Raman Lidar Measurements during the International H2O Project. Part II: Case Studies

2006 ◽  
Vol 23 (2) ◽  
pp. 170-183 ◽  
Author(s):  
D. N. Whiteman ◽  
B. Demoz ◽  
G. Schwemmer ◽  
B. Gentry ◽  
P. Di Girolamo ◽  
...  
Keyword(s):  
Water Vapor ◽  
Case Studies ◽  
The United States ◽  
Back Trajectory ◽  
Cirrus Cloud ◽  
Raman Lidar ◽  
Cloud Optical Depth ◽  
Back Trajectory Analysis ◽  
Cloud Modeling

Abstract The NASA GSFC Scanning Raman Lidar (SRL) participated in the International H2O Project (IHOP) that occurred in May and June 2002 in the midwestern part of the United States. The SRL system configuration and methods of data analysis were described in Part I of this paper. In this second part, comparisons of SRL water vapor measurements and those of Lidar Atmospheric Sensing Experiment (LASE) airborne water vapor lidar and chilled-mirror radiosonde are performed. Two case studies are then presented: one for daytime and one for nighttime. The daytime case study is of a convectively driven boundary layer event and is used to characterize the daytime SRL water vapor random error characteristics. The nighttime case study is of a thunderstorm-generated cirrus cloud case that is studied in its meteorological context. Upper-tropospheric humidification due to precipitation from the cirrus cloud is quantified as is the cirrus cloud optical depth, extinction-to-backscatter ratio, ice water content, cirrus particle size, and both particle and volume depolarization ratios. A stability and back-trajectory analysis is performed to study the origin of wave activity in one of the cloud layers. These unprecedented cirrus cloud measurements are being used in a cirrus cloud modeling study.

scholarly journals Enhanced stratospheric water vapor over the summertime continental United States and the role of overshooting convection

2017 ◽  
Vol 17 (9) ◽  
pp. 6113-6124 ◽  
Author(s):  
Robert L. Herman ◽  
Eric A. Ray ◽  
Karen H. Rosenlof ◽  
Kristopher M. Bedka ◽  
Michael J. Schwartz ◽  
...  
Keyword(s):  
United States ◽  
Water Vapor ◽  
Trajectory Analysis ◽  
The United States ◽  
Atmospheric Composition ◽  
Back Trajectory ◽  
Stratospheric Water Vapor ◽  
Mixing Ratios ◽  
The North ◽  
Back Trajectory Analysis

Abstract. The NASA ER-2 aircraft sampled the lower stratosphere over North America during the field mission for the NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS). This study reports observations of convectively influenced air parcels with enhanced water vapor in the overworld stratosphere over the summertime continental United States and investigates three case studies in detail. Water vapor mixing ratios greater than 10 ppmv, which is much higher than the background 4 to 6 ppmv of the overworld stratosphere, were measured by the JPL Laser Hygrometer (JLH Mark2) at altitudes between 16.0 and 17.5 km (potential temperatures of approximately 380 to 410 K). Overshooting cloud tops (OTs) are identified from a SEAC4RS OT detection product based on satellite infrared window channel brightness temperature gradients. Through trajectory analysis, we make the connection between these in situ water measurements and OT. Back trajectory analysis ties enhanced water to OT 1 to 7 days prior to the intercept by the aircraft. The trajectory paths are dominated by the North American monsoon (NAM) anticyclonic circulation. This connection suggests that ice is convectively transported to the overworld stratosphere in OT events and subsequently sublimated; such events may irreversibly enhance stratospheric water vapor in the summer over Mexico and the United States. A regional context is provided by water observations from the Aura Microwave Limb Sounder (MLS).

Raman Lidar Measurements during the International H2O Project. Part I: Instrumentation and Analysis Techniques

2006 ◽  
Vol 23 (2) ◽  
pp. 157-169 ◽  
Author(s):  
D. N. Whiteman ◽  
B. Demoz ◽  
K. Rush ◽  
G. Schwemmer ◽  
B. Gentry ◽  
...  
Keyword(s):  
Water Vapor ◽  
The United States ◽  
Cirrus Cloud ◽  
Raman Lidar ◽  
Error Statistics ◽  
Full Account ◽  
Nasa Goddard Space ◽  
Ice Water Content ◽  
Water Vapor Mixing Ratio ◽  
Ice Water

