Pub Date : 2023-12-05DOI: 10.1175/jamc-d-23-0043.1
Jodie E. Clark, Sen Chiao
This study investigates the connection between the arrival of dry stratospheric air with the Soberanes Fire (2016). The Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT) and Goddard Earth Observing System Forward Processing model (GEOS-FP) are used for back-trajectories and offshore deep stratospheric intrusion (SI) in conjunction with the ignition and outbreak of the fire. The back-trajectory analysis indicates most air reaching the vertical column was critically dry, exhibiting relative humidity values below 10%. As the fire ignited, dry air arrived from due west at heights of 1-3 km about 24 hours prior. During the overnight fire growth, dry air arrived from the northwest to north-northwest at heights of 3.5-5.5 km 48-72 hours prior. The synoptic and the GEOS-FP analysis demonstrate offshore mid-to-low stratospheric intrusion. On July 21, 2016, an enclosed upper-level low approached the California/Oregon border along the northwesterly subtropical jet stream hours before the fire outbreak. The GEOS-FP results of potential vorticity, specific humidity, and ozone along the back-trajectories to the west and northwest of the fire suggest a stratospheric intrusion event into the mid-to-low troposphere at the back-trajectory start points, and vertical velocity indicates sinking motion. The specific humidity analyzed at the arrival time shows the transport of the abnormally dry air to the Soberanes Fire. Results suggest a connection between dry stratospheric air transported to the Soberanes Fire at ignition and overnight accelerated growth, supported by a dark bank in satellite water vapor imagery. The prediction of low-level transport of dry stratospheric air to the coastal communities could help predict the occurrence of wildfire outbreaks, or periods of accelerated fire growth.
{"title":"Connecting an Offshore Dry Air Stratospheric Intrusion with the Outbreak of Soberanes Fire 2016","authors":"Jodie E. Clark, Sen Chiao","doi":"10.1175/jamc-d-23-0043.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0043.1","url":null,"abstract":"\u0000This study investigates the connection between the arrival of dry stratospheric air with the Soberanes Fire (2016). The Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT) and Goddard Earth Observing System Forward Processing model (GEOS-FP) are used for back-trajectories and offshore deep stratospheric intrusion (SI) in conjunction with the ignition and outbreak of the fire. The back-trajectory analysis indicates most air reaching the vertical column was critically dry, exhibiting relative humidity values below 10%. As the fire ignited, dry air arrived from due west at heights of 1-3 km about 24 hours prior. During the overnight fire growth, dry air arrived from the northwest to north-northwest at heights of 3.5-5.5 km 48-72 hours prior. The synoptic and the GEOS-FP analysis demonstrate offshore mid-to-low stratospheric intrusion. On July 21, 2016, an enclosed upper-level low approached the California/Oregon border along the northwesterly subtropical jet stream hours before the fire outbreak. The GEOS-FP results of potential vorticity, specific humidity, and ozone along the back-trajectories to the west and northwest of the fire suggest a stratospheric intrusion event into the mid-to-low troposphere at the back-trajectory start points, and vertical velocity indicates sinking motion. The specific humidity analyzed at the arrival time shows the transport of the abnormally dry air to the Soberanes Fire. Results suggest a connection between dry stratospheric air transported to the Soberanes Fire at ignition and overnight accelerated growth, supported by a dark bank in satellite water vapor imagery. The prediction of low-level transport of dry stratospheric air to the coastal communities could help predict the occurrence of wildfire outbreaks, or periods of accelerated fire growth.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"68 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138600698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-01DOI: 10.1175/jamc-d-23-0058.1
Joana Mendes, Nosipho Zwane, Brighton Mabasa, H. Tazvinga, Karen Walter, C. Morcrette, Joel Botai
We assess site-specific surface short-wave radiation forecasts from two high resolution configurations of the South African Weather Service numerical weather prediction model, at 4 km and 1.5 km. The models exhibit good skill overall in forecasting surface short-wave radiation, with zero median error for all radiation components. This information is relevant to support a growing Renewable Energy sector in South Africa, particularly for photovoltaics. Further model performance analysis has shown an imbalance between cloud and solar radiation forecasting errors. In addition, cloud over-prediction does not necessarily equate to under-estimating solar radiation. Overcast cloud regimes are predicted too often with an associated positive mean radiation bias, whereas the relative abundance of partly cloudy regimes is under-predicted by the models with mixed radiation biases. Challenges highlighted by the misrepresentation of partly cloudy regimes in solar radiation error attribution may be used to inform improvements to the numerical core, namely the cloud and radiation schemes.
