Journal of Applied Meteorology and Climatology最新文献

{"title":"A Case Study on Wind Speed Oscillations Offshore the West Coast of Central Taiwan","authors":"Fang-Ching Chien, Chun-Wei Chang, Jen-Hsin Teng, Jing-Shan Hong","doi":"10.1175/jamc-d-23-0115.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0115.1","url":null,"abstract":"\u0000This paper investigates a wind speed oscillation event that occurred near the coastline of central Taiwan in the afternoon of 17 February 2018, using data from observations and numerical simulations. The observed wind speeds at 100-m altitude displayed a fast-oscillating pattern of about 6 cycles between strong winds of approximately 21 m s−1 and weak winds of around 2 m s−1, with periods of about 10 min. The pressure anomalies fluctuated in antiphase with the wind speed anomalies. The synoptic analysis revealed the influence of a continental high-pressure system, resulting in a cold air outbreak over Taiwan. The cold north-northeasterly winds split into two branches upon encountering Taiwan's topography, with ridging off the east coast and a lee trough off the west coast of Taiwan. Wind oscillations were detected in the low-level cold air offshore the west coast of Taiwan, depicted by wave-like structures in wind speeds, sea-level pressure, and potential temperature. The perturbations were identified as Kelvin-Helmholtz billows characterized by regions of strong wind speeds, warm and dry air, sinking motions, and low pressure collocated with each other, while regions of weaker wind speeds, cooler and moister air, ascending motions, and high pressure were associated with each other. With terrain contributing to favorable conditions, the large vertical and horizontal wind shears resulted from the southward acceleration of low-level cold air and the northward movement of the lee trough played an important role in initiating the wind oscillations.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"18 16","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139443493","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}

{"title":"Contrasts of Large-Scale Moisture and Heat Budgets between Different Sea Areas of the South China Sea and the Adjacent Land","authors":"Chunyan Zhang, Donghai Wang, Lebao Yao, Zhenzhen Wu, Qianhui Ma, Yongsheng Li, Peidong Wang","doi":"10.1175/jamc-d-23-0084.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0084.1","url":null,"abstract":"\u0000This study investigates and compares large-scale moisture and heat budgets over the eastern rainy sea area around Dongsha, the western rainless sea area around Xisha, and the northern coastland of the South China Sea. Ten-year (2011–20) surface, balloon-sounding, satellite measurements, and ERA5 reanalysis are merged into the physically consistent data to study annual and vertical variations of the budgets. It shows that the surface and column-integrated heat and moisture budgets have the smallest annual evolution over the coastland. The latent heat as a key heat contributor in summer is mainly offset by total cold advection and partially offset by net radiative cooling. The horizontal moisture advection below 700 hPa presents moistening over the sea whereas drying over the coastland during rainy months, in which the vertical moisture advection presents moistening up to 250 hPa for all three subregions. The horizontal temperature advection is weak throughout the year over the sea but displays strong top warming and bottom cooling in summer and nearly the opposite in winter over the coastland. The diabatic cooling with a peak at ∼700 hPa in winter is largely due to the enhanced radiative cooling and latent cooling. While the diabatic heating with a peak at ∼500 hPa in summer is largely due to the enhanced latent heating. The earliest atmospheric heating and moistening occur in spring over the coastland, inducing the earliest precipitation increase. The enhanced heating and moistening over Xisha have a 1-month lag relative to Dongsha, resulting in lagging precipitation.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"77 12","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139454439","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}

