Man with a mission


How fast is the earth’s climate changing and where do greenhouse gases go? A world expert in the use of satellites to study climate change is in Wellington this week to deliver a seminar. Dr David Crisp is a man with a mission. He is the principal investigator of the Orbiting Carbon Observatory (OCO) mission at the NASA Jet Propulsion Laboratory.

In order to understand how fast greenhouse gases are entering, and leaving the atmosphere, and from where, measurements must be made on a global scale. Dr Crisp is working with NIWA, and scientists worldwide to unlock these mysteries. NIWA scientists play a vital role in many international programmes like OCO and the Total Carbon Column Observing Network (TCCON).

Dr Dave Crisp says OCO-2 will be a dedicated satellite that carries a single specialised measuring instrument. The instrument will acquire the most precise measurements of atmospheric CO2 ever made from space. OCO-2 will fly in a polar orbit that enables the instrument to observe most of the Earth's surface at least once every sixteen days at the same time of day.

Dr Vanessa Sherlock, leader of NIWA’s TCCON research project at Lauder in Otago says, “When the satellite passes over Lauder, NIWA’s TCCON station, we will perform ground based, remote sensing measurements of greenhouse gases to provide essential validation of the satellite measurements”.

Validation of the OCO measurements is very important because the concentration differences scientists are trying to measure are very small. The New Zealand TCCON station in Lauder is a very good test case for this validation, because greenhouse gas concentrations are less variable in the Southern Hemisphere than in the North.

Combining the data from the surface network, the TCCON stations, the Orbiting Carbon Observatory, and other satellites will improve scientists’ understanding of future concentrations of greenhouse gases in the atmosphere. Scientists will be able to infer, and more accurately model, what happens to CO2 and other greenhouse gases as they are exchanged between atmosphere, land and sea.

30 billion tons of CO2 are emitted into the atmosphere every year. Measurements currently being collected indicate that less than half of this CO2 is accumulating in the atmosphere. The rest is being absorbed by CO2 “sinks” in the land and the oceans. Adding the validated OCO data to these measurements will give a far richer and more detailed picture of what is a very complex process.

NIWA's Sara Mikaloff Fletcher, an atmospheric modeller, is developing a carbon cycle model for New Zealand, Australia, and the surrounding ocean. The oceans and plants on land take up about 50% of all of the CO2 that we produce, making them "sinks" of atmospheric CO2. "It is essential to understand the natural sources and ‘sinks’ of CO2, methane, and other greenhouse gases in order to validate emissions reductions and predict how the sources and sinks may change in the future in response to climate change," says Dr Mikaloff Fletcher.

The new model, Carbon Tracker-Australasia, will use carbon observations from surface sites, ship-board measurements, TCCON, and, once they are available, OCO to infer the regional sources and sinks. Scientists using this 'inverse' approach to estimate emissions from data typically work with a network of only about 100 surface stations.

According to Dr. Mikaloff Fletcher, "the unprecedented global coverage that will be available through OCO and other satellite programs represents a tremendous opportunity to improve our understanding of carbon dioxide, and other greenhouse gases". 

The first OCO launch failed in February last year. The Obama administration has recently proposed a budget for NASA that includes US $2.4 billion to refly OCO, and other satellites to help scientists investigate Earth-bound problems, especially climate change.

The Foundation of Research Science and Technology has funded NIWA’s research.

NIWA Seminar 10:30 Friday 28 May at NIWA Greta Point

Remote sensing observations of atmospheric carbon dioxide

Speaker - Dr Dave Crisp


David Crisp:

Dr. David Crisp is a Senior Research Scientist at the Jet Propulsion Laboratory/California Institute of Technology and the Principal Investigator of the NASA Earth System Science Pathfinder Orbiting Carbon Observatory mission. Since receiving his Ph.D. from the Geophysical Fluid Dynamics Program at Princeton University in 1984, he has focused primarily on the development of radiative transfer algorithms for remote sensing and climate models of Venus, Earth, and Mars. Dr. Crisp has served on the science teams of several missions including the Venus VEGA Balloon Mission, Hubble Space Telescope Wide Field/Planetary Camera 2 (WFPC2), Mars Pathfinder Lander Atmospheric Structure Instrument, Mars Polar Lander MVACS Meteorology Experiment, and ESA Venus Express. He has also contributed NASA technology program by developing in situ atmospheric structure and meteorological instruments and serving as the Chief Scientist of the NASA New Millennium Program, from 1998 to 2001.

Carbon measurements at the Lauder TCCON site