This animation shows a global map of fossil-fuel CO2 emissions for the year 2010 derived from satellite imagery of night-lights and other data (courtesy Tom Oda - CSU/NOAA in collaboration with NIES). A global urban carbon monitoring system would combine surface measurement networks in the world's largest cities (highlighted here) and satellite observations of nearly all urban areas. The surface grid squares illustrate the surface footprint of future geostationary satellites that could be focused on the 2-3% of land surface area producing the majority of emissions. Animation courtesy: NASA's Goddard Space Flight Center, Conceptual Image Lab
This animation shows a perspective view of the Los Angeles basin looking north. Yellow columns represent continuous measurements of atmospheric carbon from commercial gas analyzers on radio towers and roof-tops. The California Laboratory for Atmospheric Remote Sensing (CLARS) on Mt Wilson uses reflected sunlight to track carbon across the basin.
Aircraft periodically sample the air coming in and out of the megacity domain. Satellites such as NASA's Orbiting Carbon Observatory-2 will sample the "urban domes" of carbon dioxide of Los Angeles and other megacities around the world. Animation courtesy: NASA's Goddard Space Flight Center, Conceptual Image Lab
One of the sites in the Megacities monitoring network for Los Angeles is the California Laboratory for Atmospheric Remote Sensing (CLARS) located on Mt Wilson. From an altitude of nearly 6000 ft, CLARS makes frequent scans during daylight hours across the LA basin. In this animation, the CLARS telescope mirror points sequentially to different pre-programmed points to sample sunlight scattering off the Earth's surface. The CLARS spectrometer splits the light from each reflection point into a spectrum (like colors in a rainbow) to reveal the unique "fingerprints" of carbon dioxide, methane and other gases in the atmosphere. The lines in the spectrum are due to absorption from the various gases - analysis of which is used to reveal the concentration of a given gas in a column of air for a given location. CLARS serves as a prototype for a future geostationary satellite instrument that may someday serve as a "carbon weather satellite" - providing frequent wall-to-wall mapping of greenhouse gases across entire cities and broader regions. Animation courtesy: NASA's Goddard Space Flight Center, Conceptual Image Lab
In-situ sensors located around the LA basin provide continuous, high accuracy measurements of greenhouse gas (GHG) mixing ratios of CO2, CH4, and CO. A remote-sensing instrument on Mt. Wilson provides multiple scans per day of the basin to measure slant-column mixing ratios. Another remote-sensing instrument at Caltech provides continuous daytime measurements of column mixing ratios. Aircraft and mobile laboratories provide infrequent but intensive measurements of mixing ratios. Satellites are beginning to provide remote-sensing measurements of LA. Other instruments (not shown) measure winds and boundary layer height.
Concentrations of carbon dioxide (CO2) and other greenhouse gases in the atmosphere are constantly changing in response to surface sources and sinks that emit and remove carbon but equally important, in response to atmospheric circulation including the effect of winds and the vertical motion of the atmosphere that scientist call the planetary boundary layer. So interpreting measurements of concentrations of these gases and relating them to emissions requires careful treatment of atmospheric circulation. Scientist use models of the atmosphere both to predict atmospheric CO2 concentrations based on emission data sets (such as the Hestia-LA product) and/or to transform concentration measurements into flux estimates using a process called “inverse modeling”.
Examples of model outputs are shown here for 3 scales: urban, continental, and global.
The following video first shows fossil fuel CO2 emissions data at 1 km, hourly resolution for the LA Megacity from the Hestia project (http://hestia.project.asu.edu/) for 3 days in September 2011 (assuming linear scaling from 2002). The video then shows a model simulation that predicts the resulting enhancements (over background levels) of surface atmospheric CO2 concentrations for the same period at 1.3km, hourly resolution. Driven by JPL's Weather Research and Forecasting (WRF)-Greenhouse Gas (GHG)/Vegetation Photosynthesis and Respiration Model (VPRM) framework for Southern California. These products are preliminary, still undergoing validation and are intended strictly for educational purposes. Credit: Kevin Gurney (ASU); Sha Feng, Zhijin Li, Henry Kline, JPL.
Model simulation of surface atmospheric fossil fuel CO2 concentrations for the month of January 2010,with hourly time steps, and 0.5 degree x 0.625 degree (about 50x60) resolution. Assumes fossil fuel CO2 emissions are perfectly separated from the total CO2 fluxes. The color scale ranges from 400-480. Red indicates peak values of CO2, higher than 480 parts per mission (ppm). Concentrations smaller than the current global average (about 400 ppm) have been made transparent here to show the earth's surface. Driven by NASA's Carbon Monitoring System Flux framework. http://cmsflux.jpl.nasa.gov. Credit: Richard Weidner, Meemong Lee, JPL.
Model simulation of surface atmospheric CO2 concentrations for the week of May 17-23, 2013,with hourly time steps, and 0.25 degree x 0.3125 degree (about 25km x 31 km) resolution. Driven by NASA's Carbon Monitoring System Flux framework. http://cmsflux.jpl.nasa.gov. Credit: Richard Weidner, Meemong Lee, JPL.
