Diurnal Variation of Water Vapor Mixing between the Atmospheric Boundary Layer and Free Atmosphere over Changwu, the Loess Plateau in China

The Loess Plateau is one land-atmosphere coupling hotspot. Soil moisture has an influence on atmospheric boundary layer development under specific early-morning atmospheric thermodynamic structures. This paper investigates the sensitivity of atmospheric convection to soil moisture conditions over the Loess Plateau in China by using the convective triggering potential (CTP)—humidity index (HIlow) framework. The CTP indicates atmospheric stability and the HIlow indicates atmospheric humidity in the low-level atmosphere. By comparing the model outcomes with the observations, the one-dimensional model achieves realistic daily behavior of the radiation and surface heat fluxes and the mixed layer properties with appropriate modifications. New CTP-HIlow thresholds for soil moisture-atmosphere feedbacks are found in the Loess Plateau area. By applying the new thresholds with long-time scales sounding data, we conclude that negative feedback is dominant in the north and west portion of the Loess Plateau; positive feedback is predominant in the south and east portion. In general, this framework has predictive significance for the impact of soil moisture on precipitation. By using this new CTP-HIlow framework, we can determine under what atmospheric conditions soil moisture can affect the triggering of precipitation and under what atmospheric conditions soil moisture has no influence on the triggering of precipitation.

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STUDY OF THE WATER VAPOR CONCENTRATION IN THE ATMOSPHERIC BOUNDARY LAYER 2 OVER THE BRAZIL-MALVINAS CONFLUENCE REGION

Brazilian Journal of Geophysics ◽

10.22564/rbgf.v38i1.2038 ◽

2020 ◽

Vol 38 (1) ◽

Author(s):

Rose Ane Pereira de Freitas

Keyword(s):

Boundary Layer ◽

Water Vapor ◽

Atmospheric Boundary Layer ◽

Observational Data ◽

Specific Humidity ◽

Radiosonde Data ◽

Vapor Concentration ◽

Free Atmosphere ◽

Atmospheric Infrared Sounder ◽

Southwestern Atlantic Ocean

ABSTRACT. The concentration of water vapor on the marine atmospheric boundary layer (MABL) at the Brazil-Malvinas Confluence (BMC) region in the Southwestern Atlantic Ocean was analyzed from 130 radiosondes collected during 10 oceanographic cruises carried out during the months of October or November from 2004 to 2015. During the same period, specific humidity and air temperature data from reanalysis (CFSR/CFSv2) and from the Atmospheric Infrared Sounder (AIRS) onboard the Aqua satellite were also used. The results of show that the thermal gradients between the warm waters of the Brazil Current (BC) and the cold waters of the Malvinas Current (MC) in BMC region are capable to produce significant differences on the MABL's water vapor content on both sides of the oceanographic front. On the average over the warmer waters of the BC the MABL is more humid. However, transient atmospheric systems, can mitigate or intensify the concentration of water vapor inside the MABL. The comparison between in situ radiosonde data and AIRS and CFSR profiles revealed that, in general, the CFSR/ CFSv2 data presented a better agreement with observational data in both sides of the BMC. The AIRS data satisfactorily represent the observational data in conditions of a cloud-free atmosphere. ESTUDO DA CONCENTRAÇÃO DE VAPOR D’ÁGUA NA CAMADA LIMITE ATMOSFÉRICA SOBRE A REGIÃO DA CONFLUÊNCIA BRASIL-MALVINAS RESUMO. A concentração de vapor d’água na camada limite atmosférica marítima (CLAM) na região da Confluência BrasilMalvinas (CBM) no Oceano Atlântico Sudoeste foi analisada a partir de 130 radiossondas coletadas durante 10 cruzeiros oceanográficos realizados nos meses de outubro ou novembro de 2004 até 2015. Durante o mesmo período, também foram utilizados dados de umidade específica e temperatura do ar provenientes da reanálise (CFSR/CFSv2) e do Atmospheric Infrared Sounder (AIRS) a bordo do satélite Aqua. Os resultados mostram que os gradientes térmicos entre as águas quentes da Corrente do Brasil (CB) e as águas frias da Corrente de Malvinas (CM) na região do CBM são capazes de produzir diferenças significativas no conteúdo de vapor de água da CLAM em ambos os lados da frente oceanográfica. Em média, sobre as águas mais quentes do CB, o CLAM é mais úmido. Entretanto, sistemas atmosféricos transientes podem mitigar ou intensificar a concentração de vapor de água dentro do CLAM. A comparações entre os dados mostraram que, em geral, os dados do CFSR/ CFSv2 apresentaram melhor concordância com os dados observacionais em ambos os lados da CBM. Os dados do AIRS representam satisfatoriamente os dados observacionais em condições atmosféricas livre de nuvens.

