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Giovanni Workshop Lets Earth Scientists Share Global Earth Science Data
- Published on Tuesday, 02 April 2013 12:33
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The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), one of NASA’s nine Distributed Active Archive Centers (DAACs), provides a broad variety of remote-sensing data from several NASA satellites. The GES DISC’s particular data specialty is atmospheric and precipitation data, highlighted by data from the Atmospheric Infrared Sounder (AIRS), the Tropical Rainfall Measuring Mission (TRMM), the Ozone Measuring Instrument (OMI), the Microwave Limb Sounder (MLS), and the High Resolution Dynamic Limb Sounder (HIRDLS).
Additionally, the GES DISC also archives data from modeling projects, such as the Modern Era Retrospective-analysis for Research and Applications (MERRA) and the Land Data Assimilation System (LDAS), along with heritage data sets, typified by new data sets being added under the Making Earth Science Data Records for Use in Research Environments (MEaSUREs) program.
The GES DISC has a history of support for the NASA Earth Observing System (EOS) program satellites, and has in the past also archived data from the Moderate Resolution Imaging Spectroradiometer (MODIS), the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), and even Normalized Difference Vegetation Index (NDVI) data from the Advanced Very High Resolution Radiometer (AVHRR) on polar-orbiting satellites operated by the National Oceanic and Atmospheric Administration (NOAA). Both the current and heritage data archive of the GES DISC allow scientists to investigate the physical and chemical dynamics of the atmosphere, hydrology, ocean-atmosphere interactions, and significant geophysical events, both short-term and long-term.
In 2002-2003, the large amount of data in the GES DISC archive, and its remarkable variety, inspired a collaboration of research scientists at Goddard Space Flight Center (GSFC) with the GES DISC to come up with a new way to work with the data, taking advantage of the growing capabilities of the World Wide Web, personal computer Web browsers, and existing data analysis software, such as the Grid Analysis and Display System (GrADS). Led by Dr. Yoram Kaufman of the GSFC Atmospheres Laboratory and Dr. Gregory Leptoukh of the GES DISC, a system was created that was given the acronym “GES DISC Interactive Online Visualization ANd aNalysis Infrastructure” – GIOVANNI. (Over the ensuing years, it has become much easier to simply refer to the system as ‘Giovanni’). A guiding principle was to make Giovanni usable by accomplished scientists who were unskilled in computer data analysis (a category in which Kaufman included himself). More fundamentally, the goal of the system was to make it easier to explore data – to visualize it with different types of plots, like maps or time-series graphs; to be able to easily subdivide the data by geographical specifications or particular periods of time; and even to do relatively simple things like use different color palettes on data maps or adjust plot axis numerical ranges. In so doing, the more traditional steps of searching for data, downloading data, and then analyzing the data with other methods and software were eliminated, or at least streamlined.
Giovanni originally incorporated data from MODIS and TRMM, and soon expanded by adding ocean color data from SeaWiFS and ozone data from the Total Ozone Mapping Spectrometer (TOMS). The system grew with more data sets and more analytical capabilities, eventually requiring a new “in-house” version, unifying initially distinct and independent data type “instances” into a single somewhat manageable system, Giovanni-3 (the current Giovanni). As the science community became more aware of Giovanni’s ease-of-use and growing analytical suite, research groups, international programs, and new missions sought to include its capabilities. Leptoukh tirelessly led this effort by seeking and establishing collaborations, pushing for the development of more capabilities, maintaining data integrity within the system, improving documentation of what Giovanni actually did with the data, and acting as its ambassador at many different scientific meetings. Leptoukh continued these activities until his sudden and tragic passing in January 2012.
One indicator of Giovanni’s success was the rapidly increasing number of publications using the system (now numbering nearly 700) in scientific journals. This growing usage, with publications in 2012 nearing 200 compared to 50 in 2008, begat the idea of an event in which the use of Giovanni for scientific research could be highlighted. Because the system was clearly being used by scientists in many different countries, convening a traditional meeting in one location was perceived to be difficult. It was decided to organize an online scientific workshop about Giovanni, inviting researchers who had authored recent papers to present their research, and allowing participants to join the meeting online, from office, home, library, or coffee shop, and minimizing (to a very large extent) travel expenses. Such an event and format had been discussed with Leptoukh, so it was deemed appropriate to name this workshop in honor of the man who had become casually known as the “father” of Giovanni.
