scholarly journals Initial MST radar observations of upper tropospheric-lower stratospheric duct-like structures over Jicamarca, Peru

2012 ◽  
Vol 12 (22) ◽  
pp. 11085-11093 ◽  
Author(s):  
Z. Li ◽  
S. Naqvi ◽  
A. J. Gerrard ◽  
J. L. Chau ◽  
Y. Bhattacharya
Keyword(s):  
Gravity Waves ◽  
Lower Stratosphere ◽  
Physical Nature ◽  
High Quality ◽  
Data Set ◽  
Upper Troposphere ◽  
Atmospheric Fronts ◽  
Mst Radar ◽  
Wind Measurements

Abstract. Persistent wind jet structures along zonal and meridional fields, believed to be caused by stationary gravity waves, were detected in February 1999 in mesosphere-stratosphere-troposphere (MST) radar wind measurements of the troposphere and lower stratosphere over Jicamarca, Peru. Over a continuous seven day span of MST-data analyzed in this study, two days of observations showed signatures of wave-like structures in the upper troposphere/lower stratosphere wind jets associated with the phases of the stationary gravity waves. We believe these wave-like structures are ducted gravity waves. We present these initial observations, their characteristics, and the results of simple numerical simulations used in an attempt to mimic these observed features. Although a fair replication of the observed ducted structure in the numerical model is found, the observed period of ~90 min is nonetheless much longer than what is traditionally observed. As a result, the specific physical nature of the observed structures is not fully established. Nevertheless, given the high quality of the observations, we demonstrate here that continued analysis of this data set and concurrent modeling efforts will allow for a better understanding of Doppler ducts at high spatial and temporal resolution, and the results presented here can ultimately be applied to studies of middle atmospheric fronts, ducts, and bores.

scholarly journals Numerical modeling of lower stratospheric Doppler ducted gravity waves over Jicamarca, Peru

2011 ◽  
Vol 11 (7) ◽  
pp. 19011-19027
Author(s):  
Z. Li ◽  
S. Naqvi ◽  
A. J. Gerrard ◽  
J. L. Chau ◽  
Y. Bhattacharya
Keyword(s):  
Numerical Modeling ◽  
Numerical Model ◽  
Gravity Waves ◽  
Lower Stratosphere ◽  
Physical Nature ◽  
High Quality ◽  
Data Set ◽  
Upper Troposphere ◽  
Wind Measurements

Abstract. Persistent jet structures along zonal and meridional fields, believed to be caused by stationary gravity waves, were detected in February 1999 in MST wind measurements of the troposphere and lower stratosphere over Jicamarca, Peru. Over a seven day span, two days of observations showed signatures of a Doppler ducted gravity wave in the upper troposphere/lower stratosphere. Herein we present the observations, their characteristics, and results of numerical simulations used to mimic these observed features. Though a fair replication of the observed ducted structure in the numerical model is found, the observed period of ~90 min is nonetheless longer than anticipated and raises concern as to the specific physical nature of the observed structures. However, given the high quality of the observations, we demonstrate that continued analysis of this data set and concurrent modeling will allow for a better understanding of Doppler ducts at high spatial and temporal resolution which can ultimately be applied to studies of mesospheric ducts and bores.

scholarly journals Aircraft measurements of gravity waves in the upper troposphere and lower stratosphere during the START08 field experiment

2015 ◽  
Vol 15 (13) ◽  
pp. 7667-7684 ◽  
Author(s):  
Fuqing Zhang ◽  
Junhong Wei ◽  
Meng Zhang ◽  
K. P. Bowman ◽  
L. L. Pan ◽  
...  
Keyword(s):  
Power Law ◽  
Gravity Waves ◽  
Lower Stratosphere ◽  
Potential Temperature ◽  
Shear Instability ◽  
Aircraft Measurements ◽  
Upper Troposphere ◽  
Airborne Measurements ◽  
Wide Range

