Abstract Source–receptor relationships for mercury (Hg) and other trace elements wet deposited in southeastern Florida were investigated using daily event precipitation samples collected over a 1-yr period in 1995–96. Data collected in Davie, Florida, showed significantly higher (2.2 times) volume-weighted mean (VWM) Hg concentrations during the spring and summer seasons relative to winter. A meteorological tracer analysis, utilizing the ratio of trace elements lanthanum (La) to cerium (Ce), determined that “feed” air to precipitation cells arriving at the site incorporated local urban emissions more frequently during the spring and summer seasons. Using Weather Surveillance Radar-1988 Doppler (WSR-88D) data, analysis of precipitation-cell path histories for events collected at 17 sites in southeastern Florida over 1 month in the summer of 1995 showed significantly higher (2.0 times) VWM Hg concentrations in events with easterly cell paths than in those with westerly paths for storms arriving at Everglade...
{"title":"The Influence of Meteorological Conditions on the Wet Deposition of Mercury in Southern Florida","authors":"J. Dvonch, G. Keeler, F. Marsik","doi":"10.1175/JAM2272.1","DOIUrl":"https://doi.org/10.1175/JAM2272.1","url":null,"abstract":"Abstract Source–receptor relationships for mercury (Hg) and other trace elements wet deposited in southeastern Florida were investigated using daily event precipitation samples collected over a 1-yr period in 1995–96. Data collected in Davie, Florida, showed significantly higher (2.2 times) volume-weighted mean (VWM) Hg concentrations during the spring and summer seasons relative to winter. A meteorological tracer analysis, utilizing the ratio of trace elements lanthanum (La) to cerium (Ce), determined that “feed” air to precipitation cells arriving at the site incorporated local urban emissions more frequently during the spring and summer seasons. Using Weather Surveillance Radar-1988 Doppler (WSR-88D) data, analysis of precipitation-cell path histories for events collected at 17 sites in southeastern Florida over 1 month in the summer of 1995 showed significantly higher (2.0 times) VWM Hg concentrations in events with easterly cell paths than in those with westerly paths for storms arriving at Everglade...","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"44 1","pages":"1421-1435"},"PeriodicalIF":0.0,"publicationDate":"2005-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78674553","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}
Daily rainfall totals are a key input for hydrological models that are designed to simulate water and pollutant flow through both soil and waterways. Within New Zealand there are large areas and many river catchments where no long-term rainfall observations exist. A method for estimating daily rainfall over the whole of New Zealand on a 5-km grid is described and tested over a period from January 1985 to April 2002. Improvement over a spatial interpolation method was gained by scaling high-elevation rainfall estimates using simulated mesoscale model rainfall surfaces that are generated for short periods in 1994 and 1996. This method is judged to produce reasonable and useful estimates of daily rainfall.
{"title":"Generating Multiyear Gridded Daily Rainfall over New Zealand","authors":"A. Tait, R. Turner","doi":"10.1175/JAM2279.1","DOIUrl":"https://doi.org/10.1175/JAM2279.1","url":null,"abstract":"Daily rainfall totals are a key input for hydrological models that are designed to simulate water and pollutant flow through both soil and waterways. Within New Zealand there are large areas and many river catchments where no long-term rainfall observations exist. A method for estimating daily rainfall over the whole of New Zealand on a 5-km grid is described and tested over a period from January 1985 to April 2002. Improvement over a spatial interpolation method was gained by scaling high-elevation rainfall estimates using simulated mesoscale model rainfall surfaces that are generated for short periods in 1994 and 1996. This method is judged to produce reasonable and useful estimates of daily rainfall.","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"22 1 1","pages":"1315-1323"},"PeriodicalIF":0.0,"publicationDate":"2005-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73204639","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}
Abstract A detailed urban parameterization scheme is used in and above a street canyon. To validate this new scheme, the model is run offline on a vertical column (one-dimensional simulations), using measurements from a 30-m-high tower for upper boundary conditions. Measurements were obtained during the intensive observation period of the Basel Urban Boundary Layer Experiment (BUBBLE). Vertical profiles of meteorological variables are simulated in the street canyon. The validation of the parameterization is made with measurements from the tower in the street canyon and directly above roof height. The results show that the urban parameterization scheme is able to catch most of the typical processes that are induced by an urban surface near the ground. The fit to measured profiles is improved in comparison with a model using the traditional approach for urban parameterization (variation of z0 to take into account the presence of a city).