The Giovanni online workshop
The workshop was organized in early 2012, and convened during the last week of September. The workshop used the online meeting environment WebEx (Cisco Systems) and was conducted silently, with presenters typing their comments into the WebEx chat box as their slides were displayed. Use of the chat box allowed the capture of verbatim narration and any question-and-answer dialogue from participants, so that it could be included with the presentations on a workshop Proceedings Web page.
Twitter and YouTube.The introductory session of the workshop on the morning of Sept. 23 began with a tribute and short biography of Gregory Leptoukh and opening remarks from GES DISC Head Steve Kempler. An update on the current status of Giovanni and the 2012 research highlights was given by (article author) James Acker. More than 70 participants were virtually in attendance for the subsequent presentation on the development of the next-generation Giovanni system, Giovanni-4 (G4), by GES DISC software engineer Dr. Christopher Lynnes. The introductory session concluded with a brief overview of how those interested can follow Giovanni news and developments using social media connections, such as
Rachel Pinker of the University of Maryland – College Park commenced the first science session of the workshop in the afternoon. Her research group makes use of MODIS data to calculate radiative fluxes, which are primary drivers of the Earth’s climate systems. A selection of several MODIS atmospheric data products (particularly cloud and water vapor data) available in Giovanni enable Pinker to make radiative flux estimates. Pinker’s slides discussed the difficulties of estimating radiative fluxes over the oceans and at high latitudes.
The next two presentations constituted a mini-theme of Earth science data and public health. GES DISC-based Radina Soebiyanto (Universities Space Research Association, USRA) described several instances of communicable disease research using Giovanni. Her four examples were studies of malaria, dengue fever, avian influenza, and seasonal (human) influenza transmission.
She was followed by Michael Wemberly of South Dakota State University, who discussed the use of various data types for malaria prediction in Ethiopia. Wemberly and his associates assessed the use of several data variables, such as land surface temperature, soil moisture, and precipitation (obtained from Giovanni), as well as vegetation indices, which were employed as indicators of near-surface moisture levels. Precipitation was the main theme of the next presentation by David Mocko of GSFC and SAIC, who collaborates with the GES DISC to provide data from the North American and Global Land Data Assimilation Systems (NLDAS and GLDAS, respectively). Mocko’s presentation described these data sets, and how they were used to investigate several recent events, including the unusually warm winter and summer of 2011 in the United States, the effect of Hurricane Isaac on ongoing Midwest drought conditions, and the derecho event of June 29, 2012, that caused massive power outages in Midwestern and Mid-Atlantic states. Weather and rain also were the primary subjects of presentations by Amita Mehta (GSFC/UMBC –JCET) and co-author Ana Prados. They showed Giovanni precipitation data plots for several extreme rain events contributing to dangerous flooding.
The evening session on Sept. 23 (in the morning for residents of the Pacific Western Rim and eastern Asia) demonstrated the global reach and educational prowess of Giovanni. Paul Adams of Fort Hays State University in Kansas discussed the Earth System Science Educational Alliance (ESSEA), which creates projects that can be used for advanced teacher training in climate and environmental subjects. Adams showed projects in which he used Giovanni to illustrate particular concepts in ESSEA training “modules” he has developed. Adams was followed by Suhung Shen of GSFC and George Mason University, who gave her presentation from Beijing, China, while visiting her parents. Shen’s topic was appropriate, as she described many land remote sensing data products in Giovanni, including remarkable 1- and 0.5-kilometer resolution land surface temperature and land cover type data. The high resolution data is available only over the Asian region, but 5.6-kilometer land cover classification data is available globally. Shen’s presentation covered drought research and urban heat island effects of major cities in China.
