The Open Atmospheric Science Journal最新文献

{"title":"Editorial-Long-Term Changes in the Atmosphere","authors":"A. Elias","doi":"10.2174/1874282301105010001","DOIUrl":"https://doi.org/10.2174/1874282301105010001","url":null,"abstract":"The subject of trends in the atmosphere, which involves among several other topics, the global warming of the lower atmosphere and cooling of the middle and upper atmosphere, is of great interest to meteorologists, geoscientists and environmental scientists. The scope of this special issue is to include studies of trends and long-term variations of the different layers of the atmosphere linked to the increase in greenhouse gases, long term variations in solar and geomagnetic activity, secular variations of the Earth's magnetic field, or any other possible cause of trends in the atmosphere.","PeriodicalId":122982,"journal":{"name":"The Open Atmospheric Science Journal","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132565443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atmospheric Profiling in the Inter-Tropical Ocean Area Based on Neural Network Approach Using GPS Radio Occultations","authors":"S. Bonafoni","doi":"10.2174/1874282301004010202","DOIUrl":"https://doi.org/10.2174/1874282301004010202","url":null,"abstract":"In this study we have proposed a method based on neural networks to retrieve refractivity, temperature, pressure and humidity profiles by using FORMOSAT-3/COSMIC GPS radio occultation data. To overcome the constraint of an independent knowledge of one atmospheric parameter at each GPS occultation, we trained three neural networks with refractivity profiles as input computed from the geometrical occultation parameters relative to the FORMOSAT- 3/COSMIC satellites, while the targets were the dry and wet refractivity profiles and the dry pressure profiles obtained from the contemporary European Centre for Medium-Range Weather Forecast data. We have considered 1041 available satellite radio occultations covering the entire ocean area spanning within the Tropics during July-August 2006. We have used 937 profiles for training the neural networks, the remaining 104 ones for the independent test.","PeriodicalId":122982,"journal":{"name":"The Open Atmospheric Science Journal","volume":"224 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124453517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Upslope Flows in Atmosphere and Water Tank, Part II: Fluid-Dynamical Smoothness as a Possible Cause for Velocity Similarity Violation","authors":"C. Reuten, D. Steyn, S. Allen","doi":"10.2174/1874282301004010188","DOIUrl":"https://doi.org/10.2174/1874282301004010188","url":null,"abstract":"Water-tank models of meso-scale atmospheric processes often show good qualitative agreement of bulk quantities and flow characteristics and good quantitative agreement of turbulence quantities with field observations. However, it was demonstrated in the first part of this two-part communication that the similarity of velocities of thermally driven upslope flows in atmosphere and water tank is violated. It is shown in this part that the velocities of thermally driven upslope flows in the atmosphere and in a water-tank model have statistically different dependences on proposed governing parameters. Of four substantially different hypotheses of upslope velocities, three agree with field observations because of large uncertainties and sparse data, but all hypotheses disagree with tank observations. One hypothesis that includes the influence of the total slope height agrees with field and tank observations when assuming fluid-dynamically rough atmospheric flows and fluid-dynamically smooth tank flows. The non-dimensional upslope flow velocities corresponding to rough and smooth flows depend differently on the governing parameters. Therefore, non-dimensional upslope flow velocities are different for atmosphere and water tank. Furthermore, as this hypothesis includes a dependence of the upslope flow velocity on the total height of the slope it implies that upslope flow systems are non-local phenomena. Because fluid-dynamical roughness is technically difficult to achieve in water-tank models, velocity similarity violations can also be expected in water-tank models of other thermally driven meso-scale flows and our technique of explicitly including roughness length dependence may have wider applications.","PeriodicalId":122982,"journal":{"name":"The Open Atmospheric Science Journal","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126882772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Upslope Flows in Atmosphere and Water Tank, Part I: Scaling","authors":"C. Reuten, D. Steyn, S. Allen","doi":"10.2174/1874282301004010178","DOIUrl":"https://doi.org/10.2174/1874282301004010178","url":null,"abstract":"Upslope flows are a crucial mechanism in the transport of air pollutants in complex terrain, both as separate flow systems and as part of other thermally driven flows. Resolving steep complex terrain in numerical models requires horizontal resolutions that are