{"title":"An Analysis of the Effects of Clouds in High-Resolution Forecasting of Surface Short-wave Radiation in South Africa","authors":"Joana Mendes, Nosipho Zwane, Brighton Mabasa, H. Tazvinga, Karen Walter, C. Morcrette, Joel Botai","doi":"10.1175/jamc-d-23-0058.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0058.1","url":null,"abstract":"\u0000We assess site-specific surface short-wave radiation forecasts from two high resolution configurations of the South African Weather Service numerical weather prediction model, at 4 km and 1.5 km. The models exhibit good skill overall in forecasting surface short-wave radiation, with zero median error for all radiation components. This information is relevant to support a growing Renewable Energy sector in South Africa, particularly for photovoltaics. Further model performance analysis has shown an imbalance between cloud and solar radiation forecasting errors. In addition, cloud over-prediction does not necessarily equate to under-estimating solar radiation. Overcast cloud regimes are predicted too often with an associated positive mean radiation bias, whereas the relative abundance of partly cloudy regimes is under-predicted by the models with mixed radiation biases. Challenges highlighted by the misrepresentation of partly cloudy regimes in solar radiation error attribution may be used to inform improvements to the numerical core, namely the cloud and radiation schemes.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" 22","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138611550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-28DOI: 10.1175/jamc-d-23-0078.1
Jordan Clark, Charles E. Konrad
Wet bulb globe temperature (WBGT) is used to assess environmental heat stress and accounts for the influences of air temperature, humidity, wind speed, and radiation on heat stress. Measurements of WBGT are highly sensitive to slight changes in environmental conditions and can vary several degrees Celsius across small distances (10s to 100s of meters). Compared to observations with an ISO-compliant WBGT meter, this work assesses the accuracy of WBGT measurements made with a popular handheld meter (the Kestrel 5400 Heat Stress Tracker) and WBGT estimates. Measurements were made during the summers of 2019-2021 in a variety of suburban and urban environments in North Carolina, including three high school campuses. WBGT can be estimated from standard weather station variables, and many of these stations report cloud cover in lieu of solar radiation. Therefore, this work also evaluates the accuracy of clear-sky radiation estimates and adjustments to those estimates based on cloud cover. WBGT estimated with the method from Liljegren et al. (2008) from a weather station were on average 0.2°C warmer than observed WBGT, while the Kestrel 5400 WBGT was 0.7°C warmer. Large variations in WBGT were observed across surfaces and shade conditions, with differences of 0.9°C (0.3–1.4°C) between a tennis court and a neighboring grass field. The method for estimating clear-sky radiation in Ryan & Stolzenbach (1972) was most accurate and the clear-sky radiation modified by percentage cloud cover was found to be within 75 w/m2 of observations on average.
