scholarly journals Anomalous holiday precipitation over southern China

2018 ◽  
Vol 18 (22) ◽  
pp. 16775-16791 ◽  
Author(s):  
Jiahui Zhang ◽  
Dao-Yi Gong ◽  
Rui Mao ◽  
Jing Yang ◽  
Ziyin Zhang ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Cloud Cover ◽  
Southern China ◽  
Eastern China ◽  
Time Lag ◽  
Precipitation Amount ◽  
Specific Humidity ◽  
Middle Troposphere ◽  
The Mean

Abstract. The Chinese Spring Festival (CSF, also known as the Chinese New Year or Lunar New Year) is the most important festival in China. Lunar New Year's Day (LNYD) is the first day of the Lunar New Year. Traditionally, the CSF holiday begins a couple of days before LNYD and ends on lantern day, lasting for approximately 2 weeks. In this paper, based on the long-term station observations from 1979 to 2012, the precipitation during the holiday over southern China (108–123° E and 21–33° N, 155 stations) tends to be lower than that before and after the holiday. The mean precipitation frequency anomaly from the fourth day to the sixth day after LNYD (i.e., days [+4, +6]) decreases by −7.4 %. Simultaneously, the daily precipitation amount experiences a reduction of −0.62 mm day−1 during days [+2, +5]. The holiday precipitation anomalies are strongly linked to the anomalies of relative humidity (ΔRH) and cloud cover. The station observations of the ΔRH show an evident decrease from day +2 to day +7, and a minimum appears on days [+4, +6], with a mean of −3.9 %. The ΔRH vertical profile displays significant drying below approximately 800 hPa. Between 800 and 1000 hPa, the mean ΔRH is −3.9 %. The observed station daytime low cloud cover (LCC) evidently decreases by −6.1 % during days [+4, +6]. Meanwhile, the ERA-Interim daily LCC also shows a comparable reduction of −5.0 %. The anomalous relative humidity is mainly caused by the decreased water vapor in the lower-middle troposphere. Evident negative specific humidity anomalies persist from day −3 to day +7 in the station observations. The average specific humidity anomaly for days [+4, +6] is −0.73 g kg−1. When the precipitation days are excluded, the anomaly remains significant at −0.46 g kg−1. A significant water vapor deficit is observed in the lower troposphere below 700 hPa. Between 800 and 1000 hPa, the mean specific humidity drops by −0.70 g kg−1. This drier lower-middle troposphere is due to anomalous northerly winds, which are closely related to the cyclonic circulation anomaly over the northwestern Pacific. The time-lag correlation demonstrates that approximately 1 week after a lower temperature occurs over eastern China, a stronger cyclone is observed over the western Pacific. The possible mechanism needs further clarification through elaborate observation and numerical modeling.

scholarly journals Anomalous holiday precipitation over southern China

2018 ◽  
Author(s):  
Jiahui Zhang ◽  
Dao-Yi Gong ◽  
Rui Mao ◽  
Jing Yang ◽  
Ziyin Zhang ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Cloud Cover ◽  
Southern China ◽  
Lower Troposphere ◽  
Specific Humidity ◽  
Precipitation Frequency ◽  
Middle Troposphere ◽  
Low Cloud ◽  
The Mean