difficult to achieve. Water-tank models of upslope flows provide additional insights but require idealizations that have typically limited comparisons with atmospheric observations to order-of-magnitude estimations. This paper applies scaling to a water tank that was specifically designed to achieve quantitative similarity with field measurements at a particular site. Non-dimensional boundary-layer depths near the base of slope in atmosphere and water tank agree within the measurement uncertainties of the field observations (20%). We show that boundary-layer depth and upslope flow velocity at any point in time are completely determined by instantaneous and integrated surface heat fluxes (from the beginning of positive heat flux to the point in time), regardless of the surface heat flux's particular path in time. While velocities in two independent tank experiments with steady and sinusoidal surface heat flux, respectively, agree reasonably well at the expected time of similarity, they disagree statistically significantly with velocities in the atmosphere. This disagreement implies a dependence on molecular quantities (viscosity, thermal diffusivity). Since different definitions of Reynolds numbers provide inconclusive values and both the appropriate velocity scale and length scale for a Reynolds number are functions of the flow itself, we derive an alternative set of governing parameters. This set provides the basis for a detailed hypothesis for the similarity violation of upslope flow velocities in atmosphere and water tank in a companion paper.","PeriodicalId":122982,"journal":{"name":"The Open Atmospheric Science Journal","volume":"42 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123182560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improvement of Mesoscale Forecasts of Monsoon Depressions Through Assimilation of QuikSCAT Wind Data: Two Case Studies Over India","authors":"P. Sinha, A. Chandrasekar","doi":"10.2174/1874282301004010160","DOIUrl":"https://doi.org/10.2174/1874282301004010160","url":null,"abstract":"Monsoon depressions form during the Southwest Indian Monsoon over the Bay of Bengal and provide copious rainfall over the eastern and central parts of the country. Since these depressions form over sea, a region of data scarcity, satellite data provides only source of information of the meteorological system. Furthermore, for short-range prediction, it is extremely important to have accurate initial conditions for better model performance. In this study, effects of three dimensional variational (3DVAR) assimilation of the Quick Scatterometer (QuikSCAT) data is used in the simulation of two monsoon depressions (MDs) that formed during 2-5 September and 27-30 September 2006 using the Weather Research and Forecast (WRF) modeling system. The National Center for Environmental Prediction - Global Forecast (NCEP-GFS) fields were used for the initial and lateral boundary conditions. Two model runs were employed in this study; first a control (CTRL) or a base run without any data assimilation and another a 3DVAR run in which QuikSCAT data was assimilated using the 3DVAR assimilation. The model results from both runs were compared with one another as well as with Tropical Rainfall Measurement Mission (TRMM) observations and Global Analysis (GFS-ANL) fields. The results of the time and area averaged vertical profile of relative vorticity over monsoon depressions indicate that the 3DVAR run is in closer agreement with GFS-ANL as compared to the CTRL run. Furthermore, the well-known temperature structure of a monsoon depression (cold core at low levels and warm core at upper levels) is better simulated by the 3DVAR run. While there is a clear and marked positive impact of ingesting the QuikSCAT data in terms of simulated precipitation for the depression that formed during 27-30 September 2006, improvement in the simulated rainfall due to QuikSCAT assimilation is slight for the other depression that formed during 2-5 September 2006. Consistent with the above observations, there is a clear improvement in the quantitative measures of the skill scores with lower bias, lower false alarms and higher probability of detection for almost all rainfall thresholds for the model runs which have assimilated the QuikSCAT observations.","PeriodicalId":122982,"journal":{"name":"The Open Atmospheric Science Journal","volume":"6 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126909932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observation of precipitation and drop-size distribution associated with a typhoon using VHF radar.","authors":"V. Anandan, C. Pan, K. Reddy, T. N. Rao, S. Rao","doi":"10.2174/1874282301004010114","DOIUrl":"https://doi.org/10.2174/1874282301004010114","url":null,"abstract":"This paper describes some of the microphysical and kinematic properties of precipitating systems associated with a typhoon using Chug-Li VHF radar. In order to gain a better understanding of these mechanisms and the vertical structure of the precipitation associated with a typhoon at different