scholarly journals The coupling of ClONO2, ClO, and NO2in the lower stratosphere from in situ observations using the NASA ER-2 aircraft

1999 ◽  
Vol 104 (D21) ◽  
pp. 26705-26714 ◽  
Author(s):  
R. M. Stimpfle ◽  
R. C. Cohen ◽  
G. P. Bonne ◽  
P. B. Voss ◽  
K. K. Perkins ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
In Situ Observations

scholarly journals Simulation of convective moistening of extratropical lower stratosphere using a numerical weather prediction model

2019 ◽  
Author(s):  
Zhipeng Qu ◽  
Yi Huang ◽  
Paul A. Vaillancourt ◽  
Jason N. S. Cole ◽  
Jason A. Milbrandt ◽  
...  
Keyword(s):  
Water Vapor ◽  
High Resolution ◽  
Lower Stratosphere ◽  
Water Vapor Content ◽  
Grid Spacing ◽  
Stratospheric Water Vapor ◽  
In Situ Observations ◽  
Horizontal Grid ◽  
Resolution Simulation

Abstract. Stratospheric water vapor (SWV) is a climatically important atmospheric constituent due to its impacts on the radiation budget and atmospheric chemical composition. Despite the important role of SWV in the climate system, the processes controlling the distribution and variation of water vapor in the upper troposphere and lower stratosphere (UTLS) are not well understood. In order to better understand the mechanism of transport of water vapor through the tropopause, this study uses the high resolution Global Environmental Multiscale model of the Environment and Climate Change Canada, to simulate a lower stratosphere moistening event over North America. Satellite remote sensing and aircraft in situ observations are used to evaluate the quality of model simulation. The main focus of this study is to evaluate the processes that influence the lower stratosphere water vapor budget, particularly the direct water vapor transport and the moistening due to the ice sublimation. In the high-resolution simulations with horizontal grid-spacing less than 2.5 km, it is found that the main contribution to lower-stratospheric moistening is the upward transport caused by the breaking of gravity waves. In contrast, for the lower-resolution simulation with horizontal grid-spacing of 10 km, the lower-stratospheric moistening is dominated by the sublimation of ice. In comparison with the aircraft in situ observations, the high-resolution simulations predict well the water vapor content in the UTLS, while the lower resolution simulation over-estimates the water vapor content. This overestimation is associated with the overly abundant ice in the UTLS along with too-high sublimation rate in the lower stratosphere. The results of this study affirm the strong influence of overshooting convection on the lower-stratospheric water vapor and highlight the importance of both dynamics and microphysics in simulating the water vapor distribution in the UTLS region.

scholarly journals Evaluation of single-footprint AIRS CH<sub>4</sub> Profile Retrieval Uncertainties Using Aircraft Profile Measurements

2020 ◽  
Author(s):  
Susan S. Kulawik ◽  
John R. Worden ◽  
Vivienne H. Payne ◽  
Dejian Fu ◽  
Steve C. Wofsy ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Optimal Estimation ◽  
Observation Error ◽  
Atmospheric Methane ◽  
Single Measurement ◽  
Atmospheric Infrared Sounder ◽  
Infrared Observations ◽  
In Situ Observations ◽  
Spatio Temporal