{"title":"Validation of an Urban Surface Exchange Parameterization for Mesoscale Models— 1D Case in a Street Canyon","authors":"Y. Roulet, A. Martilli, M. Rotach, A. Clappier","doi":"10.1175/JAM2273.1","DOIUrl":"https://doi.org/10.1175/JAM2273.1","url":null,"abstract":"Abstract A detailed urban parameterization scheme is used in and above a street canyon. To validate this new scheme, the model is run offline on a vertical column (one-dimensional simulations), using measurements from a 30-m-high tower for upper boundary conditions. Measurements were obtained during the intensive observation period of the Basel Urban Boundary Layer Experiment (BUBBLE). Vertical profiles of meteorological variables are simulated in the street canyon. The validation of the parameterization is made with measurements from the tower in the street canyon and directly above roof height. The results show that the urban parameterization scheme is able to catch most of the typical processes that are induced by an urban surface near the ground. The fit to measured profiles is improved in comparison with a model using the traditional approach for urban parameterization (variation of z0 to take into account the presence of a city).","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"56 1","pages":"1484-1498"},"PeriodicalIF":0.0,"publicationDate":"2005-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84780000","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}
Abstract A simplified scale of apparent temperature, considering only dry-bulb temperature and humidity, has become known as the temperature–humidity index (THI). The index was empirically constructed and was presented in the form of a table. It is often useful to have a formula instead for use in interpolation or for programming calculators or computers. The National Weather Service uses a polynomial multiple regression formula, but it is in some ways unsatisfactory. A new model of the THI is presented that is much simpler—having only 3 parameters as compared with 16 for the NWS model. The new model also more closely fits the tabulated values and has the advantage that it allows extrapolation outside of the temperature range of the table. Temperature–humidity pairs above the effective range of the NWS model are occasionally encountered, and the ability to extrapolate into colder temperature ranges allows the new model to be more effectively contained as part of a more general apparent temperature index.
{"title":"A New Empirical Model of the Temperature-Humidity Index","authors":"C. Schoen","doi":"10.1175/JAM2285.1","DOIUrl":"https://doi.org/10.1175/JAM2285.1","url":null,"abstract":"Abstract A simplified scale of apparent temperature, considering only dry-bulb temperature and humidity, has become known as the temperature–humidity index (THI). The index was empirically constructed and was presented in the form of a table. It is often useful to have a formula instead for use in interpolation or for programming calculators or computers. The National Weather Service uses a polynomial multiple regression formula, but it is in some ways unsatisfactory. A new model of the THI is presented that is much simpler—having only 3 parameters as compared with 16 for the NWS model. The new model also more closely fits the tabulated values and has the advantage that it allows extrapolation outside of the temperature range of the table. Temperature–humidity pairs above the effective range of the NWS model are occasionally encountered, and the ability to extrapolate into colder temperature ranges allows the new model to be more effectively contained as part of a more general apparent temperature index.","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"54 56 1","pages":"1413-1420"},"PeriodicalIF":0.0,"publicationDate":"2005-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86252680","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}
J. Pirttilä, M. Lehtinen, A. Huuskonen, M. Markkanen
Abstract Based on the measurement principles used on incoherent scatter radars, the authors have developed the Simultaneous Multiple Pulse Repetition Frequency (SMPRF) code that is intended to solve the range–Doppler dilemma and that can be used with modern magnetron radars. The working principle of the code is explained in mathematical terms and with the help of a simplified model. Results from the SMPRF and traditional fixed PRF weather radar measurements are compared, and the reasons for the differences are explained. The practical results show that the SMPRF code seems to work in the manner that is predicted by the theoretical and model calculations. The SMPRF code provides enough information to produce a high-resolution measured spectrum for each range gate. The shape of these measured spectra are seldom purely Gaussian. It is possible that more advanced raw products, other than just reflectivity, velocity, and width, can be produced with the help of these high-resolution spectra.