stages of development, an analysis has been carried out of the radar back-scattered signal in order to obtain the power, velocity and velocity width of the Doppler spectrum of clear air and hydrometeors. The vertical profiles of raindrop size distribution (DSD) parameters are estimated through model-based regression analysis. The study reveals that during a typhoon, different convective and stratiform types of precipitation occur at different times with varying intensities. This study also reports on some of the characteristic features of the convective systems observed during the typhoon.","PeriodicalId":122982,"journal":{"name":"The Open Atmospheric Science Journal","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134166309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Linkage Between Solar Insolation and Dust in the Major World Deserts","authors":"J. Barkan, P. Alpert","doi":"10.2174/1874282301004010101","DOIUrl":"https://doi.org/10.2174/1874282301004010101","url":null,"abstract":"The annual link between the solar insolation, the surface temperature, and the dust load in the atmosphere as estimated by the TOMS Aerosol Index was compared in five major sandy deserts around the globe. A high correlation was found between the insolation and the dust in all deserts, while the correlation of dust with temperature was lower. The peaks of the insolation and the dust occurred almost simultaneously on the same date in three out of the five deserts i.e. Sahara, S.W. North American, Atacama. In the other two deserts i.e., Australian, Taklimakan, the peak of the dust occurs earlier in the year. The temperature peaks occur on a later date in all the deserts. Our conclusion is, that in the deserts of the world the radiation is the major cause of the total dust loading. Alpert et al. 2006 (1) found that the total amount of dust in the atmosphere is highly correlated with the solar insolation over the Saharan desert. Moreover, the annual maximum is reached almost on the same day, while the maximum temperature occurs a month later. This high match exists in the very great expanse of the Sahara, while in smaller areas (like the three distinct parts of the Sahara that were examined), other variables, like the local topography, the synoptic situation, etc., appear to weaken the link between dust and insolation, thus lowering the correlation. The theoretical foundation for this high correlation was discussed in detail in that paper and are summarized in chapter 2 of this paper. In this manuscript, we compare the annual link between dust, solar insolation, and the surface temperature in the Sahara and four other major sandy deserts in the world. The four other deserts examined are: the sandy part of the Australian desert, the Arizona and Sonora deserts in the Southwestern U.S and Mexico, the Taklimakan Desert in China, and the Atacama Desert in Chile. We show that in all these deserts the role of solar insolation concerning dust loading is very important, even dominant. This, in spite of the smaller areas of these deserts when compared with the Sahara, as well as their less favorable environment, such as more rugged topography, and stronger and more erratic synoptic systems. One potential application of the present findings may be the direct incorporation of the solar insolation in dust prediction models. The strong correlation of radiation and dust load dates in the major deserts around the world can further improve these models. Better models for short and long term forecasting of dust events can aid in dealing with","PeriodicalId":122982,"journal":{"name":"The Open Atmospheric Science Journal","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127998889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Challenges Associated with Classifying Urban Meteorological Stations: The Oklahoma City Micronet Example","authors":"Amanda J. Schroeder, J. Basara, Bradley G. Illston","doi":"10.2174/1874282301004010088","DOIUrl":"https://doi.org/10.2174/1874282301004010088","url":null,"abstract":"During 2007-2008, a dense network of meteorological stations was deployed across the Oklahoma City metropolitan area to collect real-time, research-quality observations of atmospheric variables throughout the urban environment: the Oklahoma City Micronet (OKCNET). Because surface characteristics can be vastly different between rural and urban areas as well as throughout a city, significant variability exists in the local microclimates observed by meteorological stations deployed in an urban area. As such, documenting the characteristics near any site (i.e., metadata) is critical to fully understand the overall representativeness of the site and the associated evolution of atmospheric conditions. To date, a universal classification system for urban meteorological stations does not exist. Thus, this study utilized four different methodologies to classify OKCNET sites and increase the metadata for the individual sites and the overall network. The results demonstrated that while each classification system had specific