A Novel Sounding Protocol for Lower Boundary Layer Characterization

Meteorological forecasting in the new millennium has had a paradigm shift in the way such information is disseminated. Current trends predict a breakthrough in forecasts through the use of decentralized local techniques. Weather prediction codes for general circulation models, such as the Weather Research and Forecasting (WRF) model, are now freely available for offline use enabling individuals, local bodies, and institutions to create state-of-the-art weather forecasts for local community needs.

Meteorological data pooling is on a robust footing in the United States and the European Union. However, developing countries like China and India can gear up to an equally robust acquisition also. India in particular, has immense manpower specializing in information technology applets for cyclone alerts using mobile telephony (S. Ghosh, Vivek Vidyasagaran, Subramanian Sandeep, Smart Cyclone Alerts over the Indian Subcontinent, Atmospheric Science Letters, Volume 15, Issue 2, pages 157-158, April/June 2014). In the years to come, this computer-savvy nation can make great headway in this direction. However, modelers in these countries are seriously constrained by the lack of local meteorological soundings - procuring soundings from the India Meteorological Department (IMD) is not straightforward and can often be expensive. Recent research has demonstrated that WRF forecasts can help give cyclone alerts at least five days in advance enabling a meaningful evacuation as was observed during the time when Cyclone Phailin hit India's coastline.

In this paper, we provide a novel protocol wherein a helium-based airship of approximately 6 m3 volume, when fully inflated, equipped with temperature and humidity sensor (SHT15) of resolution of 0.01oC and 0.05% RH respectively is released into the air up to an altitude of 1.5 km. Unlike comparable sounding launches, this carefully constructed airship can afford spectacular maneuverability - it works along the principles of Vertical Take-off and Landing (VTOL) and thrust-vectoring. It is easy to handle and is able to carry a payload of up to 1.5 kg. This mechanism invokes the ZigBee Protocol (XBee) with the use of an Arduino (ATmega2560). Additionally, a GPS receiver (Trimble Copernicus II) and transmitter (u-blox 6 NEO-6) module can be integrated with the payload to obtain the precise altitude of the airship. Once the data is collected, it can be readily converted to WRF compatible input sounding files which can be readily used for the subsequent chain runs.

The full package allows the user to choose a fully formatted ASCII readable file of the potential temperature, equivalent potential temperature, total moisture ratio and pressure profile for the meteorological data requirements of WRF. Further, the package can be customized for other GCM interfaces. The initial profile requirement of the potential temperature, u-v winds and the total moisture profiles for Large Eddy Models (LEM) shall be an additional user option.

The package comes with a demonstration video with instructions in English, Hindi and Tamil for inflation, deflation, launch, control and retrieval of useful information. The user may retrieve in situ data along the ascent and descent paths of the airship. Since one can get accurate data at intervals of 1 microsecond, right up to the lifting condensation levels, this product will set the scene for alerts for tropical cyclone and cloud bursts over the Indian Subcontinent - it seamlessly supplies the most difficult to obtain initial WRF profiles for user initiated configurations.