Abstract. We evaluate the uncertainties of methane optimal estimation retrievals from single footprint thermal infrared observations from the Atmospheric Infrared Sounder (AIRS). These retrievals are primarily sensitive to atmospheric methane in the mid-troposphere through the lower stratosphere (~2 to ~17 km). We compare to in situ observations made from aircraft during the Hiaper Pole to Pole Observations (HIPPO), the NASA Atmospheric Tomography Mission (ATom) campaigns, and from the NOAA ESRL aircraft network, between the surface and 5–13 km, across a range of years, latitudes between 60 S to 80 N, and over land and ocean. After a global, pressure dependent bias correction, we find that the land and ocean have similar biases and that the reported observation error (combined measurement and interference errors) of ~27  ppb is consistent with the standard deviation between aircraft and individual AIRS observations. A single measurement has measurement (noise related) uncertainty of ~17 ppb, a ~20 ppb uncertainty from radiative interferences (e.g. from water, temperature, etc.), and ~ 30 ppb due to smoothing error, which is partially removed when making comparisons to in situ measurements or models in a way that account for this regularization. We estimate a 16 ppb validation error because the aircraft typically did not measure methane at altitudes where the AIRS measurements have some sensitivity, e.g. the stratosphere. Daily averaged AIRS measurements of at least 9 observations over spatio-temporal domains of

scholarly journals Simulation of convective moistening of the extratropical lower stratosphere using a numerical weather prediction model

2020 ◽  
Vol 20 (4) ◽  
pp. 2143-2159 ◽  
Author(s):  
Zhipeng Qu ◽  
Yi Huang ◽  
Paul A. Vaillancourt ◽  
Jason N. S. Cole ◽  
Jason A. Milbrandt ◽  
...  
Keyword(s):  
High Resolution ◽  
Water Vapour ◽  
Lower Stratosphere ◽  
Grid Spacing ◽  
Water Vapour Content ◽  
In Situ Observations ◽  
Horizontal Grid ◽  
Stratospheric Water Vapour ◽  
Resolution Simulation

Abstract. Stratospheric water vapour (SWV) is a climatically important atmospheric constituent due to its impacts on the radiation budget and atmospheric chemical composition. Despite the important role of SWV in the climate system, the processes controlling the distribution and variation in water vapour in the upper troposphere and lower stratosphere (UTLS) are not well understood. In order to better understand the mechanism of transport of water vapour through the tropopause, this study uses the high-resolution Global Environmental Multiscale model of the Environment and Climate Change Canada to simulate a lower stratosphere moistening event over North America. Satellite remote sensing and aircraft in situ observations are used to evaluate the quality of model simulation. The main focus of this study is to evaluate the processes that influence the lower stratosphere water vapour budget, particularly the direct water vapour transport and the moistening due to the ice sublimation. In the high-resolution simulations with horizontal grid spacing of less than 2.5 km, it is found that the main contribution to lower stratospheric moistening is the upward transport caused by the breaking of gravity waves. In contrast, for the lower-resolution simulation with horizontal grid spacing of 10 km, the lower stratospheric moistening is dominated by the sublimation of ice. In comparison with the aircraft in situ observations, the high-resolution simulations predict the water vapour content in the UTLS well, while the lower-resolution simulation overestimates the water vapour content. This overestimation is associated with the overly abundant ice in the UTLS along with a sublimation rate that is too high in the lower stratosphere. The results of this study affirm the strong influence of overshooting convection on the lower stratospheric water vapour and highlight the importance of both dynamics and microphysics in simulating the water vapour distribution in the UTLS region.

In situ observations in aircraft exhaust plumes in the lower stratosphere at midlatitudes

1995 ◽  
Vol 100 (D2) ◽  
pp. 3065 ◽  
Author(s):  
D. W. Fahey ◽  
E. R. Keim ◽  
E. L. Woodbridge ◽  
R. S. Gao ◽  
K. A. Boering ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Exhaust Plumes ◽  
In Situ Observations

Isentropic transport of water vapor into the extra-tropical lower stratosphere

2020 ◽  
Author(s):  
Christian Rolf ◽  
Felix Plöger ◽  
Martina Krämer ◽  
Martin Riese
Keyword(s):  
Water Vapor ◽  
Greenhouse Gases ◽  
Northern Hemisphere ◽  
Planetary Wave ◽  
Lower Stratosphere ◽  
Planetary Waves ◽  
Boreal Summer ◽  
In Situ Observations ◽  
Vapor Distribution

