CA Babu

Cochin University of Science and Technology | CUSAT · Department of Atmospheric Sciences

The impact of climatic change on the summer monsoon season is studied to understand the rainfall pattern towards the end of the century utilizing the Coupled Model Intercomparison Project, Phase 6 (CMIP6) released by the World Climate Research Programme (WCRP). The analysis of model simulations from CMIP6 was carried out using 64 years of the histo...

In this study, we investigated the possible relation between the Indian summer monsoon and the combination of the different phases of Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO) before and after the climate shift in 1976. This study is carried out using IMD’s rainfall dataset, HadISST v1.1 dataset and twentieth century...

In the present study, we have examined extreme rainfall events during the southwest monsoon and their relationship with vertically integrated atmospheric moisture transport. For the analysis, we have used daily rainfall data from IMD, wind and humidity data from NCEP from 1951 to 2020. Extreme rainfall events are identified when the daily rainfall...

In this study, characteristics of summer monsoon rainfall (SMR) are investigated for two regions, West Coast (WC) and Central India (CI), in the Indian subcontinent during 1901–2020. We classified rain events into different intensity bins, viz. dry, low, moderate, high, very high and extreme. SMR in CI exhibits a significant decreasing trend of −5....

In this study, we investigated the possible relation between the Indian summer monsoon and the combination of the different phases of Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO) before and after the climate shift in 1976. This study is carried out using IMD’s rainfall dataset, HadISST v1.1 dataset and twentieth century...

Structure of the atmospheric boundary layer (ABL) over the west coast of India has been investigated using conserved variable analysis (CVA). Daily radiosonde data of Thiruvananthapuram (TVM), Mangalore (MNG) and Mumbai (MUM) at 00 UTC during the monsoon season of 2018 procured from India Meteorological Department have been primarily utilised for t...

Images obtained from five wavelength channels of Indian National Satellite (INSAT)-3D/3DR were utilized to interpret the nature of clouds associated with a Western Disturbance (WD) over north India during the winter season. Physical parameters like its shape, size, shadow, highlight and cloud toptemperature were studied to extract information on it...

A diagnostic investigation of extreme rainfall episodes associated with western disturbances that occurred during winter in recent years between 2009 and 2018 over North India is carried out using data from a suite of surface observations and reanalysis datasets. Observations indicate the source of the moisture flux as advection from the adjoining...

Land and sea breezes are formed due to differential heating between land and sea surfaces and are prominent local circulation in the tropical region. We present the first observational analysis of the overview of sea-breeze characteristics based on Automatic Weather Station (AWS) data and radiosonde ascends at Bachok Marine Research Station in peni...

In the present paper, the variabilities and long-term trends of summer monsoon rainfall for different intensity bins (dry, low, moderate, high, very high, and extreme) are studied for five homogeneous regions, namely Northeast India (NEI), Northcentral India (NCI), Northwest India (NWI), Westcentral India (WCI), and Peninsular India (PI) for 118 ye...

The study investigates thermodynamic structure of the atmospheric boundary layer (ABL) over the west coast of India during the southwest monsoon season. Radiosonde profiles at 00 UTC (0530 IST) are utilized for three stations, namely Thiruvananthapuram (TVM), Mangalore (MNG) and Mumbai (MUM) to represent south, central and north parts of the west c...

Rivers represent one of the sources of freshwater. The existence and survival of humanity is intricately connected with the availability of freshwater resources. It is valuable to provide comprehensive information of all water resources through online geo-visual interfaces. Specific web slices can be of use, such as the illustration of headwater so...

Western disturbance is defined as a low on the surface or an upper air cyclonic circulation in the westerly wind regime seen over northern parts of the Indian subcontinent. These systems originate over Mediterranean Sea, Caspian Sea or Black Sea and move eastward across north India. The precipitation over the northern parts of India during the wint...

Trends and features of Atmospheric Boundary Layer (ABL) over southern part of west coast of India has been studied using MERRA datasets for 1980–2018 during different seasons incorporating the marine and continental influences. A significant decrease in the ABL height (ABLH) has been observed in the westerly regimes of the west coast. The shallow A...

