CLIMATE Change Indicators: Upper Atmosphere
Post on 23-Feb-2016
DESCRIPTIONCLIMATE Change Indicators: Upper Atmosphere. Changes occurring in the Lower Atmosphere (Troposphere) . Arctic sea ice Glaciers Lake ice Snow cover Snowpack Growing season Plant hardiness Leaf/Bloom dates Bird wintering ranges. Global Temperatures GHG emissions - PowerPoint PPT Presentation
Change Indicators in the Upper Atmosphere
CLIMATE Change Indicators:Upper AtmosphereThe upper atmosphere is define as the thermosphere/ionosphere 1 Global Temperatures GHG emissions Heat waves Drought Precipitation Flooding Cyclones Sea Surface Temp Sea level Ocean acidification
Arctic sea ice Glaciers Lake ice Snow cover Snowpack Growing season Plant hardiness Leaf/Bloom dates Bird wintering ranges
Changes occurring in the Lower Atmosphere (Troposphere) 2
Its easy to notice or hear about change when its happening around you (in the troposphere)
What about the other layers of the atmosphere? Are changes occurring there? 3How is the upper atmosphere measured from the ground?RADAR (RAdio Detection And Ranging) is a technique for detecting and studying remote targets by transmitting a radio wave in the direction of the target and observing the reflection of the waveTarget of incoherent scatter radar is electrons in the earth's ionosphere rather than a discrete hard target (like an airplane)High energy ultraviolet radiation from the sun removes electrons from some of the atoms and molecules in this region, and these electrons can scatter radio wavesAmount of energy scattered from each electron is well known, the strength of the echo received from the ionosphere measures the number of electrons in the scattering volumeScattering technique can determine density, temperature, velocity, and composition of the charged upper atmosphere [ionosphere]
Incoherent Scatter Radar MIT Haystack teaches us more about RADARs The most basic property of a target which can be measured by radar is its distance from the radar, known as the range. This is accomplished by transmitting short bursts, or pulses, and measuring the time between the transmission and the reception of the echo. Since radio waves travel at the speed of light (c = 300,000 km/sec = 186,000 miles per second), range = c*time/2, where the factor of 2 is because the measured time is for a round trip to and from the target. The range, together with the direction of the target, determines its location, which is what is needed for many radar applications such as air traffic control..
The strength of the received echo can also be measured. This will vary with the distance of the target, its size, its shape and its composition. For example, the echo from a Boeing 747 airliner will be much stronger that the echo from a small commuter aircraft. The echo from a stealth aircraft is much smaller than from a commercial aircraft of the same size because its shape and composition are carefully chosen to minimize radar returns.
Remember the ionosphere extends from about 100 km (60 miles) to 1000 km (600 miles) above the earth's surface.The density of the electrons ranges from about 10,000 to 1,000,000 per cubic centimeter in the ionosphere.
4This map shows all of the world's operational incoherent scatter radarsThere are only 9 worldwide (as of 2000)Where are Incoherent Scatter Radars?
MIT Haystack2000Lets look at a few of these locations
Located in Westford, MA
Capable of making observations ranging from 90 to 1000 km in altitude
Radar systemA fixed vertically pointing antenna (Zenith) uses megawatt transmitter and 68 m diameter fixed antenna [1963 - now]A fully steerable antenna (MISA), 46 meter diameter [1978 now]
MIT Haystack The Millstone Hill Incoherent Scatter Radar system is a high power large aperature radar that is used to observe the near space environment. The primary measurement technique used by the system is incoherent scatter from ionospheric plasma. This technique allows the density, temperature, velocity, and composition of the near space environment (ionosphere) to be determined with great accuracy. The system can also observe scatter from ionospheric turbulence, meteors, and satellites.
The radar is capable of making observations over a range from 90 to 1000 km in altitude. Geographic coverage is from just short of the arctic circle to the north, past Florida to the south, to the central Atlantic ocean to the east, and out to Iowa in the west.
The radar system uses a high power transmitter in combination with a large antenna and highly sensitive radio receivers. A fixed vertically pointing antenna (Zenith) and a fully steerable antenna (MISA) are available for making ionospheric measurements. The fixed antenna is often used while moving the steerable one. By making measurements in multiple directions the radar system can be used to determine the flows and electric fields which are present in the ionosphere.
