Operational Status:
requestable, ready for deployment
General Description:
- MEDUSA provides the capability for collecting samples of air integrated over 25-s sample periods. Sixteen cryogenically dried 1.5 L air samples can be collected in glass flasks by an automated sampler that controls the flow and pressure to the flasks. As used for example in the HIPPO campaign, MEDUSA provided a discretely-sampled comparison for onboard (“in-situ”) real-time O2/N2 ratio measurements from the AO2 instrument, a redundant measurement of CO2, and the only measurement of argon and 13C, 14C, and 18O isotopes. The complementary measurements (CO2, O2/N2) allow ground-truthing of onboard instrument measurements in a laboratory setting, where analysis conditions can often be more stringently proscribed and carefully monitored. Isotope and argon measurements can provide additional information about land and ocean controls over the carbon cycle, about the age and source of the air sampled, and about the convective activity of the troposphere.
- The following photograph shows the system as used during the HIPPO multi-year campaign:
- The following photograph shows the system as used during the HIPPO multi-year campaign:
MEDUSA consists of an onboard computer, two pressure controllers, two pumps, three multi-position selector valves, and a host of other hardware that control and direct the air samples. All air is dehydrated by passing it through traps immersed in a -80° Celsius dry ice bath, adjusted to match atmospheric pressure at sea level, and then automatically sealed in place by a valve. Flasks are later analyzed on a sector-magnet mass spectrometer and a LiCor non-dispersive infrared CO2 analyzer by the Atmospheric Oxygen Research Group at Scripps Institution of Oceanography.
- MEDUSA provides the capability for collecting samples of air integrated over 25-s sample periods. Sixteen cryogenically dried 1.5 L air samples can be collected in glass flasks by an automated sampler that controls the flow and pressure to the flasks. As used for example in the HIPPO campaign, MEDUSA provided a discretely-sampled comparison for onboard (“in-situ”) real-time O2/N2 ratio measurements from the AO2 instrument, a redundant measurement of CO2, and the only measurement of argon and 13C, 14C, and 18O isotopes. The complementary measurements (CO2, O2/N2) allow ground-truthing of onboard instrument measurements in a laboratory setting, where analysis conditions can often be more stringently proscribed and carefully monitored. Isotope and argon measurements can provide additional information about land and ocean controls over the carbon cycle, about the age and source of the air sampled, and about the convective activity of the troposphere.
Measurement Characteristics:
- Overall estimate of uncertainty: variable depending on sampled species
- Response time: Samples are integrated over 25 s
- Precision:
- Other measurement characteristics (comments on signal/noise, bias limits, etc):