This study examines the response of surface layer parameters and ABL height (ABLH) to the change in cloudiness over Kochi. Outgoing long wave radiation (OLR) is considered as a proxy for the cloudiness. Temperature, horizontal wind speed, vertical velocity variance (VVV), sensible heat flux, momentum flux, turbulent kinetic energy (TKE), drag coeff...

The accuracy of Weather Research and Forecasting (WRF) model derived meteorological fields during the passage of a tropical storm, Pabuk, over the southern South China Sea is investigated. The European Centre for Medium‐Range Weather Forecasts’ ERA‐Interim data were also used for comparison. Data from a MetOcean buoy which captured tropical storm P...

We observe significant changes in the ENSO-Indian summer monsoon rainfall (ISMR) relationship in past three multidecadal epochs (early epoch: 1931-1960, middle epoch: 1961-1990, and recent epoch: 1991-2015) based on consistent correlation. The rainfall during early epoch was above normal, however, in other two epochs it was relatively dry. The ENSO...

The extreme rainfall events over India during 2017 southwest monsoon and associated mechanisms are investigated using daily rainfall, winds and SST data sets. Extreme events occurred over mainly four locations according to the designed criteria, which are westcentral India (WC), central India (CI), northeast (NE) India and northwest coastal region...

The study investigates the mechanism responsible for the deficit rainfall over southwest peninsular India during the 2016 monsoon season. Analysis shows that the large-scale variation in circulation pattern due to the strong, negative Indian Ocean Dipole phenomenon was the reason for the deficit rainfall. Significant reduction in the number of nort...

Westward propagation and the dynamics of intensification of Lakshadweep low (LL) have been investigated in detail. In this study, it is observed that LL is not propagated westwards in a single stretch to the western boundary of the southern Arabian Sea but takes place in multiple phases of propagation as well as through multiple eddy formations. LL...

This study presents the contrasting trends of rainfall in the northern and southern Western Ghats (WG) and examines possible reasons for the phenomenon. The WG is one of the important mountain ranges that run parallel to the west coast of India. The mountain chain lies almost perpendicular to the low level jet stream (LLJ) and hence, receives about...

The paper addresses observational aspects of widespread rain associated with the organized convection that forms over the southwest peninsular India during the pre-monsoon season. The evolution of the cloud band over the equatorial region, its northward propagation, development of cross equatorial flow near the Somalia coast, and appearance of equa...

This study analyses the variations of aerosol optical depth, total column ozone and water vapour, measured by a Microtops-II (MICRO-processor based Total Ozone Portable Spectrometer) ozonometer/sunphotometer over a coastal station in southwest peninsular India, Kochi. Observations of ozone and aerosols are analysed for a period, May 2012 to May 201...

This study explores the features of atmospheric surface layer over Kochi during active and weak phases of the southwest monsoon season. The classification of active and weak phases of monsoon is made on the basis of monsoon organized convection over the region. When the monsoon organized convection is over (away from) Kochi, considered it as an act...

Rivers represent one of the sources of freshwater. The existence and survival of humanity is intricately connected with the availability of freshwater resources. It is valuable to provide comprehensive information of all water resources through online geo-visual interfaces. Specific web slices can be of use, such as the illustration of headwater so...

Three strong western disturbances (WDs) that occurred over north India in 2008 and 2009 are simulated with two different types of land-use data using a Weather Research and Forecasting (WRF) model. The two different land-use land covers (LULCs) used are Advanced Wide Field Sensor (AWiFS) data and United States Geological Survey (USGS) data. The dis...

The effect of global climate change on Indian summer monsoon has been analysed with special emphasis on active-break cycle. The changes in intensity and duration of active and break monsoon conditions towards the end of the century are studied by using 850 hPa zonal circulations. The analysis is carried out using twenty year climatology of historic...