Abstract. The Chinese Spring Festival (CSF) is the most important festival in China. Officially, this holiday lasts approximately one week. Based on the long-term station observations from 1979 to 2012, this manuscript reports that during the holidays, the precipitation over southern China (108° E–123° E and 21° N–33° N, 155 stations) has been significantly reduced. The precipitation frequency anomalies from the fourth day to the sixth day after Lunar New Year's Day (i.e., days [+4, +6]) were found to decrease by −7.4 %. At the same time, the daily precipitation amounts experienced a reduction of −0.62 mm d−1 during days +2 to +5. The holiday precipitation anomalies are strongly linked to the relative humidity (ΔRH) and cloud cover. The station observations of the ΔRH showed an evident decrease from day +2 to +7, and a minimum appeared on days [+4, +6], with a mean of −3.9 %. The ΔRH vertical profile displays a significant drying below approximately 800 hPa. Between 800 hPa and 1000 hPa, the mean ΔRH is −3.9 %. The observed station daytime low cloud cover (LCC) evidently decreased by −6.1 % during days [+4, +6]. Meanwhile, the ERA-Interim daily LCC also shows a comparable reduction of −5.0 %. The anomalous relative humidity is mainly caused by the lower water vapor in the lower-middle troposphere. Evident negative specific humidity anomalies persist from day −3 to day +7 in the station observations. The average specific humidity anomaly for days [+4, +6] is −0.73 g kg−1. When the precipitation days exclude the mean, the anomaly remains significant, being −0.46 g kg−1. A significant deficit of water vapor is observed in the lower troposphere below 700 hPa. Between 800 hPa and 1000 hPa, the mean specific humidity dropped by −0.70 g kg−1. This drier lower-middle troposphere is due to anomalous northerly winds. Authors have proposed that the anomalous atmospheric circulation is likely related to the holiday aerosol anomaly. Station and satellite observations show that the East Asian aerosol concentrations during the CSF decrease evidently, the largest reduction occurring on days [−3, −1]. At the same time, a concurrent cooling is observed in the lower troposphere. In addition, an anomalous low pressure tilting westward occurs in the troposphere over East Asia. The anomalous cold advection seems to help trigger/strengthen a cyclonic circulation anomaly, which is responsible for the northerly winds and the less precipitation around the holidays. This possible mechanism needs further clarification by elaborate observation analysis and modeling.

Multimodel Analysis of the Water Vapor Feedback in the Tropical Upper Troposphere

2006 ◽  
Vol 19 (20) ◽  
pp. 5455-5464 ◽  
Author(s):  
Ken Minschwaner ◽  
Andrew E. Dessler ◽  
Parnchai Sawaengphokhai
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Sea Surface ◽  
Specific Humidity ◽  
Upper Troposphere ◽  
The Mean ◽  
Tropical Upper Troposphere

Abstract Relationships between the mean humidity in the tropical upper troposphere and tropical sea surface temperatures in 17 coupled ocean–atmosphere global climate models were investigated. This analysis builds on a prior study of humidity and surface temperature measurements that suggested an overall positive climate feedback by water vapor in the tropical upper troposphere whereby the mean specific humidity increases with warmer sea surface temperature (SST). The model results for present-day simulations show a large range in mean humidity, mean air temperature, and mean SST, but they consistently show increases in upper-tropospheric specific humidity with warmer SST. The model average increase in water vapor at 250 mb with convective mean SST is 44 ppmv K−1, with a standard deviation of 14 ppmv K−1. Furthermore, the implied feedback in the models is not as strong as would be the case if relative humidity remained constant in the upper troposphere. The model mean decrease in relative humidity is −2.3% ± 1.0% K−1 at 250 mb, whereas observations indicate decreases of −4.8% ± 1.7% K−1 near 215 mb. These two values agree within the respective ranges of uncertainty, indicating that current global climate models are simulating the observed behavior of water vapor in the tropical upper troposphere with reasonable accuracy.

scholarly journals Assessment of COSMIC radio occultation retrieval product using global radiosonde data

2013 ◽  
Vol 6 (4) ◽  
pp. 1073-1083 ◽  
Author(s):  
B.-R. Wang ◽  
X.-Y. Liu ◽  
J.-K. Wang
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Relative Error ◽  
Radio Occultation ◽  
Water Vapor Pressure ◽  
Specific Humidity ◽  
Radiosonde Data ◽  
Cosmic Radio ◽  
The Mean ◽  
Matching Criteria

Abstract. The radio occultation retrieval product of the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Radio Occultation sounding system was verified using the global radiosonde data from 2007 to 2010. Samples of 4 yr were used to collect quantities of data using much stricter matching criteria than previous studies to obtain more accurate results. The horizontal distance between the radiosonde station and the occultation event is within 100 km, and the time window is 1 h. The comparison was performed from 925 hPa to 10 hPa. The results indicated that the COSMIC's temperature data agreed well with the radiosonde data. The global mean temperature bias was −0.09 K, with a standard deviation (SD) of 1.72 K. According to the data filtration used in this paper, the mean specific humidity bias of 925–200 hPa is −0.012 g kg−1, with a SD of 0.666 g kg−1, and the mean relative error of water vapor pressure is about 33.3%, with a SD of 107.5%. The COSMIC quality control process failed to detect some of the abnormal extremely small humidity data which occurred frequently in subtropical zone. Despite the large relative error of water vapor pressure, the relative error of refractivity is small. This paper also provides a comparison of eight radiosonde types with COSMIC product. Because the retrieval product is affected by the background error which differed between different regions, the COSMIC retrieval product could be used as a benchmark if the precision requirement is not strict.

