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1.
The Dynamical-Statistical-Analog Ensemble Forecast model for landfalling tropical cyclones (TCs) precipitation (DSAEF_LTP) utilises an operational numerical weather prediction (NWP) model for the forecast track, while the precipitation forecast is obtained by finding analog cyclones, and making a precipitation forecast from an ensemble of the analogs. This study addresses TCs that occurred from 2004 to 2019 in Southeast China with 47 TCs as training samples and 18 TCs for independent forecast experiments. Experiments use four model versions. The control experiment DSAEF_LTP_1 includes three factors including TC track, landfall season, and TC intensity to determine analogs. Versions DSAEF_LTP_2, DSAEF_LTP_3, and DSAEF_LTP_4 respectively integrate improved similarity region, improved ensemble method, and improvements in both parameters. Results show that the DSAEF_LTP model with new values of similarity region and ensemble method (DSAEF_LTP_4) performs best in the simulation experiment, while the DSAEF_LTP model with new values only of ensemble method (DSAEF_LTP_3) performs best in the forecast experiment. The reason for the difference between simulation (training sample) and forecast (independent sample) may be that the proportion of TC with typical tracks (southeast to northwest movement or landfall over Southeast China) has changed significantly between samples. Forecast performance is compared with that of three global dynamical models (ECMWF, GRAPES, and GFS) and a regional dynamical model (SMS-WARMS). The DSAEF_LTP model performs better than the dynamical models and tends to produce more false alarms in accumulated forecast precipitation above 250 mm and 100 mm. Compared with TCs without heavy precipitation or typical tracks, TCs with these characteristics are better forecasted by the DSAEF_LTP model.  相似文献   

2.
In recent work, three physical factors of the Dynamical-Statistical-Analog Ensemble Forecast Model for Landfalling Typhoon Precipitation (DSAEF_LTP model) have been introduced, namely, tropical cyclone (TC) track, TC landfall season, and TC intensity. In the present study, we set out to test the forecasting performance of the improved model with new similarity regions and ensemble forecast schemes added. Four experiments associated with the prediction of accumulated precipitation were conducted based on 47 landfalling TCs that occurred over South China during 2004-2018. The first experiment was designed as the DSAEF_LTP model with TC track, TC landfall season, and intensity (DSAEF_LTP-1). The other three experiments were based on the first experiment, but with new ensemble forecast schemes added (DSAEF_LTP-2), new similarity regions added (DSAEF_LTP-3), and both added (DSAEF_LTP- 4), respectively. Results showed that, after new similarity regions added into the model (DSAEF_LTP-3), the forecasting performance of the DSAEF_LTP model for heavy rainfall (accumulated precipitation ≥250 mm and ≥100 mm) improved, and the sum of the threat score (TS250 + TS100) increased by 4.44%. Although the forecasting performance of DSAEF_LTP-2 was the same as that of DSAEF_LTP-1, the forecasting performance was significantly improved and better than that of DSAEF_LTP-3 when the new ensemble schemes and similarity regions were added simultaneously (DSAEF_LTP-4), with the TS increasing by 25.36%. Moreover, the forecasting performance of the four experiments was compared with four operational numerical weather prediction models, and the comparison indicated that the DSAEF_LTP model showed advantages in predicting heavy rainfall. Finally, some issues associated with the experimental results and future improvements of the DSAEF_LTP model were discussed.  相似文献   

3.
The seasonal forecasting skill with respect to the South Asian summer monsoon(SASM) was compared between the European Commission FP7 project(ENSEMBLES) and the Development of a European Multimodel Ensemble System for Seasonal to Interannual Prediction project(DEMETER). The Webster-Yang index(WYI) was chosen to represent the intensity of the SASM. First, the authors compared the ability to forecast the zonal wind at 850 h Pa(U850) and 200 h Pa(U200) between ENSEMBLES and DEMETER models. The results indicated that the models from the European Centre for Medium-Range Weather Forecasts, International Organization(ECMWF) and UK Met Office(UKMO) in ENSEMBLES possess greater skill in seasonally forecasting the JJA(June, July, and August) U850, U200, and U850 minus U200 than in DEMETER. Compared to in DEMETER, the JJA U200 and U850 minus U200 forecasting skill was greater for the model from MétéoFrance(MF) in ENSEMBLES over most of the SASM region. The three coupled models(ECMWF, MF, and UKMO), especially the UKMO model in ENSEMBLES, all demonstrated improved skill in their seasonal forecasts compared to in DEMETER with respect to the interannual variability of the SASM. The three ENSEMBLES models also showed better ability in forecasting the sea surface temperature anomalies(SSTAs) over the eastern equatorial Pacific and North Indian Ocean, and more accurately reproduced the large-scale atmospheric circulation and precipitation over northern India, which are related to the SASM. It seems that the couple between the atmospheric system and external forcing of ENSMBLES over Indian Ocean and Pacific is better than that of DEMETER.  相似文献   