Abstract. This study analyzes in situ airborne measurements from the 2008 Stratosphere–Troposphere Analyses of Regional Transport (START08) experiment to characterize gravity waves in the extratropical upper troposphere and lower stratosphere (ExUTLS). The focus is on the second research flight (RF02), which took place on 21–22 April 2008. This was the first airborne mission dedicated to probing gravity waves associated with strong upper-tropospheric jet–front systems. Based on spectral and wavelet analyses of the in situ observations, along with a diagnosis of the polarization relationships, clear signals of mesoscale variations with wavelengths ~ 50–500 km are found in almost every segment of the 8 h flight, which took place mostly in the lower stratosphere. The aircraft sampled a wide range of background conditions including the region near the jet core, the jet exit and over the Rocky Mountains with clear evidence of vertically propagating gravity waves of along-track wavelength between 100 and 120 km. The power spectra of the horizontal velocity components and potential temperature for the scale approximately between ~ 8 and ~ 256 km display an approximate −5/3 power law in agreement with past studies on aircraft measurements, while the fluctuations roll over to a −3 power law for the scale approximately between ~ 0.5 and ~ 8 km (except when this part of the spectrum is activated, as recorded clearly by one of the flight segments). However, at least part of the high-frequency signals with sampled periods of ~ 20–~ 60 s and wavelengths of ~ 5–~ 15 km might be due to intrinsic observational errors in the aircraft measurements, even though the possibilities that these fluctuations may be due to other physical phenomena (e.g., nonlinear dynamics, shear instability and/or turbulence) cannot be completely ruled out.

scholarly journals Climatology and long-term evolution of ozone and carbon monoxide in the UTLS at northern mid-latitudes, as seen by IAGOS from 1995 to 2013

2017 ◽  
Author(s):  
Yann Cohen ◽  
Hervé Petetin ◽  
Valérie Thouret ◽  
Virginie Marécal ◽  
Béatrice Josse ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Lower Stratosphere ◽  
Boreal Summer ◽  
Brazilian Coast ◽  
Seasonal Cycles ◽  
Western Coast ◽  
Data Set ◽  
Upper Troposphere ◽  
North East ◽  
Wide Range

Abstract. In situ measurements in the upper troposphere – lower stratosphere (UTLS) are performed in the framework of the European research infrastructure IAGOS (In-service Aircraft for a Global Observing System) for ozone since 1994 and for carbon monoxide since 2002. The flight tracks cover a wide range of longitudes in the northern extratropics, extending from the North American western coast (125° W) to the eastern Asian coast (135° E), and more recently over the northern Pacific ocean. Different tropical regions are also sampled frequently, such as the Brazilian coast, central and southern Africa, southeastern Asia and the western Maritime Continent. As a result, a new set of climatologies for O3 (Aug. 1994–Dec. 2013) and CO (Dec. 2001–Dec. 2013) in the upper troposphere (UT), tropopause layer and lower stratosphere (LS) are made available, including quasi-global gridded horizontal distributions, and seasonal cycles over eight well sampled regions of interest in the northern extratropics. The seasonal cycles generally show a summertime maximum in O3 and a springtime maximum in CO in the UT, in contrast with the systematic springtime maximum in O3 and the quasi-absence of seasonal cycle of CO in the LS. This study highlights some regional variabilities in the UT notably (i) a west-east difference of O3 in boreal summer with up to 15 ppb more O3 over central Russia compared with northeast America, (ii) a systematic west-east gradient of CO from 60° E to 140° E (especially noticeable in spring and summer with about 5 ppb by 10 degrees longitude), (iii) a broad spring/summer maximum of CO over North East Asia, and (iv) a spring maximum of O3 over Western North America. Thanks to almost 20 years of O3 and 12 years of CO measurements, the IAGOS database is a unique data set to derive trends in the UTLS. Trends in O3 in the UT are positive and statistically significant in most regions, ranging from +0.25 to +0.45 ppb yr−1, characterized by the significant increase of the lowest values of the distribution. No significant trends of O3 are detected in the LS. Trends of CO in the UT, tropopause and LS are all negative and statistically significant. The estimated slopes range from −1.37 to −0.59 ppb yr−1 , with a nearly homogeneous decrease of the lowest values of the monthly distribution (fifth percentile) contrasting with the high inter-regional variability of the highest values (95th percentile).

scholarly journals Evaluation of water vapour assimilation in the tropical upper troposphere and lower stratosphere by a chemical transport model

2016 ◽  
Vol 9 (9) ◽  
pp. 4355-4373 ◽  
Author(s):  
Swagata Payra ◽  
Philippe Ricaud ◽  
Rachid Abida ◽  
Laaziz El Amraoui ◽  
Jean-Luc Attié ◽  
...  
Keyword(s):  
Water Vapour ◽  
Lower Stratosphere ◽  
Transport Model ◽  
Michelson Interferometer ◽  
Model Space ◽  
Global Scale ◽  
Chemical Transport Model ◽  
Data Set ◽  
Upper Troposphere ◽  
Sensitivity Studies

