scholarly journals Distribution of the areas and heights of the radar echoes from convective clouds around Delhi during monsoon season

MAUSAM ◽  
2021 ◽  
Vol 43 (2) ◽  
pp. 15-18
Author(s):  
R. N. CHATTERJEE ◽  
PREM PRAKASH ◽  
KAUSHAR ALI
Keyword(s):  
Monsoon Season ◽  
Frequency Distributions ◽  
Convective Clouds ◽  
Radar Echoes

Distributions of areas and heights of radar echoes from convective clouds, observed in Delhi region during six monsoon seasons, 1967-1972, were studied. Stratification of the echoes according to their areas into three different scales, namely scale D scale(<100 km2), C scale (101-1000 km2) and B/C scale (> 1000 km2) indicated predominance of the echoes in D scale, with relatively small percentage in. C and B/C scales. Frequency distributions of areas and heights of these echoes tended to be lognormally distributed.  

scholarly journals Satellite Derived Aerosol Optical Depth Climatology over Tropical Coastal Station Machilipatnam, India

2015 ◽  
Vol 50 ◽  
pp. 188-198
Author(s):  
A.S. Madhusudanacharyulu ◽  
K. Samatha ◽  
K. Sailesh Kumar ◽  
K. Jagadeesh ◽  
Suneetha Rani
Keyword(s):  
Monsoon Season ◽  
Ozone Monitoring Instrument ◽  
Coastal Station ◽  
Mean Values ◽  
Frequency Distributions ◽  
A Value ◽  
Circulation Patterns ◽  
The Mean ◽  
Annual Distribution ◽  
Maximum Occurrence

Climatological aerosol optical depths (AOD) over Tropical coastal city Machilipatnam, India have been examined to bring out the temporal heterogeneity in columnar aerosol characteristics. AOD values at 388 nm derived from the Ozone Monitoring Instrument (OMI) sensor EOS-AURA satellite, for the period of 2005–2013 have been analyzed for the purpose. AOD trends exhibited seasonal annual mean variations. Frequency distributions of the AOD values are examined to infer the monthly mean values. Monthly and seasonal variations of AOD are investigated in the light of regional synoptic meteorology. AODs>0.6 showed maximum occurrence in monsoon months. The mean AOD values increased towards summer reaching ~0.69 ± 0.34 and attained peak in monsoon season with a value of ~0.74 ± 0.33 and decreased during post-monsoon reaching as low as ~0.73 ± 0.3. Positive slope ~0.016 observed for inter annual distribution trend line. Factors like synoptic scale circulation patterns which are causing modulations of AOD apart from local sources were discussed.

Diurnal and Seasonal Cycles of Cloud Occurrences, Types, and Radiative Impact over West Africa

2012 ◽  
Vol 51 (3) ◽  
pp. 534-553 ◽  
Author(s):  
Dominique Bouniol ◽  
Fleur Couvreux ◽  
Pierre-Honoré Kamsu-Tamo ◽  
Madeleine Leplay ◽  
Françoise Guichard ◽  
...  
Keyword(s):  
West Africa ◽  
Diurnal Cycle ◽  
Radiative Forcing ◽  
Monsoon Season ◽  
Seasonal Evolution ◽  
Convective Clouds ◽  
Radiative Impact ◽  
Stratocumulus Clouds ◽  
Atmospheric Radiation Measurement ◽  
High Level

AbstractThis study focuses on the occurrence and type of clouds observed in West Africa, a subject that has been neither much documented nor quantified. It takes advantage of data collected above Niamey, Niger, in 2006 with the Atmospheric Radiation Measurement (ARM) Mobile Facility. A survey of cloud characteristics inferred from ground measurements is presented with a focus on their seasonal evolution and diurnal cycle. Four types of clouds are distinguished: high-level clouds, deep convective clouds, shallow convective clouds, and midlevel clouds. A frequent occurrence of the latter clouds located at the top of the Saharan air layer is highlighted. High-level clouds are ubiquitous throughout the period whereas shallow convective clouds are mainly noticeable during the core of the monsoon. The diurnal cycle of each cloud category and its seasonal evolution are investigated. CloudSat and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are used to demonstrate that these four cloud types (in addition to stratocumulus clouds over the ocean) are not a particularity of the Niamey region and that midlevel clouds are present over the Sahara during most of the monsoon season. Moreover, using complementary datasets, the radiative impact of each type of clouds at the surface level has been quantified in the short- and longwave domains. Midlevel clouds and anvil clouds have the largest impact, respectively, in longwave (about 15 W m−2) and shortwave (about 150 W m−2) radiation. Furthermore, midlevel clouds exert a strong radiative forcing during the spring at a time when the other cloud types are less numerous.

scholarly journals Correlations of Multispectral Infrared Indicators and Applications in the Analysis of Developing Convective Clouds

