SA33A-01 INVITED
Coordinated Studies of the Middle and Upper Atmosphere Structure: Results and Lessons-learned from the NASA TIMED Mission
The terrestrial middle and upper atmosphere is at the interface between interplanetary and lower-atmospheric processes and plays a uniquely important role in the solar-terrestrial system. The NASA Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) mission is dedicated to the study of the basic structure of this interface region, its spatial and temporal variability and processes responsible for the variability. For the past seven years TIMED and its upper atmosphere research colleague have transformed our understanding of this gateway region of near-Earth space by successfully characterizing its dynamics, energetics, thermal, and composition structures. TIMED, together with its groundbased partners and other domestic and international space programs, has allowed the Heliophysics research community to observe new aspects of the cause-and-effect chains linking the Sun, heliosphere, and magnetosphere to the Earth's upper and lower atmospheres. In addition, the approved extension of TIMED operations through 2012 would provide an observational record spanning an 11-year solar cycle. Most importantly, these extended observations would also enable a quantitative understanding of the external and internal forces that drive the middle and upper atmosphere and provide the ability to address processes related to anthropogenic climate change in this gateway region. In this paper, we will present highlights of TIMED observational results, summarize our current state of knowledge, and discuss issues related to on-going and future system studies of terrestrial middle and upper atmosphere, especially in the context of quantitative understanding of sources of atmosphere variability and predictive capability of long-term climate change.
SA33A-02
The Coordinated Sodium Airglow and Lidar Observations over India
In order to investigate the relation between the sodium airglow emission and sodium atoms, a narrow-band and narrow field-of-view sodium airglow photometer was operated in campaign modes from Gadanki (13.5° N, 79.2° E) in conjunction with sodium lidar during March, 2007 and 2008. The airglow observations yielded the temporal variation of altitude-integrated sodium airglow intensity whereas sodium lidar observations provided the altitudinal profile of neutral sodium atoms from 80 to 105 km. These observations reveal the dominance of 30-60 minutes periodicity in sodium airglow variation. Interestingly, sodium airglow on 18-19 March, 2007 shows an unusual variation compared to the other nights of observations. The power spectrum analysis indicates that the periods are different from other nights over Gadanki. Both airglow intensity variation and map of Height-Time-Concentration (HTC) of neutral sodium atoms obtained from sodium lidar observation reveal oscillatory patterns. The periods from the power spectra of sodium atoms variation at 93 and 94 km match well with the periods obtained from sodium airglow variation. Correlation analysis is carried out between the sodium airglow variation and sodium atoms variation at each altitude which also reveals the same peak altitude. The volume emission rate profile of sodium airglow is derived using mesospheric ozone retrieved by SABER instrument onboard TIMED satellite (measured at 01:30 IST; IST=UT+5.5 hrs) nearly over Gadanki. Both the ozone and sodium concentration profiles at that time show a peak at around 94 km. The result obtained from this investigation will be discussed.
SA33A-03
Lidar Measurements of Gravity Waves from Eureka During the Canadian Arctic ACE Validation Campaign
The composition variations of critical species such as ozone in the polar middle atmosphere is intimately tied
to dynamical variations. The suite of instruments at the Polar Environment Atmosphere Research Laboratory
(PEARL), part of the Canadian Network for the Detection of Atmospheric Change (CANDAC), is well
complemented to measure both the chemical and dynamic state of the middle atmosphere, and in particular
perturbations and mixing due to waves. Stratospheric and mesospheric gravity wave spectra are derived from
relative density measurements made in February and March 2009 with the CANDAC - Environment Canada
DIAL lidar in Eureka, Canada (80°N, 86°W) to investigate the variability and magnitude of the
perturbations due to gravity waves. Duck and colleagues have shown previously that the gravity wave spectrum
over Eureka is highly influenced by the polar vortex and appears continuous for nightly averages. Analysis on
shorter timescales (30 minutes) for 20 nights of measurements by Whiteway showed that, in general, a
random superposition of wavelengths is observed. A distinct dominant vertical wavelength was present on only
two occasions. This result is in contrast to middle latitude measurements of the upper stratosphere using the
University of Western Ontario's Purple Crow Lidar, which show that gravity wave spectra typically comprise only
four distinct waves on any given night, with most of the kinetic energy being carried by one or two dominant
waves. The current Eureka measurements will be analyzed using Prony's method to determine if only a few
waves are indeed present at these latitudes as well. We will also investigate if the number of waves is related
to location of the vortex.
http://acebox.uwaterloo.ca/eureka/
SA33A-04 INVITED
Multi-instrument and network observations with the middle and upper atmosphere (MU) radar
The MU radar of RISH (Research Institute of Sustainable Humanosphere), Kyoto University, Japan, located at Shigaraki (136E, 35N) is a 46.5 MHz VHF radar with 1 MW output power. It has been used as an MST (Mesosphere/Stratosphere/Troposphere) and an IS (Incoherent Scatter) radar, since 1984 for 25 years. The radar and Shigaraki MU observatory is open for both domestic and international researchers as a collaborative research facility. Although the system has been upgraded every 5 E10 years and the radar is still one of the most capable atmospheric radar in the world, simultaneous observations with other instruments (both radio and optical) as well as network observations with remote places has been becoming more and more important. A review on such cooperative observations carried out recently by use of the MU radar will be presented in this paper. Also a new collaborative project of creating database of ground-based upper atmosphere observations among five institutions in Japan (National Institute of Polar Research and four universities (Kyoto, Kyushu, Nagoya, Tohoku), starting in 2009 for six years, will be briefly introduced.