4.
The number of tropical cyclone (TC) genesis over the South China Sea and the Northwest Pacific Ocean in 2009 is significantly less than the average (27.4). However, the number of landfall TC over mainland China and its associated rainfall is more than the average. This paper focuses on the performance of numerical weather prediction (NWP) of landfall TC precipitation over China in 2009. The China Meteorological Administration (CMA) and Japan Meteorological Agency (JMA) models are compared. Although the schemes of physical processes, the data assimilation system and the dynamic frame are entirely different for the two models, the results of forecast verification are similar to each other for TC rainfall and track except for TC Goni. In this paper, a day with daily rainfall amount greater than 50 mm was selected as a storm rain day when there was a TC affecting the mainland. There are 32 storm rain days related to the landing of typhoons and tropical depressions. The rainfall forecast verification methods of National Meteorological Centre (NMC) of CMA are selected to verify the models’ rainfall forecast. Observational precipitation analyses related to TCs in 2009 indicate a U-shape spatial distribution in China. It is found that the rain belt forecasted by the two models within 60 hours shows good agreement with observations, both in the location and the maximum rainfall center. Beyond 3 days, the forecasted rainfall belt shifts northward on average, and the rainfall amount of the model forecasts becomes under-predicted. The rainfall intensity of CMA model forecast is more reasonable than that of JMA model. For heavy rain, the JMA model made more missing forecasts. The TC rainfall is verified in Guangdong, Guangxi, Fujian and Hainan where rainfall amount related to TCs is relatively larger than in other regions. The results indicate that the model forecast for Guangdong and Guangxi is more skillful than that for Hainan. The rainfall forecast for Hainan remains difficult for the models because of insufficient observation data and special tropical ocean climate.  相似文献   

5.
A hydrological simulation in the Huaihe River Basin（HRB） was investigated using two different models： a coupled land surface hydrological model（CLHMS）, and a large-scale hydrological model（LSX-HMS）. The NCEP-NCAR reanalysis dataset and observed precipitation data were used as meteorological inputs. The simulation results from both models were compared in terms of flood processes forecasting during high flow periods in the summers of 2003 and 2007, and partial high flow periods in 2000. The comparison results showed that the simulated streamflow by CLHMS model agreed well with the observations with Nash-Sutcliffe coefficients larger than 0.76, in both periods of 2000 at Lutaizi and Bengbu stations in the HRB, while the skill of the LSX-HMS model was relatively poor. The simulation results for the high flow periods in 2003 and 2007 suggested that the CLHMS model can simulate both the peak time and intensity of the hydrological processes, while the LSX-HMS model provides a delayed flood peak. These results demonstrated the importance of considering the coupling between the land surface and hydrological module in achieving better predictions for hydrological processes, and CLHMS was proven to be a promising model for future applications in flood simulation and forecasting.  相似文献   

6.
Numerical Simulation of Long-Term Climate Change in East Asia   总被引：1，自引：0，他引：1       下载免费PDF全文
A 10-yr regional climate simulation was performed using the fifth-generation PSU/NCAR Mesoscale Model Version 3 (MM5V3) driven by large-scale NCEP/NCAR reanalyses. Simulations of winter and summer mean regional climate features were examined against observations. The results showed that the model could well simulate the 10-yr winter and summer mean circulation, temperature, and moisture transport at middle and low levels. The simulated winter and summer mean sea level pressure agreed with the NCAR/NCEP reanalysis data. The model could well simulate the distribution and intensity of winter mean precipitation rates as well as the distribution of summer mean precipitation rates, but it overestimated the summer mean precipitation over North China. The model's ability to simulate the regional climate change in winter was superior to that in summer. In addition, the model could simulate the inter-annual variation of seasonal precipitation and surface air temperature. Geopotential heights and temperature at middle and high levels between simulations and observations exhibited high anomaly correlation coefficients. The model also showed large variability to simulate the regional climate change associated with the El Nino events. The MM5V3 well simulated the anomalies of summer mean precipitation in 1992 and 1995, while it demonstrated much less ability to simulate that in 1998. Generally speaking, the MM5V3 is capable of simulating the regional climate change, and could be used for long-term regional climate simulation.  相似文献   

