Kuang S.,University of Alabama in Huntsville |
Burris J.F.,NASA |
Newchurch M.J.,University of Alabama in Huntsville |
Johnson S.,NASA |
Long S.,Earth System Science Center
IEEE Transactions on Geoscience and Remote Sensing | Year: 2011
A tropospheric ozone Differential Absorption Lidar system, developed jointly by The University of Alabama in Huntsville and the National Aeronautics and Space Administration, is making regular observations of ozone vertical distributions between 1 and 8 km with two receivers under both daytime and nighttime conditions using lasers at 285 and 291 nm. This paper describes the lidar system and analysis technique with some measurement examples. An iterative aerosol correction procedure reduces the retrieval error arising from differential aerosol backscatter in the lower troposphere. Lidar observations with coincident ozonesonde flights demonstrate that the retrieval accuracy ranges from better than 10% below 4 km to better than 20% below 8 km with 750-m vertical resolution and 10-min temporal integration. © 2006 IEEE.
Naeger A.R.,UAHuntsville |
Christopher S.A.,UAHuntsville |
Christopher S.A.,Earth System Science Center
Atmospheric Measurement Techniques | Year: 2014
In this paper, we develop an algorithm based on combining spectral, spatial, and temporal thresholds from the geostationary Spinning Enhanced Visible and Infrared Imager (SEVIRI) daytime measurements to identify and track different aerosol types, primarily volcanic ash. Contemporary methods typically do not use temporal information to identify ash. We focus not only on the identification and tracking of volcanic ash during the Eyjafjallajökull volcanic eruption period beginning in 14 April and ending 17 May 2010 but also on a pixel-level classification method for separating various classes in the SEVIRI images. Three case studies on 13, 16, and 17 May are analyzed in extensive detail with other satellite data including from the Moderate Resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging Spectroradiometer (MISR), and Facility for Airborne Atmospheric Measurements (FAAM) BAe146 aircraft data to verify the aerosol spatial distribution maps generated by the SEVIRI algorithm. Our results indicate that the SEVIRI algorithm is able to track volcanic ash when the solar zenith angle is lower than about 65 . Furthermore, the BAe146 aircraft data show that the SEVIRI algorithm detects nearly all ash regions when AOD > 0.2. However, the algorithm has higher uncertainties when AOD is < 0.1 over water and AOD < 0.2 over land. The ash spatial distributions provided by this algorithm can be used as a critical input and validation for atmospheric dispersion models simulated by Volcanic Ash Advisory Centers (VAACs). Identifying volcanic ash is an important first step before quantitative retrievals of ash concentration can be made. © Author(s) 2014.
Last week, U.S. agencies announced that the year 2015 had smashed records to become the hottest year ever recorded by humans, a finding that emphasizes the continued pattern of long-term global warming on Earth. The prior hottest year was just one year earlier — 2014 — and nine out of the 10 hottest years on global record have now occurred in the past decade. The announcement of the 2014 temperature record was accompanied by a startling statistic. News media reported that the odds of this spate of record-breaking years happening due to natural variations only — that is, not as the result of human-caused climate change — came to as low as one in 650 million. Now, a new paper out Monday in the journal Nature Scientific Reports conducts what the authors have described as a more rigorous calculation, concluding that the odds of this series of record-breakers — ending with 2014 — were not quite as low as reported. Even so, the calculations still make it clear that the string of record temperatures was highly unlikely to have occurred by chance alone, supporting the idea that human-caused climate change is the culprit. [The surprising way that climate change could worsen East Coast blizzards] “Individual record years and the observed runs of record-setting temperatures were extremely unlikely to have occurred in the absence of human-caused climate change,” the authors write. Led by Michael Mann, professor of atmospheric science and director of the Earth System Science Center at Pennsylvania State University, the researchers used a climate model, along with observed temperature data, to produce simulations of what temperature distributions should look like under the influence of anthropogenic climate change versus purely by chance. They paid particular attention to the recent run of record years, in which nine of the 10 warmest (and, in fact, 13 of the 15 warmest, as the authors point out) had occurred since the year 2000. The researchers calculated the odds for these record-breaking runs occurring in both the Northern Hemisphere alone and worldwide. For the Northern Hemisphere, the simulations suggested a chance of about one in 170,000 that the run of 13 out of the past 15 record breakers would have occurred since the year 2000 without the influence of anthropogenic climate change. And the odds of nine out of the past 10 record breakers occurring in the past decade due only to chance were one in 5,000. Globally, the odds of these record runs were a bit more likely — but still slim. The authors also examined the odds of individual years producing records, as opposed to strings of years together — for instance, the odds of 2014, alone, becoming the warmest year on record at the time. They noted in the paper, “We find it even less likely that natural variability might have produced the observed specific individual yearly temperature records.” This is because for an individual year to break a temperature record, it must reach a specific heat threshold all on its own, one that tops all the other heat records in individual years before it. The researchers found odds of one in a million or less that 2014’s record would have occurred without human influence — both in the Northern Hemisphere alone and globally. “That conclusion also holds for the other record years 1998, 2005, and 2010,” the authors added in the paper. On the other hand, the analysis also looked at the odds of these same records having been produced by human-caused climate change. The researchers found an 83 percent chance that the run of nine-out-of-10 record years, globally, was produced by anthropogenic global warming. And the likelihood of the 2014 record occurring globally was found to be about 40 percent. So while the odds are not quite as low as those reported in the press back at the close of 2014, they still point unequivocally to the overbearing influence of human-caused climate change in recent years. The key to producing accurate calculations, the authors pointed out in the paper, is to remember that each individual year in a “record run” is linked to the others: “The years are not independent of one another,” they write. Rather than each individual record occurring of its own accord, the factors that influence temperature trends tend to overlap and blur from one year to the next. The calculations can be taken as further evidence that human-caused climate change continues to exert an overwhelming influence on the Earth and is responsible for a long-term warming pattern that is only expected to continue in the future. The most recent news of 2015’s record-breaking status is just another confirmation. “In summary, our results suggest that the recent record temperature years are are roughly 600 to 130,000 times more likely to have occurred under conditions of anthropogenic [climate change] than in its absence,” the authors wrote in the paper. “Our findings thus underscore the profound impact that anthropogenic forcing has already had on temperature extremes.” It’s official: 2015 ‘smashed’ 2014’s global temperature record. It wasn’t even close Why clean energy is now expanding even when fossil fuels are cheap Why we’ve been hugely underestimating the overfishing of the oceans For more, you can sign up for our weekly newsletter here, and follow us on Twitter here.
