About our Atmosphere
The Level-1 and Atmosphere Archive & Distribution System (LAADS) Distributed Active Archive Center (DAAC) at the Goddard Space Flight Center (GSFC) is one of the data centers that primarily serves atmosphere data and derived data products. Scientists use these datasets to study Earth's atmosphere, which is one of the three primordial elements that sustain all life-support systems in our biosphere. This section answers four fundamental questions as an introduction to the discipline domain of the LAADS DAAC.
What is Earth's atmosphere?
Earth's atmosphere comprises a universal envelope of gases that acts as a protective shield to sustain all biospheric life on this planet. It helps absorb ultraviolet radiation from the Sun, and maintains the natural greenhouse effect — an equilibrium between the incoming and outgoing radiation — which renders a habitable Earth at an average temperature of around 59 ˚F (15 ˚C), based on 2015, the hottest year on record. Earth's atmosphere is one of the integral elements of the global ecological system that constantly interacts and exchanges with its other two elements: lithosphere and hydrosphere. Earth's atmosphere, since its forming ~5 billion years ago, has evolved considerably to its current state and composition. It comprises of a number of components that Earth scientists study both as researchers and applied scientists. They include atmospheric aerosols, water vapor, ozone, temperature, moisture, and clouds. These components also form the foundation for LAADS' data products' portfolio.
Why should we study our Earth's atmosphere?
Our Earth's atmosphere plays an increasingly important role within several contemporary planetary scale environmental problems. The Anthropocene is defined as the time epoch that roughly began with the Industrial Revolution in the late-eighteenth century. This time period also marks the beginning when the influences of human activities on Earth's atmosphere became recognizable, and ever since, have been on the rise. Since then, greenhouse gases, air pollution, ozone depletion, and acid rain constitute some of the critical problems that have impacted Earth's atmosphere, and continue to contribute to the growing debate on global warming and climate change.
Understanding the structure and composition of the components of Earth's atmosphere, and how they interact and exchange with the global terrestrial and oceanic ecosystem components of the biosphere is a critical prerequisite before we can formulate objective policy-based solutions to address these problems. Data and information describing these components provide a solid foundation to gather observations and evidence regarding their historical as well as current properties and behavior. The LAADS atmosphere data portfolio provides a reliable source of contemporary science data products to study and analyze various aspects of atmospheric science. Refining this understanding of our Earth's dynamics, especially in the context of their interactions and exchanges with other components of the planetary ecological system remains a paramount requirement to inform science policy both currently, and in the near future.
How does remote sensing-derived data facilitate studying our Earth's atmosphere?
Space-based remote sensing enables us to gather observations about atmospheric, terrestrial, and oceanic elements of our Earth's biosphere in ways that are nearly impossible to replicate using ground-based methods. Earth's life-support systems are driven by the dominant Sun, and remote sensing attempts to observe and measure Sun's energy in its various manifestations. Radiative forcing is the difference between the incoming solar radiation energy, which is absorbed by Earth and that, which is radiated back into space. This delicate radiation balance is critical in determining Earth's average temperature, and is affected by a number of factors. They include the intensity of solar radiation, atmospheric composition, primarily aerosols, cloud cover, and greenhouse gases and their absorption potential, albedo or reflectivity of different surfaces, snow-cover, vegetation, and land-use patterns.
Three major exchange cycles drive our understanding of Earth's planetary scale environmental dynamics, and remote sensing-derived data provide an efficient mechanism to observe and measure their attributes and behavior. They include the global energy budget, hydrological cycle, and carbon cycle. The energy budget involves solar heating, IR cooling, and the transport of heat between the surface and the atmosphere. Heat is also transported from equator to poles by the atmosphere and ocean. Clouds are evidence of moisture fluxes transported vertically from the surface to varying atmospheric levels and transported horizontally by wind advection. Aerosol plumes are a signature for both natural (volcanic, dust) and anthropogenic (coal burning, deforestation) processes, with the latter contributing prominently in the carbon cycle as sources of atmospheric CO2. Moderate Resolution Imaging Spectroradiometer (MODIS)-derived datasets play a key role in monitoring how the atmosphere responds to various forcings, whether from new volcanic eruptions, sea surface temperature changes, new land use patterns or increasing greenhouse gas concentrations. They also help scientists characterize the many natural oscillations of the coupled atmosphere-ocean system including El Niño Southern Oscillation, seasonal monsoons, and Arctic/northern hemisphere anomalies.