7.
Projections of future precipitation change over China are studied based on the output of a global AGCM, ECHAM5, with a high resolution of T319 (equivalent to 40 km). Evaluation of the model’s performance in simulating present-day precipitation shows encouraging results. The spatial distributions of both mean and extreme precipitation, especially the locations of main precipitation centers, are reproduced reasonably. The simulated annual cycle of precipitation is close to the observed. The performance of the model over eastern China is generally better than that over western China. A weakness of the model is the overestimation of precipitation over northern and western China. Analyses on the potential change in precipitation projected under the A1B scenario show that both annual mean precipitation intensity and extreme precipitation would increase significantly over southeastern China. The percentage increase in extreme precipitation is larger than that of mean precipitation. Meanwhile, decreases in mean and extreme precipitation are evident over the southern Tibetan Plateau. For precipitation days, extreme precipitation days are projected to increase over all of China. Both consecutive dry days over northern China and consecutive wet days over southern China would decrease.  相似文献   

8.
Medium to long-term precipitation forecasting plays a pivotal role in water resource management and development of warning systems.Recently,the Copernicus Climate Change Service(C3S)database has been releasing monthly forecasts for lead times of up to three months for public use.This study evaluated the ensemble forecasts of three C3S models over the period 1993-2017 in Iran’s eight classified precipitation clusters for one-to three-month lead times.Probabilistic and non-probabilistic criteria were used for evaluation.Furthermore,the skill of selected models was analyzed in dry and wet periods in different precipitation clusters.The results indicated that the models performed best in western precipitation clusters,while in the northern humid cluster the models had negative skill scores.All models were better at forecasting upper-tercile events in dry seasons and lower-tercile events in wet seasons.Moreover,with increasing lead time,the forecast skill of the models worsened.In terms of forecasting in dry and wet years,the forecasts of the models were generally close to observations,albeit they underestimated several severe dry periods and overestimated a few wet periods.Moreover,the multi-model forecasts generated via multivariate regression of the forecasts of the three models yielded better results compared with those of individual models.In general,the ECMWF and UKMO models were found to be appropriate for one-month-ahead precipitation forecasting in most clusters of Iran.For the clusters considered in Iran and for the long-range system versions considered,the Météo France model had lower skill than the other models.  相似文献   

9.
In phase Ⅱ of the Regional Climate Model Inter-comparison Project （RMIP） for Asia, the regional climate has been simulated for July 1988 through December 1998 by five regional climate models and one global variable resolution model. Comparison of the 10-year simulated precipitation with the observations was carried out. The results show that most models have the capacity to reproduce the basic spatial pattern of precipitation for Asia, and the main rainbelt can be reproduced by most models, but there are distinctions in the location and the intensity. Most models overestimate the precipitation over most continental regions. Interannual variability of the precipitation can also be basically simulated, while differences exist between various models and the observations. The biases in the stream field are important reasons behind the simulation errors of the Regional Climate Models （RCMs）. The cumulus scheme and land surface process have large influences on the precipitation simulation. Generally, the Grell cumulus scheme produces more precipitation than the Kuo scheme.  相似文献   

10.
This study evaluates the performance of the regional climate model RegCM4 in simulating tropical cyclone (TC) activities over the Western North Pacific (WNP) and their landfalling in China. The model is driven by ERA-Interim boundary conditions at a grid spacing of 25 km, with the simulation period as 1991–2010. Results show that RegCM4 performs well in capturing the main structural features of observed TCs, and in simulating the genesis number and annual cycle of the genesis. The model reproduces the general pattern of the observed TC tracks and occurrence frequency. However, significant underestimation of the occurrence frequency as well as the TC intensity is found. Number of the landfalling TCs over China is also much less than the observed. Bias of the model in reproducing the large-scale circulation pattern and steering flow may contribute to the underestimated landfalling TC numbers.  相似文献   

