scholarly journals A Compact Rayleigh Autonomous Lidar (CORAL) for the middle atmosphere

2021 ◽  
Vol 14 (2) ◽  
pp. 1715-1732
Author(s):  
Bernd Kaifler ◽  
Natalie Kaifler
Keyword(s):  
Middle Atmosphere ◽  
Temperature Profiles ◽  
Atmospheric Gravity Wave ◽  
Data Set ◽  
Additional Information ◽  
Wave Event ◽  
System Data ◽  
Forecasting System ◽  
Safety Features ◽  
Sky Conditions

Abstract. The Compact Rayleigh Autonomous Lidar (CORAL) is the first fully autonomous middle atmosphere lidar system to provide density and temperature profiles from 15 to approximately 90 km altitude. From October 2019 to October 2020, CORAL acquired temperature profiles on 243 out of the 365 nights (66 %) above Río Grande, southern Argentina, a cadence which is 3–8 times larger as compared to conventional human-operated lidars. The result is an unprecedented data set with measurements on 2 out of 3 nights on average and high temporal (20 min) and vertical (900 m) resolution. The first studies using CORAL data have shown, for example, the evolution of a strong atmospheric gravity wave event and its impact on the stratospheric circulation. We describe the instrument and its novel software which enables automatic and unattended observations over periods of more than a year. A frequency-doubled diode-pumped pulsed Nd:YAG laser is used as the light source, and backscattered photons are detected using three elastic channels (532 nm wavelength) and one Raman channel (608 nm wavelength). Automatic tracking of the laser beam is realized by the implementation of the conical scan (conscan) method. The CORAL software detects blue sky conditions and makes the decision to start the instrument based on local meteorological measurements, detection of stars in all-sky images, and analysis of European Center for Medium-range Weather Forecasts Integrated Forecasting System data. After the instrument is up and running, the strength of the lidar return signal is used as additional information to assess sky conditions. Safety features in the software allow for the operation of the lidar even in marginal weather, which is a prerequisite to achieving the very high observation cadence.

scholarly journals A Compact Rayleigh Autonomous Lidar (CORAL) for the middle atmosphere

2020 ◽  
Author(s):  
Bernd Kaifler ◽  
Natalie Kaifler
Keyword(s):  
Middle Atmosphere ◽  
Temperature Profiles ◽  
Atmospheric Gravity Wave ◽  
Data Set ◽  
Weather Forecasts ◽  
Additional Information ◽  
Wave Event ◽  
Diode Pumped ◽  
Safety Features ◽  
Sky Conditions

Abstract. The Compact Rayleigh Autonomous Lidar (CORAL) is the first fully autonomous middle atmosphere lidar system to provide density and temperature profiles from 15 km to approximately 90 km altitude. From October 2019 to October 2020 CORAL acquired temperature profiles on 243 out of the 365 nights (66 %) above Rio Grande, southern Argentina, a cadence which is 3–8 times larger as compared to conventional human operated lidars. The result is an unprecedented data set with measurements on two out of three nights on average and high temporal (20 min) and vertical (900 m) resolution. First studies using CORAL data show for example the evolution of a strong atmospheric gravity wave event and its impact on the stratospheric circulation. We describe the instrument and its novel software which enables automatic and unattended observations over periods of more than a year. A frequency-doubled diode-pumped pulsed Nd:YAG laser is used as light source and backscattered photons are detected using three elastic channels (532 nm wavelength) and one Raman channel (608 nm wavelength). Automatic tracking of the laser beam is realized by implementation of the conical scan (conscan) method. The CORAL software detects blue sky conditions and makes the decision to start the instrument based on local meteorological measurements, detection of stars in all-sky images, and analysis of ECMWF weather forecasts. After the instrument is up and running, the strength of the lidar return signal is used as additional information to assess sky conditions. Safety features in the software allow operation of the lidar even in marginal weather which is a prerequisite to achieving the very high observation cadence.

