Middle atmosphere ionization from auroral particle precipitation as observed by the SSUSI satellite instruments

2020 ◽  
Author(s):  
Stefan Bender ◽  
Patrick Espy ◽  
Larry Paxton
Keyword(s):  
Climate Models ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Auroral Zone ◽  
Polar Regions ◽  
Electron Densities ◽  
Current Standard ◽  
Initial Comparison ◽  
Eiscat Radar ◽  
Satellite Instruments

<p>Solar, auroral, and radiation belt electrons enter the atmosphere at polar regions leading to ionization and affecting its chemistry. Climate models usually parametrize this ionization and the related changes in chemistry based on satellite particle measurements. Precise measurements of the particle and energy influx into the upper atmosphere are difficult because they vary substantially in location and time. Widely used particle data are derived from the POES and GOES satellite measurements which provide electron and proton spectra.</p><p>We present electron energy and flux measurements from the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) satellite instruments on board the Defense Meteorological Satellite Program (DMSP) satellites. This formation of now four satellites observes the auroral zone in the UV from which electron energies and fluxes are inferred in the range from 2 keV to 20 keV. We use these observed electron energies and fluxes to calculate ionization rates and electron densities in the upper mesosphere and lower thermosphere (≈ 70–200 km). We present an initial comparison of these rates to other models and compare the electron densities to those measured by the EISCAT radar. This comparison shows that with the current standard parametrizations, the SSUSI inferred auroral (90–120 km) electron densities are larger than the ground-based measured ones by a factor of 2–5. It is still under investigation if this difference is due to collocation (in space and time) and EISCAT mode characteristics or caused by incompletely modelling the ionization and recombination in that energy range.</p>

ARISE - Atmospheric Dynamics Research InfraStructure in Europe

2021 ◽  
Author(s):  
Patrick Hupe ◽  
Keyword(s):  
Climate Models ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Volcanic Eruptions ◽  
Atmospheric Dynamics ◽  
Research Infrastructure ◽  
Atmospheric Composition ◽  
The European Union ◽  
Horizon 2020 ◽  
Ctbt Verification

<p>The Atmospheric dynamics Research InfraStructure in Europe (ARISE) project has integrated different meteorological and geophysical station networks and technologies providing observations from the ground to the lower thermosphere. A particular emphasis is on improving observations in the middle atmosphere, as this is a crucial region affecting tropospheric weather and climate. Besides supporting innovative prototypes of mobile lidars and microwave radiometers, ARISE utilized the global infrasound network developed for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification, the lidar Network for the Detection of Atmospheric Composition Change (NDACC), meteor radars, wind radiometers, ionospheric sounders and satellites.</p> <p>This presentation highlights the objectives and results as well as perspectives of the first two project phases – one within the European Union’s 7th Framework Programme and the second within the Horizon 2020 programme. ARISE has facilitated multi-instrument stations and collocated measurement campaigns at different latitudes in Europe, including the observatories ALOMAR in northern Norway, OHP in southern France and Maïdo on Reunion Island (France), as well as the infrasound station in southern Germany. One ARISE study, for instance, analyzed different ground-based and space-borne observation technologies, revealing systematic biases for temperature and wind in both analysis and reanalysis models. Such biases are critical to the CTBT verification when validating infrasound signal detections by propagation modelling. Also, the potential of infrasound to be assimilated in weather or climate models was proposed, as infrasound can be used to probe winds and cross-wind effects in the middle atmosphere. Meanwhile, offline assimilation tests relying on infrasound data from ground-truth explosion events and wind data of ECMWF’s ERA5 model have been conducted. Overall, the interest of ARISE is to provide atmospheric data products and services for both scientific and civilian-security applications, including the monitoring of extreme events that have an atmospheric signature, such as meteors, thunderstorms or volcanic eruptions. For early warnings on volcanic eruptions, the Volcano Information System (VIS) was proposed as an ARISE product in cooperation with the CTBT organization and the Toulouse Volcanic Ash Advisory Center (VAAC).</p>

The Role of the Middle Atmosphere in Simulations of the Troposphere during Northern Hemisphere Winter: Differences between High- and Low-Top Models

2010 ◽  
Vol 67 (9) ◽  
pp. 3048-3064 ◽  
Author(s):  
Fabrizio Sassi ◽  
R. R. Garcia ◽  
D. Marsh ◽  
K. W. Hoppel
Keyword(s):  
Climate Models ◽  
Middle Atmosphere ◽  
State Of The Art ◽  
Lower Thermosphere ◽  
Numerical Algorithms ◽  
Conventional Model ◽  
Downward Propagation ◽  
Hemisphere Winter ◽  
Mean State