11.
On the determination of the height of the Ekman boundary layer   总被引：1，自引：1，他引：1  
The heighth of the Ekman turbulent boundary layer determined by the momentum flux profile is estimated with the aid of considerations of similarity and an analysis of the dynamic equations. Asymptotic formulae have been obtained showing that, with increasing instability,h increases as ¦¦1/2 (where is the non-dimensional stratification parameter); with increasing stability, on the other hand,h decreases as –1/2. For comparison, a simple estimate of the boundary-layer heighth u determined by the velocity profile is given. As is shown, in unstable stratification,h u behaves asymptotically as ¦¦–1, i.e., in a manner entirely different from that ofh .  相似文献   

12.
《大气与海洋》2012,50(4):77-91
The seasonal characteristics of water masses, mixed-layer depth and the current field east of Luzon Strait are studied using Argo profiling float data. Based on data from March 2006 to November 2010, the temperature-salinity relation indicates that the seasonal variation of water masses is not obvious, except that the surface temperature is lower and the salinity is higher in spring and winter; the water masses in other layers change little. The seasonal variation of the mixed-layer depth, which is deepest at over 170 m in winter and shallowest at about 25 m in summer, is also discussed. Based on the P-vector method, multi-year seasonal mean Argo data and Levitus data are used to calculate the respective current fields. The surface geostrophic current derived from altimetric data is compared with those computed from Argo data and Levitus data. It is shown that, the current field computed from Argo data, which shows the Kuroshio and eddies clearly, is similar to that obtained from altimetric data, except that the current speed is less in the former case than in the latter one; this may be related to the scarcity and uneven distribution of Argo floats, the subsequent interpolation and extrapolation errors, the shortcomings of the P-vector method, the lack of a barotropic component in the calculation or the altimetry-derived current error associated with the marine geoid, but the resultant current field is much better than that obtained from Levitus data. Moreover, Argo data have an advantage in that they can be used to derive a three-dimensional current field, whereas the altimetric data can only be used to derive the surface current field. The seasonal variations in the vertical current structure and the Kuroshio transport east of Taiwan Island are also discussed; it is found that the thickness of the northward Kuroshio is about 700 m, and the seasonal zonal variation in the main axis of the Kuroshio is obvious.

RÉSUMÉ?[Traduit par la rédaction] Nous étudions les caractéristiques saisonnières des masses d'eau, la profondeur de la couche de mélange et le champ de courant à l'est du détroit de Luçon à l'aide des données des flotteurs profileurs Argo. D'après les données recueillies entre mars 2006 et novembre 2010, la relation température-salinité indique que la variation saisonnière des masses d'eau n'est pas évidente, sauf que la température de surface est plus basse et la salinité plus élevée au printemps et en hiver; les masses d'eau dans les autres couches changent peu. Nous discutons aussi de la variation saisonnière de la profondeur de la couche de mélange, qui est maximale à plus de 170 m en hiver et minimale à environ 25 m en été. En nous basant sur la méthode des vecteurs P, nous utilisons les données Argo et les données Levitus pluriannuelles de moyennes saisonnières pour calculer les champs de courant respectifs. Nous comparons le courant géostrophique de surface déduit des données altimétriques avec ceux calculés à l'aide des données Argo et des données Levitus. Il apparait que le champ de courant calculé d'après les données Argo, qui montre clairement le Kuroshio et les remous, est semblable à celui obtenu des données altimétriques, sauf que la vitesse du courant est moindre dans le premier cas que dans le dernier; cela peut être lié à la rareté et à la distribution inégale des flotteurs Argo, aux erreurs subséquentes d'interpolation et d'extrapolation, aux faiblesses de la méthode des vecteurs P, au manque d'une composante barotropique dans les calculs ou à l'erreur dans le courant déduit des données altimétriques associée au géoïde marin, mais le champ de courant résultant est bien meilleur que celui obtenu à l'aide des données Levitus. De plus, les données Argo présentent l'avantage de pouvoir être utilisées pour déduire un champ de courant tridimensionnel, alors que les données altimétriques ne permettent que de déduire le champ de courant de surface. Nous discutons aussi des variations saisonnières dans la structure verticale du courant et dans le transport par le Kuroshio à l'est de l’île de Taïwan; nous trouvons que la profondeur du Kuroshio circulant vers le nord est d'environ 700 m et la variation saisonnière zonale dans l'axe principal du Kuroshio est évidente.  相似文献   