Addressing user needs for data to characterize and understand Earth's environmental dynamics, the LAADS DAAC produces and serves a complement of atmosphere product collections from two major Earth science missions, NASA Earth Observing System's Terra- and Aqua-MODIS, and Suomi National Polar-orbiting Partnership's (SNPP) Visible Infrared Imaging Radiometer Suite (VIIRS). The latter collection will become available in 2016. Besides LAADS DAAC, three other NASA DAACs offer a variety of other atmosphere data products as well. The next question attempts to clarify their similarities and differences.
How do LAADS DAAC atmosphere products differ from what the Goddard Earth Science-Data and Information Services Center (GES-DISC), Langley Atmospheric Science Data Center (ASDC), and the Global Hydrology Resource Center (GHRC) offer?
Each of the four DAACs host and serve a variety of atmosphere products that demonstrate not only the wide range among them but also the unique tools and services that each offers to their users. The following brief descriptions attempt to describe what is unique about each of these data centers specific to their stewardship of atmosphere data products. These descriptions do not provide an exhaustive listing of each of their collections, tools, and services. Prospective users are encouraged to visit their respective Web pages to understand the full complement of their holdings, tools, and services, and the nuances that distinguish them.
The following table is a very broad attempt to portray the disciplines or sub-disciplines that each of the data centers caters to, under the common atmospheric science domain. Given the variety of satellite and airborne missions, field campaigns, and field experiments, it does not render it possible to capture the full breadth of the similarities and uniqueness among all their holdings within such a simple table. Also, the discipline categories identified below are not mutually exclusive, and only serve to deliver a highly synoptic snapshot.
|Water vapor||Water vapor||Water vapor||Water vapor|
Goddard Earth Science-Data and Information Services Center
GES-DISC's discipline domain is precipitation, hydrology, and atmospheric composition and dynamics. It specializes in providing a portal approach both from the perspectives of different missions as well as specific science components that comprise its discipline domain. For example, ozone data from a variety of missions — Satellite, Shuttle, Aircraft, Balloon & Rocket, Ground-based, Field Experiments, and Model Assimilations — are provided. In addition, they offer a host of analysis tools, including Geospatial Interactive Online Visualization and Analysis Infrastructure (Giovanni), a Web-based analysis and visualization tool that leverages input data straight from the archive thus freeing the user from initially having to download those inputs. GES-DISC also offers a number of atmospheric, terrestrial, and oceanic data assimilation products used by the modeling community.
Langley Atmospheric Science Data Center
ASDC's discipline domain includes Aerosols, Clouds, Radiation Budget, and Tropospheric Chemistry, and offers data derived from a number of satellite and airborne missions, field campaigns and field experiments. Tropospheric Chemistry is an umbrella group, and hence includes similar products to those offered by the other three data centers. ASDC is the only data center that uniquely serves an array of Radiation Budget products. Also among its tools to conduct parameter-level searches, ASDC offers the Ontology-Driven Interactive Search Environment for Earth Science (ODISEES).
Global Hydrology Resource Center
GHRC uniquely caters to those studying severe weather and hydrology phenomena, by providing data collections that span lightning, hurricanes, wind direction, water vapor and precipitation. Similar to the other three data centers, they also support aerosols, clouds, water vapor, and atmospheric temperature datasets from very diverse sources as well. GHRC data collections are distinguished by the fact that they are derived from a wide variety of sources that include ground stations, field campaigns, ground validation, satellite, aircraft, balloon, aerosonde, dropwindsonde, and modeling analyses.
Level-1 and Atmosphere Archive & Distribution System
LAADS is primarily the MODIS and VIIRS atmosphere data center, although it also supports their terrestrial production component for its NASA EOSDIS stakeholders as well. LAADS' lineage is closely linked to the MODIS Adaptive Processing System (MODAPS), which produces all atmosphere and land data products from L1 and higher levels. Currently, LAADS offers aerosols, clouds, water vapor, temperature, ozone, and moisture profiles, and will offer a similar complement of products from the SNPP VIIRS mission in 2016.
Last updated: December 17, 2015