scholarly journals Some statistical characteristics of occurrence of fog over Patna airport

MAUSAM ◽  
2021 ◽  
Vol 64 (2) ◽  
pp. 345-350
Author(s):  
S.I. LASKAR ◽  
S.K.ROY BHOWMIK ◽  
VIVEK SINHA
Keyword(s):  
Stability Index ◽  
Statistical Characteristics ◽  
Radiosonde Data ◽  
Occurrence Time ◽  
Percentage Frequency ◽  
Weather Observations

bl 'kks/k i= esa o"kZ 2000 ls 2010 rd 10 o"kksZa ds uoacj ls Qjojh ekg  dh vof/k ds vk¡dMksa dk mi;ksx djrs gq, iVuk gokbZ vMMs ij Nkus okys dqgjs dh lkaf[;dh; fo’ks"krkvksa tSls & dksgjk Nkus dh ckjEckjrk] Nkus dk le;] vof/k] l?kurk rFkk folfjr gksus ds le; dk  v/;;u fd;k x;k gSA bl v/;;u ls izkIr gq, ifj.kke ls irk pyk gS fd foxr 10 o"kksZa ds nkSjku iVuk gokbZ vMMs ij pkjksa gh eghuksa esa dqgjs dh ckjEckjrk  esa o"kZ 1961&90 rFkk 1951&80 ds tyok;fodh esa miyC/k flukWfIVd rFkk rRdkfyd ekSkle izs{k.kksa dh rqyuk esa fo’ks"k :i ls o`f) gqbZ gSA iVuk gokbZ vMMs ij dqgjk Nkus dk lcls vuqdwy eghuk fnlEcj vkSj mlds ckn tuojh dk ekuk x;k gsA fnlacj vkSj tuojh ds eghuksa esa 5 ?kaVsa ls vf/kd vof/k rd  dqgjk Nkus dh vko`fRr  dh izfr’kr~rk vf/kdre jgh gS tcfd uoacj ,oa Qjojh ds eghuksa esa 2 ?kaVs ls de vof/k dh vko`fRr lcls vf/kd jgh gSA dqgjk dk cuuk vDlj 0000&0200 ;w-Vh-lh- ds nkSjku vkSj bldk {k; gksuk  0200&0500 ;w- Vh- lh- ds nkSjku ns[kk x;k gSA cgqr ?kus dqgjs dh vf/kdre vko`fRr & izfr’krrk uoacj ekg esa ns[kh xbZ gSA fnlacj vkSj tuojh ds eghuksa dh vf/kdrj fLFkfr;ksa esa 1200 ;w-Vh-ij vxyh jkr@lqcg ds le; iMs+ dksgjs ds jsfM;ksa lkSans ds vk¡dMksa ds vk/kkj ij rS;kj fd, x, dqgjk LFkkf;Ro lwpdkad ¼,Q-,l-vkbZ-½ 40 ls de ik;k x;k gSA  In this paper some statistical characteristics of fog, such as frequencies of occurrence, time of onset, duration, intensity and time of dispersal  over Patna airport are studied  making use of 10 years data for the period November-February, 2000-2010.  The result shows that during the last ten years frequency of fog over Patna airport has increased significantly in all the four months as compared to the climatology based on available synoptic and current weather observations during 1961-90 and 1951-80. The most favourable month for occurrence of fog over Patna airport has been identified as December followed by January. Percentage frequency is highest for duration of fog for more than 5 hours in the months of December and January whereas in the months of November and February frequency is highest for duration less than 2 hours. The formation of fog mostly observed during 0000-0200 UTC and dissipation during 0200-0500 UTC. Percentage frequency of very thick fog was found to be highest in the month of November. In the   months of December and January in most of the cases Fog Stability Index (FSI) based on 1200 UTC radiosonde data leading to occurrence of fog during following night/morning has been found to be less than 40.

scholarly journals Tropopause and jetlet characteristics in relation to thunderstorm development over Cyprus