Abstract. The present analysis deals with one of the most debated aspects of the studies on the upper troposphere/lower stratosphere (UTLS), namely the budget of water vapour (H2O) at the tropical tropopause. Within the French project “Multiscale water budget in the upper troposphere and lower stratosphere in the TROpics” (TRO-pico), a global-scale analysis has been set up based on space-borne observations, models and assimilation techniques. The MOCAGE-VALENTINA assimilation tool has been used to assimilate the Aura Microwave Limb Sounder (MLS) version 3.3 H2O measurements within the 316–5 hPa range from August 2011 to March 2013 with an assimilation window of 1 h. Diagnostics based on observations minus analysis and forecast are developed to assess the quality of the assimilated H2O fields. Comparison with an independent source of H2O measurements in the UTLS based on the space-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) observations and with meteorological ARPEGE analyses is also shown. Sensitivity studies of the analysed fields have been performed by (1) considering periods when no MLS measurements are available and (2) using H2O data from another MLS version (4.2). The studies have been performed within three different spaces in time and space coincidences with MLS (hereafter referred to as MLS space) and MIPAS (MIPAS space) observations and with the model (model space) outputs and at three different levels: 121 hPa (upper troposphere), 100 hPa (tropopause) and 68 hPa (lower stratosphere) in January and February 2012. In the MLS space, the analyses behave consistently with the MLS observations from the upper troposphere to the lower stratosphere. In the model space, the analyses are wetter than the reference atmosphere as represented by ARPEGE and MLS in the upper troposphere (121 hPa) and around the tropopause (100 hPa), but are consistent with MLS and MIPAS in the lower stratosphere (68 hPa). In the MIPAS space, the sensitivity and the vertical resolution of the MIPAS data set at 121 and 100 hPa prevent assessment of the behaviour of the analyses at 121 and 100 hPa, particularly over intense convective areas as the South American, the African and the Maritime continents but, in the lower stratosphere (68 hPa), the analyses are very consistent with MIPAS. Sensitivity studies show the improvement on the H2O analyses in the tropical UTLS when assimilating space-borne measurements of better quality, particularly over the convective areas.

scholarly journals Testing the validity of regional detail in global analyses of Sea surface temperature – the case of Chinese coastal waters

2018 ◽  
Author(s):  
Yan Li ◽  
Hans von Storch ◽  
Qingyyuan Wang ◽  
Qingliang Zhou
Keyword(s):  
Quality Data ◽  
Careful Examination ◽  
Local Data ◽  
High Quality ◽  
Data Set ◽  
Time Period ◽  
Chinese Coast ◽  
Local Quality ◽  
Break Points

Abstract. We have designed a method for testing the quality of multidecadal analyses of SST in regional seas by using a set of high-quality local SST observations. In recognizing that local data may reflect local effects, we focus on dominant EOFs of the local data and of the localized data of the analyses. We examine patterns, and the variability as well as the trends of the principal components. This method is applied to examine four different SST analyses, namely HadISST1, ERSST, COBE SST, and NOAA OISST. They are assessed using a newly constructed high-quality data set of SST at 26 coastal stations along the Chinese coast in 1960–2015 which underwent careful examination with respect to quality, and a number of corrections of inhomogeneities. The four gridded analyses perform by and large well, in particular since 1980. However, for the pre-satellite time period, before 1980, the analyses differ among each other and show some inconsistencies with the local data, such as artificial break points, periods of bias and differences in trends. We conclude that gridded SST-analyses need improvement in the pre-satellite time (prior to 1980s), by re-examining in detail archives of local quality-controlled SST data in many data-sparse regions of the world.