Abstract The NASA Goddard Space Flight Center (GSFC) Scanning Raman Lidar (SRL) participated in the International H2O Project (IHOP), which occurred in May and June 2002 in the midwestern part of the United States. The SRL received extensive optical modifications prior to and during the IHOP campaign that added new measurement capabilities and enabled unprecedented daytime water vapor measurements by a Raman lidar system. Improvements were also realized in nighttime upper-tropospheric water vapor measurements. The other new measurements that were added to the SRL for the IHOP deployment included rotational Raman temperature, depolarization, cloud liquid water, and cirrus cloud ice water content. In this first of two parts, the details of the operational configuration of the SRL during IHOP are provided along with a description of the analysis and calibration procedures for water vapor mixing ratio, aerosol depolarization, and cirrus cloud extinction-to-backscatter ratio. For the first time, a Raman water vapor lidar calibration is performed, taking full account of the temperature sensitivity of water vapor and nitrogen Raman scattering. Part II presents case studies that permit the daytime and nighttime error statistics to be quantified.

scholarly journals Enhanced Stratospheric Water Vapor over the Summertime Continental United States and the Role of Overshooting Convection

2016 ◽  
Author(s):  
Robert L. Herman ◽  
Eric A. Ray ◽  
Karen H. Rosenlof ◽  
Kristopher M. Bedka ◽  
Michael J. Schwartz ◽  
...  
Keyword(s):  
United States ◽  
Water Vapor ◽  
The United States ◽  
Atmospheric Composition ◽  
North American Monsoon ◽  
Back Trajectory ◽  
Stratospheric Water Vapor ◽  
Mixing Ratios ◽  
The North ◽  
Back Trajectory Analysis

Abstract. The NASA ER-2 aircraft sampled the UTLS region over North America during the NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field mission. This study reports three case studies of convectively-influenced air parcels with enhanced water vapor in the overworld stratosphere over the summertime continental United States. Water vapor mixing ratios greater than 10 ppmv, more than twice the stratospheric background levels, were measured by the JPL Laser Hygrometer (JLH Mark2) at pressure levels between 80 and 160 hPa. Through satellite observations and analysis, we make the connection between these in situ water measurements and overshooting cloud tops. The overshooting tops (OT) are identified from a SEAC4RS OT detection product based on satellite infrared window channel brightness temperature gradients. Back trajectory analysis ties enhanced water to OT one to seven days prior to the intercept by the aircraft. The trajectory paths are dominated by the North American Monsoon (NAM) anticyclonic circulation. This connection suggests that ice is convectively transported to the overworld stratosphere in OT events and subsequently sublimated; such events may irreversibly enhance stratospheric water vapor in the summer over Mexico and the United States. Regional context is provided by water observations from the Aura Microwave Limb Sounder (MLS).

THE USE OF CASE STUDY METHOD IN TEACHING THE TERMINOLOGY IN THE FIELD OF AGRICULTURAL MACHINERY

2019 ◽  
pp. 123-130
Keyword(s):  
Case Studies ◽  
High Performance ◽  
Mechanical Engineering ◽  
The United States ◽  
Machine Building ◽  
Soil Tillage ◽  
Case Study Method ◽  
Agricultural Machine ◽  
Manufacturing Machine

The scientific research works concerning the field of mechanical engineering such as, manufacturing machine slate, soil tillage, sowing and harvesting based on the requirements for the implementation of agrotechnical measures for the cultivation of plants in its transportation, through the development of mastering new types of high-performance and energy-saving machines in manufacturing machine slate, creation of multifunctional machines, allowing simultaneous soil cultivation, by means of several planting operations, integration of agricultural machine designs are taken into account in manufacturing of the local universal tractor designed basing on high ergonomic indicators. For this reason, this article explores the use of case studies in teaching agricultural terminology by means analyzing the researches in machine building. Case study method was firstly used in 1870 in Harvard University of Law School in the United States. Also in the article, we give the examples of agricultural machine-building terms, teaching terminology and case methods, case study process and case studies method itself. The research works in the field of mechanical engineering and the use of case studies in teaching terminology have also been analyzed. In addition, the requirements for the development of case study tasks are given in their practical didactic nature. We also give case study models that allow us analyzing and evaluating students' activities.

scholarly journals A case study of convectively sourced water vapor observed in the overworld stratosphere over the United States

