The AIM measurements have provided the first comprehensive global-scale view of the complex life cycle of these clouds, also called Polar Mesospheric Clouds (PMCs), over three entire Northern Hemisphere and two Southern Hemisphere seasons revealing more about their formation, frequency and brightness and why they appear to be occurring at lower latitudes than ever before.
"The AIM findings have altered our previous understanding of why PMCs form and vary," stated AIM principal investigator Dr. James Russell III of Hampton University in Hampton, Va. "We have captured the brightest clouds ever observed and they display large variations in size and structure signifying a great sensitivity to the environment in which the clouds form. The cloud season abruptly turns on and off going from no clouds to near complete coverage in a matter of days with the reverse pattern occurring at the season end."
These bright "night-shining" clouds, which form 50 miles above Earth's surface, are seen by the spacecraft's instruments, starting in late May and lasting until late August in the north and from late November to late February in the south. The AIM satellite reports daily observations of the clouds at all longitudes and over a broad latitude range extending from 60 to 85 degrees in both hemispheres.
The clouds usually form at high latitudes during the summer of each hemisphere. They are made of ice crystals formed when water vapor condenses onto dust particles in the brutal cold of this region, at temperatures around minus 210 to minus 235 degrees Fahrenheit. They are called "night shining" clouds by observers on the ground because their high altitude allows them to continue reflecting sunlight after the sun has set below the horizon. They form a spectacular silvery blue display visible well into the night time.
Sophisticated multidimensional models have also advanced significantly in the last few years and together with AIM and other space and ground-based data have led to important advances in understanding these unusual and provocative clouds. The satellite data has shown that:
1. Temperature appears to control season onset, variability during the season, and season end. Water vapor is surely important but the role it plays in NLC variability is only now becoming more understood,
2. Large scale planetary waves in the Earth's upper atmosphere cause NLCs to vary globally, while shorter scale gravity waves cause the clouds to disappear regionally;
3. There is coupling between the summer and winter hemispheres: when temperature changes in the winter hemisphere, NLCs change correspondingly in the opposite hemisphere.
Computer models that include detailed physics of the clouds and couple the upper atmosphere environment where they occur with the lower regions of the atmosphere are being used to study the reasons the NLCs form and the causes for their variability. These models are able to reproduce many of the features found by AIM. Validation of the results using AIM and other data will help determine the underlying causes of the observed changes in NLCs.
The AIM results were produced by Mr. Larry Gordley and Dr. Mark Hervig and the Solar Occultation for Ice Experiment (SOFIE) team, Gats, Inc., Newport News, Va. and Dr. Cora Randall and the Cloud Imaging and Particle Size (CIPS) experiment team, University of Colorado, Laboratory for Atmospheric and Space Physics in Boulder and Dr. Scott Bailey, Va. Tech, Blacksburg, Va.; Modeling results were developed by Dr. Daniel Marsh of the National Center for Atmospheric Research in Boulder, Colorado and Professor Franz-Josef Lübken of the Leibniz-Institute of Atmospheric Physics, Kühlungsborn, Germany.
AIM is a NASA-funded SMall EXplorers (SMEX) mission. NASA's Goddard Space Flight Center manages the program for the agency's Science Mission Directorate at NASA Headquarters in Washington. The mission is led by the Principal Investigator from the Center for Atmospheric Sciences at Hampton University in VA. Instruments were built by the Laboratory for Atmospheric and Space Physics (LASP), University of Colorado, Boulder, and the Space Dynamics Laboratory, Utah State University. LASP also manages the AIM mission and controls the satellite. Orbital Sciences Corporation, Dulles, Va., designed, manufactured, and tested the AIM spacecraft, and provided the Pegasus launch vehicle.
Cynthia O'Carroll | EurekAlert!
First Juno science results supported by University of Leicester's Jupiter 'forecast'
26.05.2017 | University of Leicester
Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy