Abstract This paper seeks to understand the role that climate variability has on annual yield of sugarcane in Louisiana. Unique features of sugarcane growth in Louisiana and nonclimatic, yield-influencing factors make this goal an interesting and challenging one. Several methods of seeking and establishing the relations between yield and climate variables are employed. First, yield–climate relations were investigated at a single research station where crop variety and growing conditions could be held constant and yield relations could be established between a predominant older crop variety and a newer one. Interviews with crop experts and a literature survey were used to identify potential climatic factors that control yield. A statistical analysis was performed using statewide yield data from the American Sugar Cane League from 1963 to 2002 and a climate database. Yield values for later years were adjusted downward to form an adjusted yield dataset. The climate database was principally constructed from d...
{"title":"Climate Variability and Sugarcane Yield in Louisiana","authors":"D. Greenland","doi":"10.1175/JAM2299.1","DOIUrl":"https://doi.org/10.1175/JAM2299.1","url":null,"abstract":"Abstract This paper seeks to understand the role that climate variability has on annual yield of sugarcane in Louisiana. Unique features of sugarcane growth in Louisiana and nonclimatic, yield-influencing factors make this goal an interesting and challenging one. Several methods of seeking and establishing the relations between yield and climate variables are employed. First, yield–climate relations were investigated at a single research station where crop variety and growing conditions could be held constant and yield relations could be established between a predominant older crop variety and a newer one. Interviews with crop experts and a literature survey were used to identify potential climatic factors that control yield. A statistical analysis was performed using statewide yield data from the American Sugar Cane League from 1963 to 2002 and a climate database. Yield values for later years were adjusted downward to form an adjusted yield dataset. The climate database was principally constructed from d...","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"114 1","pages":"1655-1666"},"PeriodicalIF":0.0,"publicationDate":"2005-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75756473","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 lake-breeze circulation that forms over Lake Michigan during the summer influences the Chicago, Illinois, metropolitan area’s weather in several ways. Of particular significance is the circulation’s effect on the dispersion of pollutants such as ozone and aerosols produced in and around the city. To investigate these effects, the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) was used to perform numerical simulations for two lake-breeze events—one in July 1999 and another in July 2002. The model runs were verified with data from several locations around the Chicago area. The simulated breeze circulation decreased the rate of increase in air temperature while penetrating roughly 12 km inland and lasting about 8 h, in reasonable agreement with observations. Furthermore, the inland penetration distance was related to the strength of the maximum vertical velocity within the front. Calculations of trajectories and transport of particle...
{"title":"The Characteristics of the Chicago Lake Breeze and Its Effects on Trace Particle Transport: Results from an Episodic Event Simulation","authors":"L. Harris, V. Kotamarthi","doi":"10.1175/JAM2301.1","DOIUrl":"https://doi.org/10.1175/JAM2301.1","url":null,"abstract":"Abstract The lake-breeze circulation that forms over Lake Michigan during the summer influences the Chicago, Illinois, metropolitan area’s weather in several ways. Of particular significance is the circulation’s effect on the dispersion of pollutants such as ozone and aerosols produced in and around the city. To investigate these effects, the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) was used to perform numerical simulations for two lake-breeze events—one in July 1999 and another in July 2002. The model runs were verified with data from several locations around the Chicago area. The simulated breeze circulation decreased the rate of increase in air temperature while penetrating roughly 12 km inland and lasting about 8 h, in reasonable agreement with observations. Furthermore, the inland penetration distance was related to the strength of the maximum vertical velocity within the front. Calculations of trajectories and transport of particle...","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"16 1","pages":"1637-1654"},"PeriodicalIF":0.0,"publicationDate":"2005-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79652406","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 On the basis of temporally sampled data obtained from satellites, spatial statistics of rainfall can be estimated. In this paper, the authors compare the estimated spatial statistics with their “true” or ensemble values calculated using 5 yr of 15-min radar-based rainfall data at a spatial domain of 512 km × 512 km in the central United States. The authors conducted a Monte Carlo sampling experiment to simulate different sampling scenarios for variable sampling intervals and rainfall averaging periods. The spatial statistics used are the moments of spatial distribution of rainfall, the spatial scaling exponents, and the spatial cross correlations between the sample and ensemble rainfall fields. The results demonstrated that the expected value of the relative error in the mean rain-rate estimate is zero for rainfall averaged over 5 days or longer, better temporal sampling produces average fields that are “less noisy” spatially, an increase in the sampling interval causes the sampled rainfall to be...