2017 ◽  
Vol 122 (17) ◽  
pp. 9529-9554 ◽  
Author(s):  
Jessica B. Smith ◽  
David M. Wilmouth ◽  
Kristopher M. Bedka ◽  
Kenneth P. Bowman ◽  
Cameron R. Homeyer ◽  
...  
Keyword(s):  
United States ◽  
Water Vapor ◽  
The United States

scholarly journals A Raman lidar at La Reunion (20.8° S, 55.5° E) for monitoring water vapor and cirrus distributions in the subtropical upper troposphere: preliminary analyses and description of a future system

2011 ◽  
Vol 4 (5) ◽  
pp. 6449-6496
Author(s):  
C. Hoareau ◽  
P. Keckhut ◽  
J.-L. Baray ◽  
L. Robert ◽  
Y. Courcoux ◽  
...  
Keyword(s):  
Water Vapor ◽  
Cirrus Cloud ◽  
La Réunion ◽  
Raman Lidar ◽  
Data Set ◽  
Upper Troposphere ◽  
Future System ◽  
Rayleigh Lidar ◽  
Term Monitoring

Abstract. A ground based Rayleigh lidar has provided continuous observations of tropospheric water vapor profiles and cirrus cloud using a preliminary Raman channels setup on an existing Rayleigh lidar above La Reunion over the period 2002–2005. With this instrument, we performed a first measurement campaign of 350 independent water vapor profiles. A statistical study of the distribution of water vapor profiles is presented and some investigations concerning the calibration are discussed. The data set having several long acquisition measurements during nighttime, an analysis of the diurnal cycle of water vapor has also been investigated. Analysis regarding the cirrus clouds is presented and a classification has been performed showing 3 distinct classes. Based on these results, the characteristics and the design of a future lidar system to be implemented at the new Reunion Island altitude observatory (2200 m) for long-term monitoring is presented and numerical simulations of system performance have been realized to compare both instruments.

Estimating Lightning NOx Production Using NO2 Columns from the TROPOMI Instrument and Flashes from the Geostationary Lightning Mappers

2020 ◽  
Author(s):  
Kenneth Pickering ◽  
Dale Allen ◽  
Eric Bucsela ◽  
Jos van Geffen ◽  
Henk Eskes ◽  
...  
Keyword(s):  
United States ◽  
Case Studies ◽  
The United States ◽  
Data Set ◽  
Case Study Analysis ◽  
Convective Systems ◽  
Convective Clouds ◽  
Deep Convective Clouds ◽  
The One

<p>Nitric oxide (NO) is produced in lightning channels and quickly comes into equilibrium with nitrogen dioxide (NO<sub>2</sub>) in the atmosphere.  The production of NO<sub>x</sub> (NO + NO<sub>2</sub>) leads to subsequent increases in the concentrations of ozone (O<sub>3</sub>) and the hydroxyl radical (OH) and decreases in the concentration of methane (CH<sub>4</sub>), thus impacting the climate system.  Global production of NO<sub>x</sub> from lightning is uncertain by a factor of four.  NO<sub>x</sub> production by lightning will be examined using NO<sub>2</sub> columns from the TROPOspheric Monitoring Instrument (TROPOMI) on board the Copernicus Sentinel-5 Precursor Satellite with an overpass time of approximately 1330 LT and flash rates from the Geostationary Lightning Mapper (GLM) on board the NOAA GOES-16 (75.2° W) and GOES-17 (137.2° W) satellites.  Where there is overlap in coverage of the two GLM instruments, the greater of the two flash counts is used.  Two approaches have been undertaken for this analysis:  a series of case studies of storm systems over the United States, and a gridded analysis over the entire contiguous United States, Central America, northern South America, and surrounding oceans.  A modified Copernicus Sentinel 5P TROPOMI NO<sub>2</sub> data set is used here for the case-study analysis to improve data coverage over deep convective clouds.  In both approaches, only TROPOMI pixels with cloud fraction > 0.95 and cloud pressure < 500 hPa are used.  The stratospheric column is removed from the total slant column, and the result is divided by air mass factors appropriate for deep convective clouds containing lightning NO<sub>x</sub> (LNO<sub>x</sub>).  Case studies have been selected from deep convective systems over and near the United States during the warm seasons of 2018 and 2019.  For each of these systems, NO<sub>x</sub> production per flash is determined by multiplying a TROPOMI-based estimate of the mean tropospheric column of LNO<sub>x</sub> over each system by the storm area and then dividing by a GLM-based estimate of the flashes that contribute to the column.  In the large temporal and spatial scale analysis, the TROPOMI data are aggregated on a 0.5 x 0.5 degree grid and converted to moles LNO<sub>x</sub>*.  GLM flash counts during the one-hour period before TROPOMI overpass are similarly binned. A tropospheric background of LNO<sub>x</sub>* is estimated from grid cells without lightning and subtracted from LNO<sub>x</sub>* in cells with lightning to yield an estimate of freshly produced lightning NO<sub>x</sub>, designated LNO<sub>x</sub>.  Results of the two approaches are compared and discussed with respect to previous LNO<sub>x</sub> per flash estimates.</p><p> </p>