scholarly journals Comparison between XBT data and TOPEX/Poseidon satellite altimetry in the Ligurian-Tyrrhenian area

2003 ◽  
Vol 21 (1) ◽  
pp. 123-135 ◽  
Author(s):  
S. Vignudelli ◽  
P. Cipollini ◽  
F. Reseghetti ◽  
G. Fusco ◽  
G. P. Gasparini ◽  
...  
Keyword(s):  
Pilot Project ◽  
Atlantic Water ◽  
Data Sets ◽  
Tyrrhenian Sea ◽  
Satellite Altimeter ◽  
Ligurian Sea ◽  
Data Set ◽  
Additional Information ◽  
Forecasting System ◽  
Computational Errors

Abstract. From September 1999 to December 2000, eXpendable Bathy-Thermograph (XBT) profiles were collected along the Genova-Palermo shipping route in the framework of the Mediterranean Forecasting System Pilot Project (MFSPP). The route is virtually coincident with track 0044 of the TOPEX/Poseidon satellite altimeter, crossing the Ligurian and Tyrrhenian basins in an approximate N–S direction. This allows a direct comparison between XBT and altimetry, whose findings are presented in this paper. XBT sections reveal the presence of the major features of the regional circulation, namely the eastern boundary of the Ligurian gyre, the Bonifacio gyre and the Modified Atlantic Water inflow along the Sicily coast. Twenty-two comparisons of steric heights derived from the XBT data set with concurrent realizations of single-pass altimetric heights are made. The overall correlation is around 0.55 with an RMS difference of less than 3 cm. In the Tyrrhenian Sea the spectra are remarkably similar in shape, but in general the altimetric heights contain more energy. This difference is explained in terms of oceanographic signals, which are captured with a different intensity by the satellite altimeter and XBTs, as well as computational errors. On scales larger than 100 km, the data sets are also significantly coherent, with increasing coherence values at longer wavelengths. The XBTs were dropped every 18–20 km along the track: as a consequence, the spacing scale was unable to resolve adequately the internal radius of deformation (< 20 km). Furthermore, few XBT drops were carried out in the Ligurian Sea, due to the limited north-south extent of this basin, so the comparison is problematic there. On the contrary, the major features observed in the XBT data in the Tyrrhenian Sea are also detected by TOPEX/Poseidon. The manuscript is completed by a discussion on how to integrate the two data sets, in order to extract additional information. In particular, the results emphasize their complementariety in providing a dynamically complete description of the observed structures. Key words. Oceanography: general (descriptive and regional oceanography) Oceanography: physical (sea level variations; instruments and techniques)

scholarly journals Polar middle atmosphere temperature climatology from Rayleigh lidar measurements at ALOMAR (69° N)

2008 ◽  
Vol 26 (7) ◽  
pp. 1681-1698 ◽  
Author(s):  
A. Schöch ◽  
G. Baumgarten ◽  
J. Fiedler
Keyword(s):  
Middle Atmosphere ◽  
Lidar Data ◽  
Temperature Profiles ◽  
Raman Lidar ◽  
Data Set ◽  
Unique Data ◽  
Falling Sphere ◽  
Lidar Measurements ◽  
Atmosphere Temperature ◽  
Rayleigh Lidar

Abstract. Rayleigh lidar temperature profiles have been derived in the polar middle atmosphere from 834 measurements with the ALOMAR Rayleigh/Mie/Raman lidar (69.3° N, 16.0° E) in the years 1997–2005. Since our instrument is able to operate under full daylight conditions, the unique data set presented here extends over the entire year and covers the altitude region 30 km–85 km in winter and 30 km–65 km in summer. Comparisons of our lidar data set to reference atmospheres and ECMWF analyses show agreement within a few Kelvin in summer but in winter higher temperatures below 55 km and lower temperatures above by as much as 25 K, due likely to superior resolution of stratospheric warming and associated mesospheric cooling events. We also present a temperature climatology for the entire lower and middle atmosphere at 69° N obtained from a combination of lidar measurements, falling sphere measurements and ECMWF analyses. Day to day temperature variability in the lidar data is found to be largest in winter and smallest in summer.