EISCAT/ESR European Incoherent Scatter Scientific Association
It operates three incoherent scatter radar systemsTwo in Northern Scandinavia One in SvalbardWikipedia | Credit Tom GrydelandInformation Wikipedia 7AreciboRadio Telescope located in Puerto Rico
305 m in diameter (largest single-aperture telescope)
Makes frequent appearances in movies and TV shows
NOAA accessed via Wikipedia Information Wikipedia
8Jicamarca Radio Observatory (JRO)Studies the equatorial ionosphere in Lima, Peru
Main antenna is the largest of all the incoherent scatter radars in the world300m x 300m square array
Wikipedia | Public Domain Information Wikipedia
9NASA Upper Atmosphere Satellite ProjectsTIMED - Thermosphere, Ionosphere, Mesosphere, Energetics and DynamicsDeveloped to explore Earths atmosphere above 60 kmLaunched December 2001
The Mission The Instrument SABER - Sounding of the Atmosphere using Broadband Emission Radiometry
Designed to measure energy budget of the mesosphere and lower thermosphere
Collected data over 8 years
NASAThermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) explores the Earth's Mesosphere and Lower Thermosphere (60-180 kilometers up), the least explored and understood region of our atmosphere. It is known that the global structure of this region can be perturbed during stratospheric warmings and solar-terrestrial events, but the overall structure and dynamics responses of these effects are not understood. Advances in remote sensing technology employed by TIMED will enable us to explore this region on a global basis from space.
10Cutting Edge Research ~40 years (1968 2006) of ionospheric data taken from the Millstone Hill Incoherent Scatter Radar is used
MIT scientists have been studying, analyzing and interpreting the results
Here is what they have discovered 11What trend do you notice?
Zhang, Shun-Rong | MIT Haystack Ion temperature taken over the past ~40 years at an altitude between 140 160 km.
MIT Scientists state a +1.9K/year
Zhang, Shun-Rong | MIT Haystack 13What trend do you notice?
Zhang, Shun-Rong | MIT Haystack Ion temperature taken over the past ~40 years at an altitude between 250 300km.
14MIT Scientists state a -1.2 K/year
Zhang, Shun-Rong | MIT Haystack 15What trend do you notice?
Zhang, Shun-Rong | MIT Haystack Ion temperature taken over the past ~40 years at an altitude between 400 450km.
16MIT Scientists state a -3.2 K/year
Zhang, Shun-Rong | MIT Haystack 17
Zhang, Shun-Rong | MIT Haystack Looking at each layer 18Altitude vs. Ion Temperature % change per decade There is more error in the lower atmosphere because there are fewer measurements made
The temperature profile indicates a DECREASE in ion temperature in the upper atmosphere above 200km
Zhang, Shun-Rong | MIT Haystack The difference in the varying errors with height has to do with the radar's observational modes. As a result, we didn't have as much data in the low altitudes (the ionospheric E and F1 regions/layers) as in the high altitudes (the ionospheric F2 layer), in particular, in the 1990s, we didn't took much E and F1 region observations, therefore the E and F1 region data show larger scatter(as can be seen in FA.jpg), and the derived trend shows larger uncertainty. Lets Compare Things are heating up Average global temperature has increased at a rate of roughly 0.15 - 0.20C per decade over the past 40 years This seems small, but has triggered many changes (polar cap melting, etc.)Things are cooling down Trend shows a 2 - 3C decrease per decade over the past 40 yearsChange is much bigger (10X!) than in the lower atmosphereTotal change is readily observable in data recordLOWER ATMOSPHEREUPPER ATMOSPHERE 20What is causing the Upper Atmosphere to cool?The answer is Radiative Cooling Process by which a body loses heat by radiation
Greenhouse gases (particularly CO2) radiative effects become more pronounced and produce a cooling effect in the upper atmosphere
Lastovicka et al. Global Change in the Upper Atmosphere. Science v.314 no.5803 (24 November 2006) pg. 1253 1254. Picture Caption from Lastovicka et al. Global Change in the Upper Atmosphere. Science v.314 no.5803 (24 November 2006) pg. 1253 1254. Atmospheric layers (orange, right) are defined by the temperature profile. Ionospheric layers (purple, left) are defined by the electron density profile (shown here at midnight at the equator). Arrows denote the direction of observed changes in the past 3 to 4 decades: Red, warming; blue, cooling; green, no temperature change; black, changes in maximum electron density (horizontal) and the height of ionospheric layers (vertical). Most spacecraft fly at altitudes above 300 km. The aircraft and satellite shown are not to scale.
More of radiative cooling Earth absorbs the suns short wave radiation and emits that energy in the form of long wave/infrared (IR) radiation near the Earths surface. (It is hot during the day and cooler at night)
Cloudy nights are warmer than clear nights because the clouds act to re-radiate the emitted long wave radiation (heat) back towards EarthCO2 and other greenhouse gases act as clouds to keep us warm
Now, it is getting too warm in the lower atmosphere and too cold in the upper atmosphere
21A quick video may help
Click on the title to play video 22Active and Ongoing ResearchThe upper atmosphere is an area that requires further studied
More data is needed to confirm the observed trends
Observed change in upper atmospheric temperature is large, which makes it easier to measure
Photo taken by Shun Rong Zhang | used with permission 23