{"title":"Investigation of Hydrostatic Imbalance with Field Observations","authors":"Jielun Sun, Volker Wulfmeyer, Florian Späth, Holger Vömel, William Brown, Steve Oncley","doi":"10.1175/jamc-d-22-0206.1","DOIUrl":"https://doi.org/10.1175/jamc-d-22-0206.1","url":null,"abstract":"The hydrostatic equilibrium addresses the approximate balance between the positive force of the vertical pressure gradient and the negative gravity force and has been widely assumed for atmospheric applications. The hydrostatic imbalance of the mean atmospheric state for the acceleration of vertical motions in the vertical momentum balance is investigated using tower, the global positioning system radiosonde, and Doppler lidar and radar observations throughout the diurnally varying atmospheric boundary layer (ABL) under clear-sky conditions. Because of the negligibly small mean vertical velocity, the acceleration of vertical motions is dominated by vertical variations of vertical turbulent velocity variances. The imbalance is found to be mainly due to the vertical turbulent transport of changing air density as a result of thermal expansion/contraction in response to air temperature changes following surface temperature changes. In contrast, any pressure change associated with air temperature changes is small, and the positive vertical pressure-gradient force is strongly influenced by its background value. The vertical variation of the turbulent velocity variance from its vertical increase in the lower convective boundary layer (CBL) to its vertical decrease in the upper CBL is observed to be associated with the sign change of the imbalance from positive to negative due to the vertical decrease of the positive vertical pressure-gradient force and the relative increase of the negative gravity force as a result of the decreasing upward transport of the low-density air. The imbalance is reduced significantly at night but does not steadily approach zero. Understanding the development of hydrostatic imbalance has important implications for understanding large-scale atmosphere, especially for cloud development. It is well known that the hydrostatic imbalance between the positive pressure-gradient force due to the vertical decrease of atmospheric pressure and the negative gravity forces in the vertical momentum balance equation has important impacts on the vertical acceleration of atmospheric vertical motions. Vertical motions for mass, momentum, and energy transfers contribute significantly to changing atmospheric dynamics and thermodynamics. This study investigates the often-assumed hydrostatic equilibrium and investigate how the hydrostatic imbalance is developed using field observations in the atmospheric boundary layer under clear-sky conditions. The results reveal that hydrostatic imbalance can develop from the large-eddy turbulent transfer of changing air density in response to the surface diabatic heating/cooling. The overwhelming turbulence in response to large-scale thermal forcing and mechanical work of the vast Earth surface contributes to the hydrostatic imbalance on large spatial and temporal scales in numerical weather forecast and climate models.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"11 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139127904","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}

{"title":"Automated and Objective Thunderstorm Identification and Tracking Using Geostationary Lightning Mapper (GLM) Data","authors":"Kelley M. Murphy, Lawrence D. Carey, Christopher J. Schultz, N. Curtis, Kristin M. Calhoun","doi":"10.1175/jamc-d-22-0143.1","DOIUrl":"https://doi.org/10.1175/jamc-d-22-0143.1","url":null,"abstract":"A unique storm identification and tracking method is analyzed in varying storm environments within the United States spanning 273 hours in 2018. The methodology uses a quantity calculated through fusion of radar-based vertically integrated liquid (VIL) and satellite-based GLM flash rate density (FRD) called VILFRD to identify storms in space and time. This research analyzes GLM data use within VILFRD for the first time (method original: O), assesses four modifications to VILFRD implementation to find a more stable storm size with time (method new: N), larger storms (method original dilated: OD), or both (method new dilated: ND), and compares VILFRD methods with storm tracking using the 35-dBZ isosurface at −10°C (method non-VILFRD: NV). A case study analysis from 2019 is included to assess methods on a smaller scale and introduce a “lightning only” (LO) version of VILFRD. Large study results highlight that VILFRD-based storm identification produces smaller storms with more lightning than the NV method, and the NV method produces larger storms with a more stable size over time. Methods N and ND create smaller storm size fluctuations, but size changes more often. Dilation (OD, ND) creates larger storms and almost double the number of storms identified relative to nondilated methods (O, N, NV). The case study results closely resemble the large sample results and show that the LO method identifies storms with more lightning and shorter durations. Overall, these findings can aid in choice of storm tracking method based on desired user application and promote further testing of a lightning-only version of VILFRD.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"63 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139128256","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}

{"title":"Long Memory in Average Monthly Temperatures and Precipitations in Guatemala","authors":"Luis A. Gil-Alana, Marlon J. Castillo","doi":"10.1175/jamc-d-23-0007.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0007.1","url":null,"abstract":"\u0000In this paper, we perform a fractional integration analysis of the average monthly temperature and precipitation data in 17 departments of Guatemala. Two analyses are performed, the first with the original data and the second with the anomalies based on the period January 1994–December 1999. The results indicate that there is a significant positive time trend in temperatures in the departments of Guatemala (0.0045°C month−1), Quetzaltenango (0.0040°C month−1), Escuintla (0.0034°C month−1), and Huehuetenango (0.0047°C month−1), whereas in the case of precipitation no time trend was observed. An important relevant result is that the departments of El Progreso, Baja Verapaz, and Guatemala occupy the second, third and fourth highest levels of persistence for both temperatures and precipitation, with Sacatepéquez and Quiché displaying the first places for temperature and precipitation, respectively, thus making these five departments the ones that are most vulnerable to climate change since a shock would take a long time to disappear.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":" 106","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139393474","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}