Abstract This paper compares present-day simulations made with two state-of-the-art climate models: a conventional model specifically designed to represent the tropospheric climate, which has a poorly resolved middle atmosphere, and a configuration that is built on the same physics and numerical algorithms but represents realistically the middle atmosphere and lower thermosphere. The atmospheric behavior is found to be different between the two model configurations, and it is shown that the differences in the two simulations can be attributed to differences in the behavior of the zonal mean state of the stratosphere, where reflection of quasi-stationary resolved planetary waves from the lid of the low-top model is prominent; the more realistic physics in the high-top model is not relevant. It is also shown that downward propagation of zonal wind anomalies during weak stratospheric vortex events is substantially different in the two model configurations. These findings extend earlier results that a poorly resolved stratosphere can influence simulations throughout the troposphere.

scholarly journals Large-Scale Waves in the Mesosphere and Lower Thermosphere Observed by SABER

2005 ◽  
Vol 62 (12) ◽  
pp. 4384-4399 ◽  
Author(s):  
Rolando R. Garcia ◽  
Ruth Lieberman ◽  
James M. Russell ◽  
Martin G. Mlynczak
Keyword(s):  
Large Scale ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Normal Modes ◽  
Zonal Winds ◽  
Broadband Emission ◽  
Summer Hemisphere ◽  
Mean Structure ◽  
Mesosphere And Lower Thermosphere ◽  
The Tropics

Abstract Observations made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board NASA’s Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics (TIMED) satellite have been processed using Salby’s fast Fourier synoptic mapping (FFSM) algorithm. The mapped data provide a first synoptic look at the mean structure and traveling waves of the mesosphere and lower thermosphere (MLT) since the launch of the TIMED satellite in December 2001. The results show the presence of various wave modes in the MLT, which reach largest amplitude above the mesopause and include Kelvin and Rossby–gravity waves, eastward-propagating diurnal oscillations (“non-sun-synchronous tides”), and a set of quasi-normal modes associated with the so-called 2-day wave. The latter exhibits marked seasonal variability, attaining large amplitudes during the solstices and all but disappearing at the equinoxes. SABER data also show a strong quasi-stationary Rossby wave signal throughout the middle atmosphere of the winter hemisphere; the signal extends into the Tropics and even into the summer hemisphere in the MLT, suggesting ducting by westerly background zonal winds. At certain times of the year, the 5-day Rossby normal mode and the 4-day wave associated with instability of the polar night jet are also prominent in SABER data.

Middle Atmosphere Temperature Changes Derived from SABER Observations during 2002-2020

2021 ◽  
pp. 1
Author(s):  
X. R. Zhao ◽  
Z. Sheng ◽  
H. Q. Shi ◽  
L. B. Weng ◽  
Y. He
Keyword(s):  
Solar Cycle ◽  
Middle Atmosphere ◽  
Southern Oscillation ◽  
Linear Trend ◽  
Stratospheric Ozone ◽  
Recovery Period ◽  
Lower Thermosphere ◽  
Quasi Biennial Oscillation ◽  
Atmosphere Temperature ◽  
Temperature Responses

AbstractUsing temperature data measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument from February 2002 to March 2020, the temperature linear trend and temperature responses to the solar cycle (SC), Quasi-Biennial Oscillation (QBO), and El Niño-Southern Oscillation (ENSO) were investigated from 20 km to 110 km for the latitude range of 50°S-50°N. A four-component harmonic fit was used to remove the seasonal variation from the observed monthly temperature series. Multiple linear regression (MLR) was applied to analyze the linear trend, SC, QBO, and ENSO terms. In this study, the near-global mean temperature shows consistent cooling trends throughout the entire middle atmosphere, ranging from -0.28 to -0.97 K/decade. Additionally, it shows positive responses to the solar cycle, varying from -0.05 to 4.53 K/100sfu. A solar temperature response boundary between 50°S and 50°N is given, above which the atmospheric temperature is strongly affected by solar activity. The boundary penetrates deep below the stratopause to ~ 42 km over the tropical region and rises to higher altitudes with latitude. Temperature responses to the QBO and ENSO can be observed up to the upper mesosphere and lower thermosphere. In the equatorial region, 40%-70% of the total variance is explained by QBO signals in the stratosphere and 30%-50% is explained by the solar signal in the upper middle atmosphere. Our results, obtained from 18-year SABER observations, are expected to be an updated reliable estimation of the middle atmosphere temperature variability for the stratospheric ozone recovery period.