13.
The photodissociation coefficient, J NO2 of NO2 in the atmosphere was calculated at 235 and 298 K using the measured temperature dependences of the absorption cross-sections and quantum yields. These calculations gave a ratio J NO2(298 K)/J NO2(235 K)=1.155±0.010 which is only weakly dependent on altitude, surface albedo and solar zenith angle.  相似文献   

14.
Summary After an extended critical evaluation of a wealth of historical sources, the history of the Dead Sea level fluctuations is reviewed with accuracy since 1800 (Klein, 1961). Earlier data since 1100 AD based on landmarks and tree-ring data (Klein, 1982, 1985) are also summarized. Since 1930 interannual fluctuations are compared with area-averaged rainfall data from the western and eastern part of the catchment, as well as with rainfall records from Jerusalem and Amman. Correlation analysis lead to two linear regression equations for the period 1930/1931–1962/1963 (undisturbed) and 1963/1964–1983/1984 after diversion of water from Lake Tiberias and Jordan River. From these equations, the average annual effect of this diversion results to about –24 cm; in very moist years this effect is insignificant.
Zusammenfassung Auf der Grundlage einer kritischen Auswertung einer Fülle von Quellen werden zunächst die Spiegelschwankungen des Toten Meeres seit 1800 genau behandelt (Klein, 1961). Eine zusammenfassende Darstellung der Schwankungen ab 1100 A. D. wird aus historischen Quellen über die Landmarken des Seeufers und Baumringdaten (Klein, 1982, 1985) abgeleitet. Die interannulären Schwankungen des Seespiegels seit 1930 werden verglichen mit Gebietsmitteln des Niederschlages vom westlichen wie vom östlichen Teil des Einzugsgebietes, ebenso mit den Niederschlagsreihen von Jerusalem und Amman. Eine Korrelationsanalyse führt zu zwei linearen Regressionsgleichungen für die ungestörte Periode 1930/1931 bis 1962/1963, sowie für die Periode 1963/1964 bis 1983/1984, nach der Ableitung von Wasser zu Bewässerungszwecken aus dem See Genezareth und dem Jordan-Fluß. Eine Abschätzung des mittleren Effektes aus diesen Gleichungen ergibt etwa –24 cm pro Jahr; in sehr feuchten Jahren ist der Effekt unbedeutend.

With 4 Figures  相似文献   

15.
Summary The total amount of incoming radiation to the Earth' surface, for particular latitudes and for selected months, has been computed from recent investigations regarding the distribution of solar radiation penetrating the atmosphere. The charts constructed byBudyko andBerliand [1955] and byBlack [1956] under different theoretical assumptions are compared and discussed.The seasonal change in the amount of radiation has been investigated and the influence of prevailing cloudy conditions upon these amounts of heat has been illustrated by examples of desert and ocean regions. In desert regions the amount of radiation penetrating to the surface may reach a monthly mean of 74 per cent of the extraterrestrial solar radiation. Over ocean regions this percentage during months of maximum may reach only 50 per cent.The results give new evidence for two statements formulated elsewhere by the author (Burdecki [1955, 1957]) that (1) the thermal rhythm of the whole atmospheric ocean is dominated by the rhythm of the Northern Hemisphere; (2) the heat circulation over both hemispheres appears to be quite asymmetric.
Zusammenfassung Die durch die Atmosphäre bis zur Erdoberfläche gelangenden Globalstrahlungsmengen werden auf Grund neuer Forschungen über die Verteilung der Sonnenstrahlung für die einzelnen Breitengrade und für ausgewählte Monate berechnet. VonBudyko undBerliand [1955] und vonBlack [1956] unter Zugrundelegung verschiedener theoretischer Voraussetzungen konstruierte Karten werden verglichen und näher erörtert.Die jahreszeitliche Änderung der globalen Strahlungssummen wird untersucht und der Einfluß der vorherrschenden Bewölkung auf diese Wärmemengen wird durch Beispiele von Wüstenregionen und ozeanischen Gebieten näher erläutert. Im Wüstenklima kann die zur Erdoberfläche gelangende Wärmestrahlung im Monatsmittel sogar 74% der extraterrestrischen Sonnenstrahlung überschreiten. Für ozeanische Gebiete erreicht dieser Betrag in Monaten der Maxima höchstens 50%.Die Resultate weisen erneut auf zwei Feststellungen hin, die schon zuvor vom Verfasser (Burdecki [1955, 1957]) formuliert sind: 1. Die Wärmeschwankung des gesamten atmosphärischen Ozeans wird von der Schwankung der Nordhemisphäre beherrscht; 2. die Wärmezirkulation über beiden Hemisphären scheint in völliger Asymmetrie zu verlaufen.
Résumé Les résultats de récentes recherches sur la répartition du rayonnement solaire ont permis de calculer, pour différentes latitudes et pour certains mois, la quantité de rayonnement global qui, à travers l'atmosphère, parvient à la surface de la terre. L'auteur compare et discute les cartes qui ont été destinées parBudyko etBerliand en 1955 et parBlack en 1956 à partir de différentes hypothèses théoriques.On étudie en outre les variations saisonnières des sommes du rayonnement global; l'influence de la nébulosité dominante sur ces quantités de chaleur est discutée à l'aide d'exemples de régions à climat désertique et à climat maritime. Dans le climat désertique le rayonnement calorifique parvenant à la surface de la terre peut dépasser 74% du rayonnement solaire extraterrestre, tandis que dans les régions océaniques il atteint au maximum 50% pendant les mois les plus favorables.Les constatations que l'auteur avait faites ces dernières années (Burdecki [1955, 1957]) se voient confirmées: 1) le rythme thermique de tout l'océan atmosphérique est dominé par le rythme de l'hémisphère nord; 2) la circulation thermique au-dessus des deux hémisphères semble être tout à fait asymétrique.