{"title":"Observations and Estimates of Wet Bulb Globe Temperature in Varied Microclimates","authors":"Jordan Clark, Charles E. Konrad","doi":"10.1175/jamc-d-23-0078.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0078.1","url":null,"abstract":"Wet bulb globe temperature (WBGT) is used to assess environmental heat stress and accounts for the influences of air temperature, humidity, wind speed, and radiation on heat stress. Measurements of WBGT are highly sensitive to slight changes in environmental conditions and can vary several degrees Celsius across small distances (10s to 100s of meters). Compared to observations with an ISO-compliant WBGT meter, this work assesses the accuracy of WBGT measurements made with a popular handheld meter (the Kestrel 5400 Heat Stress Tracker) and WBGT estimates. Measurements were made during the summers of 2019-2021 in a variety of suburban and urban environments in North Carolina, including three high school campuses. WBGT can be estimated from standard weather station variables, and many of these stations report cloud cover in lieu of solar radiation. Therefore, this work also evaluates the accuracy of clear-sky radiation estimates and adjustments to those estimates based on cloud cover. WBGT estimated with the method from Liljegren et al. (2008) from a weather station were on average 0.2°C warmer than observed WBGT, while the Kestrel 5400 WBGT was 0.7°C warmer. Large variations in WBGT were observed across surfaces and shade conditions, with differences of 0.9°C (0.3–1.4°C) between a tennis court and a neighboring grass field. The method for estimating clear-sky radiation in Ryan & Stolzenbach (1972) was most accurate and the clear-sky radiation modified by percentage cloud cover was found to be within 75 w/m2 of observations on average.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"59 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139222394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-23DOI: 10.1175/jamc-d-22-0112.1
Ruth Mendez-Rivas, Maycol Mena Palacios, Reiner Palomino Lemus
We investigated 9 indices of Spatio-temporal extreme precipitation events over Nicaragua during 2001-2016, from GPCC, CHIRPS, and IMERG, and their correlation with teleconnection patterns. The main objectives were to evaluate the variability of extreme precipitation events, to know the performance of IMERG and CHIRPS in the characterization of these extreme events, using GPCC and 4 rain gauges as references, and finally to determine the teleconnection patterns that have the highest correlation with these indices. The spatial coverage of the area with the highest number of consecutive days with daily precipitation less than 1 mm corresponds to the Pacific region, with annual mean values of up to 120 continuous days. Some extreme precipitation event indices (RR, RX1day, and RX5day) show a decreasing trend, suggesting that the study area has been experiencing a reduction of extreme precipitation indices in terms of intensities and duration throughout the study period. In addition, it was observed that CHIRPS shows a better fit when dealing with precipitation events that do not exceed certain thresholds and IMERG improves when describing intense precipitation event patterns. We found that EOFPAC, NIÑA 3.4, PACWARM, and SOI have a greater influence on extreme precipitation events, these results suggest that they are being controlled by ENSO episodes, providing a better understanding of the climate configuration, as a prediction and forecasting potential, useful for agriculture, land use and risk management.
{"title":"Spatiotemporal variability of extreme rainfall indices over Nicaragua between 2001-2016 and their relationship with teleconnection patterns","authors":"Ruth Mendez-Rivas, Maycol Mena Palacios, Reiner Palomino Lemus","doi":"10.1175/jamc-d-22-0112.1","DOIUrl":"https://doi.org/10.1175/jamc-d-22-0112.1","url":null,"abstract":"We investigated 9 indices of Spatio-temporal extreme precipitation events over Nicaragua during 2001-2016, from GPCC, CHIRPS, and IMERG, and their correlation with teleconnection patterns. The main objectives were to evaluate the variability of extreme precipitation events, to know the performance of IMERG and CHIRPS in the characterization of these extreme events, using GPCC and 4 rain gauges as references, and finally to determine the teleconnection patterns that have the highest correlation with these indices. The spatial coverage of the area with the highest number of consecutive days with daily precipitation less than 1 mm corresponds to the Pacific region, with annual mean values of up to 120 continuous days. Some extreme precipitation event indices (RR, RX1day, and RX5day) show a decreasing trend, suggesting that the study area has been experiencing a reduction of extreme precipitation indices in terms of intensities and duration throughout the study period. In addition, it was observed that CHIRPS shows a better fit when dealing with precipitation events that do not exceed certain thresholds and IMERG improves when describing intense precipitation event patterns. We found that EOFPAC, NIÑA 3.4, PACWARM, and SOI have a greater influence on extreme precipitation events, these results suggest that they are being controlled by ENSO episodes, providing a better understanding of the climate configuration, as a prediction and forecasting potential, useful for agriculture, land use and risk management.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"365 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139246003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-22DOI: 10.1175/jamc-d-22-0181.1