2016 ◽  
Vol 55 (4) ◽  
pp. 945-960 ◽  
Author(s):  
Qiong Wu ◽  
Hong-Qing Wang ◽  
Yi-Zhou Zhuang ◽  
Yin-Jing Lin ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Life Cycle ◽  
Water Vapor ◽  
Conceptual Model ◽  
Time Trend ◽  
Preliminary Test ◽  
Two Dimensional ◽  
Test Results ◽  
Frequency Distributions ◽  
Convective Clouds ◽  
Cumulus Congestus

AbstractThree infrared (IR) indicators were included in this study: the 10.8-μm brightness temperature (BT10.8), the BT difference between 12.0 and 10.8 μm (BTD12.0–10.8), and the BT difference between 6.7 and 10.8 μm (BTD6.7–10.8). Correlations among these IR indicators were investigated using MTSAT-1R images for summer 2007 over East Asia. Temporal, spatial, and numerical frequency distributions were used to represent the correlations. The results showed that large BTD12.0–10.8 values can be observed in the growth of cumulus congestus and associated with the boundary of different terrain where convection was more likely to generate and develop. The results also showed that numerical correlation between any two IR indicators could be expressed by two-dimensional histograms (HT2D). Because of differences in the tropopause heights and in the temperature and water vapor fields, the shapes of the HT2Ds varied with latitude and the type of underlying surface. After carefully analyzing the correlations among the IR indicators, a conceptual model of the convection life cycle was constructed according to these HT2Ds. A new cloud convection index (CCI) was defined with the combination of BTD12.0–10.8 and BTD6.7–10.8 on the basis of the conceptual model. The preliminary test results demonstrated that CCI could effectively identify convective clouds. CCI value and its time trend could reflect the growth or decline of convective clouds.

scholarly journals A study of evening convective clouds over Kochi and neighbourhood

MAUSAM ◽  
2022 ◽  
Vol 52 (3) ◽  
pp. 463-468
Author(s):  
A. J. MATHEW ◽  
S. U. KAIMAL
Keyword(s):  
Arabian Sea ◽  
El Nino ◽  
Convective Cloud ◽  
Convective Activity ◽  
Convective Clouds ◽  
Post Monsoon ◽  
Radar Echoes ◽  
Sst Anomaly ◽  
The Mean ◽  
Cloud Tops

Radar echoes of 0900 and 1100 UTC over Kochi and 200 km around were studied from 1996 to 1999 along with SST of southeast Arabian Sea and Kochi. The following results are obtained : Monsoon convective cloud tops were lower than Pre-monsoon and Post-monsoon convective cloud tops. (ii) In the mean, monsoon cloud tops gradually increased from 1996 to 1998 and then decreased. (iii) Very large convective activity existed during August 1997 to June 1998 compared to other periods of this study. Seasonally the higher the SST, the higher is convective cloud top. (v) Interannually, large positive SST anomaly coincided with high convective activity and this may be related to then prevailing El Nino.

Frequency distributions of the heights of convective clouds in different regions in India

1991 ◽  
Vol 26 (5) ◽  
pp. 445-454 ◽  
Author(s):  
R.N. Chatterjee ◽  
Prem Prakash ◽  
Kaushar Ali
Keyword(s):  
Frequency Distributions ◽  
Convective Clouds

scholarly journals Diurnal variation of cloudiness during southwest monsoon season using I NSAT-IB radiance data

MAUSAM ◽  
2022 ◽  
Vol 44 (2) ◽  
pp. 127-134
Author(s):  
A. V. R. K. RAO ◽  
V. R RAO
Keyword(s):  
Diurnal Variation ◽  
Monsoon Season ◽  
Southwest Monsoon ◽  
Threshold Temperature ◽  
Convective Activity ◽  
Small Areas ◽  
Convective Clouds ◽  
Full Resolution ◽  
Threshold Temperatures ◽  
Head Bay Of Bengal

An attempt has been made to study the diurnal variation of convective clouds. For this study 3 hourly full resolution infrared data of INSAT-IB have been used for the monsoon season (Jun-Sep) of 1987-89. The area of study extends from 35°N to 25°S and 40oE to l00oE, which is subdivided into small areas of 2.5x 2.5 Lat./Long. Mean temperature and the fractional area covered by clouds colder than a given threshold temperature over each sub area are the parameters used for this study. Two threshold temperatures. namely 265°K & 235oK are chosen to represent convective clouds and deep convective clouds respectively. Using the three hourly observations, times of maximum and minimum convective activity are also obtained. Maximum convective activity is observed over head Bay of Bengal at about noon and this maximum migrates westward onto land till midnight and swings back to oceanic area by morning. This eastwest oscillation is less over equatorial regions (open ocean).

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