&lt;p&gt;Water vapor is one of the most important greenhouse gases in the Earth&amp;#8217;s atmosphere. Due to the high sensitivity of atmospheric radiative forcing to changes in greenhouse gases in the cold upper troposphere and lower stratosphere (UTLS) region, even small variations in water vapor in the lower LS are an important source of the decadal variability of the surface temperature. This implies the need for a detailed understanding of the observed water vapor variability in the UTLS and their underlying processes.&lt;/p&gt;&lt;p&gt;Isentropic transport of water vapor due to planetary waves and their breaking provides a mechanism for bringing moist tropical tropospheric air into the dry lower extra-tropical stratosphere (exLS, see e.g. McIntyre and Palmer, 1983). Uplifted moist air masses by the Asian and American monsoons at the sub-tropical jet generate maximum water vapor concentrations in the summer/fall season. This water vapor maximum coincides with a maximum in planetary wave breaking in the northern hemisphere lower stratosphere and thus subsequent horizontal poleward transport. This transport serves as the dominant pathway to moisten the exLS in boreal summer (e.g. Ploeger et al., 2013 , Rolf et al. 2018).&lt;/p&gt;&lt;p&gt;We investigate this transport pathway with measurements to better understand the water vapor distribution and their annual cycle in the exLS. Here, we use in-situ measurements of water vapor obtained with the FISH instrument (Fast In-situ Stratospheric Hygrometer) during the aircraft field campaigns TACTS in August/ September 2012 and WISE in September/October 2017. Water vapor observations with the AURA MLS satellite instrument encompassing the entire exLS are used to put the temporal and spatial limited in-situ observations into a larger perspective. A very good agreement between the median of the in-situ water vapor distribution and the satellite observation is found, which shows that the in-situ observations are representative for the water vapor distribution of the exLS. Isentropic transport is shown to be dependent on the planetary wave activity by using the divergence of the Eliassen-Palm flux. Together with an extensive backward trajectory analysis we show that the isentropic transport is the dominant pathway of moistening the exLS up to 420 K potential temperature.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;ul&gt;&lt;li&gt; &lt;p&gt;McIntyre, M. E., and T. N. Palmer (1983), Breaking planetary waves in the stratosphere, Nature, 305, 593-600.&lt;/p&gt; &lt;/li&gt; &lt;li&gt; &lt;p&gt;Ploeger, F., G&amp;#252;nther, G., Konopka, P., Fueglistaler, S., M&amp;#252;ller, R., Hoppe, C., Kunz, A., Spang, R., Groo&amp;#223;, J.&amp;#8208;U., and Riese, M. ( 2013), Horizontal water vapor transport in the lower stratosphere from subtropics to high latitudes during boreal summer, &lt;em&gt;J. Geophys. Res. Atmos.&lt;/em&gt;, 118, 8111&amp;#8211; 8127, doi:&lt;span&gt;&lt;/span&gt;.&lt;/p&gt; &lt;/li&gt; &lt;li&gt; &lt;p&gt;Rolf, C., Vogel, B., Hoor, P., Afchine, A., G&amp;#252;nther, G., Kr&amp;#228;mer, M., M&amp;#252;ller, R., M&amp;#252;ller, S., Spelten, N., and Riese, M.: Water vapor increase in the lower stratosphere of the Northern Hemisphere due to the Asian monsoon anticyclone observed during the TACTS/ESMVal campaigns, Atmos. Chem. Phys., 18, 2973&amp;#8211;2983, https://doi.org/10.5194/acp-18-2973-2018, 2018.&lt;/p&gt; &lt;/li&gt; &lt;/ul&gt;

In situ observations of electromigration induced void behavior

1995 ◽  
Vol 53 ◽  
pp. 244-245
Author(s):  
T. Marieb ◽  
J. C. Bravman ◽  
P. Flinn ◽  
D. Gardner ◽  
M. Madden
Keyword(s):  
Electron Microscopy ◽  
Void Nucleation ◽  
Plan View ◽  
Transmission Electron ◽  
Nucleation Sites ◽  
Microelectronics Industry ◽  
In Situ Observations ◽  
Backscatter Electron Detector ◽  
Voltage Scanning