With 5 Figures  相似文献   

16.
A partial balance of mineral N is given for the basins of two coastal rivers in a forest zone in the Ivory Coast. The dry and wet depositions on the basin surfaces is given for particulate matter (NO3 –, NH4 +). The quantity of mineral N washed away in the rivers is evaluated. The losses from leaching of the soils by rainwater are about 0.33 to 1.0% of the atmospheric depositions for NH4 +–N and 2.2 to 5.8% for NO3 ––N. The yearly atmospheric input of N compounds to the ecosystem, about 1.4 g N m–2 y–1, is at least 14% of mineral N formed in the soils and is therefore quite significant.  相似文献   

17.
Further laboratory studies of emission by O(1 S) and by O2 A 3 u + ,A3 u andc 1 u – in the oxygen afterglow lead to the conclusion that Barth's mechanism for the excitation of the auroral green line O 2 * +O(3P=O2+O(1S)–(1) is correct and that levelsv=6 and 7 of O2 A 3 u + are Barth precursors. The value ofk 1=7×10–11 cm3 s–1 deduced for these levels is shown to be in fair agreement with atmospheric measurements.  相似文献   

18.
In 1997 and 1998 several field campaigns for monitoring non-methane volatile organic compounds (NMVOCs) and nitrogen oxides (NOx) were carried out in a road traffic tunnel and in the city center of Wuppertal, Germany. C2–C10 aliphatic and aromatic hydrocarbons were monitored using a compact GC instrument. DOAS White and long path systems were used to measure aromatic hydrocarbons and oxygenated aromatic compounds. A formaldehyde monitor was used to measure formaldehyde. Chemiluminescence NO analysers with NO2 converter were used for measuring NO and NO2. The high mixing ratios of the NMVOCs observed in the road traffic tunnel, especially 2.9 ppbv phenol, 1.5ppbv para-cresol and 4.4 ppbv benzaldehyde, in comparison with themeasured background concentration clearly indicate that these compounds were directly emitted from road traffic. Para-Cresol was for the first timeselectively detected as primary pollutant from traffic. From the measured data a NMVOC profile of the tunnel air and the city air, normalised to benzene (ppbC/ppbC), was derived. For most compounds the observed city air NMVOC profile is almost identical with that obtained in the traffic tunnel. Since benzene originates mainly from road traffic emission, the comparison of the normalised emission ratios indicate that the road traffic emissions in Wuppertal have still the largest impact on the city air composition, which is in contrast to the German emission inventory. In both NMVOC profiles, aromatic compounds have remarkably large contributions of more than 40 ppbC%. In addtion, total NMVOC/NOx ratios from 0.6 up to 3.0ppbC/ppb in the traffic tunnel air and 3.4± 0.5 in the city air of Wuppertal were obtained. From the observed para-cresol/toluene and ortho-cresol/toluene ratios in the city air, evidence was found thatalso during daytime NO3 radical reactions play an important role in urban air.  相似文献   