Hestia (http://hestia.project.asu.edu) combines extensive public database “data-mining” with traffic simulation and building-level energy-consumption modeling. Its high-resolution maps clearly identify CO2 emission sources. A preliminary version of the Hestia data set has been developed for the LA megacity and will be released shortly. Meanwhile the following images illustrate the utility of this data set.
Figures 1-3 courtesy Kevin Gurney, Risa Patarasuk, Yang Song (ASU). Figure 4 courtesy Preeti Rao (JPL).
One of the objectives of the Megacities Carbon Project is to test new scientific methods and technologies for tracking greenhouse gas emissions. One such emerging technology is offered by a new generation of satellites capable of measuring the carbon dioxide (CO2) emissions of cities from space. The following graphics illustrate how enhanced levels of CO2 in the atmosphere over Los Angeles are "seen" by NASA's Orbiting Carbon Observatory (OCO-2) (launched in July 2014).
Graphics courtesy: Henry Kline, Sha Feng, Zhijin Li, Annmarie Eldering, and John Howard (JPL).
The first image is a snapshot of patterns of surface CO2 concentrations over Los Angeles. The colors indicate the relative intensity of local CO2 compared to average background CO2 levels (about 400 parts per million or ppm, and rising). In this example, CO2 ranges from 3 ppm (purple) to nearly 30 ppm (lime) with the most intense levels over Pasadena. In reality the CO2 concentrations over LA are constantly changing in response to emissions and motion of the atmosphere (and can often exceed 70 ppm in different locations).
Since OCO-2 was designed to study the global carbon cycle it spends most of its time uniformly sampling the globe in either "nadir" or "glint" mode (learn more about OCO modes here). The following animation illustrates a single nadir-mode pass from OCO-2 over the Los Angeles basin - capturing a slice of the LA CO2 pattern. In this way OCO-2 will collect 8 footprints of data across the 10km wide swath, with orbit tracks that move east and west through the seasons.
The following animation illustrates the collection of OCO-2 "target mode" data over Caltech in Pasadena. Caltech is one of 19 sites around the world that track the sun to collect up-looking measurements of CO2 to validate OCO-2 remote sensing measurements and link them to international standards of CO2. During a Target Mode pass, the spacecraft points towards Caltech from far away, and with a small sweeping motion, stays focused on the target (Caltech) as the spacecraft moves overhead and past the target over a period of about 15 minutes. The animation shows that a large portion of the LA basin is sampled - with the most dense, overlapping sets of data collected around Caltech.
This video illustrates how the spacecraft "wiggles" to perform Target mode observations (in this example, for the ground site at Lamont, Oklahoma).
OCO-3 is an instrument being assembled from spare parts from the OCO-2 mission and additional equipment for future deployment on the International Space Station (launch status: TBD). OCO-3 is intended to continue the OCO-2 CO2 data record for carbon cycle science but also has an additional capability enabled by a more flexible pointing system: City Mode. OCO-3 would allow regular sampling of more of the world's cities and power plants (over 80% of fossil-fuel CO2 emission sources every month) than available with OCO-2. OCO-3 would also provide broader mapping of each city's CO2 footprint as shown here for Los Angeles.
A ground-based remote sensing instrument located at the California Laboratory for Atmospheric Remote Sensing (CLARS) on Mount Wilson has been mapping CO2, CH4 and other important trace gases across the Los Angeles megacity since 2010. The figures below show how column-averaged concentrations of CO2 vary across the LA basin in both space and time. Both figures show data collected on May 29, 2010 (left: 8:30 am, right: 1:30 pm). The combined effects of atmospheric motion (particularly the peak growth of the planetary boundary layer around midday) and localized emissions account for the observed transition between the relatively "flat" distribution seen in the morning compared to the strong gradient in the afternoon. The goals of CLARS are to derive high spatio-temporal top-down greenhouse gas emissions in the megacity, and to serve as a testbed for a potential future geostationary satellite mission (the Global Carbon Process Investigation). Courtesy: Stanley P. Sander (stanley.p.sander at jpl.nasa.gov) and Clare Wong (clare.wong at jpl.nasa.gov). See our publications page for papers on CLARS by Wong et al (2014) and Fu et al (2014).
This time-lapse video was created from hourly snapshots from a webcam at our monitoring site at USC. Looking north towards the downtown LA skyline we can watch a “month in the life” (August 2014) – illustrating the daily ebb and flow of a small but important cross-section of the LA megacity. With Mount Wilson and the San Gabriels as a backdrop we can experience the range of atmospheric conditions that prevail in LA such as the evening marine layer and development of the midday inversion layer that traps polluted air including visible aerosols and invisible greenhouse gases. We can also see evidence of cycles of human activity including traffic on the 10 freeway at the base of the skyscrapers and the use of nightlights. We even catch the demolition of a small building around August 20 (watch carefully, it happens fast). Even heavily built-up cities like LA exhibit behavior that some scientists liken to the “metabolism” of a huge organism.