2010 ◽  
Vol 23 ◽  
pp. 113-117
Author(s):  
A. Orphanou ◽  
K. Nicolaides ◽  
D. Charalambous ◽  
P. Lingis ◽  
S. C. Michaelides
Keyword(s):  
Wind Direction ◽  
The Other ◽  
Statistical Characteristics ◽  
Radiosonde Data ◽  
Data Sets ◽  
Other Hand ◽  
The One

Abstract. In the present study, the monthly statistical characteristics of jetlet and tropopause in relation to the development of thunderstorms over Cyprus are examined. For the needs of the study the 12:00 UTC radiosonde data obtained from the Athalassa station (33.4° E, 35.1° N) for an 11-year period, from 1997 till 2007, were employed. On the basis of this dataset, the height and the temperature of the tropopause, as well as the height, wind direction and speed of the jetlet were estimated. Additionally, the days in the above period with observed thunderstorms were selected and the aforementioned characteristics of the jetlet and tropopause were noted. The two data sets were subsequently contrasted in an attempt to identify possible relations between thunderstorm development, on the one hand, and tropopause and jetlet characteristics, on the other hand.

scholarly journals Antarctic Low-Tropospheric Humidity Inversions: 10-Yr Climatology

2013 ◽  
Vol 26 (14) ◽  
pp. 5205-5219 ◽  
Author(s):  
Tiina Nygård ◽  
Teresa Valkonen ◽  
Timo Vihma
Keyword(s):  
Water Vapor ◽  
Climate Models ◽  
Weather Prediction ◽  
Temperature Inversion ◽  
Statistical Characteristics ◽  
The Arctic ◽  
Radiosonde Data ◽  
Atmospheric Moisture Budget ◽  
Temperature Inversions ◽  
The Antarctic

Abstract Humidity inversions are nearly permanently present in the coastal Antarctic atmosphere. This is shown based on an investigation of statistical characteristics of humidity inversions at 11 Antarctic coastal stations using radiosonde data from the Integrated Global Radiosonde Archive (IGRA) from 2000 to 2009. The humidity inversion occurrence was highest in winter and spring, and high atmospheric pressure and cloud-free conditions generally increased the occurrence. A typical humidity inversion was less than 200 m deep and 0.2 g kg−1 strong, and a typical humidity profile contained several separate inversion layers. The inversion base height had notable seasonal variations, but generally the humidity inversions were located at higher altitudes than temperature inversions. Roughly half of the humidity inversions were associated with temperature inversions, especially near the surface, and humidity and temperature inversion strengths as well as depths correlated at several stations. On the other hand, approximately 60% of the humidity inversions were accompanied by horizontal advection of water vapor increasing with height, which is also a probable factor supporting humidity inversions. The spatial variability of humidity inversions was linked to the topography and the water vapor content of the air. Compared to previous results for the Arctic, the most striking differences in humidity inversions in the Antarctic were a much higher frequency of occurrence in summer, at least under clear skies, and a reverse seasonal cycle of the inversion height. The results can be used as a baseline for validation of weather prediction and climate models and for studies addressing changes in atmospheric moisture budget in the Antarctic.

scholarly journals IASI temperature and water vapor retrievals – error assessment and validation

2009 ◽  
Vol 9 (17) ◽  
pp. 6453-6458 ◽  
Author(s):  
N. Pougatchev ◽  
T. August ◽  
X. Calbet ◽  
T. Hultberg ◽  
O. Oduleye ◽  
...  
Keyword(s):  
Water Vapor ◽  
Assessment Model ◽  
Statistical Characteristics ◽  
Radiosonde Data ◽  
Statistical Validation ◽  
Data Set ◽  
Error Covariance ◽  
Recent Version ◽  
Level 2 ◽  
Good Agreement

Abstract. The METOP-A satellite Infrared Atmospheric Sounding Interferometer (IASI) Level 2 products comprise retrievals of vertical profiles of temperature and water vapor. The error covariance matrices and biases of the most recent version (4.3.1) of the L2 data were assessed, and the assessment was validated using radiosonde data for reference. The radiosonde data set includes dedicated and synoptic time launches at the Lindenberg station in Germany. For optimal validation, the linear statistical Validation Assessment Model (VAM) was used. The VAM uses radiosonde profiles as input and provides optimal estimate of the nominal IASI retrieval by utilizing IASI averaging kernels and statistical characteristics of the ensembles of the reference radiosondes. For temperatures above 900 mb and water retrievals above 700 mb, level expected and assessed errors are in good agreement. Below those levels, noticeable excess in assessed error is observed, possibly due to inaccurate surface parameters and undetected clouds/haze.