Application of RTM 3D angle gathers to wide-azimuth data subsalt imaging

Geophysics ◽  
2011 ◽  
Vol 76 (5) ◽  
pp. WB175-WB182 ◽  
Author(s):  
Yan Huang ◽  
Bing Bai ◽  
Haiyong Quan ◽  
Tony Huang ◽  
Sheng Xu ◽  
...  
Keyword(s):  
Model Updating ◽  
Velocity Model ◽  
Azimuth Angle ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
Data Set ◽  
Additional Information ◽  
Time Migration ◽  
Reflection Angle ◽  
Subsalt Imaging

The availability of wide-azimuth data and the use of reverse time migration (RTM) have dramatically increased the capabilities of imaging complex subsalt geology. With these improvements, the current obstacle for creating accurate subsalt images now lies in the velocity model. One of the challenges is to generate common image gathers that take full advantage of the additional information provided by wide-azimuth data and the additional accuracy provided by RTM for velocity model updating. A solution is to generate 3D angle domain common image gathers from RTM, which are indexed by subsurface reflection angle and subsurface azimuth angle. We apply these 3D angle gathers to subsalt tomography with the result that there were improvements in velocity updating with a wide-azimuth data set in the Gulf of Mexico.

scholarly journals NLC and the background atmosphere above ALOMAR

2011 ◽  
Vol 11 (12) ◽  
pp. 5701-5717 ◽  
Author(s):  
J. Fiedler ◽  
G. Baumgarten ◽  
U. Berger ◽  
P. Hoffmann ◽  
N. Kaifler ◽  
...  
Keyword(s):  
Diurnal Cycle ◽  
Middle Atmosphere ◽  
Thermal State ◽  
Atmospheric Tides ◽  
Data Set ◽  
Ice Particles ◽  
Cloud Water Content ◽  
Radar Measurements ◽  
Mf Radar

Abstract. Noctilucent clouds (NLC) have been measured by the Rayleigh/Mie/Raman-lidar at the ALOMAR research facility in Northern Norway (69° N, 16° E). From 1997 to 2010 NLC were detected during more than 1850 h on 440 different days. Colocated MF-radar measurements and calculations with the Leibniz-Institute Middle Atmosphere (LIMA-) model are used to characterize the background atmosphere. Temperatures as well as horizontal winds at 83 km altitude show distinct differences during NLC observations compared to when NLC are absent. The seasonally averaged temperature is lower and the winds are stronger westward when NLC are detected. The wind separation is a robust feature as it shows up in measurements as well as in model results and it is consistent with the current understanding that lower temperatures support the existence of ice particles. For the whole 14-year data set there is no statistically significant relation between NLC occurrence and solar Lyman-α radiation. On the other hand NLC occurrence and temperatures at 83 km show a significant anti-correlation, which suggests that the thermal state plays a major role for the existence of ice particles and dominates the pure Lyman-α influence on water vapor during certain years. We find the seasonal mean NLC altitudes to be correlated to both Lyman-α radiation and temperature. NLC above ALOMAR are strongly influenced by atmospheric tides. The cloud water content varies by a factor of 2.8 over the diurnal cycle. Diurnal and semidiurnal amplitudes and phases show some pronounced year-to-year variations. In general, amplitudes as well as phases vary in a different manner. Amplitudes change by a factor of more than 3 and phases vary by up to 7 h. Such variability could impact long-term NLC observations which do not cover the full diurnal cycle.