The paper addresses influence of dust particles on the aerosol loading over the major deserts in the northern hemisphere. The role of dust aerosols in the total aerosol concentration and size distribution of the particles are analysed. It is observed that the aerosol loading is high in the northern hemisphere of which the deserts and adjoining area...

Actually this is a research monograph on the Oceans in the outer solar system. This monograph is an attempt to provide general features of oceans existing in the natural planets and satellites of the solar system. This brings out newly discovered liquid bodies in the outer Solar System beyond the Mars. A significant aspect of science communication...

The weather/climate of south India is entirely different from that of north India. So the aerosol loading and variability in the regions also show considerable difference. The present study investigates the aerosol distribution over the south Indian region. The transport of aerosols over the region is studied in detail and climate features of the r...

The Sultanate of Oman is located in the south-eastern part of the Arabian Peninsula and covers the larger part of the southern coasts of the Arabian Peninsula in both arid and semi-arid environments except for the southern part which is swept by the monsoon affecting the Arabian Sea during the period from June to September. The summer rainfall over...

A detailed analysis of the precipitation pattern of the Arabian Peninsula and its temporal and spatial variability were investigated in connection with ENSO. Also, the variability of precipitable water and circulation characteristics was examined for a better understanding. The study was carried out utilizing TRMM rainfall, NOAA OLR, precipitable w...

The southern coasts of Caspian Sea is subjected to synoptic/mesoscale weather systems ranging from locally enhanced sea breeze formation and small local front systems to synoptic scale cyclones. This study presents climatology of cyclones over the southern coasts of Caspian Sea covering a ten year period 1996-2005. Altogether 57 cyclones were forme...

In this study, changes in the spatial and temporal patterns of climate extreme indices were analyzed. Daily maximum and minimum air temperature, precipitation, and their association with climate change were used as the basis for tracking changes at 50 meteorological stations in Iran over the period 1975–2010. Sixteen indices of extreme temperature...

The surface boundary layer processes are the driving forces for the growth of almost all the weather systems. The micro scale interactions between surface and the atmosphere take place through the ABL and hence ABL plays vital role in the transport mechanism. The surface boundary layer processes associated with the weather systems over the tropics...

The southern coasts of Caspian Sea is subjected to synoptic/mesoscale weather systems ranging from locally enhanced sea breeze formation and small local front systems to synoptic scale cyclones. This study presents climatology of cyclones over the southern coasts of Caspian Sea covering a ten year period 1996-2005. Altogether 57 cyclones were forme...

The surface boundary layer processes are the driving forces for the growth of almost all the weather systems which is not yet understood properly. In this back ground detailed analysis of surface ABL processes during occurrence of different weather systems is investigated in this book. The book consists of 7 chapters. The general introduction about...

The southern coasts of Caspian Sea is subjected to synoptic/mesoscale weather systems ranging from locally enhanced sea breeze formation and small local front systems to synoptic scale cyclones. This study presents climatology of cyclones over the southern coasts of Caspian Sea covering a ten year period 1996-2005. Altogether 57 cyclones were forme...

Among the major celestial bodies of the Solar System, the presence of an ocean, abounding with marine flora, fauna and sloshing waves, so far has been constrained in the planet Earth only. Astronomical progresses in space technology have allowed rapid observations of our space environment to reveal the presence of myriad oceanic like features throug...

The study brings out the response of surface boundary layer parameters during the occurrence of thunderstorms over a tropical station utilizing fast response sensor data from a sonic anemometer.•The microscale evolution of the surface boundary layer features is examined further with the 1 min averaged data during the formation of thunderstorm from...

The present study investigates the seasonal variability in the vertical distribution of aerosol over the Indian region and its surroundings, and the possible mechanisms in the atmosphere that give rise to vertical transport of the aerosols. During boreal summer months, the aerosols reach a higher altitude of above 5 km over the Indian region. In th...

Onset features of the Summer monsoon-2007 were analyzed using data from five different sources, namely, the Tropical Rainfall Measuring Mission (TRMM) 3-hourly rainfall, National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) wind reanalysis data set, NOAA Outgoing Longwave Radiation (OLR), cloud imageries...

