Introduction

IHY-Africa kickoff meeting

Integrated Preciptable Water and Total Electron Content

Africa GPS database at NGDC

GPS Efforts at NOAA

Concluding remarks

References

Integrated Precipitable Water and Total Electron Content using GPS

The International Heliophysical Year Effort that is responsible for helping us move foward with development of the GPS database has been strongly influenced by our need to evaluate two key climatological variables that are not well understood over Africa. These variables are Integrated Total Electron Content in the Ionosphere and Integrated Precipitable Water Vapor in the Troposphere.

As part of the IHY effort, a better understanding of space weather and challenges in sattelite communications are of central concern. In the Earth's Ionosphere, there is an electrical current that travels around the planet near the Equator. This current is known as the Equatorial Electrojet. Understanding the Equatorial Electrojet is very important for interpretation and understanding of Space Weather, Geomagnetism, and spacecraft communication issues. This has a wide range of applications that range from operation of spacecraft, to naviagation, cross polar air travel, communications, and even the power industry. Africa is a region of particular interest because until now, we have not had adequate observational coverage, and Africa is the only place in the world where there is a large mass of land below the electrojet from which we can place instruments and make our observations. The below image shows a map of the Ionospheric Electron Content over North America. The Africa GPS network will allow us to create these types of maps over the African content.

Tim Fuller-Rowell - SPWC

The second field of primary interest to the IHY-Africa GPS collaborators is in the analysis of Precipitable Water Vapor near Earth's surface (IPW), and how variations in IPW contribute to climate change and behavior of Tropospheric weather systems.

The water cycle over Africa has many implications for climate change and economic stability over the region. Variations in the precipitable water budget can be estimated with GPS, and has been shown to represent a wide array of climatological indicators that are not well known. Particularly, diurnal variations in precipitable water have been shown to expose weakness in global climate models and can provide a mechanism to improve our predictive capability (Boch 2007).

Below is a map of the IPW over the surface of the Earth. IPW can abe adequately evaluated over the ocean's using satellite born detectors, but over land, variations in ground composition and moisture content make this impossible without application of GPS technology. Having a robust network of reference stations over Africa will help us evaluate how water vapor variations occur over the continent and provide insight on the mechanisms that are forcing climate variations.

Seth Gutman - ESRL