Formation of the double stratopause and elevated stratopause associated with the major stratospheric sudden warming in 2018/19

2021 ◽  
Author(s):  
Haruka Okui ◽  
Kaoru Sato ◽  
Dai Koshin ◽  
Shingo Watanabe
Keyword(s):  
General Circulation ◽  
Middle Atmosphere ◽  
Baroclinic Instability ◽  
Lower Thermosphere ◽  
Circulation Model ◽  
Lower Atmosphere ◽  
Temperature Structure ◽  
Residual Circulation ◽  
Stratospheric Sudden Warming

<p>After several recent stratospheric sudden warming (SSW) events, the stratopause disappeared and reformed at a higher altitude, forming an elevated stratopause (ES). The relative roles of atmospheric waves in the mechanism of ES formation are still not fully understood. We performed a hindcast of the 2018/19 SSW event using a gravity-wave (GW) permitting general circulation model containing the mesosphere and lower thermosphere (MLT), and analyzed dynamical phenomena throughout the entire middle atmosphere. An ES formed after the major warming on 1 January 2019. There was a marked temperature maximum in the polar upper mesosphere around 28 December 2018 prior to the disappearance of the descending stratopause associated with the SSW. This temperature structure with two maxima in the vertical is referred to as a double stratopause (DS). We showed that adiabatic heating from the residual circulation driven by GW forcing (GWF) causes barotropic and/or baroclinic instability before DS formation, causing in situ generation of planetary waves (PWs). These PWs propagate into the MLT and exert negative forcing, which contributes to DS formation. Both negative GWF and PWF above the recovered eastward jet play crucial roles in ES formation. The altitude of the recovered eastward jet, which regulates GWF and PWF height, is likely affected by the DS structure. Simple vertical propagation from the lower atmosphere is insufficient to explain the presence of the GWs observed in this event.</p>

scholarly journals Interhemispheric differences of mesosphere/lower thermosphere winds and tides investigated from three whole atmosphere models and meteor radar observations

2021 ◽  
Author(s):  
Gunter Stober ◽  
Ales Kuchar ◽  
Dimitry Pokhotelov ◽  
Huixin Liu ◽  
Han-Li Liu ◽  
...  
Keyword(s):  
General Circulation ◽  
Climate Models ◽  
Climate Model ◽  
Lower Thermosphere ◽  
Winter Season ◽  
General Circulation Models ◽  
Meteor Radar ◽  
Radar Observations ◽  
Seasonal Characteristics

Abstract. Long-term and continuous observations of mesospheric/lower thermospheric winds are rare, but they are important to investigate climatological changes at these altitudes on time scales of several years, covering a solar cycle and longer. Such long time series are a natural heritage of the mesosphere/lower thermosphere climate, and they are valuable to compare climate models or long term runs of general circulation models (GCMs). Here we present a climatological comparison of wind observations from six meteor radars at two conjugate latitudes to validate the corresponding mean winds and atmospheric diurnal and semidiurnal tides from three GCMs, namely Ground-to-Topside Model of Atmosphere and Ionosphere for Aeronomy (GAIA), Whole Atmosphere Community Climate Model Extension (Specified Dynamics) (WACCM-X(SD)) and Upper Atmosphere ICOsahedral Non-hydrostatic (UA-ICON) model. Our results indicate that there are interhemispheric differences in the seasonal characteristics of the diurnal and semidiurnal tide. There also are some differences in the mean wind climatologies of the models and the observations. Our results indicate that GAIA shows a reasonable agreement with the meteor radar observations during the winter season, whereas WACCM-X(SD) shows a better agreement with the radars for the hemispheric zonal summer wind reversal, which is more consistent with the meteor radar observations. The free running UA-ICON tends to show similar winds and tides compared to WACCM-X(SD).

scholarly journals Horizontally resolved structures of radar backscatter from polar mesospheric layers

2012 ◽  
Vol 10 ◽  
pp. 285-290 ◽  
Author(s):  
R. Latteck ◽  
W. Singer ◽  
M. Rapp ◽  
T. Renkwitz ◽  
G. Stober
Keyword(s):  
Middle Atmosphere ◽  
Beam Steering ◽  
Lower Thermosphere ◽  
The Arctic ◽  
Phased Array Antenna ◽  
Vhf Radar ◽  
The North ◽  
Expansion Stage ◽  
Arctic Atmosphere ◽  
High Flexibility