merits, significant challenges existed in establishing consistent metadata for the sites due to (a) limitations associated with the methodologies and (b) the heterogeneity of surface conditions. In particular, stations deployed within the transition zones form urban to suburban and suburban to rural posed the greatest challenges in establishing consistent metadata for the sites.","PeriodicalId":122982,"journal":{"name":"The Open Atmospheric Science Journal","volume":"185 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132604983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Method of Correcting for Tilt from Horizontal in Downwelling Shortwave Irradiance Measurements on Moving Platforms","authors":"C. Long, A. Bucholtz, H. Jonsson, B. Schmid, A. Vogelmann, John Wood","doi":"10.2174/1874282301004010078","DOIUrl":"https://doi.org/10.2174/1874282301004010078","url":null,"abstract":"The downwelling shortwave irradiance typically consists of both a direct component of radiation from the sun, and a diffuse component of scattered sunlight from the sky. Significant offsets can occur in downwelling shortwave irradiance measurements made from moving platforms due to the tilt of the instruments from horizontal which changes the angular orientation of the direct component of sunlight to the instrument and causes an artificial variation in the measured signal. To properly correct for this tilt, a-priori knowledge of the partitioning between the direct and diffuse components of the total shortwave irradiance is needed to properly apply a correction for tilt. This partitioning information can be adequately provided using a newly available commercial radiometer named the SPN1 that produces reasonable measurements of the total and diffuse shortwave irradiance (and by subtraction the direct shortwave irradiance) with no moving parts and regardless of azimuthal orientation. We have developed methodologies for determining the constant pitch and roll offsets of the radiometers for aircraft applications, and for applying a tilt correction to the total shortwave irradiance data. Results suggest that the methodology is accurate for tilt up to +/-10°, with 90% of the data corrected to within 10 Wm -2 at least for clear-sky data. Without a proper tilt correction, even data limited to 5° of tilt can still exhibit large errors, greater than 100 Wm -2 in some cases. Given the low cost, low weight, and low power consumption of the SPN1 total and diffuse radiometer, opportunities previously excluded for moving platform measurements such as small Unmanned Aerial Vehicles and solar powered buoys now become feasible using our methodology. The increase in measurement accuracy is important, given current concerns over long-term climate variability and change especially over the 70% of the Earth's surface covered by ocean where long-term records of these measurements are sorely needed and must be made on ships and buoys.","PeriodicalId":122982,"journal":{"name":"The Open Atmospheric Science Journal","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126111749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of Variational Analysis of Wind Field Based on Lidar Conical Scans to Air Quality Monitoring","authors":"P. Chan, F. Yu","doi":"10.2174/1874282301004010064","DOIUrl":"https://doi.org/10.2174/1874282301004010064","url":null,"abstract":"Conical scans of Doppler LIDAR were made at a specific elevation angle to monitor the wind fields in cases of plume dispersion in western Australia. To better visualize the airflow patterns in relation to the plume direction, variational analysis is performed on the radial velocity data of the LIDAR to retrieve the 2D wind fields. Compared to the 4DVAR method, the 2D variational analysis as adopted in the present paper is computationally more efficient yet provides sufficient details of the flow patterns. Examples of the plume dispersion are shown with the 2D analyzed wind fields as presented in the paper. In general, the analyzed wind fields are consistent with the plume directions as observed from the backscattered power data of the LIDAR. A 2D wind retrieval algorithm developed for the Hong Kong International Airport (1) is used to derive the wind field from the Doppler LIDAR conical scans for an analysis of the plume dispersion at the Wagerup air quality monitoring experiment in Western Australia in 2006. The radial velocity data obtained from Doppler LIDAR scans are not straightforward for an interpretation of the wind vectors for relating to the plume dispersion. It would be quite handy to have the full wind vectors overlaid on top of the radial velocity data to assist the analysis of the wind dynamics and the dispersion mechanism. The 2D wind retrieval method is computationally more efficient than the four dimensional variational (4DVAR) LIDAR data analysis (2, 3). th and 29 th","PeriodicalId":122982,"journal":{"name":"The Open Atmospheric Science Journal","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121104208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}