasting model documented a total of 310 days after infection, fire blight DIV risk index showed the highest E amylovora by PETΣ to occur. Apple orchards in all observed the last two seasons did not fire blight the garden, it was found that the greatest manifestation of the pathogen by orchards PETΣ option was: „Luksnėnų sodai” UAB... [to full text]

Mechanisms controlling the productivity, abundançe and taxonomic composition of phytoplankton in tropical Lake Malawi were examined by monitoring phytoplankton dynamics in 8 regions covering the length of the lake (560 km) over a 10-12 month period, and relating these dynamics to spatio-temporal changes in thermal structure, nutrient availability, and meteorological conditions. In addition, nearshore benthic photosynthetic rates were measured in 7 different months.Spatial and temporal changes in areal photosynthetic rates were due almost entirely to changes in the efficiency of light utilization by the phyroplankton community. An evaluation of potential factors which might influence tight utilization indicates that nutrient availabitity is the most important. Most of the photosynthetic N and P demand is met by internal recycling within the upper 200 m, and therefore spatio-temporal variation of phytoplankton photosynthetic rate is closely related to changes in mixing regime. It is shown that the dominant meteorological factors responsible for changes in the mixing regime were solar radiation and windspeed. A comparison with previous photosynthesis data for Lake Malawi indicates that windspeed is a dominant factor controlling interannual variability. Shallow areas of the lake were more productive than deep areas, due to more intense upwelling and more efficient internal nutrient recycling in shallow waters. Within the littoral zone, benthic photosynthetic rates were very high, accounting for 14% to 28% of total net photosynthesis within the shallow southeast arm. Phytoplankton biomass was not correlated with photosynthetic rate, indicating that biomass loss processes were important in controlling biomass variability. Changes in phytoplankton taxonomic composition were related to changes in mixing regime. Cyanobacteria and chlorophytes were dominant throughout much of the study period, but diatoms made up a significant proportion of total biomass during periods of increased turbulence and nutrient availability. An analysis of phytoplankton surface area : volume ratios revealed that organism shape and size are important determinants in species succession. Previous studies have emphasized the low variability of phytoplankton biomass and photosynthetic rates in tropical lakes, relative to temperate lakes. An inter-lake comparison reveals that this tenet does not apply to large lakes. Fluctuations in the mixing regime of large tropical lakes have an effect on phytoplankton variability similar in magnitude to the effect of fluctuating solar irradiance in large temperate lakes.

Aktinidijų uogų cheminės sudėties priklausomybė nuo meteorologinių sąlygų 2008-2009 m. tirta margalapės aktinidijos (Actinidia kolomikta) veislių ‘Laiba’, ‘Lankė’, ‘Landė’, ‘Paukstės Šakarva’, augančių Lietuvos žemės ūkio universiteto pomologiniame sode, uogų cheminė sudėtis. Standartiniais metodais uogose nustatyti sausųjų, tirpių sausųjų medžiagų, askorbo rūgšties, žalių pelenų, žalios ląstelienos, žalių baltymų ir aminorūgščių kiekiai, taip pat vidutinė uogos masė. Išanalizuota meteorologinių sąlygų įtaka aktinidijų uogų cheminei sudėčiai. Tyrimais nustatyta, didžiausia vienos uogos masė – 3,22 g – ‘Paukštės Šakarva’ aktinidijų. Mažiausios uogos buvo ‛Lankė’ aktinidijų - 2,09 g. Vidutinė vienos uogos masė – 2,64 g. Daugiausiai sausųjų medžiagų sukaupė ‛Laiba’ uogos – 21,08 %, mažiausiai - ‛Landė’ – 18,02 %. Tirpių sausųjų medžiagų daugiausiai sukaupė ‛Laiba’ – 12,72 %, mažiausiai - ‘Paukštės Šakarva’ – 10,83 %. Didžiausi askorbo rūgšties kiekiai aptinkami sunokusiose ‛Landė’- 5479,86 mg kg-1, mažiausi nesunokusiose ‘Lankė’ – 2698,25 mg kg-1. Daugiausiai žalių pelenų aktinidijų uogų sausojoje medžiagoje sukaupė ‛Laiba’ - vidutiniškai 6,20 %. / The investigation of Actinidia kolomikta