{"title":"Effect of Temporal Sampling on Inferred Rainfall Spatial Statistics","authors":"M. Gebremichael, W. Krajewski","doi":"10.1175/JAM2283.1","DOIUrl":"https://doi.org/10.1175/JAM2283.1","url":null,"abstract":"Abstract On the basis of temporally sampled data obtained from satellites, spatial statistics of rainfall can be estimated. In this paper, the authors compare the estimated spatial statistics with their “true” or ensemble values calculated using 5 yr of 15-min radar-based rainfall data at a spatial domain of 512 km × 512 km in the central United States. The authors conducted a Monte Carlo sampling experiment to simulate different sampling scenarios for variable sampling intervals and rainfall averaging periods. The spatial statistics used are the moments of spatial distribution of rainfall, the spatial scaling exponents, and the spatial cross correlations between the sample and ensemble rainfall fields. The results demonstrated that the expected value of the relative error in the mean rain-rate estimate is zero for rainfall averaged over 5 days or longer, better temporal sampling produces average fields that are “less noisy” spatially, an increase in the sampling interval causes the sampled rainfall to be...","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"18 1","pages":"1626-1633"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85043846","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}
During the wet season in the southwestern Amazon region, daytime water transport out of the atmospheric mixed layer into the deeper atmosphere is shown to depend upon cloud amounts and types and synoptic-scale velocity fields. Interactions among clouds, convective conditions, and subcloud-layer properties were estimated for two dominant flow regimes observed during the 1999 Tropical Rainfall Measuring Mission component of the Brazilian Large-Scale Biosphere–Atmosphere (TRMM-LBA) field campaign. During daytime the cloud and subcloud layers were coupled by radiative, convective, and precipitation processes. The properties of cloud and subcloud layers varied according to the different convective influences of easterly versus westerly lower-tropospheric flows. The most pronounced flow-regime effects on composite cloud cycles occurred under persistent lower-tropospheric flows, which produced strong convective cloud growth with a near absence of low-level stratiform clouds, minimal cumulative attenuation of incoming solar irradiance (25%), rapid daytime mixed-layer growth ( 100 mh 1 ), and boundary layer drying (0.22 g kg 1 h 1 ), high convective velocities (1.5 m s 1 ), high surface buoyancy flux ( 200 Wm 2 ), and high latent heat flux (600 W m 2 ) into cloud layer. In contrast, persistent westerly flows were less convective, showing a strong morning presence of low-level stratiform genera (0.9 cloud amount), greater cumulative attenuation of incoming solar irradiance (47%), slower mixed-layer growth ( 50 mh 1 ) with a slight tendency for mixed-layer moistening, and a delayed peak in the low-level cumuliform cloud cycle (2000 versus 1700 UTC). The results reported in this article indicate that numerical models need to account for cloud amounts and types when estimating water vapor transport to the cloud layer.