scholarly journals Water Vapor Transport and Moisture Budget over Eastern China: Remote Forcing from the Two Types of El Niño

2014 ◽  
Vol 27 (23) ◽  
pp. 8778-8792 ◽  
Author(s):  
Xiuzhen Li ◽  
Wen Zhou ◽  
Deliang Chen ◽  
Chongyin Li ◽  
Jie Song
Keyword(s):  
Water Vapor ◽  
El Niño ◽  
El Nino ◽  
Eastern China ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Moisture Budget ◽  
Southern Boundary ◽  
Middle Troposphere ◽  
Moisture Deficit

Abstract The water vapor transport and moisture budget over eastern China remotely forced by the cold-tongue (CT) and warm-pool (WP) El Niño show striking differences throughout their lifetime. The water vapor transport response is weak in the developing summer but strong in the remaining phases of CT El Niño, whereas the opposite occurs during WP El Niño. WP El Niño causes a moisture deficit over the Yangtze River valley (YZ) in the developing summer and over southeastern China (SE) in the developing fall, whereas CT El Niño induces a moisture surplus first over SE during the developing fall with the influential area expanding in the decaying spring and shifting northward in the decaying summer. It is the divergence of meridional water vapor transport that dominates the total water vapor divergence anomaly, with the divergence of zonal transport showing an opposite pattern with smaller magnitude. Investigation of the vertical profile of moisture budget shows a great baroclinicity, with the strongest abnormal moisture budget occurring in different levels. The moisture transport via the southern boundary plays a crucial role in the regional moisture budget anomalies and is located near the surface over SE, in the lower troposphere over the YZ, and at the lower-middle troposphere over the eastern part of northern China. The enhanced moisture surplus near the surface forced by WP El Niño over SE in the mature winter and decaying spring is offset by a moisture deficit within the lower-middle troposphere due to a diverse response circulation at different vertical levels.

Chart of Air-Vapor Mixture Properties at Different Pressures

1941 ◽  
Vol 8 (1) ◽  
pp. A14-A16
Author(s):  
R. C. Binder
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Total Pressure ◽  
Limited Range ◽  
Dew Point ◽  
Specific Humidity ◽  
Vapor Mixture ◽  
Close Approximation ◽  
Point Temperature ◽  
Dew Point Temperature

Abstract A discussion is given of the use of a total pressure-temperature diagram provided with reversible adiabatic and specific-humidity lines for mixtures of air and water vapor. The graphical relation between dew-point temperature, dry-bulb temperature, and specific humidity is given directly for any total pressure on this chart. From this relation the vapor pressure and relative humidity can be easily calculated. Certain chart lines give a close approximation to the wet-bulb temperature for a limited range. This pressure-temperature chart should be convenient and useful for a wide variety of problems which involve these fundamental thermodynamic properties.

scholarly journals Characterization and Corrections of Relative Humidity Measurement from Meteomodem M10 Radiosondes at Midlatitude Stations

2020 ◽  
Vol 37 (5) ◽  
pp. 857-871
Author(s):  
Jean-Charles Dupont ◽  
Martial Haeffelin ◽  
Jordi Badosa ◽  
Gaelle Clain ◽  
Christophe Raux ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Humidity Sensor ◽  
Global Climate ◽  
Time Lag ◽  
Capacitive Sensor ◽  
Cold Temperatures ◽  
Humidity Measurements ◽  
Main Effects ◽  
Very High

AbstractMeasurement of water vapor or humidity in the atmosphere is fundamental for many applications. Relative humidity measurements with a capacitive sensor in radiosondes are affected by several factors that need to be assessed and corrected. This work aims to address corrections for the main effects for the Meteomodem M10 radiosonde as a step to meet the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) requirements. The considered corrections are 1) the calibration correction; 2) a slow regime due to the slow diffusion of molecules through the sensor, especially at very high and very low relative humidity conditions; 3) the relative humidity sensor dependence on the gradient of temperature; and 4) the time lag at cold temperatures, which affects measurements in regions of strong relative humidity gradients. These corrections were tested for 26 nighttime and 25 daytime radiosondes in two midlatitude locations for which both Meteomodem M10 and Vaisala RS92 measurements were available. The results show that, after correcting for the four effects, M10 relative humidity measurements are, on average, consistent with the Vaisala RS92 relative humidity values within 2% RH at all altitudes for the nighttime launches (against 6% RH before the correction) and within 5% RH at all altitudes for the daytime launches (against 9% RH before the correction).

