scholarly journals Basic Diagnosis and Prediction of Persistent Contrail Occurrence Using High-Resolution Numerical Weather Analyses/Forecasts and Logistic Regression. Part II: Evaluation of Sample Models

2009 ◽  
Vol 48 (9) ◽  
pp. 1790-1802 ◽  
Author(s):  
David P. Duda ◽  
Patrick Minnis

Abstract A probabilistic forecast to accurately predict contrail formation over the conterminous United States (CONUS) is created by using meteorological data based on hourly meteorological analyses from the Advanced Regional Prediction System (ARPS) and the Rapid Update Cycle (RUC) combined with surface and satellite observations of contrails. Two groups of logistic models were created. The first group of models (SURFACE models) is based on surface-based contrail observations supplemented with satellite observations of contrail occurrence. The most common predictors selected for the SURFACE models tend to be related to temperature, relative humidity, and wind direction when the models are generated using RUC or ARPS analyses. The second group of models (OUTBREAK models) is derived from a selected subgroup of satellite-based observations of widespread persistent contrails. The most common predictors for the OUTBREAK models tend to be wind direction, atmospheric lapse rate, temperature, relative humidity, and the product of temperature and humidity.

2009 ◽  
Vol 9 (4) ◽  
pp. 1357-1364 ◽  
Author(s):  
D. P. Duda ◽  
R. Palikonda ◽  
P. Minnis

Abstract. The potential for using high-resolution meteorological data from two operational numerical weather analyses (NWA) to diagnose and predict persistent contrail formation is evaluated using two independent contrail observation databases. Contrail occurrence statistics derived from surface and satellite observations between April 2004 and June 2005 are matched to the humidity, vertical velocity, wind shear and atmospheric stability derived from analyses from the Rapid Update Cycle (RUC) and the Advanced Regional Prediction System (ARPS) models. The relationships between contrail occurrence and the NWA-derived statistics are analyzed to determine under which atmospheric conditions persistent contrail formation is favored within NWAs. Humidity is the most important factor determining whether contrails are short-lived or persistent, and persistent contrails are more likely to appear when vertical velocities are positive. The model-derived atmospheric stability and wind shear do not appear to have a significant effect on contrail occurrence.


FLORESTA ◽  
2011 ◽  
Vol 41 (3) ◽  
Author(s):  
Christopher Thomas Blum ◽  
Carlos Vellozo Roderjan ◽  
Franklin Galvão

O estudo teve como objetivo caracterizar aspectos climáticos, com enfoque na temperatura e umidade relativa do ar e sua influência sobre a distribuição da vegetação numa encosta da Serra da Prata, Morretes, Paraná, coberta pelas formações Submontana e Montana da Floresta Ombrófila Densa. Entre julho de 2009 e junho de 2010 foram obtidos dados meteorológicos, aos 400 e 1.000 m s.n.m. As temperaturas médias no período foram 19,0 ºC (400 m) e 16,3 ºC (1.000 m). A taxa de redução térmica com a elevação altitudinal foi 0,44 ºC/100 m. Detectou-se uma região de transição climática em torno dos 700 m de altitude, com o clima Cfb acima e o Cfa abaixo. A isoterma da temperatura média de 13 ºC no mês mais frio, estimada para a região dos 800 m s.n.m., coincide com o limite inferior de ocorrência da formação Montana, denotando a influência das baixas temperaturas na diferenciação da vegetação. As médias de umidade relativa do ar foram elevadas, devido ao constante aporte das massas de ar úmido oriundas do oceano. As médias das amplitudes diárias de temperatura e umidade foram muito semelhantes para as duas altitudes, demonstrando que a variação altitudinal parece não exercer influência sobre suas variações diárias na encosta estudada.Palavras-chave:  Gradiente altitudinal; Serra do Mar; Floresta Atlântica; temperatura; umidade relativa do ar. AbstractClimate and his influence over the Atlantic Dense Rainforest distribution in the Prata Mountain Range, Morretes, Paraná, South Brazil. This study aimed to characterize climatic aspects, focusing air temperature and relative humidity, as well as its influence to vegetation distribution in a slope of Prata Mountain Range, Morretes, Paraná, covered by Submontane and Montane formations of the Atlantic Rainforest. Between July of 2009 and June of 2010 meteorological data was collected, at 400 and 1,000 m a.s.l. The average temperature along this period was 19.0 ºC (400 m) and 16.3 ºC (1,000 m). The temperature lapse rate was 0.44 ºC/100 m. It was detected a climatic transition region at about 700 m a.s.l., with the Cfb type above, and the Cfa type below. The isotherm of the average temperature of 13 ºC in the coldest month, estimated for the region of about 800 m a.s.l., agrees with the inferior limit of the Montane formation, denoting influence of low temperatures in the vegetation distinction. The air relative humidity average was high, because the regular arrival of moist air masses from the ocean. The average of daily amplitude of temperature and relative humidity were very similar for both studied altitudes, denoting not apparent influence of the altitudinal variation to the daily variation of these climatic variables in the slope.Keywords:              Altitudinal gradient; Serra do Mar; Atlantic Ombrophilous Dense Forest; temperature; air relative humidity.