An investigation into the characteristics of inertia gravity waves in the upper troposphere/lower stratosphere using a 205 MHz wind profiling radar

2017 ◽  
Vol 9 (3) ◽  
pp. 284-293 ◽  
Author(s):  
Ajil Kottayil ◽  
Karathazhiyath Satheesan ◽  
Kesavapillai Mohankumar ◽  
Sivan Chandran ◽  
Titu Samson
Keyword(s):  
Gravity Waves ◽  
Lower Stratosphere ◽  
Upper Troposphere ◽  
Inertia Gravity Waves

scholarly journals Tropospheric mixing and parametrization of unresolved convection as implemented into the Chemical Lagrangian Model of the Stratosphere (CLaMS)

2018 ◽  
Author(s):  
Paul Konopka ◽  
Mengchu Tao ◽  
Felix Ploeger ◽  
Mohamadou Diallo ◽  
Martin Riese
Keyword(s):  
Lower Stratosphere ◽  
Transport Model ◽  
Longwave Radiation ◽  
Vertical Transport ◽  
Lagrangian Model ◽  
Data Set ◽  
Numerical Diffusion ◽  
Upper Troposphere ◽  
Good Ability ◽  
Observation Network

Abstract. Inaccurate representation of mixing in chemistry transport model, mainly suffering from an excessive numerical diffusion, strongly influences the quantitative estimates of the stratosphere-troposphere exchange (STE). The Lagrangian view of transport offers an alternative to exploit the numerical diffusion for parametrization of the physical mixing. Here, we follow this concept and discuss how to extend the representation of tropospheric transport in the Chemical Lagrangian Model of the Stratosphere (CLaMS). Although the current transport scheme in CLaMS shows good ability of representing transport of tracers in the stably stratified stratosphere (Pommrich et al., (2014) and the references therein), there are deficiencies in representation of the effects of convective uplift and mixing due to weak vertical stability in the troposphere. We show how the CLaMS transport scheme was modified by including additional tropospheric mixing and vertical transport due to unresolved convection by parametrizing these processes in terms of the dry and moist Brunt-Vaisala frequency, respectively. The regions with enhanced vertical transport in the novel CLaMS simulation covering the 2005-08 period coincide with regions of enhanced convection as diagnosed from the satellite observations of the Outgoing Longwave Radiation (OLR). We analyze how well this approach improves the CLaMS representation of CO2 in the upper troposphere and lower stratosphere, in particular the propagation of the CO2 seasonal cycle from the Planetary Boundary Layer (PBL) into the lower stratosphere. The CO2 values in the PBL are specified by the CarbonTracker data set (version CT2013B) and the Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL) observations are used to validate the model. The proposed extension of tropospheric transport increases the tropospheric influence in the middle and upper troposphere and at the same time influences the STE. The effect on mean age away from the troposphere in the deep stratosphere is weak.

scholarly journals The SPARC water vapour assessment II: profile-to-profile and climatological comparisons of stratospheric <i>δ</i>D(H<sub>2</sub>O) observations from satellite

2019 ◽  
Vol 19 (4) ◽  
pp. 2497-2526 ◽  
Author(s):  
Charlotta Högberg ◽  
Stefan Lossow ◽  
Farahnaz Khosrawi ◽  
Ralf Bauer ◽  
Kaley A. Walker ◽  
...  
Keyword(s):  
Water Vapour ◽  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
Isotopic Ratio ◽  
Michelson Interferometer ◽  
Data Sets ◽  
Comprehensive Overview ◽  
Data Set ◽  
Upper Troposphere ◽  
Modelling Studies