scholarly journals Application of AIRS Soundings to Afternoon Convection Forecasting and Nowcasting at Airports

Atmosphere ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 61
Author(s):  
Nan-Ching Yeh ◽  
Yao-Chung Chuang ◽  
Hsin-Shuo Peng ◽  
Chih-Ying Chen
Keyword(s):  
Predictive Accuracy ◽  
Atmospheric Stability ◽  
Stability Index ◽  
Precipitable Water ◽  
Radiosonde Data ◽  
Observation Data ◽  
Accuracy Rate ◽  
Coverage Area ◽  
Forecast Precision ◽  
Data Coverage

In Taiwan, the frequency of afternoon convection increases in summer (July and August), and the peak hour of afternoon convection occurs at 1500–1600 local solar time (LST). Afternoon convection events are forecasted based on the atmospheric stability index, as computed from the 0800 LST radiosonde data. However, the temporal and spatial resolution and forecast precision are not satisfactory. This study used the observation data of Aqua satellite overpass near Taiwan around 1–3 h before the occurrence of afternoon convection. Its advantages are that it improves the prediction accuracy and increases the data coverage area, which means that more airports can use results of this research, especially those without radiosondes. In order to determine the availability of Atmospheric Infrared Sounder (AIRS) in Taiwan, 2010–2016 AIRS and radiosonde-sounding data were used to determine the accuracy of AIRS. This study also used 2017–2018 AIRS data to establish K index (KI) and total precipitable water (TPW) thresholds for the occurrence of afternoon convection of four airports in Taiwan. Finally, the KI and TPW were calculated using the independent AIRS atmospheric sounding (2019–2020) to forecast the occurrence of afternoon convection at each airport. The average predictive accuracy rate of the four airports is 84%. Case studies at Hualien Airport show the average predictive accuracy rate of this study is 81.8%, which is 9.1% higher than that of the traditional sounding forecast (72.7%) during the same period. Research results show that using AIRS data to predict afternoon convection in this study could not only increase data coverage area but also improve the accuracy of the prediction effectively.

scholarly journals Some characteristics of fog over Guwahati airport

MAUSAM ◽  
2021 ◽  
Vol 59 (2) ◽  
pp. 159-166
Author(s):  
SURESH RAM ◽  
M. MOHAPATRA
Keyword(s):  
Coefficient Of Variation ◽  
Meteorological Parameters ◽  
Surface Wind ◽  
Dew Point ◽  
Statistical Characteristics ◽  
Occurrence Time ◽  
Probability Of Occurrence ◽  
Intraseasonal Variations ◽  
Duration Time

The statistical characteristics like frequencies of occurrence, time of onset, duration, time of dispersal and intensity of fog over Guwahati airport are found out and analysed using 10 years data during 1994-95 to 2003-04 for the months of November to February. Also the interannual and intraseasonal variations of occurrence of fog are analysed by calculating the coefficient of variation of monthly frequency of fog and by calculating the significant periodicities in the daily probability of occurrence of fog respectively. The meteorological parameters at 1200 UTC leading to fog in the following night or morning over Guwahati airport are analysed to find out the precursors for occurrence of fog. Statistical characteristics are given in tables and their significance discussed. It is observed that monitoring of Dew Point Depression (DPD) and surface wind can help prediction of occurrence of fog and its intensity over Guwahati airport.