News Article | December 22, 2015
Have you noticed that the voices of climate change disbelievers have become a little quieter lately? Many hope that the Paris Agreement has stilled these counterproductive contrarians. Climate Nexus puts its view nicely: “They lost the battle and the war when the world came together and agreed to transition away from fossil fuels.” Dr. Michael E. Mann, Director of the Earth System Science Center at Pennsylvania State University, recently told Brad Friedman on the BradCast: “It’s difficult to understate the significance of this agreement. I think we are witnessing the end of the age of fossil fuels and the beginning of a new age of a clean global energy economy.” Mann joined the IPCC and Al Gore as a co-Nobel Prize winner in 2007 for his creation of the “hockey stick graph,” which showed proxy climate reconstructions that reveal drastic recent temperature increases after centuries of relative inactivity. Media Matters, relentless in its revelation of duplicity in reporting, quantifies the in several recent articles. It begins by noting how the event scheduled by climate change deniers in Paris was “a flop.” The mainstream press ignored or belittled it, noting that the climate change challengers now bucked the tide of both of the science and history. Politico pointed out there was “little interest” in the event, and even the usually calm Reuters news agency referred to deniers as “yesterday’s men.” As it did several years ago in covering the same subject, Media Matters reviewed the opinion pages of major newspapers. Only four of the ten most widely circulated US newspapers published the views of climate change deniers after the Paris Agreement was formed. “The vast majority of coverage was sensible,” MMFA found. Nine pieces out of hundreds about the talks that the organization reviewed took an adversarial stance: four from the Wall Street Journal, running true to form; two from USA Today, which still hasn’t gotten the hint about false balance; two from the New York Post (hardly a paragon of serious journalism); and one from the Orange County Register (not exactly a national press organ). Perhaps we can all breathe a sigh of relief that the arguments over climate change have moved from debating its veracity to choosing among and implementing viable solutions. Dr. Mann draws a conclusion from past and future findings about climate change about the role of science in steering public information and politics: “We must convey what is known in plainspoken jargon-free language, while acknowledging the real uncertainties that exist. Further, we must explain the implications of those uncertainties, which in many cases imply the possibility of greater, not lesser, risk. Finally, we must not be averse to discussing the policy implications of the science, lest we fail to provide our audience with critical information that can help them make informed choices about their own actions as citizens.” Get CleanTechnica’s 1st (completely free) electric car report → “Electric Cars: What Early Adopters & First Followers Want.” Come attend CleanTechnica’s 1st “Cleantech Revolution Tour” event → in Berlin, Germany, April 9–10. Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.
Jones T.A.,Earth System Science Center |
Jones T.A.,Cooperative Institute for Mesoscale Meteorological Studies |
Christopher S.A.,Earth System Science Center
Atmospheric Chemistry and Physics | Year: 2011
Using daily Goddard Chemistry Aerosol Radiation and Transport (GOCART) model simulations and columnar retrievals of 0.55 μm aerosol optical thickness (AOT) and fine mode fraction (FMF) from the Moderate Resolution Imaging Spectroradiometer (MODIS), we estimate the satellite-derived aerosol properties over the global oceans between June 2006 and May 2007 due to black carbon (BC), organic carbon (OC), dust (DU), sea-salt (SS), and sulfate (SU) components. Using Aqua-MODIS aerosol properties embedded in the CERES-SSF product, we find that the mean MODIS FMF values for each aerosol type are SS: 0.31 ± 0.09, DU: 0.49 ± 0.13, SU: 0.77 ± 0.16, and (BC + OC): 0.80 ± 0.16. We further combine information from the ultraviolet spectrum using the Ozone Monitoring Instrument (OMI) onboard the Aura satellite to improve the classification process, since dust and carbonate aerosols have positive Aerosol Index (AI) values >0.5 while other aerosol types have near zero values. By combining MODIS and OMI datasets, we were able to identify and remove data in the SU, OC, and BC regions that were not associated with those aerosol types. The same methods used to estimate aerosol size characteristics from MODIS data within the CERES-SSF product were applied to Level 2 (L2) MODIS aerosol data from both Terra and Aqua satellites for the same time period. As expected, FMF estimates from L2 Aqua data agreed well with the CERES-SSF dataset from Aqua. However, the FMF estimate for DU from Terra data was significantly lower (0.37 vs. 0.49) indicating that sensor calibration, sampling differences, and/or diurnal changes in DU aerosol size characteristics were occurring. Differences for other aerosol types were generally smaller. Sensitivity studies show that a difference of 0.1 in the estimate of the anthropogenic component of FMF produces a corresponding change of 0.2 in the anthropogenic component of AOT (assuming a unit value of AOT). This uncertainty would then be passed along to any satellite-derived estimates of anthropogenic aerosol radiative effects. © 2011 Author(s).