Austin P. Hope, Israel Lopez-Coto, K. Hajny, J. Tomlin, R. Kaeser, B. Stirm, A. Karion, P. Shepson
We investigated the ability of three planetary boundary layer (PBL) schemes in the Weather Research and Forecasting (WRF) model to simulate boundary layer turbulence in the “grey zone” (i.e. resolutions from 100 m to 1 km). The three schemes chosen are the well-established MYNN PBL scheme and the two newest PBL schemes added to WRF: the SMS-3DTKE scheme and the EEPS scheme. The SMS-3DTKE scheme is designed to be scale-aware and avoid the double-counting of turbulent kinetic energy (TKE) in simulations within the grey zone. We evaluated their performance using aircraft measurements obtained during three research flights immediately downwind of Manhattan, New York City. The MYNN PBL scheme simulates TKE best, despite not being scale-aware and slightly underestimating TKE from observations, while the SMS-3DTKE scheme appears to be overly scale-aware for the three flights examined, in particular when combined with the MM5 surface layer scheme. The EEPS scheme significantly underestimates TKE, mostly in the elevated layers of the boundary layer. Additionally, we examined the impact of flow over tall buildings on observed TKE and found that only the windiest day showed a significant increase in TKE directly downwind of Manhattan. This impact was, however, not reproduced by any of the model configurations, regardless of the land use data selected, although the better resolved NLCD land use led to a slight improvement of the spatial distribution of TKE, implying that more explicit representation of the impact of tall buildings may be needed to fully capture their impact on boundary layer turbulence.
{"title":"Analyzing “grey zone” turbulent kinetic energy predictions in the boundary layer from three WRF PBL schemes over New York City and comparison to aircraft measurements","authors":"Austin P. Hope, Israel Lopez-Coto, K. Hajny, J. Tomlin, R. Kaeser, B. Stirm, A. Karion, P. Shepson","doi":"10.1175/jamc-d-22-0181.1","DOIUrl":"https://doi.org/10.1175/jamc-d-22-0181.1","url":null,"abstract":"We investigated the ability of three planetary boundary layer (PBL) schemes in the Weather Research and Forecasting (WRF) model to simulate boundary layer turbulence in the “grey zone” (i.e. resolutions from 100 m to 1 km). The three schemes chosen are the well-established MYNN PBL scheme and the two newest PBL schemes added to WRF: the SMS-3DTKE scheme and the EEPS scheme. The SMS-3DTKE scheme is designed to be scale-aware and avoid the double-counting of turbulent kinetic energy (TKE) in simulations within the grey zone. We evaluated their performance using aircraft measurements obtained during three research flights immediately downwind of Manhattan, New York City. The MYNN PBL scheme simulates TKE best, despite not being scale-aware and slightly underestimating TKE from observations, while the SMS-3DTKE scheme appears to be overly scale-aware for the three flights examined, in particular when combined with the MM5 surface layer scheme. The EEPS scheme significantly underestimates TKE, mostly in the elevated layers of the boundary layer. Additionally, we examined the impact of flow over tall buildings on observed TKE and found that only the windiest day showed a significant increase in TKE directly downwind of Manhattan. This impact was, however, not reproduced by any of the model configurations, regardless of the land use data selected, although the better resolved NLCD land use led to a slight improvement of the spatial distribution of TKE, implying that more explicit representation of the impact of tall buildings may be needed to fully capture their impact on boundary layer turbulence.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"154 ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139246693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-21DOI: 10.1175/jamc-d-23-0034.1
R. Sospedra‐Alfonso, W. Merryfield, Viatsheslav V. Kharin, Woo-Sung Lee, Hai Lin, G. T. Diro, Ryan Muncaster
We evaluate the soil moisture hindcasts and the reconstruction runs giving the hindcasts initial conditions in version 2.1 of the Canadian Seasonal to Interannual Prediction System (CanSIPSv2.1). Different strategies are used to initialize the hindcasts for the two CanSIPSv2.1 models, CanCM4i and GEM5-NEMO, with contrasting impacts on the soil moisture initial conditions and forecast performance. Forecast correlation skill is decomposed into contributions from persistence of the initial anomalies and contributions not linked to persistence, with performance largely driven by the accuracy of the initial conditions in regions of strong persistence. Seasonal soil moisture correlation skill is significant for several months into the hindcasts depending on initial and target months, with contributions not linked to persistence becoming more notable at longer lead times. For the first 2-4 months, the quality of CanSIPSv2.1 ensemble mean forecasts tend to be higher on average during summer and fall, and is comparable to that of the best performing model, whereas CanSIPSv2.1 outperforms the single models during spring and winter. For longer lead times, remote climate influences from the Pacific Ocean are notable and contribute to predictable soil moisture variability in teleconnected regions.