Abstract. The Leibniz-Institute of Atmospheric Physics in Kühlungsborn, Germany (IAP) installed a new powerful VHF radar on the North-Norwegian island Andøya (69.30° N, 16.04° E) from 2009 to 2011. The new Middle Atmosphere Alomar Radar System (MAARSY) replaces the existing ALWIN radar which has been in continuous operation on Andøya for more than 10 yr. MAARSY is a monostatic radar operated at 53.5 MHz with an active phased array antenna consisting of 433 Yagi antennas each connected to its own transceiver with independent control of frequency, phase and power of the transmitted signal. This arrangement provides a very high flexibility of beam forming and beam steering. It allows classical beam swinging operation as well as experiments with simultaneous multiple beams and the use of modern interferometric applications for improved studies of the Arctic atmosphere from the troposphere up to the lower thermosphere with high spatial-temporal resolution. The installation of the antenna was completed in August 2009. An initial expansion stage of 196 transceiver modules was installed in spring 2010, upgraded to 343 transceiver modules in December 2010 and the installation of the radar was completed in spring 2011. Beside standard observations of tropospheric winds and Polar Mesosphere Summer Echoes, multi-beam experiments using up to 91 beams quasi-simultaneously in the mesosphere have been carried out using the different expansion stages of the system during campaigns in 2010 and 2011. These results provided a first insight into the horizontal variability of Polar Mesosphere Summer and Winter Echoes in an area of about 80 km by 80 km with time resolutions between 3 and 9 min.

scholarly journals Arctic and Antarctic precipitation simulations produced by the NCAR community climate models

1995 ◽  
Vol 21 ◽  
pp. 117-122 ◽  
Author(s):  
David H. Bromwich ◽  
Biao Chen ◽  
Ren-Yow Tzeng
Keyword(s):  
Moisture Transport ◽  
Climate Models ◽  
Climate Model ◽  
Polar Regions ◽  
Moisture Budget ◽  
Atmospheric Moisture ◽  
Atmospheric Moisture Budget ◽  
Antarctic Precipitation ◽  
Climatic Characteristics ◽  
Community Climate

Precipitation predictions from globai-climate models (GCMs) for the ice-covered Arctic Ocean and the ice sheets of Antarctica are among the most important aspects of the inferred response of the polar areas to climate change. It is generally recognized that the atmospheric hydrologic cycle, which includes precipitation as a key part, is one of the components of the climate system that GCMs do not handle particularly well. The present-day atmospheric-moisture budget poleward of 70° latitude in both hemispheres, as represented by two versions of the NCAR (U.S. National Center for Atmospheric Research) community climate model (CCM1 and CCM2), is compared with observational analyses. The quantities examined on the seasonal and annual timescales are precipitation, evaporation/sublimation and atmospheric poleward moisture transport. The results are discussed in terms of the physiographic and climatic characteristics of both polar regions and how the particular models handle moisture transport: CCM1 uses the positive-moisture fixer and CCM2 the semi- Lagrangian transport. A particularly important test both for models and for observations is the degree to which the independently determined moisture-budget quantities actually balance. Deficiencies of both observations and models are discussed.

scholarly journals Impact of ocean circulation on regional polar climate simulations using the Arctic Region Climate System Model

1997 ◽  
Vol 25 ◽  
pp. 203-207 ◽  
Author(s):  
David A. Bailey ◽  
Amanda H. Lynch ◽  
Katherine S. Hedström
Keyword(s):  
Sea Ice ◽  
Mixed Layer ◽  
Climate Models ◽  
Regional Climate ◽  
The Arctic ◽  
Water Runoff ◽  
Polar Regions ◽  
Ice Dynamics ◽  
Climate System Model ◽  
Ice Model

Global climate models have pointed to the polar regions as very sensitive areas in response to climate change. However, these models often do not contain representations of processes peculiar to the polar regions such as dynamic sea ice, permafrost, and Arctic stratus clouds. Further, global models do not have the resolution necessary to model accurately many of the important processes and feedbacks. Thus, there is a need for regional climate models of higher resolution. Our such model (ARCSy M) has been developed by A. Lynch and W. Chapman. This model incorporates the NCAR Regional Climate Model (RegCM2) with the addition of Flato–Hibler cavitating fluid sea-ice dynamics and Parkinson–Washington ice thermodynamic formulation. Recently work has been conducted to couple a mixed-layer ocean to the atmosphere–ice model, and a three-dimensional (3-D) dynamical ocean model, in this case the S-Coordinate Primitive Equation Model (SPEM), to the ice model. Simulations including oceanic circulation will allow investigations of the feedbacks involved in fresh-water runoff from sea-ice melt and sea-ice transport. Further, it is shown that the definition of the mixed-layer depth has significant impact on ice thermodynamics.

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