No abstract

The study discusses the features of wind, turbulence, and surface roughness parameter over the coastal boundary layer of the Peninsular Indian Station, Thumba Equatorial Rocket Launching Station (TERLS). Every 5 min measurements from an ultrasonic anemometer at 3.3 m agl from May 2007 to December 2012 are used for this work. Symmetries in mesoscale turbulence, stress off-wind angle computations, structure of scalar wind, resultant wind direction, momentum flux ( ), Obukhov length ( ), frictional velocity ( * ), w-component, turbulent heat flux ( ), drag coefficient ( ), turbulent intensities, standard deviation of wind directions ( ), wind steadiness factor-relationship, bivariate normal distribution (BND) wind model, surface roughness parameter ( 0 ), 0 and wind direction ( ) relationship, and variation of 0 with the Indian South West monsoon activity are discussed.

This paper brings out mainly on the quantitative approach to delineate wind direction variability through Wind Steadiness Factor (WSF) - a single parameter which depends on height, wind speed and wind direction. This can be used as a prognostic parameter for the onset and withdrawal of south west monsoon (SW Monsoon) over Kerala. A brief sketch on wind climatology up to 35 km over TERLS (8° 32' N / 76° 52' E) is also discussed to have a background knowledge. From the derived WSF climatology, it is seen that the region between 12.5 km to 18 km is of highest WSF during the SW Monsoon due to the Tropical Easterly Jet (TEJ). Vertical variation of annual WSF has shown well demarcated four layered structure and the wind rose constructed for each layer provides the contribution of WSF attributed by the dominant direction for that particular layer. A WSF value was estimated for the region between 12.5 km to 18 km over Thiruvananthapuram for each available rawin profile [0530 and 1730 hrs (IST)] and inferred that an early incidence and maintenance of WSF well above 80% prior the SW Monsoon supports an early SW Monsoon onset and reverse for a late onset. A late/early WSF decrease from a value of 80% followed by systematic further decrease is associated with late/early withdrawal of the SW Monsoon.

Long-term (45 years) diversified surface meteorological records from Thumba Equatorial Rocket Launching Station (TERLS), India, were collected and analysed to study the long-term changes in the overall climatology, climatology pertained to a particular observational time, mean daily climatology in temperature, inter-annual variability in temperature, interannual variability in surface pressure, and rainfall for the main Indian seasons—South West and North East monsoons and inter-annual mean monthly anomaly structure in temperature. Results on various analyses show strong and vivid features contributed by climate change for this South Peninsular Indian Arabian Sea Coastal Station, and this paper may be a first time venture which discusses climate change imparted perturbations in several meteorological parameters in different time domains, like a specific time, daily, monthly, and interannually over a station. Being a coastal rocket launching station, climatic change information is crucial for long-term planning of its facilities as well as for various rocket range operational demands.