{"title":"Uncertainty of Atmospheric Winds in Three Widely Used Global Reanalysis Datasets","authors":"Longtao Wu, Hui Su, Xubin Zeng, Derek J. Posselt, Sun Wong, Shuyi Chen, A. Stoffelen","doi":"10.1175/jamc-d-22-0198.1","DOIUrl":"https://doi.org/10.1175/jamc-d-22-0198.1","url":null,"abstract":"Atmospheric winds are crucial to the transport of heat, moisture, momentum, and chemical species, facilitating Earth’s climate system interactions. Existing weather and climate studies rely heavily on the wind fields from reanalysis datasets. In this study, we analyze the uncertainty of instantaneous atmospheric winds in three reanalysis (ERA5, MERRA2 and CFSv2) datasets. We show that the mean wind vector differences (WVDs) between the reanalysis datasets are about 3–6 m s−1 in the troposphere. The mean absolute wind direction differences can be more than 50°. Large WVDs greater than 5 m s−1 are found for 30–50% of the time when the observed precipitation rate is larger than 0.1 mm hr−1 over Eastern Pacific, Indian Ocean, Atlantic and some mountain areas. The mean WVDs exhibit seasonal variations but no significant diurnal variations. The uncertainty of vertical wind shear has a correlation of 0.59 with the uncertainty of winds at 300 hPa. The magnitudes of vorticity and horizontal divergence uncertainties are on the order of 1×10−5 s−1, which is comparable to the mean values of vorticity and horizontal divergence. In comparison to some limited observations from field campaigns, the reanalysis datasets exhibit a mean WVD ranging from 2–4.5 m s−1. Among the three reanalysis datasets, ERA5 shows the closest agreement with the observations while MERRA2 has the largest discrepancy. The substantial uncertainty and errors of the reanalysis wind products highlight the critical need for new satellite missions dedicated to 3D wind measurements.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"9 18","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139155676","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}

{"title":"Late-Winter and Springtime Temperature Variations throughout New Jersey in a Warming Climate","authors":"Andra J. Garner, Daniel P. Duran","doi":"10.1175/jamc-d-23-0152.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0152.1","url":null,"abstract":"Large temperature variations in a temperate climate, particularly in late-winter and early spring, can be disruptive for native ecosystems and agricultural crops. As warmer temperatures occur earlier in the year in midlatitude regions due to anthropogenic climate change, springtime temperatures may become less consistent, leading to potential damage to species and crops that are vulnerable to the return of historically cooler temperatures, including Late-Spring Frosts, after an initial warm-up. In this work, we quantify shifting patterns in late-winter and springtime temperature variations at eight sites across New Jersey from 1950-2019. Many sites located along the coast or in the coastal plain experience increases in the number of times the temperature climbs above 15.5°C (60°F), and then falls below freezing (i.e., 0°C, or 32°F). Sites in southern New Jersey (where much of the state’s agriculture is located) experience the most significant (P<0.05) increases in large springtime temperature variations. Across all sites, there is a general increase in both the percentage and magnitude of temperature variations that occur as early as February. Finally, at 75% of sites, day-to-day variation in daily maximum temperature has increased from the 1950s through 2019; day-to-day variation in daily minimum temperatures has increased over the same time at more than half of sites considered. These amplifications in extreme temperature variations indicate the need for both mitigation and adaptation strategies to protect vulnerable crops and ecosystems in the region during this critical time of the year.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"19 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139168848","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}

{"title":"Why does Japan’s south foehn, “Jintsu-Oroshi,” tend to onset during the night? : An investigation based on two case studies","authors":"Hiroyuki Kusaka, Satoshi Nishiba, Yuki Asano","doi":"10.1175/jamc-d-23-0063.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0063.1","url":null,"abstract":"\u0000The Jintsu-Oroshi refers to Japan’s south foehn, which blows over the Toyama Plain in the Hokuriku region. This region faces the Sea of Japan to the north and the central mountain range to the south. The Jintsu-Oroshi occurs more frequently at night than during the day. In this study, we determined the primary factors causing this feature using the Weather Research and Forecasting (WRF) model. We selected a typical Jintsu-Oroshi case in May 2016 for analysis. An extratropical cyclone traversed the Sea of Japan during the event, leading to a temporal change in the synoptic-scale pressure pattern. The observations and numerical simulation results showed that the collapse of the mixed layer over the mountains and the end of the sea breeze are key factors for the nighttime onset of the Jintsu-Oroshi. Indeed, mountain waves and their resulting downslope winds did not occur under near-neutral atmospheric stability conditions over the mountains during the daytime. After sunset, the atmospheric stability changed to stable conditions, which caused the downslope winds to blow. However, the downslope winds did not reach the plains because of the sea breeze. After several hours, the sea breeze disappeared, and the downslope winds reached the leeward plains and increased the temperature there. Similar features were confirmed in August 2013 for another typical Jintsu-Oroshi case under atmospheric conditions, without temporal changes in the synoptic-scale pressure pattern. We expect the results obtained in this study to advance our understanding of foehn occurrence in regions where mountains adjoin seas, similar to the coastal areas adjacent to the Sea of Japan.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"18 5","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138954899","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}