SA33A-05
A PEARL Near the Pole: Measuring the Atmosphere in the High Arctic
The Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Nunavut (80N, 86W) is one of the highest latitude atmospheric measurement sites in the world. Constructing and operating this laboratory has been, and continues to be a challenge, but the importance of measurements at these high latitudes makes the challenge worth the effort. Atmospheric measurements at PEARL span the altitude range from the surface to 100km and cover a wide range of atmospheric parameters that is steadily increasing with time as the site is further instrumented. Currently the site hosts more than 25 instruments including spectrometers, radiometers, imagers, radars and lidars. The high latitude at PEARL means that measurements can be made both inside and outside of the winter polar vortex depending upon the phase of the vortex. The winter/summer light/dark cycle is very much in evidence and a profitable way of thinking of the atmosphere at this latitude is that it has a "day" that lasts a year. This talk will discuss the challenges of setting up an observatory and keeping it operating at such a remote location and at such low temperatures. PEARL is supported by the Canadian Foundation for Innovation (CFI); Canadian Foundation for Climate and Atmospheric Science (CFCAS); Canadian Space Agency (CSA); Environment Canada (EC); Indian and Northern Affairs Canada (INAC); Government of Canada International Polar Year (IPY) funding; Ontario Innovation Trust (OIT); Natural Sciences and Engineering Research Council (NSERC); Nova Scotia Research Innovation Trust (NSRIT); Ontario Research Fund (ORF); and the Polar Continental Shelf Program (PCSP).
SA33A-06
Understanding the Arctic stratosphere during IPY through a combination of ground-based measurements, models and dynamical analyses
While chemical ozone depletion in the Antarctic spring-time stratosphere is now an annually occurring and well-understood phenomenon, dynamical variability in the Arctic stratosphere means ozone depletion in the northern polar vortex is both less predictable and more susceptible to changes resulting from climate change than in the southern vortex. In order to examine ozone-depleting processes and quantify chemical changes occurring in the Arctic polar stratosphere, it is important to combine a range of data sources to describe both the chemistry and the dynamics of the polar vortex. Ground-based Fourier transform spectroscopy provides a well-defined and useful data set of atmospheric trace gas measurements around the globe. Key chemical species involved in stratospheric ozone depletion, including chlorine reservoirs HCl and ClONO2, nitrogen reservoir HNO3, fluorine reservoir HF and ozone itself are standard measurements for the Network for the Detection of Atmospheric Composition Change (NDACC) Fourier transform infrared (FTIR) spectrometers. During the 2007 and 2008 International Polar Year (IPY) spring periods, measurements were made with ground-based FTIR spectrometers at six NDACC stations around the Arctic. In this work, these measurements will be used in conjunction with dynamical analyses in order to characterize the Arctic polar stratosphere. In addition, the measurements will be compared and contrasted with the IPY runs of two meteorologically assimilated global chemistry models, the Canadian Middle Atmosphere Model - Data Assimilated (CMAM-DA), and the Environment Canada Global Environmental Multiscale stratospheric model, run with the BIRA (Belgian Institute for Space Aeronomy) online chemistry package (GEM-BACH) in order to better quantify our current understanding of the processes occurring in the polar atmosphere.
SA33A-07
Examination of tracer-tracer correlations between NOy and N2O, and between NOy and O3 using ACE-FTS measurements
Correlations between long-lived species provide a useful tool for investigating both dynamical and chemical processes in the atmosphere. Global tracer-tracer correlations between total odd nitrogen (NOy) and N2O, and between NOy and O3 have been studied using measurements made by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on the Canadian Space Agency's SciSat platform. ACE-FTS has been measuring O3, N2O, and NOy species from orbit since February 2004 using infrared solar occultation. NOy is calculated by using measurements of NO, NO2, N2O5, HNO3, ClONO2, and HNO4. The seasonal and monthly correlations between NOy and N2O, and between NOy and O3 have been investigated in the equatorial region, at mid-latitudes, and in the polar regions using the first four years of ACE-FTS data. The correlations between NOy and N2O show a compact relationship, with the exception of the southern hemisphere polar spring, due to denitrification and descent of N2O inside the polar vortex. The correlations between NOy and O3 are not compact in all seasons. In spring in both polar regions, particularly in the southern hemisphere, the mixing ratios of both O3 and NOy are low due to ozone depletion and denitrification. We will present the results of this correlation study and assess them in comparison with previous measurements of NOy correlations.
SA33A-08 INVITED
Modeling of Middle Atmosphere Dynamics Using Lower Atmosphere ECMWF Data
The new circulation model called LIMA (Leibniz-Institute Middle Atmosphere) is used to study the dynamics of the middle atmosphere. LIMA takes advantage of global ECMWF-ERA-40 data sets from troposphere/lower stratosphere regions which are processed through data assimilation techniques. This allows in middle atmosphere modeling to investigate in detail the effects of the lower atmosphere conditions on the upper atmosphere through upward wave activity propagation. One example of LIMA studies is the simulation of the thermal state at the summer upper mesosphere and its impact on the morphology of ice particle related phenomena such as noctilucent clouds (NLC), and polar mesosphere clouds (PMC). LIMA allows to investigate inter-hemispheric differences as well as decadal long term trends in NLC/PMC formation. The NLC/PMC characteristics deduced from LIMA are validated with various data sets from different lidar (ground station ALOMAR), satellite (SBUV, SNOE), rockets and radar observations. LIMA nicely reproduces the mean characteristics of observed ice layers, for example their NH/SH differences in variation with season, altitude, and latitude. Not only seasonal means, but also 11-y solar cycle effects and decadal long term behavior nicely agree with satellite data. This emphasizes the importance of lower atmosphere conditions described by ECMWF data which seem to control to a high degree the thermal state of the upper atmosphere and hence the observed morphology of ice clouds.