AGW manifestations in the Earth neutral atmosphere and ionosphere

2021 ◽  
Author(s):  
Tatiana Syrenova ◽  
Alexander Beletsky
Keyword(s):  
Optical System ◽  
Deep Convection ◽  
Lower Atmosphere ◽  
Automatic Identification ◽  
Complex Data ◽  
Neutral Atmosphere ◽  
Data Set ◽  
Acoustic Gravity Waves ◽  
Wave Disturbances ◽  
System Data

&lt;p&gt;Acoustic gravity waves (AGW) manifestations spread from the lower atmosphere to the upper layers due to processes such as orography, weather fronts, deep convection atmosphere, and vice versa, can form in the upper atmosphere during geomagnetic activity, receiving energy from the magnetosphere. These wave processes can be considered as a dynamic process that transfers energy between different atmospheric and latitudinal regions, therefore it is important to understand their basic parameters and behavior.&lt;/p&gt;&lt;p&gt;In this work, to study wave disturbances, we used the Keo Sentinel optical system data, designed to record the spatial pattern of the 630 nm emission intensity (emission height 180-300 km). The system is located at the Geophysical Observatory (GPO) of the ISTP SB RAS, near the Tory, Buryatiya, Russia (52&lt;sup&gt;0&lt;/sup&gt; N, 103&lt;sup&gt;0&lt;/sup&gt; E, height 670 m). The&amp;#160; interference filter transmission half-width is ~ 2 nm. Sight direction - zenith, field of view 145 degrees, exposure time 30-60 s (http://atmos.iszf.irk.ru/ru/data/keo).&lt;/p&gt;&lt;p&gt;For the analysis, we chose data obtained on clear, moonless nights from 2014 to March 2019. The total number of nights selected for analysis was 71 (~ 491 hours). An algorithm for the wave events and their characteristics automatic identification from the optic data was developed and tested. The approbation was carried out on a data set previously processed manually [Syrenova, Beletsky, 2019]. A comparison was made with traveling ionospheric disturbances (TID) characteristics obtained from the ISTP SB RAS radio-physical complex data [Medvedev et al., 2012].&lt;/p&gt;&lt;p&gt;The main directions of wave disturbances propagation obtained with automatic optical system data processing - southward (~ 175&amp;#186;) and eastward (~ 90&amp;#186;) - are similar to the TID directions. From the radiophysical complex data, the TID distribution from North to South prevails, the most probable azimuth is ~ 135&amp;#186; during the day, and ~ 205&amp;#186; at night. The most probable values &amp;#8203;&amp;#8203;of the wave disturbances propagation velocity obtained as a result of automatic processing are about 80 m/s. These values &amp;#8203;&amp;#8203;also accept well with the TID values.&lt;/p&gt;&lt;p&gt;The main characteristics obtained using the data of the optical and radiophysical complexes agree with each other. Differences in the preferred propagation direction of the recorded wave structures from the KEO Sentinel data from the directions obtained with photometers at the same observation point [Tashchilin, 2010, Podlesny, 2018], probably, associated with different observation heights.&lt;/p&gt;

Observations of internal gravity waves in vicinity of jet streams during SouthTRAC flight on 16 September 2019

2021 ◽  
Author(s):  
Wolfgang Woiwode ◽  
Andreas Dörnbrack ◽  
Felix Friedl-Vallon ◽  
Markus Geldenhuys ◽  
Andreas Giez ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Middle Atmosphere ◽  
Internal Gravity Waves ◽  
Polar Front ◽  
Airborne Lidar ◽  
Jet Streams ◽  
Transport Dynamics ◽  
Research Aircraft ◽  
Forecasting System ◽  
Complex Temperature