1997 ◽  
Vol 23 (14) ◽  
pp. 2243-2256 ◽  
Author(s):  
A. Sathye ◽  
M. Xue ◽  
G. Bassett ◽  
K. Droegemeier

MAUSAM ◽  
2021 ◽  
Vol 58 (4) ◽  
pp. 471-480
Author(s):  
GIRISH SEMWAL ◽  
R. K. GIRI

Operational weather prediction over western Himalayan region is a challenging job due to scarcity of data and complex topography that interacts with approaching weather system. Accurate prediction of complex weather phenomena requires dense data network which is difficult to establish in mountain due to complex terrain and hostile weather conditions over Himalaya. The alternate method to overcome this problem is by ingesting three-dimensional meteorological variables from global model’s analysis and forecast values as initial and lateral boundary conditions in meso-scale numerical models. Simultaneously, data assimilation is a potential tool in which non-conventional [satellite, radar and Automatic Weather Station (AWS)] and conventional (surface and upper air observations) data are ingested in the numerical models to generate high resolution and accurate initial fields for the initialization of the mesoscale model. In the present study, Advanced Regional Prediction System (ARPS) model has been used for the prediction of synoptic weather system known as Western Disturbance (WD) that affects the weather of western and central Himalaya during winter period (November – April).The ARPS model has been selected for this study because the model has its own objective analysis and quality control system. It has the capacity to ingest the satellite, Doppler weather radar data and other types of observations. Its assimilation system can also be used to overcome the problem of data scarcity in Himalayan region. In this study, initial and lateral boundary fields are taken from the T-80 spectral global model operationally used at National Centre for Medium Range Prediction (NCMRWF), Noida (UP), India. The global model’s analysis was taken as the initial condition and 24 hour’s interval forecasts as lateral boundary conditions. The model has been used for the simulation of few WDs for 96 hours (Four days). The comparison of ARPS simulation with T-80 forecast shows that the ARPS model could produce better results in respect of the circulation of WDs and hence it can be utilized for the operational weather prediction over the Indian region.  


2008 ◽  
Vol 8 (5) ◽  
pp. 18385-18407
Author(s):  
D. P. Duda ◽  
R. Palikonda ◽  
P. Minnis

Abstract. The potential for using high-resolution meteorological data from two operational numerical weather analyses (NWA) to diagnose and predict persistent contrail formation is evaluated using two independent contrail observation databases. Contrail occurrence statistics derived from surface and satellite observations between April 2004 and June 2005 are matched to the humidity, vertical velocity, wind shear and atmospheric stability derived from analyses from the Rapid Update Cycle (RUC) and the Advanced Regional Prediction System (ARPS) models. The relationships between contrail occurrence and the NWA-derived statistics are analyzed to determine under which atmospheric conditions persistent contrail formation is favored within NWAs. Humidity is the most important factor determining whether contrails are short-lived or persistent, and persistent contrails are more likely to appear when vertical velocities are positive, and more likely to spread when the atmosphere is less stable. Although artificial upper limits on upper tropospheric humidity within the NWAs prevent a direct quantitative agreement of model data with contrail formation theory, logistic regression or similar statistical methods may improve the prediction of contrail occurrence.


Author(s):  
C. O. Nwokocha ◽  
C. U. Okujagu ◽  
P. I. Enyinna

Effects of meteorological parameters of relative humidity and wind direction on visibility in the Niger Delta, Nigeria (4.15°N-7.17°N, 5.05°E-8.68°E) for a period of 31 years (1981-2012) have been investigated. The data on visibility, relative humidity and wind direction were obtained from Nigerian Meteorological Agency (NIMET) and National Center for Environmental Prediction (NCEP) respectively. The visibility and meteorological data were analyzed to study the temporal variation of atmospheric visibility and its relationship with meteorological parameters in the region. The analysis was done using statistical techniques and the results show that cities in the Eastward (Calaber, Uyo and Port Harcourt) have more inverse correlation between Relative humidity and visibility while Westward cities (Owerri, Warri and Akure) are more directly correlated to visibility. Again it shows that visibility is more correlated with relative humidity in places of high hydrocarbon activities like Port Harcourt while it is better correlated with wind direction in places with less hydrocarbon activities like Akure.


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