Abstract. Within the framework of the second SPARC (Stratosphere-troposphere Processes And their Role in Climate) water vapour assessment (WAVAS-II), we evaluated five data sets of δD(H2O) obtained from observations by Odin/SMR (Sub-Millimetre Radiometer), Envisat/MIPAS (Environmental Satellite/Michelson Interferometer for Passive Atmospheric Sounding), and SCISAT/ACE-FTS (Science Satellite/Atmospheric Chemistry Experiment – Fourier Transform Spectrometer) using profile-to-profile and climatological comparisons. These comparisons aimed to provide a comprehensive overview of typical uncertainties in the observational database that could be considered in the future in observational and modelling studies. Our primary focus is on stratospheric altitudes, but results for the upper troposphere and lower mesosphere are also shown. There are clear quantitative differences in the measurements of the isotopic ratio, mainly with regard to comparisons between the SMR data set and both the MIPAS and ACE-FTS data sets. In the lower stratosphere, the SMR data set shows a higher depletion in δD than the MIPAS and ACE-FTS data sets. The differences maximise close to 50 hPa and exceed 200 ‰. With increasing altitude, the biases decrease. Above 4 hPa, the SMR data set shows a lower δD depletion than the MIPAS data sets, occasionally exceeding 100 ‰. Overall, the δD biases of the SMR data set are driven by HDO biases in the lower stratosphere and by H2O biases in the upper stratosphere and lower mesosphere. In between, in the middle stratosphere, the biases in δD are the result of deviations in both HDO and H2O. These biases are attributed to issues with the calibration, in particular in terms of the sideband filtering, and uncertainties in spectroscopic parameters. The MIPAS and ACE-FTS data sets agree rather well between about 100 and 10 hPa. The MIPAS data sets show less depletion below approximately 15 hPa (up to about 30 ‰), due to differences in both HDO and H2O. Higher up this behaviour is reversed, and towards the upper stratosphere the biases increase. This is driven by increasing biases in H2O, and on occasion the differences in δD exceed 80 ‰. Below 100 hPa, the differences between the MIPAS and ACE-FTS data sets are even larger. In the climatological comparisons, the MIPAS data sets continue to show less depletion in δD than the ACE-FTS data sets below 15 hPa during all seasons, with some variations in magnitude. The differences between the MIPAS and ACE-FTS data have multiple causes, such as differences in the temporal and spatial sampling (except for the profile-to-profile comparisons), cloud influence, vertical resolution, and the microwindows and spectroscopic database chosen. Differences between data sets from the same instrument are typically small in the stratosphere. Overall, if the data sets are considered together, the differences in δD among them in key areas of scientific interest (e.g. tropical and polar lower stratosphere, lower mesosphere, and upper troposphere) are too large to draw robust conclusions on atmospheric processes affecting the water vapour budget and distribution, e.g. the relative importance of different mechanisms transporting water vapour into the stratosphere.

scholarly journals Sulfur dioxide (SO<sub>2</sub>) from MIPAS in the upper troposphere and lower stratosphere 2002–2012

2015 ◽  
Vol 15 (12) ◽  
pp. 7017-7037 ◽  
Author(s):  
M. Höpfner ◽  
C. D. Boone ◽  
B. Funke ◽  
N. Glatthor ◽  
U. Grabowski ◽  
...  
Keyword(s):  
Sulfur Dioxide ◽  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
Michelson Interferometer ◽  
Volcanic Eruptions ◽  
Aerosol Layer ◽  
Mixing Ratio ◽  
So2 Emissions ◽  
Data Set ◽  
Upper Troposphere

Abstract. Vertically resolved distributions of sulfur dioxide (SO2) with global coverage in the height region from the upper troposphere to ~20 km altitude have been derived from observations by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat for the period July 2002 to April 2012. Retrieved volume mixing ratio profiles representing single measurements are characterized by typical errors in the range of 70–100 pptv and by a vertical resolution ranging from 3 to 5 km. Comparison with observations by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) revealed a slightly varying bias with altitude of −20 to 50 pptv for the MIPAS data set in case of volcanically enhanced concentrations. For background concentrations the comparison showed a systematic difference between the two major MIPAS observation periods. After debiasing, the difference could be reduced to biases within −10 to 20 pptv in the altitude range of 10–20 km with respect to ACE-FTS. Further comparisons of the debiased MIPAS data set with in situ measurements from various aircraft campaigns showed no obvious inconsistencies within a range of around ±50 pptv. The SO2 emissions of more than 30 volcanic eruptions could be identified in the upper troposphere and lower stratosphere (UTLS). Emitted SO2 masses and lifetimes within different altitude ranges in the UTLS have been derived for a large part of these eruptions. Masses are in most cases within estimations derived from other instruments. From three of the major eruptions within the MIPAS measurement period – Kasatochi in August 2008, Sarychev in June 2009 and Nabro in June 2011 – derived lifetimes of SO2 for the altitude ranges 10–14, 14–18 and 18–22 km are 13.3 ± 2.1, 23.6 ± 1.2 and 32.3 ± 5.5 days respectively. By omitting periods with obvious volcanic influence we have derived background mixing ratio distributions of SO2. At 10 km altitude these indicate an annual cycle at northern mid- and high latitudes with maximum values in summer and an amplitude of about 30 pptv. At higher altitudes of about 16–18 km, enhanced mixing ratios of SO2 can be found in the regions of the Asian and the North American monsoons in summer – a possible connection to an aerosol layer discovered by Vernier et al. (2011b) in that region.

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