Statistical characteristics of the surface ducts over the South China Sea from GPS radiosonde data

2015 ◽  
Vol 34 (11) ◽  
pp. 63-70 ◽  
Author(s):  
Yinhe Cheng ◽  
Shengqi Zhou ◽  
Dongxiao Wang ◽  
Yuanzheng Lu ◽  
Jinglong Yao
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
Statistical Characteristics ◽  
Radiosonde Data ◽  
The South ◽  
China Sea ◽  
Gps Radiosonde

scholarly journals Freezing precipitation in Russia and the Ukraine

2007 ◽  
Vol 10 ◽  
pp. 25-29
Author(s):  
I. A. Khomenko ◽  
A. R. Ivanova ◽  
N. P. Chakina ◽  
E. N. Skriptunova ◽  
A. A. Zavyalova
Keyword(s):  
Surface Air Temperature ◽  
Analysis Data ◽  
Statistical Characteristics ◽  
Radiosonde Data ◽  
Cloud Base ◽  
Negative Temperatures ◽  
Frequency Dependences ◽  
Cloud Base Height ◽  
Surface Observations ◽  
Classical Mechanism

Abstract. Conditions for freezing precipitation (FP), including freezing rain (FR) and freezing drizzle (FZ) for 8 airports in Russia and 4 in the Ukraine are studied on the basis of 10 to 20-year series of surface observations, radiosonde and objective analysis data. Statistical characteristics are presented of the FP episode durations and of occurrence frequency dependences on surface air temperature, wind direction and speed and cloud base height. From the radiosonde data, it is found that the "classical mechanism" of FP generation (for which, stratification of "warm nose" type in the cloud layer is necessary) is not frequent: most of FP cases are associated with "all cold" conditions in the lower 3-km layer, that is, with negative temperatures in and below the clouds.

scholarly journals IASI temperature and water vapor retrievals – error assessment and validation

2009 ◽  
Vol 9 (2) ◽  
pp. 7971-7989 ◽  
Author(s):  
N. Pougatchev ◽  
T. August ◽  
X. Calbet ◽  
T. Hultberg ◽  
O. Oduleye ◽  
...  
Keyword(s):  
Water Vapor ◽  
Assessment Model ◽  
Statistical Characteristics ◽  
Radiosonde Data ◽  
Statistical Validation ◽  
Data Set ◽  
Error Covariance ◽  
Recent Version ◽  
Level 2 ◽  
Good Agreement

Abstract. The METOP-A satellite Infrared Atmospheric Sounding Interferometer (IASI) Level 2 products comprise retrievals of vertical profiles of temperature and water vapor. The error covariance matrices and biases of the most recent version (4.3.1) of the L2 data were assessed, and the assessment was validated using radiosonde data for reference. The radiosonde data set includes dedicated and synoptic time launches at the Lindenberg station in Germany. For optimal validation, the linear statistical Validation Assessment Model (VAM) was used. The VAM uses radiosonde profiles as input and provides optimal estimate of the nominal IASI retrieval by utilizing IASI averaging kernels and statistical characteristics of the ensembles of the reference radiosondes. For temperature temperatures above 900 mb and water retrievals above 700 mb, level expected and assessed errors are in good agreement. Below those levels, noticeable excess in assessed error is observed, possibly due to inaccurate surface parameters and undetected clouds/haze.

scholarly journals Role of total-totals stability index in forecasting of thunderstorm/non-thunderstorm days over Kolkata during pre-monsoon season

MAUSAM ◽  
2021 ◽  
Vol 58 (3) ◽  
pp. 369-374
Author(s):  
MEDHA KHOLE ◽  
H. R. BISWAS
Keyword(s):  
Monsoon Season ◽  
Stability Index ◽  
Threshold Value ◽  
Thunderstorm Activity ◽  
Radiosonde Data ◽  
Atmospheric Conditions ◽  
Probability Of Occurrence ◽  
Index Value

The thunderstorm activity over Kolkata during pre-monsoon months (March, April and May) has been studied using the radiosonde data of Kolkata (Dumdum). The objective of the study is to examine the utility of Total-Totals Index (TTI) in forecasting occurrence/non-occurrence of thunderstorm over Kolkata. The investigation reveals that Total-Totals Index can be preliminarily used as a predictor to differentiate thunderstorm and non-thunderstorm days. The probability of occurrence of thunderstorm is higher when Total-Totals Index value is higher. While the exact prediction of thunderstorm in all the cases, using the TTI alone, is obviously not possible as TTI alone does not describe the total atmospheric conditions. However, a significant forecast can be furnished by using a threshold value of Total-Totals Index.

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