{"title":"A Proposed Solution to the Range–Doppler Dilemma of Weather Radar Measurements by Using the SMPRF Codes, Practical Results, and a Comparison with Operational Measurements","authors":"J. Pirttilä, M. Lehtinen, A. Huuskonen, M. Markkanen","doi":"10.1175/JAM2288.1","DOIUrl":"https://doi.org/10.1175/JAM2288.1","url":null,"abstract":"Abstract Based on the measurement principles used on incoherent scatter radars, the authors have developed the Simultaneous Multiple Pulse Repetition Frequency (SMPRF) code that is intended to solve the range–Doppler dilemma and that can be used with modern magnetron radars. The working principle of the code is explained in mathematical terms and with the help of a simplified model. Results from the SMPRF and traditional fixed PRF weather radar measurements are compared, and the reasons for the differences are explained. The practical results show that the SMPRF code seems to work in the manner that is predicted by the theoretical and model calculations. The SMPRF code provides enough information to produce a high-resolution measured spectrum for each range gate. The shape of these measured spectra are seldom purely Gaussian. It is possible that more advanced raw products, other than just reflectivity, velocity, and width, can be produced with the help of these high-resolution spectra.","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"34 1","pages":"1375-1390"},"PeriodicalIF":0.0,"publicationDate":"2005-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81083169","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}
J. Salmond, T. Oke, C. Grimmond, Sarah M. Roberts, B. Offerle
Turbulent fluxes of carbon dioxide and sensible heat were observed in the surface layer of the weakly convective nocturnal boundary layer over the center of the city of Marseille, France, during the Experience sur Sites pour Contraindre les Modeles de Pollution Atmospherique et de Transport d’Emission (ESCOMPTE) field experiment in the summer of 2001. The data reveal intermittent events or bursts in the time series of carbon dioxide (CO2) concentration and air temperature that are superimposed upon the background values. These features relate to intermittent structures in the fluxes of CO2 and sensible heat. In Marseille, CO2 is primarily emitted into the atmosphere at street level from vehicle exhausts. In a similar way, nocturnal sensible heat fluxes are most likely to originate in the deep street canyons that are warmer than adjacent roof surfaces. Wavelet analysis is used to examine the hypothesis that CO2 concentrations can be used as a tracer to identify characteristics of the venting of pollutants and heat from street canyons into the above-roof nocturnal urban boundary layer. Wavelet analysis is shown to be effective in the identification and analysis of significant events and coherent structures within the turbulent time series. Late in the evening, there is a strong correlation between the burst structures observed in the air temperature and CO2 time series. Evidence suggests that the localized increases of temperature and CO2 observed above roof level in the urban boundary layer (UBL) are related to intermittent venting of sensible heat from the warmer urban canopy layer (UCL). However, later in the night, local advection of CO2 in the UBL, combined with reduced traffic emissions in the UCL, limit the value of CO2 as a tracer of convective plumes in the UBL.
{"title":"Venting of Heat and Carbon Dioxide from Urban Canyons at Night","authors":"J. Salmond, T. Oke, C. Grimmond, Sarah M. Roberts, B. Offerle","doi":"10.1175/JAM2260.1","DOIUrl":"https://doi.org/10.1175/JAM2260.1","url":null,"abstract":"Turbulent fluxes of carbon dioxide and sensible heat were observed in the surface layer of the weakly convective nocturnal boundary layer over the center of the city of Marseille, France, during the Experience sur Sites pour Contraindre les Modeles de Pollution Atmospherique et de Transport d’Emission (ESCOMPTE) field experiment in the summer of 2001. The data reveal intermittent events or bursts in the time series of carbon dioxide (CO2) concentration and air temperature that are superimposed upon the background values. These features relate to intermittent structures in the fluxes of CO2 and sensible heat. In Marseille, CO2 is primarily emitted into the atmosphere at street level from vehicle exhausts. In a similar way, nocturnal sensible heat fluxes are most likely to originate in the deep street canyons that are warmer than adjacent roof surfaces. Wavelet analysis is used to examine the hypothesis that CO2 concentrations can be used as a tracer to identify characteristics of the venting of pollutants and heat from street canyons into the above-roof nocturnal urban boundary layer. Wavelet analysis is shown to be effective in the identification and analysis of significant events and coherent structures within the turbulent time series. Late in the evening, there is a strong correlation between the burst structures observed in the air temperature and CO2 time series. Evidence suggests that the localized increases of temperature and CO2 observed above roof level in the urban boundary layer (UBL) are related to intermittent venting of sensible heat from the warmer urban canopy layer (UCL). However, later in the night, local advection of CO2 in the UBL, combined with reduced traffic emissions in the UCL, limit the value of CO2 as a tracer of convective plumes in the UBL.","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"55 1","pages":"1180-1194"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91333456","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}
A. Uematsu, H. Hashiguchi, M. Teshiba, Hisamichi Tanaka, Koichi Hirashima, S. Fukao
Abstract Observations of fogs with a millimeter-wave scanning Doppler radar were conducted at Kushiro in Hokkaido, Japan, in the summer seasons of 1999 and 2000. Three typical types of plan position indicator (PPI) displays were observed: cellular echoes with high radar reflectivity factors (∼−10 dBZ), uniformly distributed echoes with high reflectivities (∼−10 dBZ), and uniformly distributed echoes with low reflectivities (∼−30 dBZ). The authors focused on advection fog with cellular echoes observed on 5 August 1999 and 31 July 2000. Echoes showed structures of cells with a reflectivity of −10 dBZ and with intervals of about 1 km. This echo pattern moved northward (i.e., from the sea to the land). There was a vertical shear of the horizontal wind at a height around 200 m in both cases, and structures of each cell were upright above the shear line and were leaning below it. The direction and the speed of the echo pattern in both PPI and range–height indicator (RHI) displays agreed well with that of the ho...