在亚马逊河西南地区的雨季，白天从大气混合层向深层大气的水输送取决于云的数量和类型以及天气尺度的速度场。对1999年巴西大尺度生物圈-大气(TRMM-LBA)野外活动的热带降雨测量任务组成部分观测到的两种主要气流形式的云、对流条件和亚云层特性之间的相互作用进行了估计。在白天，云层和亚云层通过辐射、对流和降水过程耦合。云层和亚云层的性质随对流层低层气流的东西风对流影响的不同而变化。对复合云周期影响最显著的是持续的对流层低层流动，这产生了强对流云增长，几乎没有低层层状云，入射太阳辐照度的累积衰减最小(25%)，日间混合层快速增长(100 mh 1)，边界层干燥(0.22 g kg 1 h 1)，高对流速度(1.5 m s 1)，高地表浮力通量(200 Wm 2)。高潜热通量(600 wm2)进入云层。相比之下，持续的西风对流较少，表现出强烈的低层层状云(0.9云量)的早晨存在，入射太阳辐照度的累积衰减更大(47%)，混合层增长较慢(50 mh 1)，混合层略有湿润趋势，低层积雨云周期的峰值延迟(2000年与1700 UTC)。本文报告的结果表明，数值模式在估计水汽输送到云层时需要考虑云的数量和类型。
{"title":"Daytime Cycle of Low-Level Clouds and the Tropical Convective Boundary Layer in Southwestern Amazonia","authors":"C. Strong, J. Fuentes, M. Garstang, A. Betts","doi":"10.1175/JAM2266.1","DOIUrl":"https://doi.org/10.1175/JAM2266.1","url":null,"abstract":"During the wet season in the southwestern Amazon region, daytime water transport out of the atmospheric mixed layer into the deeper atmosphere is shown to depend upon cloud amounts and types and synoptic-scale velocity fields. Interactions among clouds, convective conditions, and subcloud-layer properties were estimated for two dominant flow regimes observed during the 1999 Tropical Rainfall Measuring Mission component of the Brazilian Large-Scale Biosphere–Atmosphere (TRMM-LBA) field campaign. During daytime the cloud and subcloud layers were coupled by radiative, convective, and precipitation processes. The properties of cloud and subcloud layers varied according to the different convective influences of easterly versus westerly lower-tropospheric flows. The most pronounced flow-regime effects on composite cloud cycles occurred under persistent lower-tropospheric flows, which produced strong convective cloud growth with a near absence of low-level stratiform clouds, minimal cumulative attenuation of incoming solar irradiance (25%), rapid daytime mixed-layer growth ( 100 mh 1 ), and boundary layer drying (0.22 g kg 1 h 1 ), high convective velocities (1.5 m s 1 ), high surface buoyancy flux ( 200 Wm 2 ), and high latent heat flux (600 W m 2 ) into cloud layer. In contrast, persistent westerly flows were less convective, showing a strong morning presence of low-level stratiform genera (0.9 cloud amount), greater cumulative attenuation of incoming solar irradiance (47%), slower mixed-layer growth ( 50 mh 1 ) with a slight tendency for mixed-layer moistening, and a delayed peak in the low-level cumuliform cloud cycle (2000 versus 1700 UTC). The results reported in this article indicate that numerical models need to account for cloud amounts and types when estimating water vapor transport to the cloud layer.","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"55 1","pages":"1607-1619"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88401464","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 unique dataset obtained with combinations of minisodars and 915-MHz wind profilers at the Atmospheric Boundary Layer Experiments (ABLE) facility in Kansas was used to examine the detailed characteristics of the nocturnal low-level jet (LLJ). In contrast to instruments used in earlier studies, the ABLE instruments provide hourly, high-resolution vertical profiles of wind velocity from just above the surface to approximately 2 km above ground level (AGL). Furthermore, the 6-yr span of the dataset allowed the examination of interannual variability in jet properties with improved statistical reliability. It was found that LLJs occurred during 63% of the nighttime periods sampled. Although most of the observed jets were southerly, a substantial fraction (28%) was northerly. Wind maxima occurred most frequently at 200–400 m AGL, though some jets were found as low as 50 m, and the strongest jets tended to occur above 300 m. Comparison of LLJ heights at three locations within the ABLE domain and at one location outside the domain suggests that the jet is equipotential rather than terrain following. The occurrence of southerly LLJ varied annually in a way that suggests a connection between the tendency for jet formation and the large-scale circulation patterns associated with El Nino and La Nina, as well as with the Pacific decadal oscillation. Frequent and strong southerly jets that transport moisture downstream do not necessarily lead to more precipitation locally, however.