&lt;p&gt;The combination of the airborne GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) and ALIMA (Airborne LIdar for Middle Atmosphere research) instruments allows for probing of temperature perturbations associated with gravity waves within the range from the troposphere up to the mesosphere. Both instruments were part of the scientific payload of the German HALO (High Altitude and LOng Range Research Aircraft) during the SouthTRAC-GW (Southern hemisphere Transport, Dynamics, and Chemistry - Gravity Waves) mission, aiming at probing gravity waves in the hotspot region around South America and the Antarctic peninsula. For the research flight on 16 September 2019, complex temperature perturbations attributed to internal gravity waves were forecasted well above the Atlantic to the south-west of Buenos Aires, Argentina. The forecasted temperature perturbations were located in a region where the polar front jet stream met with the subtropical jet, with the polar night jet above. We present temperature perturbations observed by GLORIA and ALIMA during the discussed flight and compare the data with ECMWF IFS (European Centre for Medium-Range Weather Forecasts &amp;#8211; Integrated Forecasting System) high-resolution deterministic forecasts, aiming at validating the IFS data and identifying sources of the observed wave patterns.&lt;/p&gt;

scholarly journals Trend differences in lower stratospheric water vapour between Boulder and the zonal mean and their role in understanding fundamental observational discrepancies

2018 ◽  
Vol 18 (11) ◽  
pp. 8331-8351 ◽  
Author(s):  
Stefan Lossow ◽  
Dale F. Hurst ◽  
Karen H. Rosenlof ◽  
Gabriele P. Stiller ◽  
Thomas von Clarmann ◽  
...  
Keyword(s):  
Water Vapour ◽  
Satellite Data ◽  
Middle Atmosphere ◽  
Michelson Interferometer ◽  
Lagrangian Model ◽  
Data Set ◽  
Temporal Behaviour ◽  
Model Simulations ◽  
Time Period ◽  
Stratospheric Water Vapour

Abstract. Trend estimates with different signs are reported in the literature for lower stratospheric water vapour considering the time period between the late 1980s and 2010. The NOAA (National Oceanic and Atmospheric Administration) frost point hygrometer (FPH) observations at Boulder (Colorado, 40.0° N, 105.2° W) indicate positive trends (about 0.1 to 0.45 ppmv decade−1). On the contrary, negative trends (approximately −0.2 to −0.1 ppmv decade−1) are derived from a merged zonal mean satellite data set for a latitude band around the Boulder latitude. Overall, the trend differences between the two data sets range from about 0.3 to 0.5 ppmv decade−1, depending on altitude. It has been proposed that a possible explanation for these discrepancies is a different temporal behaviour at Boulder and the zonal mean. In this work we investigate trend differences between Boulder and the zonal mean using primarily simulations from ECHAM/MESSy (European Centre for Medium-Range Weather Forecasts Hamburg/Modular Earth Submodel System) Atmospheric Chemistry (EMAC), WACCM (Whole Atmosphere Community Climate Model), CMAM (Canadian Middle Atmosphere Model) and CLaMS (Chemical Lagrangian Model of the Stratosphere). On shorter timescales we address this aspect also based on satellite observations from UARS/HALOE (Upper Atmosphere Research Satellite/Halogen Occultation Experiment), Envisat/MIPAS (Environmental Satellite/Michelson Interferometer for Passive Atmospheric Sounding) and Aura/MLS (Microwave Limb Sounder). Overall, both the simulations and observations exhibit trend differences between Boulder and the zonal mean. The differences are dependent on altitude and the time period considered. The model simulations indicate only small trend differences between Boulder and the zonal mean for the time period between the late 1980s and 2010. These are clearly not sufficient to explain the discrepancies between the trend estimates derived from the FPH observations and the merged zonal mean satellite data set. Unless the simulations underrepresent variability or the trend differences originate from smaller spatial and temporal scales than resolved by the model simulations, trends at Boulder for this time period should also be quite representative for the zonal mean and even other latitude bands. Trend differences for a decade of data are larger and need to be kept in mind when comparing results for Boulder and the zonal mean on this timescale. Beyond that, we find that the trend estimates for the time period between the late 1980s and 2010 also significantly differ among the simulations. They are larger than those derived from the merged satellite data set and smaller than the trend estimates derived from the FPH observations.

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