{"title":"Moving Cellular Structure of Fog Echoes Obtained with a Millimeter-Wave Scanning Doppler Radar at Kushiro, Japan","authors":"A. Uematsu, H. Hashiguchi, M. Teshiba, Hisamichi Tanaka, Koichi Hirashima, S. Fukao","doi":"10.1175/JAM2274.1","DOIUrl":"https://doi.org/10.1175/JAM2274.1","url":null,"abstract":"Abstract Observations of fogs with a millimeter-wave scanning Doppler radar were conducted at Kushiro in Hokkaido, Japan, in the summer seasons of 1999 and 2000. Three typical types of plan position indicator (PPI) displays were observed: cellular echoes with high radar reflectivity factors (∼−10 dBZ), uniformly distributed echoes with high reflectivities (∼−10 dBZ), and uniformly distributed echoes with low reflectivities (∼−30 dBZ). The authors focused on advection fog with cellular echoes observed on 5 August 1999 and 31 July 2000. Echoes showed structures of cells with a reflectivity of −10 dBZ and with intervals of about 1 km. This echo pattern moved northward (i.e., from the sea to the land). There was a vertical shear of the horizontal wind at a height around 200 m in both cases, and structures of each cell were upright above the shear line and were leaning below it. The direction and the speed of the echo pattern in both PPI and range–height indicator (RHI) displays agreed well with that of the ho...","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"83 1","pages":"1260-1273"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80728423","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}
Abstract The moment estimators frequently used to estimate parameters for drop size distribution (DSD) functions being “fitted” to observed raindrop size distributions are biased. Consequently, the fitted functions often do not represent well either the raindrop samples or the underlying populations from which the samples were taken. Monte Carlo simulations of the process of sampling from a known exponential DSD, followed by the application of a variety of moment estimators, demonstrate this bias. Skewness in the sampling distributions of the DSD moments is the root cause of this bias, and this skewness increases with the order of the moment. As a result, the bias is stronger when higher-order moments are used in the procedures. Correlations of the sample moments with the size of the largest drop in a sample (Dmax) lead to correlations of the estimated parameters with Dmax, and, in turn, to spurious correlations between the parameters. These things can lead to erroneous inferences about characteristics of...
{"title":"The Bias in Moment Estimators for Parameters of Drop Size Distribution Functions: Sampling from Exponential Distributions","authors":"Paul L. Smith, D. Kliche","doi":"10.1175/JAM2258.1","DOIUrl":"https://doi.org/10.1175/JAM2258.1","url":null,"abstract":"Abstract The moment estimators frequently used to estimate parameters for drop size distribution (DSD) functions being “fitted” to observed raindrop size distributions are biased. Consequently, the fitted functions often do not represent well either the raindrop samples or the underlying populations from which the samples were taken. Monte Carlo simulations of the process of sampling from a known exponential DSD, followed by the application of a variety of moment estimators, demonstrate this bias. Skewness in the sampling distributions of the DSD moments is the root cause of this bias, and this skewness increases with the order of the moment. As a result, the bias is stronger when higher-order moments are used in the procedures. Correlations of the sample moments with the size of the largest drop in a sample (Dmax) lead to correlations of the estimated parameters with Dmax, and, in turn, to spurious correlations between the parameters. These things can lead to erroneous inferences about characteristics of...","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"30 1","pages":"1195-1205"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87296526","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}
One of the goals of the Global Precipitation Measurement project, the successor to the Tropical Rainfall Measuring Mission (TRMM), is to produce a 3-hourly global rainfall map using several spaceborne microwave radiometers. It is important, although often difficult, to classify radiometer observations over land as either “rain” or “no rain” because background land surface conditions change significantly with time and location. In this study, a no-rain brightness temperature database was created to infer land surface conditions using simultaneous observations by TRMM Microwave Imager (TMI) and precipitation radar (PR) with a resolution of 1 month and 1° latitude 1° longitude. This paper proposes new rain/no-rain classification (RNC) methods that use the database to determine the background brightness temperature. The proposed RNC methods and the RNC method developed for the Goddard profiling algorithm (GPROF; the standard rain-rate retrieval algorithm for TMI) are applied to all TMI observations for the entire year of 2000, and the results are evaluated against the RNC made by PR as the “truth.” The first method (M1) simply uses the average brightness temperature at 85-GHz vertical polarization [denoted as TB (85 V)] under no-rain conditions as the background brightness temperature at 85-GHz vertical polarization [denoted as TBe (85 V)]. The second method (M2) uses a regression equation between TB (85 V) and TB (22 V) under no-rain conditions from the database. Here, TBe (85 V) is calculated by substituting the observed TB (22 V) into the regression equation. The ratio of accurate rain detection by GPROF to all rain occurrences detected by PR was 59%. This ratio was 57% for M1 and 63% for M2. The ratio with the weight of the rain rate was 81% for M1 and 86% for M2; it was 80% for GPROF. These comparisons were made by setting a threshold using a constant coefficient k0 to make the ratio of false rain detection to all no-rain occurrences detected by PR almost the same (approximately 0.85%) for all three methods. Further comparisons among the methods are made, and the reasons for the differences are investigated herein.