cultivars ‘Laiba’, ‘Lanke’, ‘Lande’, ‘Paukstes Sakarva’, grown in Lithuanian University of Agriculture polomogycal garden, chemical composition of berries were caried out during the period of 2008 – 2009. The amount of dry agent, dry deliquescent agent, ascorbic acid, crude ash, crude fibre, crude protein, amino acids and the average berry weight were investigated by standart methods. During investigation there were analyzed the influence of meteorological conditions to A. kolomikta berries chemical composition. The investigation showed the highest weight of A. kolomikta ‘Paukstes Sakarva’breed fruits - 3,22 g. The smallest berries of A. kolomikta breed ‛Lankė’ - 2,09 g. The average weight of berry - 2,64 g. The biggest amounts of dry matters were established in fruits of ‘Laiba’ cultivar – 21,08 %, the smallest amount in fruits of ‘Lande’ cultivar – 18,02 %. The biggest amounts of dry deliquescent matters were established in fruits of ‘Laiba’ cultivar plants –12,72 %, the smallest amount in fruits of ‘Paukstes Sakarva’ cultivar plants – 10,83 %. The biggest amounts of ascorbic acid were determined in ripe fruits of cultivar ‛Lande’- 5479,86 mg kg-1, the lowest level of ascorbic acid were established in immature fruits of cultivar ‘Lanke’ – 2698,25 mg kg-1. Cultivar ‘Laiba’ accumulated the highest contents of crude ash in dry agent of berries (about 6,20 % on average).

Dažniausiai inversijos sąlygos pavojingos miestams/ didmiesčiams, kurių didžiausias teršalų kiekis išmetamas dienos metu, o naktį teršalams išsisklaidyti trukdo inversijos reiškinys, kuris išsilaiko iki paryčių. Todėl yra svarbu kuo aiškiau apibrėžti inversijos sąlygų susidarymo priežastis ir išanalizuoti šio reiškinio įtaką miesto taršai. Taigi šіo dаrbo tіkѕlаѕ – nuѕtаtytі temperаtūroѕ іnverѕіјoѕ dėѕnіngumų įtаkа oro teršаlų ѕklаіdаі Kаuno mіeѕte. Pagrindiniai uždaviniai: nuѕtаtytі temperаtūroѕ іnverѕіјoѕ dėѕnіngumą pаroјe ѕkіrtіngаіѕ metų lаіkаіѕ, tuomet іšаnаlіzuotі temperаtūroѕ іnverѕіјoѕ įtаką teršаlų koncentrаcіјаі іr ѕtаtіѕtіškаі įvertіntі ryšіnę prіklаuѕomybę tаrp šіų rodiklių, taip pat įvertіntі kіtų meteorologіnіų rodiklių įtаką temperаtūroѕ іnverѕіјoѕ formаvіmuіѕі beі teršаlų pаѕіѕkіrѕtymuі kartu įvertinant oro teršalų koncentracijų ribinių verčių dinamiką 2006-2008 metais. Pagrindinis darbo metodas - duomenų analizė ir jų statistinių sąryšių kiekybinis įvertinimas. Atlikus tyrimą paaiškėjo kad, naktinės temperаtūroѕ іnverѕіјoѕ reіškіnyѕ Kаuno mіeѕte pаѕіreіškіа bet kurіuo metų lаіku іr ѕkіrіаѕі tіk vertіkаlаuѕ temperаtūroѕ grаdіento аmplіtudė. Taip pat nustatytos teigiamos vidutinio stiprumo teršalų koncentracijos priklausomybės nuo temperatūros inversijos išskyrus SO2. Be to nustatyta, kad KD10 koncentracija 2006 -2008 metų kovo pabaigoje ir balandžio pradžioje pasiekia didžiausią lygį ir viršija leistiną paros koncentracijos vertę, kai NO2 koncentracija ore... [toliau žr. visą tekstą] / Most inversion conditions dangerous cities / cities with the highest emissions of pollutants during the day and night to disperse pollutants prevents inversion phenomenon, which exists to morning. It is important to clarify the reasons for the formation of inversion conditions and analyze the impact of the phenomenon of urban pollution. The main thesis goal is to identify temperature inversions conditions and its impaction to the spread of pollutant Main tasks: identify temperature inversion phenomenon in different cycles of year, then calculate temperature inversion and pollutants correlation plus to analyze the concentration amount of pollutants in 2006- 2008 years. The method used for this investigation is the analysis of the data correlations calculation. The investigation revealed that temperature inversion exist on all cycles of year and detectable on night. Also the positive dependence of pollutant concentration to temperature inversion is detected, with the exception of SO2. In addition, it was found that the concentration of KD10 exceeded maximum values on 2006 -2008 in the end of March and beginning of April. What is more, NO2 concentration in air exceeds its level a several times a year and this is the signal for our health.