{"title":"Evaluation of soil moisture in the Canadian Seasonal to Interannual Prediction System version 2.1 (CanSIPSv2.1)","authors":"R. Sospedra‐Alfonso, W. Merryfield, Viatsheslav V. Kharin, Woo-Sung Lee, Hai Lin, G. T. Diro, Ryan Muncaster","doi":"10.1175/jamc-d-23-0034.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0034.1","url":null,"abstract":"We evaluate the soil moisture hindcasts and the reconstruction runs giving the hindcasts initial conditions in version 2.1 of the Canadian Seasonal to Interannual Prediction System (CanSIPSv2.1). Different strategies are used to initialize the hindcasts for the two CanSIPSv2.1 models, CanCM4i and GEM5-NEMO, with contrasting impacts on the soil moisture initial conditions and forecast performance. Forecast correlation skill is decomposed into contributions from persistence of the initial anomalies and contributions not linked to persistence, with performance largely driven by the accuracy of the initial conditions in regions of strong persistence. Seasonal soil moisture correlation skill is significant for several months into the hindcasts depending on initial and target months, with contributions not linked to persistence becoming more notable at longer lead times. For the first 2-4 months, the quality of CanSIPSv2.1 ensemble mean forecasts tend to be higher on average during summer and fall, and is comparable to that of the best performing model, whereas CanSIPSv2.1 outperforms the single models during spring and winter. For longer lead times, remote climate influences from the Pacific Ocean are notable and contribute to predictable soil moisture variability in teleconnected regions.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"1 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139251001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-15DOI: 10.1175/jamc-d-23-0031.1
Shanchuan Xiao, Di Cheng, Ning Hu, Yongwei Wang, Huilin Zhang, Yuwang Gou, Xiang Li, Zhenglin Lv
The use of high-albedo roof materials is a simple and effective way to reduce roof temperature, conserve electricity required for air conditioning, and ease power shortages. In this study, three common cooling roof materials, namely white elastomeric acrylic (AC) paint, a white thermoplastic polyolefin (TPO) membrane, and an aluminum foil composite film–covered styrene–butadiene–styrene bituminous (SBS) membranes, were chosen to conduct a nearly-four-year experiment in Nanjing, China, to study the difference in surface temperatures (ΔTs) between the cooling roof materials and concrete. The results showed that even during heat waves, ΔTs was only 2.1° (AC), 3.8° (TPO), and 7.0° (SBS) on average and 6.9°–18.2° to the greatest extent, which was far less than those reported by many studies. The intensity of solar radiation where the cooling roof material is used and the roof material’s albedo contribute to the difference in ΔTs. The initial albedo of the AC was 0.53 and dropped to 0.16 due to rapid aging, which is close to that of concrete, in less than three months. The albedo of TPO and SBS dropped to 0.16 after 9 and 4.7 years, respectively. Further, SBS is optimal choice in terms of cost and performance, costing only 0.67 USD m−2 per year. However, its albedo exhibits seasonal fluctuations and is significantly affected by air pollution. In particular, particulate matter settles on the surface, thereby decreasing the albedo. Nevertheless, manual cleaning can recover the albedo, extend service life, and further reduce costs.