The next session on the morning of Sept. 24 centered on atmospheric phenomena, but the initial presentation, by Jan Verbesselt from Wageningen University, Netherlands, had a different flavor. Verbesselt and his co-authors have accessed data in Giovanni as part of their effort to perform near-real-time disturbance monitoring with satellite data. The investigation Verbesselt described focused on severe drought conditions in Somalia. Detection of disturbances was enabled by creating a regional data history and then comparing near-real-time data to the data history. Maksym Petrenko of GSFC, who frequently collaborated with Leptoukh, described two results of their work together, the Multi-Sensor Aerosol Products Sampling System (MAPSS), and the AeroStat aerosol data analysis system, both of which feature a Giovanni-based interface.
The next presenter, Sarah Strode (GSFC/USRA), used Giovanni to characterize smoke aerosols from forest fires in her research on the transport of the radioactive isotope Cesium-137 in the Northern Hemisphere. This isotope entered Earth’s ecosystems originally due to 1960s-era nuclear testing, and received an extra dose from the Chernobyl accident. Now, intense wildfires in northern forests can remobilize Cesium-137, a potential human health hazard if inhaled downwind. Dust aerosols were the main subject of Richard Hansell (of GSFC’s Climate and Radiation Laboratory and the University of Maryland), who investigated longwave radiation effects of aerosols with the aid of Giovanni, and also showed some ground-based pictures of a mobile laboratory deployment in the Cape Verde islands, which are frequently overswept by Saharan dust storms.
The second day’s afternoon session revolved around Earth’s watery realm. Eurico D’Sa of Louisana State University provided a detailed view of the Louisiana-Texas coast, merging SeaWiFS chlorophyll data from Giovanni with QuikSCAT wind data from the Jet Propulsion Laboratory’s Physical Oceanography DAAC (PODAAC). D’sa found that prevailing monthly wind direction significantly affected chlorophyll concentration offshore, while river discharge was the primary nearshore determining factor. Following D’Sa, Acker of the GES DISC previewed Giovanni’s MODIS-Aqua ocean color data anomaly analysis capability by examining 10 years of Lake Michigan euphotic depth anomalies. Euphotic depth is an indicator of water clarity. Acker showed that a regularly-recurring reduction in water clarity usually occurring in the spring in southern Lake Michigan became quite irregular in springs of the years 2003-2012.
Tracy van Holt of East Carolina University provided one of the workshop’s more unusual presentations, describing her work on the choices facing Chilean fishermen. Fishermen here can seek either the abalone-like shellfish loco or the eel-like fish congrio. Giovanni showed her that chlorophyll concentrations were higher offshore of river outlets draining forest plantations. The higher chlorophyll concentrations were correlated with less desirable and thus lower-priced locos, due to the presence of organisms latching onto the loco shell – a vital factor in choosing between loco and congrio. Cecile Rousseaux’s (GSFC) presentation looked at the same region of the ocean, using the NASA Ocean Biogeochemical Model (NOBM) which she is refining with Watson Gregg. NOBM results showed a dramatic shift in the distribution of delectable (at least for zooplankton) diatoms between El Niño and La Niña conditions in the equatorial Pacific Ocean.
The session ended on a different note, with Zhen Liu of Georgia Institute of Technology describing the photochemical environment in the atmosphere above China. Liu’s predictive model of the atmosphere combined three processes: emissions, chemistry, and transport. The model did well for many chemical species, but severely underestimated satellite-observed glyoxal (CHOCHO) concentrations, which Liu found was due to large underestimates of China’s emissions of aromatic carbon compounds.
The final day of the workshop began in the early morning of Sept. 25 in the U.S., as the first five presentations were given by atmospheric and oceanographic scientists in Europe and the Middle East. Dimitris Kaskoutis (assistant professor in the Department of Physics, School of Natural Sciences, Shiv Nadar University, India) who has used Giovanni to investigate air quality in both India and Greece, chose to describe research into the atmospheric factors affecting net downward radiation in India, along with co-author P.G. Kosmopoulos. They found that increasing high clouds and aerosols are causing a declining trend in the net downward radiation over the subcontinent. Sergey Piontkovski from Sultan Qaboos University in Oman discussed the physical and biological oceanography of the Arabian Sea. Piontkovski created a grid which divided the Arabian Sea into 61 regions, and made a time-series and power spectrum for each of these regions with Giovanni data. The results described a potentially troubling reduction in the spatial extent of the zones of maximum chlorophyll concentration. Piontkovski also investigated the causes of some massive fish kills that have occurred in coastal fish farms.