A better understanding of the factors responsible for the variability in Indian summer monsoon rainfall (ISMR) is important in the present day climate because it is vulnerable to climate change. Here, we report the relationship between the Atlantic and Pacific sea surface temperature (SST) anomalies with ISMR. We developed a new ISMR index based on...

Aerosols are capable of interfering with the radiation balance and cloud properties of the Earth-atmosphere system. The present study analyses and classifies the aerosol properties over a station, Kanpur, located in the Gangetic plain, which is the area with maximum aerosol loading in Indian subcontinent. Kanpur is one of the highly populated and i...

During the period from 12 to 15 April, 2009 nearly the entire Iran, apart from the southern border, experienced an advective cooling event. While winter freezing concerns are typical, the nature of this freezing event was unusual with respect to its date of occurrence and accompanying synoptic meteorological situation. To analyze the freezing event...

The combined use of both radiosonde data and three-dimensional satellite derived data over ocean and land is useful for a better understanding of atmospheric thermodynamics. Here, an attempt is made to study the ther-modynamic structure of convective atmosphere during pre-monsoon season over southwest peninsular India utilizing satellite derived da...

The study mainly intends to investigate the meteorological aspects associated with the formation of mud banks along southwest coast of India. During the formation of mud bank, the prominent monsoon organized convection is located in the equatorial region and relatively low clouding over Indian mainland. The wind core of the low level jet stream pas...

The present paper presents a diagnostic study of two recent monsoon years, of which one is dry monsoon year (2009) and the other is wet monsoon year (2010). The study utilized the IMD gridded rainfall data set in addition to the Reynolds SST, NCEP-NCAR reanalysis wind and temperature products, and NOAA OLR. The study revealed that the months July a...

In general Indian summer monsoon rainfall did not show any significant trend in all Indian summer monsoon rainfall series, however, it was reported that the ISMR is subjected to spatial trends. This paper made an attempt to bring out long term trends of different intensity classes of summer monsoon rainfall in different regions of Indian subcontine...

According to current knowledge, convection over the tropical oceans increases with sea surface temperature (SST) from 26 to 29 °C, and at SSTs above 29 °C, it sharply decreases. Our research shows that it is only over the summer warm pool areas of Indian and west Pacific Oceans (monsoon areas) where the zone of maximum SST is away from the equator...

This study attempted to quantify the variations of the surface marine atmospheric boundary layer MABL parameters associated with the tropical Cyclone Gonu formed over the Arabian Sea during 30 May–7 June 2007 just after the monsoon onset. These characteristics were evaluated in terms of surface wind, drag coefficient, wind stress, horizontal diverg...

Atmospheric surface boundary layer parameters vary anomalously in response to the occurrence of annular solar eclipse on 15th January 2010 over Cochin. It was the longest annular solar eclipse occurred over South India with high intensity. As it occurred during the noon hours, it is considered to be much more significant because of its effects in a...

Oceans play a vital role in the global climate system. They absorb the incoming solar energy and redistribute the energy through horizontal and vertical transports. In this context it is important to investigate the variation of heat budget components during the formation of a low-pressure system. In 2007, the monsoon onset was on 28th May. A well-...

RiverineGiS is a web-based GIS Interface for understanding and to geo-visualize the water resources, including the entire rivers. Objective of the RiverineGiS Interface is the generation of a GIS based repository delivered in public domain. Presently, water resources of Kerala are being implemented with scope for the extension of global river basin...

The objective of this study is to understand the reasons for the enhancement in aerosol optical depth (AOD) over the Arabian Sea observed during June, July and August. During these months, high values of AOD are found over the sea beyond 10° N and adjacent regions. The Arabian Sea is bounded by the lands of Asia and Africa on its three sides. So th...

Arabian Sea Mini Warm Pool (ASMWP) is a part of the Indian Ocean Warm Pool and formed in the eastern Arabian Sea prior to the onset of the summer monsoon season. This warm pool attained its maximum intensity during the pre-monsoon season and dissipated with the commencement of summer monsoon. The main focus of the present work was on the triggering...