The Value of Wind Profiler Data in U.S. Weather Forecasting

2004 ◽  
Vol 85 (12) ◽  
pp. 1871-1886 ◽  
Author(s):  
Stanley G. Benjamin ◽  
Barry E. Schwartz ◽  
Edward J. Szoke ◽  
Steven E. Koch
Keyword(s):  
United States ◽  
Case Studies ◽  
Short Range ◽  
Weather Forecasting ◽  
The United States ◽  
Test Period ◽  
Data Sources ◽  
Wind Profiler ◽  
Profiler Data

An assessment of the value of data from the NOAA Profiler Network (NPN) on weather forecasting is presented. A series of experiments was conducted using the Rapid Update Cycle (RUC) model/assimilation system in which various data sources were denied in order to assess the relative importance of the profiler data for short-range wind forecasts. Average verification statistics from a 13-day cold-season test period indicate that the profiler data have a positive impact on short-range (3–12 h) forecasts over the RUC domain containing the lower 48 United States, which are strongest at the 3-h projection over a central U.S. subdomain that includes most of the profiler sites, as well as downwind of the profiler observations over the eastern United States. Overall, profiler data reduce wind forecast errors at all levels from 850 to 150 hPa, especially below 300 hPa where there are relatively few automated aircraft observations. At night when fewer commercial aircraft are flying, profiler data also contribute strongly to more accurate 3-h forecasts, including near-tropopause maximum wind levels. For the test period, the profiler data contributed up to 20%–30% (at 700 hPa) of the overall reduction of 3-h wind forecast error by all data sources combined. Inclusion of wind profiler data also reduced 3-h errors for height, relative humidity, and temperature by 5%-15%, averaged over different vertical levels. Time series and statistics from large-error events demonstrate that the impact of profiler data may be much larger in peak error situations. Three data assimilation case studies from cold and warm seasons are presented that illustrate the value of the profiler observations for improving weather forecasts. The first case study indicates that inclusion of profiler data in the RUC model runs for the 3 May 1999 Oklahoma tornado outbreak improved model guidance of convective available potential energy (CAPE), 300-hPa wind, and precipitation in southwestern Oklahoma at the onset of the event. In the second case study, inclusion of profiler data led to better RUC precipitation forecasts associated with a severe snow and ice storm that occurred over the central plains of the United States in February 2001. A third case study describes the effect of profiler data for a tornado event in Oklahoma on 8 May 2003. Summaries of National Weather Service (NWS) forecaster use of profiler data in daily operations, although subjective, support the results from these case studies and the statistical forecast model impact study in the broad sense that profiler data contribute significantly to improved short-range forecasts over the central United States where these observations currently exist.

scholarly journals Variability in cirrus cloud properties using a Polly<sup>XT</sup> Raman lidar over high and tropical latitudes

2020 ◽  
Vol 20 (7) ◽  
pp. 4427-4444 ◽  
Author(s):  
Kalliopi Artemis Voudouri ◽  
Elina Giannakaki ◽  
Mika Komppula ◽  
Dimitris Balis
Keyword(s):  
Optical Properties ◽  
Cirrus Clouds ◽  
Cirrus Cloud ◽  
Raman Lidar ◽  
Mean Values ◽  
Cloud Optical Depth ◽  
Geometrical Properties ◽  
Depolarisation Ratio ◽  
Cloud Properties ◽  
Lidar Ratio

