GPS: making sense of Earth’s atmosphere

Abstract

Weather observation techniques have improved and there have been technological advancements in predicting the weather in recent times. Despite this major scientific and technical progress, many challenges remain, hence limiting meaningful forecasts more than 5~6 days in advance. Given that biological diversity, economic growth and human health and lifestyles are affected by day-to-day weather and climate variability, a greater understanding of critical atmospheric parameters (such as refractivity, pressure, temperature and humidity) is of paramount importance. Recently many countries have investigated the feasibility of using the space-based radio navigation satellites of the Global Positioning System (GPS) for weather and environmental studies. Based on using the transmitted GPS satellite radio signals to measure atmospheric profiles of refractivity, there are two primary methods by which GPS can be used to actively sense relevant atmospheric constituents: the ground-based atmospheric sounding method and GPS radio occultation (RO) method. As the GPS technology is relatively new to the Malaysian weather forecasting community, this article describes the principles underpinning both atmospheric remote sensing techniques. Further discussion includes the presentation of an overview of studies conducted abroad, at various scales ranging from national to global and current commonly-used atmospheric sensing approaches in Malaysia.