{"title":"Climatology of the Low-Level Jet at the Southern Great Plains Atmospheric Boundary Layer Experiments Site","authors":"Jie Song, Ke Liao, R. Coulter, B. Lesht","doi":"10.1175/JAM2294.1","DOIUrl":"https://doi.org/10.1175/JAM2294.1","url":null,"abstract":"A unique dataset obtained with combinations of minisodars and 915-MHz wind profilers at the Atmospheric Boundary Layer Experiments (ABLE) facility in Kansas was used to examine the detailed characteristics of the nocturnal low-level jet (LLJ). In contrast to instruments used in earlier studies, the ABLE instruments provide hourly, high-resolution vertical profiles of wind velocity from just above the surface to approximately 2 km above ground level (AGL). Furthermore, the 6-yr span of the dataset allowed the examination of interannual variability in jet properties with improved statistical reliability. It was found that LLJs occurred during 63% of the nighttime periods sampled. Although most of the observed jets were southerly, a substantial fraction (28%) was northerly. Wind maxima occurred most frequently at 200–400 m AGL, though some jets were found as low as 50 m, and the strongest jets tended to occur above 300 m. Comparison of LLJ heights at three locations within the ABLE domain and at one location outside the domain suggests that the jet is equipotential rather than terrain following. The occurrence of southerly LLJ varied annually in a way that suggests a connection between the tendency for jet formation and the large-scale circulation patterns associated with El Nino and La Nina, as well as with the Pacific decadal oscillation. Frequent and strong southerly jets that transport moisture downstream do not necessarily lead to more precipitation locally, however.","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"62 1","pages":"1593-1606"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81179652","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 Carbon dioxide (CO2) exchange processes were incorporated into a multilayer atmosphere–soil–vegetation model known as SOLVEG, and its performance was examined using measurements obtained from a grassland site. It was also applied for the CO2 budget calculation in the surface ecosystem. The characteristic feature of this model is that it is multilayered for the atmosphere, soil, and vegetation and includes sophisticated processes involving transmission of the solar and longwave radiation fluxes in the canopy. The model framework for the heat and water exchanges between the atmosphere and ground surface was validated by comparisons of ground surface heat fluxes between the calculated and observed values in the previous papers. In this study, a new model framework that includes the exchange process of CO2 along with those of heat, water, and momentum, which interact with each other, has been developed. The performance of the model was examined by comparing the calculated and observed values for surf...
{"title":"Incorporation of CO2 Exchange Processes into a Multilayer Atmosphere–Soil–Vegetation Model","authors":"H. Nagai","doi":"10.1175/JAM2293.1","DOIUrl":"https://doi.org/10.1175/JAM2293.1","url":null,"abstract":"Abstract Carbon dioxide (CO2) exchange processes were incorporated into a multilayer atmosphere–soil–vegetation model known as SOLVEG, and its performance was examined using measurements obtained from a grassland site. It was also applied for the CO2 budget calculation in the surface ecosystem. The characteristic feature of this model is that it is multilayered for the atmosphere, soil, and vegetation and includes sophisticated processes involving transmission of the solar and longwave radiation fluxes in the canopy. The model framework for the heat and water exchanges between the atmosphere and ground surface was validated by comparisons of ground surface heat fluxes between the calculated and observed values in the previous papers. In this study, a new model framework that includes the exchange process of CO2 along with those of heat, water, and momentum, which interact with each other, has been developed. The performance of the model was examined by comparing the calculated and observed values for surf...","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"31 1","pages":"1574-1592"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81615826","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 Accurately mapped meteorological data are an essential component for hydrologic and ecological research conducted at broad scales. A simple yet effective method for mapping daily weather conditions across heterogeneous landscapes is described and assessed. Daily weather data recorded at point locations are integrated with long-term-average climate maps to reconstruct spatially explicit estimates of daily precipitation and temperature extrema. The method uses ordinary kriging to interpolate base station data spatially into fields of approximately 2-km grain size. The fields are subsequently adjusted by 30-yr-average climate maps [Parameter-Elevation Regression on Independent Slopes Model (PRISM)], which incorporate adiabatic lapse rates, orographic effects, coastal proximity, and other environmental factors. The accuracy assessment evaluated an interpolation-only approach and the new method by comparing predicted and observed values from an independent validation dataset. The results of the accura...