Abstract. Measurements of geometrical and optical properties of cirrus clouds, performed with a multi-wavelength PollyXT Raman lidar during the period 2008 to 2016, are analysed. The measurements were performed with the same instrument, during sequential periods, in three places at different latitudes, Gwal Pahari (28.43∘ N, 77.15∘ E; 243 m a.s.l.) in India, Elandsfontein (26.25∘ S, 29.43∘ E; 1745 m a.s.l.) in South Africa and Kuopio (62.74∘ N, 27.54∘ E; 190 m a.s.l.) in Finland. The lidar dataset was processed by an automatic cirrus cloud masking algorithm, developed in the frame of this work. In the following, we present a statistical analysis of the lidar-retrieved geometrical characteristics (cloud boundaries, geometrical thickness) and optical properties of cirrus clouds (cloud optical depth, lidar ratio, ice crystal depolarisation ratio) measured over the three areas that correspond to subtropical and subarctic regions as well as their seasonal variability. The effect of multiple scattering from ice particles to the derived optical products is also considered and corrected in this study. Our results show that cirrus layers, which have a noticeable monthly variability, were observed between 6.5 and 13 km, with temperatures ranging from −72 to −27 ∘C. The observed differences on cirrus clouds' geometrical and optical properties over the three regions are discussed in terms of latitudinal and temperature dependence. The latitudinal dependence of the geometrical properties is consistent with satellite observations, following the pattern observed with CloudSat, with decreasing values towards the poles. The geometrical boundaries have their highest values in the subtropical regions, and overall, our results seem to demonstrate that subarctic cirrus clouds are colder, lower and optically thinner than subtropical cirrus clouds. The dependence of cirrus cloud geometrical thickness and optical properties on mid-cirrus temperatures shows a quite similar tendency for the three sites but less variability for the subarctic dataset. Cirrus clouds are geometrically and optically thicker at temperatures between −45 and −35 ∘C, and a second peak is observed at lower temperatures ∼-70 ∘C for the subarctic site. Lidar ratio values also exhibit a pattern, showing higher values moving toward the poles, with higher mean values observed over the subarctic site. The dependency of the mid-cirrus temperatures on the lidar ratio values and the particle depolarisation values is further examined. Our study shows that the highest values of the cirrus lidar ratio correspond to higher values of cirrus depolarisation and warmer cirrus. The kind of information presented here can be rather useful in the cirrus parameterisations required as input to radiative transfer models and can be a complementary tool for satellite products that cannot provide cloud vertical structure. In addition, ground-based statistics of the cirrus properties could be useful in the validation and improvement of the corresponding derived products from satellite retrievals.

scholarly journals Study of desert dust events over the southwestern Iberian Peninsula in year 2000: two case studies

2006 ◽  
Vol 24 (6) ◽  
pp. 1493-1510 ◽  
Author(s):  
V. E. Cachorro ◽  
R. Vergaz ◽  
A. M. de Frutos ◽  
J. M. Vilaplana ◽  
D. Henriques ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Case Studies ◽  
Atlantic Coast ◽  
Single Scattering ◽  
Radiative Properties ◽  
Back Trajectory ◽  
Desert Dust ◽  
Additional Information ◽  
Back Trajectory Analysis ◽  
Dust Events

Abstract. Strong desert dust events occurring in 2000 over the southwestern Atlantic coast of the Iberian Peninsula are detected and evaluated by means of the TOMS Aerosol Index (A.I.) at three different sites, Funchal (Madeira Island, Portugal), Lisboa (Portugal) and El Arenosillo (Huelva, Spain). At the El Arenosillo station, measurements from an AERONET Cimel sunphotometer allow a more precise retrieval of the spectral AOD and the derived alpha Ångström coefficient. After using different threshold values of these parameters, we conclude that it is difficult to establish reliable and robust criteria for an automatic estimation of the number of dust episodes and the total number of dusty days per year. As a result, additional information, such as airmass trajectories, were used to improve the estimation, from which reasonable results were obtained (although some manual editting was still needed). A detailed characterization of two selected desert dust episodes, a strong event in winter and another of less intensity in summer, was carried out using AOD derived from Brewer spectrometer measurements. Size distribution parameters and radiative properties, such as arefractive index and the aerosol single scattering albedo derived from Cimel data, were analyzed in detail for one of these two case studies. Although specific to this dust episode, the retrieved range of values of these parameters clearly reflect the characteristics of desert aerosols. Back-trajectory analysis, synoptic weather maps and satellite images were also considered together, as supporting data to assess the aerosol desert characterization in this region of study.

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