Geostationary Lightning Mapper
Lightning researchers are working to develop a new way of estimating the amount of atmospheric gases produced by lightning. If successfully developed, such a technique would be used in the Geostationary Lightning Mapper (GLM) to monitor the Western Hemisphere from a weather satellite scheduled for launch in 2014. Atmospheric chemists are interested in trace gases, especially nitrogen oxides, which are produced by the lightning strikes.
Nitrogen oxides, also known as NOx, are of particular interest to researchers because of their effects on the world’s climate. To study lightning, which is the major source of NOx in the Earth’s upper atmosphere, researchers are developing a procedure to determine the extent to which lightning contributes to this gas. NOx includes nitric oxide (NO), a toxic air pollutant created by automobile engines and power plants, as well as nitrogen dioxide (NO2), a poisonous gas with a sharp odor and reddish-brown color. NOx partially controls ozone(O3) concentrations and hydroxyl radicals (OH) in the atmosphere, both of which significantly affect the atmosphere. Ozone is an important greenhouse gas and hydroxyl radicals are highly reactive molecules controlling the oxidation of a number of greenhouse gases.
Unlike the pollution from cars and industrial activity which can be measured, the influence of lightning on air pollution and climate is more difficult to assess. The difficulty lies in realistically modeling such significant characteristics of lightning strikes as lightning energy and the amount of NOx produced by a stroke of lighting. Consequently, the rate of NOx produced due to lightning is still uncertain, varying from estimates of 2 to 20 teragrams, or 2 to 20 trillion grams. NASA’s Aura satellite has provided constraints on the global chemistry and climate models, which indicate a more accurate estimate to be about 6 teragrams per year, although more work is necessary to increase the confidence in the accuracy of the estimates.
The scientists plan to use ground-based instruments at NASA’s Kennedy Space Center in Florida and data from the Lightning Imaging Sensor (LIS) aboard the Tropical Rainfall Measuring Mission (TRMM) satellite to study lightning flash energy. LIS is a camera using a very narrow spectral filter, along with other techniques, to locate the lightning optical emissions, which occur both during the day and at night. The researchers will attempt to correlate the occurrence of strikes observed by LIS with the estimates made by the ground-based sensors at the Kennedy Space Center to determine if space-based measurements can be related to estimates from the ground-based observations. This would make it possible to use space sensors to remotely receive information over a much larger area of the globe. The goal is to develop a system which can use GLM data to estimate the energy of lightning strikes, enable more accurate simulation in models and better understand the production of an important global atmospheric pollutant.
This entry was posted on Monday, August 6th, 2007 at 6:12 pm and is filed under Public Relations, Space Agency News. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