{"title":"Climatologically Aided Mapping of Daily Precipitation and Temperature","authors":"Richard D. Hunter, R. Meentemeyer","doi":"10.1175/JAM2295.1","DOIUrl":"https://doi.org/10.1175/JAM2295.1","url":null,"abstract":"Abstract Accurately mapped meteorological data are an essential component for hydrologic and ecological research conducted at broad scales. A simple yet effective method for mapping daily weather conditions across heterogeneous landscapes is described and assessed. Daily weather data recorded at point locations are integrated with long-term-average climate maps to reconstruct spatially explicit estimates of daily precipitation and temperature extrema. The method uses ordinary kriging to interpolate base station data spatially into fields of approximately 2-km grain size. The fields are subsequently adjusted by 30-yr-average climate maps [Parameter-Elevation Regression on Independent Slopes Model (PRISM)], which incorporate adiabatic lapse rates, orographic effects, coastal proximity, and other environmental factors. The accuracy assessment evaluated an interpolation-only approach and the new method by comparing predicted and observed values from an independent validation dataset. The results of the accura...","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"1 1","pages":"1501-1510"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75198734","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}
Jun Li, Hung-Lung Huang, Chian‐Yi Liu, P. Yang, T. Schmit, Heli Wei, E. Weisz, L. Guan, W. P. Menzel
The Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) measurements from the NASA Earth Observing System Aqua satellite enable global monitoring of the distribution of clouds during day and night. The MODIS is able to provide a high-spatial-resolution (1–5 km) cloud mask, cloud classification mask, cloud-phase mask, cloud-top pressure (CTP), and effective cloud amount during both the daytime and the nighttime, as well as cloud particle size (CPS) and cloud optical thickness (COT) at 0.55 m during the daytime. The AIRS high-spectral-resolution measurements reveal cloud properties with coarser spatial resolution (13.5 km at nadir). Combined, MODIS and AIRS provide cloud microphysical properties during both the daytime and nighttime. A fast cloudy radiative transfer model for AIRS that accounts for cloud scattering and absorption is described in this paper. Onedimensional variational (1DVAR) and minimum-residual (MR) methods are used to retrieve the CPS and COT from AIRS longwave window region (790–970 cm 1 or 10.31–12.66 m, and 1050–1130 cm 1 or 8.85–9.52 m) cloudy radiance measurements. In both 1DVAR and MR procedures, the CTP is derived from the AIRS radiances of carbon dioxide channels while the cloud-phase information is derived from the collocated MODIS 1-km phase mask for AIRS CPS and COT retrievals. In addition, the collocated 1-km MODIS cloud mask refines the AIRS cloud detection in both 1DVAR and MR procedures. The atmospheric temperature profile, moisture profile, and surface skin temperature used in the AIRS cloud retrieval processing are from the European Centre for Medium-Range Weather Forecasts forecast analysis. The results from 1DVAR are compared with the operational MODIS products and MR cloud microphysical property retrieval. A Hurricane Isabel case study shows that 1DVAR retrievals have a high correlation with either the operational MODIS cloud products or MR cloud property retrievals. 1DVAR provides an efficient way for cloud microphysical property retrieval during the daytime, and MR provides the cloud microphysical property retrievals during both the daytime and nighttime.