scholarly journals Ten Years of Measurements of Tropical Upper-Tropospheric Water Vapor by MOZAIC. Part I: Climatology, Variability, Transport, and Relation to Deep Convection

2007 ◽  
Vol 20 (3) ◽  
pp. 418-435 ◽  
Author(s):  
Zhengzhao Luo ◽  
Dieter Kley ◽  
Richard H. Johnson ◽  
Herman Smit
Keyword(s):  
Water Vapor ◽  
Asian Monsoon ◽  
Deep Convection ◽  
Seasonal Migration ◽  
Specific Humidity ◽  
Tropical Atlantic ◽  
Monsoon Region ◽  
Tropical Africa ◽  
Asian Monsoon Region ◽  
The Mean

Abstract Ten years (1994–2004) of measurements of tropical upper-tropospheric water vapor (UTWV) by the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) are investigated over three regions—the tropical Atlantic, tropical Africa, and the Asian monsoon region—to determine the UTWV climatology and variability on multiple scales and to understand them in relation to moisture transport and deep convection. The seasonal migration of upper-tropospheric humidity (UTH) keeps pace with that of the ITCZ, indicating the convective influence on UTH distribution. Some significant regional differences are identified with the tropical Africa and the Asian monsoon regions being moister than the tropical Atlantic. UTH generally increases with height by 10%–20% relative humidity with respect to ice (RHi) from about 300 to 200 hPa, and the differences are larger in the deep Tropics than in the subtropics. The probability density functions of tropical UTH are often bimodal. The two modes stay rather constant; differences in the mean value are largely due to the variations in the proportion of the two modes as opposed to changes in the modes themselves. In the deep Tropics, the moisture level frequently reaches ice supersaturation, the most notable case being the near-equatorial Asian monsoon region during the wet season when ice supersaturation is observed 46% of the time. Interannual variations are observed in association with the 1997–98 ENSO event. A warming of about 1–2 K is observed for all three regions equatorward of roughly 15°. Specific humidity also increases somewhat for the tropical Atlantic and tropical Africa, but the increase in temperature outweighs the increase in specific humidity such that RH decreases by 5%–15% RHi. In addition to the ENSO-related variation, MOZAIC also sees increases in both RH and specific humidity over tropical Africa from 2000 onward. Moisture fluxes are computed from MOZAIC data and decomposed into contributions from the mean circulation and from eddies. The flux divergence, which represents the moisture source/sink from horizontal transport, is also estimated. Finally, the MOZAIC climatology and variability are revisited in relation to deep convection obtained from the International Satellite Cloud Climatology Project (ISCCP).

scholarly journals Pengaruh Suhu dan Kelembaban Terhadap Rasio Kelembaban dan Entalpi (Studi Kasus: Gedung UNIFA Makassar)

2021 ◽  
pp. 102-114
Author(s):  
Ahmad Nadhil Edar
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Experimental Studies ◽  
Well Being ◽  
Specific Humidity ◽  
Unit Mass ◽  
Specific Enthalpy ◽  
Humidity Ratio ◽  
Total Enthalpy ◽  
Dry Air

Temperature affects humidity. The interaction of temperature and humidity also directly affects the health and well-being of humans. The relative humidity (RH) of the air is an indication of how much water vapor is in the air at a particular temperature compared with how much water vapor the air could actually hold at that temperature. Air at 100 % relative humidity holds the maximum amount of water possible at that particular temperature and is said to be saturated. Therefore, air at 50% relative humidity, regardless of temperature, is holding half of its total possible water capacity. In essence, cold air cannot hold as much water vapor as warm air. In a closed environment such as a display case, there will be a fixed amount of water vapor, referred to as the absolute humidity. If the temperature inside the case falls then the relative humidity will rise. If the temperature rises the relative humidity will fall. Such changes in relative humidity could be caused by many factors including direct sunlight, spotlights and air-conditioning failures. Research carried out by experimental studies that we can get the humidity ratio and specific enthalpy in a kind of rooms either using The Psychrometric Chart and The formula. The specific humidity or humidity ratio of an air sample is the ratio of the weight of water vapor contained in the sample compared to the weight of the dry air in the same sample. Enthalpy is the amount of heat (energy) in the air per unit mass. Enthalpy is the total amount of energy present in the air, both from air and water vapor contained therein. And, Specific enthalpy of moist air is defined as the total enthalpy of the dry air and the water vapor mixture - per unit mass of dry air. Keywords: Temperature; Relative Humidity; Humidity Ratio; Specific Enthalpy.