Baigiamajame darbe pateikiami lauko eksperimento, vykdyto Aleksandro Stulginskio universiteto bandymų stotyje 2010–2011 m., duomenys. Dirvožemis karbonatingas sekliai glėjiškas išplautžemis (Calc(ar)i-Epihypogleyic Luvisol). Tyrimo tikslas – įvertinti sėjos laiko įtaką linijinių ir hibridinių žieminių rapsų derliaus formavimuisi skirtingos trukmės šiltėjančiu rudens – žiemos periodu. Sėjos laikas ir veislė turėjo esminės įtakos žieminių rapsų pasėlių tankumui rudenį. Rugpjūčio 20 d., rugsėjo 5 ir 10 d. sėtų skirtingų veislių žieminių rapsų pasėlių tankumas skyrėsi esmingai – tankesni buvo linijinės veislės rapsų pasėliai. Žieminių rapsų sudygimui įtakos turėjo meteorologinės sąlygos dygimo metu, ypač – kritulių kiekis ir intensyvumas. Sėjos laikas turėjo esminės įtakos rapsų biometriniams rodikliams rudenį prieš žiemojimą. Veislės esminė įtaka nustatyta tik lapų skaičiui pasėjus žieminius rapsus rugpjūčio mėnesį. Pasibaigus atsinaujinusiai vegetacijai rudens–žiemos laikotarpiu, sėjos laiko įtaka rapsų biometriniams rodikliams išliko esminė. Didesnę antžeminės dalies masę, lapų skaičių bei šaknų masę užaugino ‘Kronos’ veislės žieminiai rapsai. Atsinaujinus vegetacijai pavasarį, sėjos laikas turėjo esminės įtakos antžeminės dalies masei bei šaknų masei, tuo tarpu lapų skaičiui esminės įtakos nebuvo. ‘Kronos’ veislės žieminiai rapsai suformavo esmingai didesnę šaknų masę, juos sėjant rugpjūčio 10 d. Trumpas pasiruošimo žiemojimui laikotarpis, nepalankios meteorologinės sąlygos... [toliau žr. visą tekstą] / Data of the field experiment completed on the experiment station at Aleksandras Stulginskis University in the period 2010 – 2011 are analysed in the thesis. Soil of the experiment field - (Calc(ar)i-Epihypogleyic Luvisol). Aim of the research – to estimate the effect of the linear and hybrid winter rape yield formation during the warming autumn – winter period. Sowing time and variety had significant effect on winter rape crop thickness in autumn. Thickness of the crop of the considered winter rape varieties sown August 20, September 5 and 10 differed, considerably. Thicker crop was recorded for the linear rape variety. Meteorological conditions especially precipitation amount and intensity were found to have significant effect on winter rape germination. Sowing time contributed significantly to the biometric rape indices before wintering. The obtained data revealed the effect of variety on the number of winter rape leaves sown in August. The effect of the sowing time after the end of renewed vegetation in autumn-winter period was found to be significant. ‘Kronos’ variety winter rape produced higher above-ground mass, leaves number and root mass. The sowing time was found to have a significant effect not only on the above-ground mass but also on root mass. ‘Kronos’ variety winter rape sown August 10 were recorded to produce considerably higher root mass. Due to unfavourable meteorological conditions at the end of winter the rape sown August 10 and 20 over-wintered. Sowing... [to full text]

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-05-14T19:13:34Z No. of bitstreams: 1 NILZELE DE VILHENA GOMES JESUS – TESE (PPGMET) 2014.pdf: 6278341 bytes, checksum: d1799ad3cede1860eb4826792903ca83 (MD5) / Made available in DSpace on 2018-05-14T19:13:34Z (GMT). No. of bitstreams: 1 NILZELE DE VILHENA GOMES JESUS – TESE (PPGMET) 2014.pdf: 6278341 bytes, checksum: d1799ad3cede1860eb4826792903ca83 (MD5) Previous issue date: 2014-08-29 / Capes / A ocorrência de condições meteorológicas adversas em aeroportos determina situações desfavoráveis ao tráfego aéreo, como restrição de visibilidade e teto, além de condições de pista