美国国家航空航天局地球观测系统Aqua卫星的中分辨率成像光谱仪(MODIS)和大气红外探测器(AIRS)测量能够在白天和夜间对全球云的分布进行监测。MODIS能够提供高空间分辨率(1-5 km)的云掩模、云分类掩模、云相掩模、白天和夜间的云顶压力(CTP)和有效云量，以及白天0.55 m的云粒径(CPS)和云光学厚度(COT)。AIRS的高光谱分辨率测量揭示了云的特性，具有较粗的空间分辨率(最低点为13.5公里)。MODIS和AIRS结合起来，在白天和夜间提供云的微物理特性。本文介绍了一种考虑云散射和吸收的大气快速多云辐射传输模型。利用一维变分(1DVAR)和最小残差(MR)方法反演AIRS长波窗区(790 ~ 970 cm 1或10.31 ~ 12.66 m, 1050 ~ 1130 cm 1或8.85 ~ 9.52 m)云雾辐射测量值的CPS和COT。在1DVAR和MR过程中，CTP都是从AIRS的二氧化碳通道辐射中获得的，而云相信息则是从AIRS CPS和COT检索的MODIS 1公里相位掩模中获得的。此外，配置的1 km MODIS云掩模改进了1DVAR和MR过程中的AIRS云检测。AIRS云检索处理中使用的大气温度廓线、湿度廓线和地表皮肤温度来自欧洲中期天气预报中心的预报分析。将1DVAR结果与实际MODIS产品和MR云微物性检索结果进行了比较。飓风伊莎贝尔案例研究表明，1DVAR检索与MODIS云产品或MR云属性检索具有高度相关性。1DVAR为白天的云微物性检索提供了一种有效的方法，MR提供了白天和夜间的云微物性检索。
{"title":"Retrieval of Cloud Microphysical Properties from MODIS and AIRS","authors":"Jun Li, Hung-Lung Huang, Chian‐Yi Liu, P. Yang, T. Schmit, Heli Wei, E. Weisz, L. Guan, W. P. Menzel","doi":"10.1175/JAM2281.1","DOIUrl":"https://doi.org/10.1175/JAM2281.1","url":null,"abstract":"The Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) measurements from the NASA Earth Observing System Aqua satellite enable global monitoring of the distribution of clouds during day and night. The MODIS is able to provide a high-spatial-resolution (1–5 km) cloud mask, cloud classification mask, cloud-phase mask, cloud-top pressure (CTP), and effective cloud amount during both the daytime and the nighttime, as well as cloud particle size (CPS) and cloud optical thickness (COT) at 0.55 m during the daytime. The AIRS high-spectral-resolution measurements reveal cloud properties with coarser spatial resolution (13.5 km at nadir). Combined, MODIS and AIRS provide cloud microphysical properties during both the daytime and nighttime. A fast cloudy radiative transfer model for AIRS that accounts for cloud scattering and absorption is described in this paper. Onedimensional variational (1DVAR) and minimum-residual (MR) methods are used to retrieve the CPS and COT from AIRS longwave window region (790–970 cm 1 or 10.31–12.66 m, and 1050–1130 cm 1 or 8.85–9.52 m) cloudy radiance measurements. In both 1DVAR and MR procedures, the CTP is derived from the AIRS radiances of carbon dioxide channels while the cloud-phase information is derived from the collocated MODIS 1-km phase mask for AIRS CPS and COT retrievals. In addition, the collocated 1-km MODIS cloud mask refines the AIRS cloud detection in both 1DVAR and MR procedures. The atmospheric temperature profile, moisture profile, and surface skin temperature used in the AIRS cloud retrieval processing are from the European Centre for Medium-Range Weather Forecasts forecast analysis. The results from 1DVAR are compared with the operational MODIS products and MR cloud microphysical property retrieval. A Hurricane Isabel case study shows that 1DVAR retrievals have a high correlation with either the operational MODIS cloud products or MR cloud property retrievals. 1DVAR provides an efficient way for cloud microphysical property retrieval during the daytime, and MR provides the cloud microphysical property retrievals during both the daytime and nighttime.","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"28 1","pages":"1526-1543"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81600462","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 An operational suite of ground-based, remote sensing retrievals for producing cloud microphysical properties is described, assessed, and applied to 1 yr of observations in the Arctic. All measurements were made in support of the Surface Heat Budget of the Arctic (SHEBA) program and First International Satellite Cloud Climatology Project Regional Experiment (FIRE) Arctic Clouds Experiment (ACE) in 1997–98. Retrieval techniques and cloud-type classifications are based on measurements from a vertically pointing 35-GHz Doppler radar, microwave and infrared radiometers, and radiosondes. The retrieval methods are assessed using aircraft in situ measurements from a limited set of case studies and by intercomparison of multiple retrievals for the same parameters. In all-liquid clouds, retrieved droplet effective radii Re have an uncertainty of up to 32% and liquid water contents (LWC) have an uncertainty of 49%–72%. In all-ice clouds, ice particle mean sizes Dmean can be retrieved with an uncertainty of ...
