A new network to monitor the radiative forcing of global warming by greenhouse gases is discussed. The greenhouse radiation is the downward infrared heat radiation from greenhouse gases in the atmosphere; this radiation is otherwise known as the surface forcing radiation. The increase in this radiation due to increased carbon dioxide and other greenhouse gases is the driving function of global warming. In an experimental project, the calibrated spectrum of the greenhouse radiation at the surface has been measured for the last 10 years in the Great Lakes area in Ontario, Canada. From these measurements the radiative flux from each greenhouse gas been extracted. There is a 10 year record of the radiative fluxes from carbon dioxide, methane, nitrous oxide and CFCs. The increases in these represent the forcing function of global warming. It is an experimental version of radiative forcing similar to but different from the radiative forcing used by IPCC. It is proposed that this radiative forcing should be monitored in a fashion similar to our monitoring of the ozone layer. We should setup a world monitoring network like the world total ozone monitoring network of Brewer and Dobson spectrophotometers. The AERI instrument already exists and there are 12 of them deployed around the world; it is manufactured by ABB BOMEM, a Canadian company. The spectral measurements have been processed to extract the radiative forcing fluxes from each greenhouse gas. This work is related to the work of Philipona et al, 2007 who measured the total radiative forcing increase due to greenhouse gases in Switzerland with broadband instruments. The methodology will be to process the AERI infrared spectrometer measurements into the downward surface radiation flux in W/m2 from each of the major greenhouse gases.

Well calibrated infrared spectral measurements of the downward infrared long wave radiation have been routinely made by the AERI instruments at the three main DOE ARM sites for over 7 years with a 12 year record at the SGP site. These are being processed into long wave radiation fluxes from each of the major greenhouse gases using a methodology already developed for similar measurements at 44° N in the Great Lakes area. Comparisons with surface radiation fluxes calculated from global climate models (GCMs) will be conducted using the methodology already successfully used to compare previous 44° N data with the Canadian and NCAR GCMs.

The uses of the data would be to:

1. Investigate the seasonal and climate regime variations of the surface greenhouse radiation flux.

2. Compare the measurements with climate model simulations of the surface forcing radiation fluxes for each greenhouse gas.

3. Evaluate the reduction of the surface forcing radiation by various types of clouds by measuring the reduction in surface radiation forcing under cloudy conditions.

4. Conduct complementary measurements of surface radiation forcing with radiative trapping measured from space with overpasses of satellites.

5. Monitor the increase with time of the forcing radiation from each gas.

This network will provide a new experimental dataset which would complement the calculated radiative forcings from climate models which are currently used for policy determination of safe levels of greenhouse gases in the atmosphere. By measuring improved scientific data on the radiative response of the greenhouse radiation to increased greenhouse gas levels, this proposed network will support the accomplishment of DOE‘s long-term goal to deliver improved scientific data and models about the potential response of the Earth's climate to increased greenhouse gas levels, thus assisting policymakers in determining safe levels of greenhouse gases in the atmosphere. The new network will give us the experimental capability to conduct long-term monitoring of the increases in greenhouse radiation due to increases in the individual greenhouse gases without using an intervening climate model. It is feasible to build a new world monitoring network for monitoring the greenhouse radiation since there are already 12 AERI instruments deployed around the globe. This also adds a new climate observable which could potentially be used to compare changes in the long wave radiation balance of the atmosphere with other climate variables.

Hence, the WMO should monitor this important variable instead of relying solely on model calculations of radiative forcing since it is the fundamental forcing function of global warming. The analysis of the data from ARM AERI sites would represent a big step towards building a world monitoring network for this very important climate observable. Since there are now 12 AERI instruments deployed around the globe, a first step in building a network to monitor radiative forcing similar to the world ozone monitoring network has already taken place. These aspects also emphasize the extreme importance of continuing the DOE ARM AERI measurements for the foreseeable future.