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HIPPO Backgrounder

This document contains the opinions and conclusions from a preliminary mission summary prepared by the HIPPO researchers. A more formal summary with up-to-date research results will be available at a later date.

arrow   What Is HIPPO?
arrow   HIPPO Science Goals and Societal Relevance
arrow   How the HIPPO Mission Addresses Societal Needs
arrow   How HIPPO Fits Within a Broader Scientific Context
arrow   HIPPO Mission Accomplishments

Go to HIAPER Returns


The HIAPER Pole-to-Pole Observation (HIPPO) program is a National Science Foundation (NSF)-sponsored effort to study the distribution of greenhouse gases and black carbon in the atmosphere.

The study, a series of five flights over the next three years, uses the full capabilities of the High-performance Instrumented Airborne Platform for Environmental Research (HIAPER), a modified Gulfstream V jet owned by the National Science Foundation (NSF) and operated by NSF's National Center for Atmospheric Research (NCAR) in Boulder, Colo., which also provided logistical support for the mission.

To date, NSF has spent approximately $4.5 million to support the HIPPO project alone. Additional support for several of the important experiments on the HIAPER aircraft comes from the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory.


The motivation for HIPPO is to understand the "budgets" for major greenhouse gases and black carbon particles in the atmosphere. "Budget" in this context refers to quantitative knowledge of 1) where are these substances coming from, 2) what are their rates of emission, and 3) what are their removal processes and rates from the atmosphere.

HIPPO Approach
HIPPO has obtained detailed, high-accuracy measurements of greenhouse gases and black carbon particles in the atmosphere, globally, from the top of the troposphere to the earth's surface, collecting data along a path that stretched nearly from pole-to-pole. These measurements will reveal new information about the global budgets of greenhouse agents.


Global efforts are underway to curb the levels of greenhouse gases and black carbon particles in the atmosphere. Planning for mitigation efforts, and the future national and international programs to implement those efforts, must be based on the best possible scientific knowledge of the sources and a clear understanding of these materials' processes, amounts, locations and attributions in the environment.

The effectiveness of future mitigation efforts must be assessed by comparing future emissions across the globe to sources that existed prior to implementation of control policies.

HIPPO provides important contributions both to the development of the scientific methods needed to plan and assess mitigation efforts, and to the measurement baseline for comparing past and future atmospheric concentration patterns.


Two of the highest-impact greenhouse gases are carbon dioxide and methane. NOAA's Earth System Research Laboratory maintains a global network of ground stations and a smaller network of low altitude aircraft that measure these and other greenhouse gases, as well as chemical species that aid interpretation of the results, at or near the surface. These data have provided scientists with information needed to make estimates of the budgets of greenhouse gases.

However, different assessments have given different answers. A key uncertainty is the way in which atmospheric motions distribute emissions with height, for which we do not have global data. NSF's HIPPO program provides "slices of the atmosphere" that show how greenhouse agents move from their sources through the atmosphere. The new data will help identify which atmospheric models work best in simulating global distributions of greenhouse agents, allowing us to refine estimates of global budgets.

In addition, HIPPO measures an even larger suite of more than one hundred gases, including pollutants, ozone, gases emitted from the sea, and others--many of which have few prior measurements and no data from an ongoing network.

The AIRS instrument on the National Aeronautics and Space Administration (NASA) Earth Observing System Aqua platform makes low-resolution measurements of carbon dioxide and methane in the upper atmosphere. The Japanese GOSAT-Ibuki mission and the NASA Orbiting Carbon Observatory (OCO) mission are just being launched to measure total amounts of CO2, though each data point represents a column of atmosphere, the variations within that column are not apparent. HIPPO data expand these data sets, providing validation and calibration checks for these satellites and supplying information required to utilize these data in combination with the NOAA networks.


The HIAPER aircraft is on the last leg of the first HIPPO global survey; four additional surveys are planned for different times of the year.

  1. HIPPO successfully obtained highly detailed cross sections of greenhouse gases and black carbon particles from the planet's surface to the top of the troposphere, collecting data along a path that stretched nearly from pole-to-pole. The mission demonstrated, for the first time, that it is feasible to obtain this kind of data set--a major achievement in itself. The data set has the highest quality, able to reveal both fine details and the large-scale picture.
  2. The HIPPO data show accumulation in the Arctic of CO2, methane, sulfur hexafluoride, and other greenhouse gases, plus black carbon particles. These materials originate mainly from human activity in northern hemisphere continental regions. Carbon dioxide emissions reflect both industrial sources and the respiration of the biosphere.
  3. The HIPPO data show the inputs of oxygen and removal of CO2 by the southern ocean, and the resulting changes in atmospheric concentrations. HIPPO has observed the large-scale effects of Southern Ocean biogeochemical exchanges that are particularly sensitive to ongoing climate change and that play an important role in the uptake of human CO2 emissions.

For both the second and third preliminary results, HIPPO data show these effects globally, in their full vertical and horizontal extent, for the first time.

The full significance of these data will not be known for some time. The data will be analyzed using global atmospheric computer models and other approaches. We are confident that the data sets will significantly reduce uncertainties and fill gaps in our understanding of global budgets of greenhouse gases and black carbon particles.

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