Using the rain rate from Tropical Rainfall Measuring Mission (TRMM) 3 h data, we made an attempt to explore the diurnal variation of rainfall occurrences in the spatial domain of Peninsular Malaysia. This data set is available for 10 years period from 1999 to 2008 at a high spatial resolution of 25 km latitude-longitude grid. The rainfall character...

The present study is focused on the intensity distribution of rainfall in different classes and their contribution to the total seasonal rainfall. In addition, we studied the spatial and diurnal variation of the rainfall in the study areas. For the present study, we retrieved data from TRMM (Tropical Rain Measuring Mission) rain rate available in e...

A distinct cold tongue has recently been noticed in the South China Sea during the winter monsoon, with the cold tongue temperature minimum occurring in the January or February. This cold tongue shows significant links with the Maritime Continent’s rainfall during the winter period. The cold tongue and its interaction with the Maritime Continent’s...

Aerosols play an important role in the radiation balance and cloud properties, thereby affect the entire climatology of the earth-atmosphere system. Besides natural sources like dust, seasalt and natural sulphates, anthropogenic activities also inject aerosols like soot and industrial sulphates. Of these sea-salt and sulphates scatter the solar rad...

The marine atmospheric boundary layer (MABL) plays a vital role in the transport of momentum and heat from the surface of the ocean into the atmosphere. A detailed study on the MABL characteristics was carried out using high-resolution surface-wind data as measured by the QuikSCAT (Quick scatterometer) satellite. Spatial variations in the surface w...

Evolution of mini warm pool in the Arabian Sea just before the onset of southwest monsoon and behavior of SST in the vicinity of weather systems formed during the premonsoon, southwest monsoon and post monsoon seasons were studied using TMI SST data. The Arabian Sea mini warm pool is formed about three weeks ahead of onset of southwest monsoon. Max...

Features of sea and land breezes, surface fluxes and drag coefficient over Cochin are studied using more than 300 daily observations of air temperature, wind speed and direction data. The duration and intensity of sea breeze circulation vary with the rain or Cloud as it reduces the differential heating. Onset of sea breeze is early in summer season...

Atmospheric Boundary layer (ABL) is the layer just above the earth surface and is influenced by the surface forcing within a short period of an hour or less. In this thesis, characteristics of the boundary layer over ocean, coastal and inland areas of the atmosphere, especially over the monsoon regime are thoroughly studied. The study of the coasta...

This study deals with the salient features of the north Indian ocean associated with the summer monsoon. The focus is given on the Arabian sea mini warm pool, which is a part of the Indian ocean. It primarily study the certain aspects of the atmosphere and ocean variability in the north Indian ocean. The attempt were made to understand various aspe...

We have studied sea surface temperature (SST) anomalies over the Indian and Pacific Oceans (domain 25 °S to 25 °N and 40 °E to 160 °W) during the three seasons following the Indian summer monsoon for wet monsoons and also for dry monsoons accompanied or not by El Niño. A dry monsoon is followed by positive SST anomalies in the longitude belt 40 to...

The objective of the study is to examine the dynamic and thermodynamic structure and the variations that occur in the surface layer during the pre-monsoon, onset and post-monsoon periods over the Indian region. The variations caused during the occurrence of micro and mesoscale systems, structure and variation in the marine boundary layer over the I...

Thermodynamic parameters of the atmosphere form part of the input to numerical forecasting models. Usually these parameters are evaluated from a thermodynamic diagram. Here, a technique is developed to evaluate these parameters quickly and accurately using a Fortran program. This technique is tested with four sets of randomly selected data and the...

Understanding of the Atmospheric Boundary Layer (ABL) is imperative in the arena of the monsoon field. Here, the features of the ABL are studied employing Conserved Variable Analysis (CVA) using equivalent potential tempera- ture and humidity. In addition, virtual potential temperature and wind are used during active and weak phases of monsoon. The...