{"title":"Experiments on the thermal performance and service life of three high-albedo roof materials in Nanjing, China","authors":"Shanchuan Xiao, Di Cheng, Ning Hu, Yongwei Wang, Huilin Zhang, Yuwang Gou, Xiang Li, Zhenglin Lv","doi":"10.1175/jamc-d-23-0031.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0031.1","url":null,"abstract":"The use of high-albedo roof materials is a simple and effective way to reduce roof temperature, conserve electricity required for air conditioning, and ease power shortages. In this study, three common cooling roof materials, namely white elastomeric acrylic (AC) paint, a white thermoplastic polyolefin (TPO) membrane, and an aluminum foil composite film–covered styrene–butadiene–styrene bituminous (SBS) membranes, were chosen to conduct a nearly-four-year experiment in Nanjing, China, to study the difference in surface temperatures (ΔTs) between the cooling roof materials and concrete. The results showed that even during heat waves, ΔTs was only 2.1° (AC), 3.8° (TPO), and 7.0° (SBS) on average and 6.9°–18.2° to the greatest extent, which was far less than those reported by many studies. The intensity of solar radiation where the cooling roof material is used and the roof material’s albedo contribute to the difference in ΔTs. The initial albedo of the AC was 0.53 and dropped to 0.16 due to rapid aging, which is close to that of concrete, in less than three months. The albedo of TPO and SBS dropped to 0.16 after 9 and 4.7 years, respectively. Further, SBS is optimal choice in terms of cost and performance, costing only 0.67 USD m−2 per year. However, its albedo exhibits seasonal fluctuations and is significantly affected by air pollution. In particular, particulate matter settles on the surface, thereby decreasing the albedo. Nevertheless, manual cleaning can recover the albedo, extend service life, and further reduce costs.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"13 3","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139273449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-08DOI: 10.1175/jamc-d-23-0018.1
Rouyi Jiang, Xiaopeng Cui, Jian Lin, Jia Tian
Abstract Southwest China (SWC) possesses complicated topography with frequent geological activities, where heavy precipitation occurs frequently in warm seasons. Few previous studies on extreme precipitation were carried out at hourly scales. In this study, spatiotemporal variations of the extreme hourly precipitation (EHP) over SWC during the warm season of 1981-2020 and the involved mechanisms are investigated. Results show that the threshold and intensity of EHP present similar spatial distribution—lower (higher) in the west (east) part of SWC, while the EHP frequency is opposite. The long-term trend of EHP amount shows a more significant positive tendency than that of hourly precipitation (HP) amount, due to synchronous increases in intensity and frequency. The significant increasing trend of EHP occurs in areas above 500 m terrain height, with a weak increasing trend below 500 m (e.g., Chongqing and eastern Sichuan). EHP appears mainly from June to August and exhibits a bimodal distribution in diurnal variation. The mechanism analysis demonstrates that occurrences of EHP are generally accompanied by positive anomalies of temperature, humidity, and geopotential height. Anomalous cyclonic circulation can also be found in the low-level wind field. The westward and northward extension of the western North Pacific subtropical high (WNPSH) as well as temperature rise may be the primary reason for the increase of EHP. For Chongqing and eastern Sichuan, the anticyclone circulation in low-level and the significantly weakened water vapor flux convergence cause poor moisture and dynamic conditions, inhibiting the growth of EHP.