escorregadia, que constituem um fator de grande risco à segurança das operações. Estes contratempos podem acarretar prejuízos vultosos para as empresas envolvidas e desconforto ao usuário da aeronavegação. Por isso, este estudo teve como objetivo a determinação de padrões atmosféricos que originam a ocorrência de condições meteorológicas adversas no Aeroporto Internacional de Belém (SBBE), através da aplicação da análise fatorial (AF) em análises de componentes principais (ACP). Foram usados os dados meteorológicos de superfície do SBBE e de Radiação de Onda Longa (ROL), em ponto de grade sobre Belém, proveniente das reanálises do National Centers for Environmental Prediction (NCEP). Através dos indicadores estatísticos, foi selecionado o conjunto de variáveis adequadas para a aplicação daACP. Os dados utilizados foram dos períodos chuvosos de 2003 a 2012, pois na estação chuvosa foi detectado o maior número de emissões de mensagens especiais (código SPECI) no SBBE. O fator dominante está associado à variação diária do aquecimento/resfriamento da superfície. O segundo fator representa as alterações no teor de umidade próximo da superfície, decorrente da variabilidade climática associada com anomalias da temperatura da superfície do mar nos Oceanos Atlântico e Pacífico. E o outro fator igualmente importante, tem relação com a presença de convecção profunda, e consequentemente, de tempestades, as quais foram desenvolvidas por mecanismos das circulações locaisdinâmicos em mesoescala, tais como circulações de brisa marítima e/ou fluvial sobre a área em que se localiza o SBBE. Este último fator foi o qual apresentou o maior número de ocorrência das variáveis que apresentam relação com o estabelecimento das situações meteorológicas adversas que limitam as operações de pousos e decolagens no SBBE. / The occurrence of adverse weather conditions at airports determines unfavorable situations to air traffic, as visibility and ceiling restriction, and slippery track conditions, which are a major risk factor for safety operations. These setbacks can cause sizeable losses for the companies involved and discomfort to the airworthiness of the users. Therefore, this study aimed at determining weather patterns that cause the occurrence of adverse weather conditions in Belem International Airport (SBBE) through the application of factor analysis (FA) on principal components analysis (PCA). It wasused meteorological surface data from the SBBE and outgoing longwave radiation (OLR), in grid point over Belém (Brazil), from the reanalysis of the National Centers for Environmental Prediction (NCEP). Through statistical indicators, it was selected the appropriate set of variables for the application of the PCA. The data used were in the rainy periods of 2003 to 2012, as the rainy season has been detected as many reports of the SPECI code in the SBBE. The dominant factor is associated with the daily variation of the heating/cooling of the surface. The second factor is the changes in the moisture content near the surface as a result of climate variability associated with temperature anomalies of the sea surface in the Atlantic and Pacific Oceans. And another equally important factor is related to the presence of deep convection, and consequently storms, which were developed by mechanisms of dynamic local mesoscale circulations such as circulations of maritime and/or fluvial breeze over the area in which is located the SBBE. This last factor was the one which had the highest number of occurrences of the variables that have relation with the establishment of the adverse weather conditions that limit of takeoffs and landings operations in the SBBE.