{"title":"Snowfall Measurements at Wind-exposed and Sheltered Sites in the Rocky Mountains of Southeastern Wyoming","authors":"Samuel A. Marlow, John M. Frank, Matthew Burkhart, Bujidmaa Borkhuu, Shelby E. Fuller, Jefferson R. Snider","doi":"10.1175/jamc-d-22-0093.1","DOIUrl":"https://doi.org/10.1175/jamc-d-22-0093.1","url":null,"abstract":"Snowfall is an important driver of physical and biological processes in alpine systems. Previous work has shown that surface deposition of snow can vary for reasons not directly related to precipitation processes and that this variance has consequence for water budgets in snow-dominated terrestrial systems. In this work, measurements were made over several winter seasons in a forest-meadow ecotone in the Rocky Mountains of Southeastern Wyoming. Two groups of measurements - both with wind-exposed and sheltered precipitation gauges - were analyzed. Reasonable agreement between snow deposition from a hotplate gauge (exposed) and snow deposition from a SNOTEL pillow gauge (sheltered) is reported. The other result is that snow deposition is enhanced at an exposed gauge that was deployed on the leeward side of a forest-meadow edge. The enhancement is approximately a factor of two and varies with wind direction and speed and with upwind forest coverage. The enhancement is greater than documented in an earlier investigation of Rocky Mountain snow deposition; however, in that study measurements were conducted above tree line.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"188 ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139174593","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}

{"title":"Irrigated Agriculture Significantly Modifies Seasonal Boundary Layer Atmosphere and Lower Tropospheric Convective Environment","authors":"Emilee Lachenmeier, Rezaul Mahmood, Chris Phillips, U. Nair, E. Rappin, Roger A. Pielke, William Brown, Steve Oncley, Joshua Wurman, K. Kosiba, Aaron Kaulfus, J. Santanello, Edward Kim, Patricia Lawston-Parker, Michael Hayes, T. Franz","doi":"10.1175/jamc-d-23-0020.1","DOIUrl":"https://doi.org/10.1175/jamc-d-23-0020.1","url":null,"abstract":"\u0000Modification of grasslands into irrigated and non-irrigated agriculture in the Great Plains results in significant impacts on weather and climate. However, there has been lack of observational data-based studies solely focused on impacts of irrigation on the PBL and convective conditions. The Great Plains Irrigation Experiment (GRAINEX) during the 2018 growing season collected data over irrigated and non-irrigated land uses over Nebraska to understand these impacts. Specifically, the objective was to determine whether the impacts of irrigation are sustained throughout the growing season.\u0000The data analyzed include latent and sensible heat flux, air temperature, dew point temperature, equivalent temperature (moist enthalpy), PBL height, lifting condensation level (LCL), level of free convection (LFC), and PBL mixing ratio. Results show increased partitioning of energy into latent heat compared to sensible heat over irrigated areas while average maximum air was decreased and dewpoint temperature was increased from the early to peak growing season. Radiosonde data suggest reduced planetary boundary layer (PBL) heights at all launch sites from the early to peak growing season. However, reduction of PBL height was much greater over irrigated areas compared to non-irrigated croplands. Compared to the early growing period, LCL and LFC heights were also lower during the peak growing period over irrigated areas. Results note, for the first time, that the impacts of irrigation on PBL evolution and convective environment can be sustained throughout the growing season and regardless of background atmospheric conditions. These are important findings and applicable to other irrigated areas in the world.","PeriodicalId":15027,"journal":{"name":"Journal of Applied Meteorology and Climatology","volume":"12 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138590231","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}