Electromigration and stress voiding have been active areas of research in the microelectronics industry for many years. While accelerated testing of these phenomena has been performed for the last 25 years[1-2], only recently has the introduction of high voltage scanning electron microscopy (HVSEM) made possible in situ testing of realistic, passivated, full thickness samples at high resolution.With a combination of in situ HVSEM and post-testing transmission electron microscopy (TEM) , electromigration void nucleation sites in both normal polycrystalline and near-bamboo pure Al were investigated. The effect of the microstructure of the lines on the void motion was also studied.The HVSEM used was a slightly modified JEOL 1200 EX II scanning TEM with a backscatter electron detector placed above the sample[3]. To observe electromigration in situ the sample was heated and the line had current supplied to it to accelerate the voiding process. After testing lines were prepared for TEM by employing the plan-view wedge technique [6].

scholarly journals In situ observations of coral spawning and spawn slick at Lankayan Island, Sabah, Malaysia

2021 ◽  
Vol 51 (1) ◽  
Author(s):  
Sze Hoon Gan ◽  
Zarinah Waheed ◽  
Fung Chen Chung ◽  
Davies Austin Spiji ◽  
Leony Sikim ◽  
...  
Keyword(s):  
Coral Spawning ◽  
In Situ Observations

scholarly journals Snow Depth Fusion Based on Machine Learning Methods for the Northern Hemisphere

2021 ◽  
Vol 13 (7) ◽  
pp. 1250
Author(s):  
Yanxing Hu ◽  
Tao Che ◽  
Liyun Dai ◽  
Lin Xiao
Keyword(s):  
Machine Learning ◽  
Northern Hemisphere ◽  
Snow Depth ◽  
Learning Algorithm ◽  
Random Forest Regression ◽  
Machine Learning Methods ◽  
Long Time ◽  
In Situ Observations ◽  
Input Variables

In this study, a machine learning algorithm was introduced to fuse gridded snow depth datasets. The input variables of the machine learning method included geolocation (latitude and longitude), topographic data (elevation), gridded snow depth datasets and in situ observations. A total of 29,565 in situ observations were used to train and optimize the machine learning algorithm. A total of five gridded snow depth datasets—Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) snow depth, Global Snow Monitoring for Climate Research (GlobSnow) snow depth, Long time series of daily snow depth over the Northern Hemisphere (NHSD) snow depth, ERA-Interim snow depth and Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) snow depth—were used as input variables. The first three snow depth datasets are retrieved from passive microwave brightness temperature or assimilation with in situ observations, while the last two are snow depth datasets obtained from meteorological reanalysis data with a land surface model and data assimilation system. Then, three machine learning methods, i.e., Artificial Neural Networks (ANN), Support Vector Regression (SVR), and Random Forest Regression (RFR), were used to produce a fused snow depth dataset from 2002 to 2004. The RFR model performed best and was thus used to produce a new snow depth product from the fusion of the five snow depth datasets and auxiliary data over the Northern Hemisphere from 2002 to 2011. The fused snow-depth product was verified at five well-known snow observation sites. The R2 of Sodankylä, Old Aspen, and Reynolds Mountains East were 0.88, 0.69, and 0.63, respectively. At the Swamp Angel Study Plot and Weissfluhjoch observation sites, which have an average snow depth exceeding 200 cm, the fused snow depth did not perform well. The spatial patterns of the average snow depth were analyzed seasonally, and the average snow depths of autumn, winter, and spring were 5.7, 25.8, and 21.5 cm, respectively. In the future, random forest regression will be used to produce a long time series of a fused snow depth dataset over the Northern Hemisphere or other specific regions.

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