19.
Summary In order to study the effect of the differential heating on the large scale sea surface flow pattern of the atmosphere vergence charts of the horizontal wind were constructed (January and July) and compared with the isotherm charts of the surface temperatures. For January a significant relation between the temperature field and the vergence field was found and this relation was as anticipated: convergence over the relatively warmer areas and divergence over the relatively colder areas. This effect is more pronounced at lower latitudes.The vergence chart of the ocean currents (January) shows in the region of the equatorial counter current a distribution of the vergence that is in good agreement with the scheme of the vertical circulation within the equatorial region of the Atlantic as proposed byA. Defant.
Zusammenfassung Zur Untersuchung der Auswirkung einer unterschiedlichen Erwärmung auf die großräumigen Strömungsformen der Atmosphäre über der Meeresoberfläche wurden Vergenzkarten der horizontalen Winde für Januar und Juli konstruiert und mit den Isothermenkarten der Oberflächentemperaturen verglichen. Für Januar wurde eine signifikante Beziehung zwischen dem Temperaturfeld und dem Vergenzfeld gefunden. Es zeigte sich Konvergenz über relativ wärmeren Gebieten und Divergenz über relativ kälteren Gebieten. Dieser Zusammenhang tritt in niedrigeren Breiten deutlicher in Erscheinung. Die Vergenzkarte der Meeresströmungen (Januar) zeigt im Gebiete des äquatorialen Gegenstromes eine Vergenzverteilung, die mit dem vonA. Defant angegebenen Schema der Vertikalzirkulation im äquatorialen Gebiet des Atlantiks in guter Übereinstimmung steht.
Résumé Dans le but d'étudier l'effet d'un réchauffement inégal sur les systèmes de circulation atmosphérique à grande échelle au-dessus des océans, l'auteur a dressé des cartes de divergence des vents horizontaux en janvier et en juillet, et les a comparées aux cartes d'isothermes de surface. En janvier il existe une relation significative entre les champs de température et de divergence; il y a convergence sur les régions relativement chaudes, et divergence sur les régions relativement froides. Cette relation est particulièrement nette aux basses latitudes. La carte de divergence des courants marins (janvier) montre dans la région du contre-courant équatorial une distribution de la divergence qui s'accorde avec le schéma de la circulation verticale donné parA. Defant pour la zone équatoriale de l'Atlantique.

With 10 Figures  相似文献   

20.
Summary From a study of five cases of pronounced fronts in the upper troposphere, it is concluded that the waterspout model offers the most satisfactory solution to the problem of connecting frontal boundaries and tropopauses. Composite cross sections of temperature, potential temperature, normal wind component and potential vorticity are presented for the five cases. On the basis of the potential vorticity measurements it is suggested that the most likely explanation for the formation of the high-level front is a folding of the tropopause.
Zusammenfassung Auf Grund einer Untersuchung von fünf Fällen ausgesprochener Fronten in der höheren Troposphäre wird der Schluß gezogen, daß die Wasserhosen-Vorstellung am besten den Zusammenhang zwischen Fronten und Tropopausen darstellt. Kombinierte Querschnitte von Temperatur, potentieller Temperatur, normaler Windkomponente und potentieller Vorticity werden für die fünf Fälle vorgelegt. Auf Grund der Bestimmungen der potentiellen Vorticity wird dargelegt, daß die wahrscheinlichste Erklärung für die Entstehung einer Front in der Höhe in der Annahme einer Faltung der Tropopause besteht.
Résumé En se fondant sur cinq cas de fronts très nets de la haute troposphère, les auteurs concluent que le schéma de trombe constitue la meilleure solution pour représenter la liaison entre zones frontales et tropopause. Ils donnent des profils combinés de température, de température potentielle, de composantes normales du vent et de vorticity potentielle pour les cinq cas. Ils montrent à l'aide de mesures de la vorticity potentielle que l'explication la plus probable de la formation d'un front en altitude consiste à admettre un plissement de la tropopause.

With 11 Figures

Contribution No. 37, Department of Meteorology and Climatology. —The research reported in this article has been supported by the Geophysical Research Directorate, Air Force Cambridge Research Center, under Contract No. AF 19 (604)-1811.  相似文献   

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