Precursors and Formation Mechanisms of Event-based Extreme Precipitation during Springtime in Central-Eastern China

2021 ◽  
pp. 1-42
Author(s):  
Wei Shang ◽  
Xuejuan Ren ◽  
Shuangshuang Li ◽  
Keqin Duan
Keyword(s):  
Water Vapor ◽  
Extreme Precipitation ◽  
Eastern China ◽  
Specific Humidity ◽  
Horizontal Wind ◽  
Formation Mechanisms ◽  
The Sea Of Japan ◽  
Budget Analysis ◽  
Central Eastern ◽  
Event Based

AbstractThis study investigates the precursors and formation mechanisms of spring (April-May) event-based extreme precipitation (EEP) during 1961-2014 in central-eastern China. The EEP events during springtime are primarily characterized by extreme precipitation that occurs at the first half of an event. During early stages of spring EEP events, a Rossby wave grows over Western Europe and the North Atlantic Ocean. The wave propagates eastward toward East Asia, exhibiting a circumglobal teleconnection (CGT) pattern. A strong anticyclone related to the CGT pattern is formed over Japan Islands in the upper troposphere, enhancing the divergence anomalies and bringing more water vapor anomalies from the Sea of Japan into central-eastern China. Meanwhile, the westerly jet jump northward and anomalous southwesterly water vapor flux is significantly prevalent, which is associated with the onset of the Bay of Bengal summer monsoon (BOBSM). Combined the anomalous southwesterly and northeasterly moisture flux into central-eastern China, strong convergence is formed and provided abundant water vapor for the extreme precipitation. The moisture budget analysis further suggests that the dynamic processes associated with horizontal wind anomalies play a crucial role in the moisture convergence for the spring EEP events. The advection of zonal and meridional moisture is strongly related with the anomalous winds of the CGT waves and BOBSM, respectively. While the horizontal thermodynamic processes related to specific humidity and vertical advection contribute much less. The results indicate the preceding signals in the midlatitude and subtropics for the spring EEP events, favoring for extreme precipitation forecasting and hydrological prediction.

scholarly journals The Relative Humidity in an Isentropic Advection–Condensation Model: Limited Poleward Influence and Properties of Subtropical Minima

2011 ◽  
Vol 68 (12) ◽  
pp. 3079-3093 ◽  
Author(s):  
Paul A. O’Gorman ◽  
Nicolas Lamquin ◽  
Tapio Schneider ◽  
Martin S. Singh
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
General Circulation ◽  
Circulation Model ◽  
Reanalysis Data ◽  
Specific Humidity ◽  
Moisture Source ◽  
Inflection Points ◽  
Isentropic Surface ◽  
Tropical Moisture

Abstract An idealized model of advection and condensation of water vapor is considered as a representation of processes influencing the humidity distribution along isentropic surfaces in the free troposphere. Results are presented for how the mean relative humidity distribution varies in response to changes in the distribution of saturation specific humidity and in the amplitude of a tropical moisture source. Changes in the tropical moisture source are found to have little effect on the relative humidity poleward of the subtropical minima, suggesting a lack of poleward influence despite much greater water vapor concentrations at lower latitudes. The subtropical minima in relative humidity are found to be located just equatorward of the inflection points of the saturation specific humidity profile along the isentropic surface. The degree of mean subsaturation is found to vary with the magnitude of the meridional gradient of saturation specific humidity when other parameters are held fixed. The atmospheric relevance of these results is investigated by comparison with the positions of the relative humidity minima in reanalysis data and by examining poleward influence of relative humidity in simulations with an idealized general circulation model. It is suggested that the limited poleward influence of relative humidity may constrain the propagation of errors in simulated humidity fields.

Sign in / Sign up

Export Citation Format

Share Document