{"title":"Arctic Cloud Microphysics Retrievals from Surface-Based Remote Sensors at SHEBA","authors":"M. Shupe, T. Uttal, S. Matrosov","doi":"10.1175/JAM2297.1","DOIUrl":"https://doi.org/10.1175/JAM2297.1","url":null,"abstract":"Abstract An operational suite of ground-based, remote sensing retrievals for producing cloud microphysical properties is described, assessed, and applied to 1 yr of observations in the Arctic. All measurements were made in support of the Surface Heat Budget of the Arctic (SHEBA) program and First International Satellite Cloud Climatology Project Regional Experiment (FIRE) Arctic Clouds Experiment (ACE) in 1997–98. Retrieval techniques and cloud-type classifications are based on measurements from a vertically pointing 35-GHz Doppler radar, microwave and infrared radiometers, and radiosondes. The retrieval methods are assessed using aircraft in situ measurements from a limited set of case studies and by intercomparison of multiple retrievals for the same parameters. In all-liquid clouds, retrieved droplet effective radii Re have an uncertainty of up to 32% and liquid water contents (LWC) have an uncertainty of 49%–72%. In all-ice clouds, ice particle mean sizes Dmean can be retrieved with an uncertainty of ...","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"107 1","pages":"1544-1562"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73217292","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 Exponential distributions of the type N = N0 exp(−λt) occur with a high frequency in a wide range of scientific disciplines. This paper argues against a widely spread method for calculating the λ parameter in this distribution. When the ln function is applied to both members, the equation of a straight line in t is obtained, which may be fit by means of linear regression. However, the paper illustrates that this is equivalent to a least squares fit with a weight function that assigns more importance to the higher values of t. It is argued that the method of maximum likelihood should be applied, because it takes into account all of the data equally. An iterative method for determining λ is proposed, based on the method of moments for cases in which only a truncated distribution is available.
N = N0 exp(−λt)型指数分布在许多科学学科中出现的频率很高。本文反对在这种分布中计算λ参数的一种广为流传的方法。当ln函数作用于两个成员时，得到t中的直线方程，可以用线性回归的方法拟合。然而，本文说明，这相当于最小二乘拟合与权重函数，赋予更大的重要性的t值。有人认为，最大似然的方法应该应用，因为它平等地考虑所有的数据。对于截断分布的情况，提出了一种基于矩量法的迭代求解λ的方法。
{"title":"Fitting an Exponential Distribution","authors":"R. Fraile, E. García‐Ortega","doi":"10.1175/JAM2271.1","DOIUrl":"https://doi.org/10.1175/JAM2271.1","url":null,"abstract":"Abstract Exponential distributions of the type N = N0 exp(−λt) occur with a high frequency in a wide range of scientific disciplines. This paper argues against a widely spread method for calculating the λ parameter in this distribution. When the ln function is applied to both members, the equation of a straight line in t is obtained, which may be fit by means of linear regression. However, the paper illustrates that this is equivalent to a least squares fit with a weight function that assigns more importance to the higher values of t. It is argued that the method of maximum likelihood should be applied, because it takes into account all of the data equally. An iterative method for determining λ is proposed, based on the method of moments for cases in which only a truncated distribution is available.","PeriodicalId":15026,"journal":{"name":"Journal of Applied Meteorology","volume":"2 1","pages":"1620-1625"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79358574","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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