{"title":"A 40-year statistics of warm-season extreme hourly precipitation over Southwest China","authors":"Rouyi Jiang, Xiaopeng Cui, Jian Lin, Jia Tian","doi":"10.1175/jamc-d-23-0018.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0018.1","url":null,"abstract":"Abstract Southwest China (SWC) possesses complicated topography with frequent geological activities, where heavy precipitation occurs frequently in warm seasons. Few previous studies on extreme precipitation were carried out at hourly scales. In this study, spatiotemporal variations of the extreme hourly precipitation (EHP) over SWC during the warm season of 1981-2020 and the involved mechanisms are investigated. Results show that the threshold and intensity of EHP present similar spatial distribution—lower (higher) in the west (east) part of SWC, while the EHP frequency is opposite. The long-term trend of EHP amount shows a more significant positive tendency than that of hourly precipitation (HP) amount, due to synchronous increases in intensity and frequency. The significant increasing trend of EHP occurs in areas above 500 m terrain height, with a weak increasing trend below 500 m (e.g., Chongqing and eastern Sichuan). EHP appears mainly from June to August and exhibits a bimodal distribution in diurnal variation. The mechanism analysis demonstrates that occurrences of EHP are generally accompanied by positive anomalies of temperature, humidity, and geopotential height. Anomalous cyclonic circulation can also be found in the low-level wind field. The westward and northward extension of the western North Pacific subtropical high (WNPSH) as well as temperature rise may be the primary reason for the increase of EHP. For Chongqing and eastern Sichuan, the anticyclone circulation in low-level and the significantly weakened water vapor flux convergence cause poor moisture and dynamic conditions, inhibiting the growth of EHP.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"26 41","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135390301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Accurate evaluation of the long-range dependence in hydroclimatic time series is important for understanding its inherent characteristics. However, the reliability of its evaluation may be questioned, since different methods may yield various outcomes. In this study, we evaluate the performances of seven widely used methods for estimating long-range dependence: absolute moment estimation, difference variance estimation, residuals variance estimation, rescaled range estimation, periodogram estimation, wavelet estimation (WLE), and discrete second derivative estimation (DSDE). We examine the influences of six major factors: data length, mean value, three nonstationary components (trend, jump, and periodicity), and one stationary component (short-range dependence). Results from the Monte-Carlo experiments show that WLE and DSDE have greater credibility than the other five methods. They also reveal that data length, as well as stationary and nonstationary components, have notable influences on the evaluation of long-range dependence. Following it, we use the WLE and DSDE methods to evaluate the long-range dependence of precipitation during 1961–2015 on Tibetan Plateau. The results indicate that the precipitation variability mirrors the long-range dependence of the Indian summer monsoon, but with obvious spatial difference. This result is consistent with the observations made by previous studies, further confirming the superiority of the WLE and DSDE methods. The outcomes from this study have important implications for modeling and prediction of hydroclimatic time series.
{"title":"Quantification of long-range dependence in hydroclimatic time series: a method-comparison study","authors":"Jingyi Niu, Ping Xie, Yan-Fang Sang, Liping Zhang, Linqian Wu, Yanxin Zhu, Bellie Sivakumar, Jingqun Huo, Deliang Chen","doi":"10.1175/jamc-d-23-0129.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0129.1","url":null,"abstract":"Abstract Accurate evaluation of the long-range dependence in hydroclimatic time series is important for understanding its inherent characteristics. However, the reliability of its evaluation may be questioned, since different methods may yield various outcomes. In this study, we evaluate the performances of seven widely used methods for estimating long-range dependence: absolute moment estimation, difference variance estimation, residuals variance estimation, rescaled range estimation, periodogram estimation, wavelet estimation (WLE), and discrete second derivative estimation (DSDE). We examine the influences of six major factors: data length, mean value, three nonstationary components (trend, jump, and periodicity), and one stationary component (short-range dependence). Results from the Monte-Carlo experiments show that WLE and DSDE have greater credibility than the other five methods. They also reveal that data length, as well as stationary and nonstationary components, have notable influences on the evaluation of long-range dependence. Following it, we use the WLE and DSDE methods to evaluate the long-range dependence of precipitation during 1961–2015 on Tibetan Plateau. The results indicate that the precipitation variability mirrors the long-range dependence of the Indian summer monsoon, but with obvious spatial difference. This result is consistent with the observations made by previous studies, further confirming the superiority of the WLE and DSDE methods. The outcomes from this study have important implications for modeling and prediction of hydroclimatic time series.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"15 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135973295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.1175/jamc-d-23-0039.1