Sergei Sitnov from the A.M. Obukhov Institute of Atmospheric Physics (one of Giovanni’s most prolific users) specializes in using NO2 data from the Ozone Measuring Instrument (OMI) to investigate air pollution. His workshop presentation described how NO2 concentrations vary with both location and day of the week around Moscow. He said similar research could be conducted for other major cities. Pavel Kishcha of Tel Aviv University, along with co-authors from that institution and JPL, looked at trends in MODIS AOD over major cities in India and correlations with population growth. Natalia Chubarova of Moscow State University followed by describing how Giovanni is an important tool for her aerosol research and environmental education curriculum.
The next session shifted back to the U.S. East Coast, featuring Leonard Druyan of Columbia University and the Goddard Institute of Space Studies (GISS) in New York. Druyan and Matthew Fulukeza used TRMM data to observe propagation of convective rainfall systems over the eastern tropical Atlantic Ocean. Charles Ichoku of GSFC looked at connections between environmental processes and drought in sub-Saharan Africa. Drought in this region influences the frequency of fires, water resources, vegetative land cover, and ultimately the economic prospects and health of the human population. Richard Kleidman (GSFC/SSAI) described how Giovanni is used in the Applied Remote Sensing Education and Training (ARSET) program, which teaches professional audiences about the potential advantages and possible pitfalls of using remote sensing data. ARSET has emphasized air quality topics, but is also developing water resources training modules.
The final workshop session in the afternoon of Sept. 25 continued on an educational theme. Daniel Zalles of SRI International, principal investigator of the Data-enhanced Investigations for Climate Change Education (DICCE) project, outlined the project’s goals and accomplishments, including a streamlined Giovanni interface with multi-disciplinary data, enhanced data information, and the project’s Learning Environment.
This presentation was followed by a Giovanni education roundtable, with panelists including Zalles, Acker, Amanda Truett of Montgomery College, Ruth Krumhansl of the Education Development Center, and Bob Myers of ESSEA. This discussion found a distinct difference in the use of Giovanni at the high school level, where teachers have limited time to develop expertise with new technology, and the undergraduate college level, where professors can expect students to figure out how to use a tool like Giovanni with less guidance, and use it for problem-based learning. It also was noted that problems with the data and difficulties in using the tool are much more significant barriers to success at the high school level. The panelists were particularly pleased that Giovanni gives both students and teachers the opportunity to work with “real” data, despite the uncertainties that can be introduced into the learning process through the use of such data.
Through the initial growth and development of Giovanni, Greg Leptoukh was greatly concerned with how the resource was being used by scientists, and if it was being used effectively. He continually led efforts to make it more useful to scientists, both in terms of the data it contained, and the quality of that data and the analytical results. This online workshop demonstrated that Giovanni has matured sufficiently to allow both straightforward and unconventional applications to diverse research questions. Giovanni now possesses a breadth and depth of data that facilitates sophisticated research, while at the same time presenting the data in an interface that is amenable to introductory learning and basic research experiences. The current development effort for Giovanni-4 will retain the current analytical capabilities but make them even faster, add new capabilities, and improve the overall usability of the system – all of which are advances that Leptoukh would certainly have approved.
The full Proceedings of the 2012 Gregory G. Leptoukh Online Giovanni Workshop are online. The Proceedings include each presentation of the workshop, accompanied by the narrative text provided by each presenter and any accompanying dialogue.
James Acker is a senior support scientist at the NASA GES DISC. He has a Ph.D. in Marine Science from the University of South Florida, and has been working in the User Services component of the GES DISC since 1996. Since the introduction of Giovanni, he has worked to promote its use for research and education in several different collaborative projects with scientists and educators, and through meeting presentations, workshops, and social media.