{"title":"Rain/No-Rain Classification Methods for Microwave Radiometer Observations over Land Using Statistical Information for Brightness Temperatures under No-Rain Conditions","authors":"S. Seto, N. Takahashi, T. Iguchi","doi":"10.1175/JAM2263.1","DOIUrl":"https://doi.org/10.1175/JAM2263.1","url":null,"abstract":"One of the goals of the Global Precipitation Measurement project, the successor to the Tropical Rainfall Measuring Mission (TRMM), is to produce a 3-hourly global rainfall map using several spaceborne microwave radiometers. It is important, although often difficult, to classify radiometer observations over land as either “rain” or “no rain” because background land surface conditions change significantly with time and location. In this study, a no-rain brightness temperature database was created to infer land surface conditions using simultaneous observations by TRMM Microwave Imager (TMI) and precipitation radar (PR) with a resolution of 1 month and 1° latitude 1° longitude. This paper proposes new rain/no-rain classification (RNC) methods that use the database to determine the background brightness temperature. The proposed RNC methods and the RNC method developed for the Goddard profiling algorithm (GPROF; the standard rain-rate retrieval algorithm for TMI) are applied to all TMI observations for the entire year of 2000, and the results are evaluated against the RNC made by PR as the “truth.” The first method (M1) simply uses the average brightness temperature at 85-GHz vertical polarization [denoted as TB (85 V)] under no-rain conditions as the background brightness temperature at 85-GHz vertical polarization [denoted as TBe (85 V)]. The second method (M2) uses a regression equation between TB (85 V) and TB (22 V) under no-rain conditions from the database. Here, TBe (85 V) is calculated by substituting the observed TB (22 V) into the regression equation. The ratio of accurate rain detection by GPROF to all rain occurrences detected by PR was 59%. This ratio was 57% for M1 and 63% for M2. The ratio with the weight of the rain rate was 81% for M1 and 86% for M2; it was 80% for GPROF. These comparisons were made by setting a threshold using a constant coefficient k0 to make the ratio of false rain detection to all no-rain occurrences detected by PR almost the same (approximately 0.85%) for all three methods. Further comparisons among the methods are made, and the reasons for the differences are investigated herein.","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"20 1","pages":"1243-1259"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87679882","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}
Abstract Total-sky imager (TSI) and hemispheric-sky imager (HSI) each have a hemispherical field of view, and many TSIs are now deployed. These instruments have been used routinely to provide a time series of the fractional sky cover only. In this study, the possible retrieval of cloud-base height (CBH) from TSI surface observations is examined. This paper presents a validation analysis of a new retrieval using both a model-output inverse problem and independent, ground-based micropulse lidar data. The obtained results suggest that, at least for single-layer cloud fields, moderately accurate (within ∼0.35 km) CBH retrieval is possible.
{"title":"Cloud-Base-Height Estimation from Paired Ground-Based Hemispherical Observations","authors":"E. Kassianov, C. Long, J. E. Christy","doi":"10.1175/JAM2277.1","DOIUrl":"https://doi.org/10.1175/JAM2277.1","url":null,"abstract":"Abstract Total-sky imager (TSI) and hemispheric-sky imager (HSI) each have a hemispherical field of view, and many TSIs are now deployed. These instruments have been used routinely to provide a time series of the fractional sky cover only. In this study, the possible retrieval of cloud-base height (CBH) from TSI surface observations is examined. This paper presents a validation analysis of a new retrieval using both a model-output inverse problem and independent, ground-based micropulse lidar data. The obtained results suggest that, at least for single-layer cloud fields, moderately accurate (within ∼0.35 km) CBH retrieval is possible.","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"437 1","pages":"1221-1233"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83657822","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}
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