E. Montoya Duque, Y. Huang, P.T. May, S.T. Siems
Abstract Recent voyages of the Australian R/V Investigator across the remote Southern Ocean have provided unprecedented observations of precipitation made with both an Ocean Rainfall and Ice-Phase Precipitation Measurement Network (OceanRAIN) maritime disdrometer and a dual-polarization C-band weather radar (OceanPOL). This present study employs these observations to evaluate the Global Precipitation Measurement (GPM) Integrated Multi-satellitE Retrievals for GPM (IMERG) and the fifth major global reanalysis produced by ECMWF (ERA5) precipitation products. Working at a resolution of 60 min and 0.25° (∼25 km), light rain and drizzle are most frequently observed across the region. The IMERG product overestimated precipitation intensity when evaluated against the OceanRAIN but captured the frequency of occurrence well. Looking at the synoptic/process scale, IMERG was found to be the least accurate (overestimated intensity) under warm-frontal and high-latitude cyclone conditions, where multilayer clouds were commonly present. Under postfrontal conditions, IMERG underestimated the precipitation frequency. In comparison, ERA5’s skill was more consistent across various synoptic conditions, except for high pressure conditions where the precipitation frequency (intensity) was highly overestimated (underestimated). Using the OceanPOL radar, an area-to-area analysis (fractional skill score) finds that ERA5 has greater skill than IMERG. There is little agreement in the phase classification between the OceanRAIN disdrometer, IMERG, and ERA5. The comparisons are complicated by the various assumptions for phase classification in the different datasets. Significance Statement Our best quantitative estimates of precipitation over the remote, pristine Southern Ocean (SO) continue to suffer from a high degree of uncertainty, with large differences present among satellite-based and reanalysis products. New instrumentation on the R/V Investigator , specifically a dual-polarization C-band weather radar (OceanPOL) and a maritime disdrometer (OceanRAIN), provide unprecedented high-quality observations of precipitation across the SO that will aid in improving precipitation estimates in this region. We use these observations to evaluate the IMERG and ERA5 precipitation products. We find that, in general, IMERG overestimated precipitation intensity, but captured the frequency of occurrence well. In comparison, ERA5 was found to overestimate the frequency of precipitation. Using the OceanPOL radar, an area-to-area analysis finds that ERA5 has greater skill than IMERG.
{"title":"An evaluation of IMERG and ERA5 quantitative precipitation estimates over the Southern Ocean using shipborne observations","authors":"E. Montoya Duque, Y. Huang, P.T. May, S.T. Siems","doi":"10.1175/jamc-d-23-0039.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0039.1","url":null,"abstract":"Abstract Recent voyages of the Australian R/V Investigator across the remote Southern Ocean have provided unprecedented observations of precipitation made with both an Ocean Rainfall and Ice-Phase Precipitation Measurement Network (OceanRAIN) maritime disdrometer and a dual-polarization C-band weather radar (OceanPOL). This present study employs these observations to evaluate the Global Precipitation Measurement (GPM) Integrated Multi-satellitE Retrievals for GPM (IMERG) and the fifth major global reanalysis produced by ECMWF (ERA5) precipitation products. Working at a resolution of 60 min and 0.25° (∼25 km), light rain and drizzle are most frequently observed across the region. The IMERG product overestimated precipitation intensity when evaluated against the OceanRAIN but captured the frequency of occurrence well. Looking at the synoptic/process scale, IMERG was found to be the least accurate (overestimated intensity) under warm-frontal and high-latitude cyclone conditions, where multilayer clouds were commonly present. Under postfrontal conditions, IMERG underestimated the precipitation frequency. In comparison, ERA5’s skill was more consistent across various synoptic conditions, except for high pressure conditions where the precipitation frequency (intensity) was highly overestimated (underestimated). Using the OceanPOL radar, an area-to-area analysis (fractional skill score) finds that ERA5 has greater skill than IMERG. There is little agreement in the phase classification between the OceanRAIN disdrometer, IMERG, and ERA5. The comparisons are complicated by the various assumptions for phase classification in the different datasets. Significance Statement Our best quantitative estimates of precipitation over the remote, pristine Southern Ocean (SO) continue to suffer from a high degree of uncertainty, with large differences present among satellite-based and reanalysis products. New instrumentation on the R/V Investigator , specifically a dual-polarization C-band weather radar (OceanPOL) and a maritime disdrometer (OceanRAIN), provide unprecedented high-quality observations of precipitation across the SO that will aid in improving precipitation estimates in this region. We use these observations to evaluate the IMERG and ERA5 precipitation products. We find that, in general, IMERG overestimated precipitation intensity, but captured the frequency of occurrence well. In comparison, ERA5 was found to overestimate the frequency of precipitation. Using the OceanPOL radar, an area-to-area analysis finds that ERA5 has greater skill than IMERG.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134996492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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