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Diurnal variability of the atmospheric boundary layer height over a tropical station in the Indian monsoon region

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-531-2017 ◽

2017 ◽

Vol 17 (1) ◽

pp. 531-549 ◽

Cited By ~ 14

Author(s):

Sanjay Kumar Mehta ◽

Madineni Venkat Ratnam ◽

Sukumarapillai V. Sunilkumar ◽

Daggumati Narayana Rao ◽

Boddapaty V. Krishna Murthy

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Diurnal Variation ◽

Indian Monsoon ◽

Winter Season ◽

Monsoon Region ◽

Diurnal Variability ◽

The Mean ◽

Indian Monsoon Region ◽

Tropical Station

Abstract. The diurnal variation of atmospheric boundary layer (ABL) height is studied using high-resolution radiosonde observations available at 3 h intervals for 3 days continuously from 34 intensive campaigns conducted during the period December 2010–March 2014 over a tropical station Gadanki (13.5° N, 79.2° E; 375 m), in the Indian monsoon region. The heights of the ABL during the different stages of its diurnal evolution, namely, the convective boundary layer (CBL), the stable boundary layer (SBL), and the residual layer (RL) are obtained to study the diurnal variabilities. A clear diurnal variation is observed in 9 campaigns out of the 34 campaigns. In 7 campaigns the SBL did not form in the entire day and in the remaining 18 campaigns the SBL formed intermittently. The SBL forms for 33–55 % of the time during nighttime and 9 and 25 % during the evening and morning hours, respectively. The mean SBL height is within 0.3 km above the surface which increases slightly just after midnight (02:00 IST) and remains almost constant until the morning. The mean CBL height is within 3.0 km above the surface, which generally increases from morning to evening. The mean RL height is within 2 km above the surface which generally decreases slowly as the night progresses. The diurnal variation of the ABL height over the Indian region is stronger during the pre-monsoon and weaker during winter season. The CBL is higher during the summer monsoon and lower during the winter season while the RL is higher during the winter season and lower during the summer season. During all the seasons, the ABL height peaks during the afternoon (∼ 14:00 IST) and remains elevated until evening (∼ 17:00 IST). The ABL suddenly collapses at 20:00 IST and increases slightly in the night. Interestingly, it is found that the low level clouds have an effect on the ABL height variability, but the deep convective clouds do not. The lifting condensation level (LCL) is generally found to occur below the ABL for the majority of the database and they are randomly related.

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TRANSPORT OF WATER VAPOR THROUGH THE ATMOSPHERIC BOUNDARY LAYER

Atmospheric Water Vapor ◽

10.1016/b978-0-12-208440-9.50037-5 ◽

1980 ◽

pp. 527-550 ◽

Cited By ~ 1

Author(s):

W.S. Lewellen

Keyword(s):

Boundary Layer ◽

Water Vapor ◽

Atmospheric Boundary Layer

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Improved Drought Monitoring Index Using GNSS-Derived Precipitable Water Vapor over the Loess Plateau Area

Sensors ◽

10.3390/s19245566 ◽

2019 ◽

Vol 19 (24) ◽

pp. 5566 ◽

Cited By ~ 2

Author(s):

Qingzhi Zhao ◽

Xiongwei Ma ◽

Wanqiang Yao ◽

Yang Liu ◽

Zheng Du ◽

...

Keyword(s):

Water Vapor ◽

Loess Plateau ◽

Meteorological Data ◽

Precipitable Water ◽

Satellite System ◽

Reanalysis Data ◽

Precipitable Water Vapor ◽

Drought Monitoring ◽

The Loess Plateau ◽

Monitoring Index

Standardized precipitation evapotranspiration index (SPEI) is an acknowledged drought monitoring index, and the evapotranspiration (ET) used to calculated SPEI is obtained based on the Thornthwaite (TH) model. However, the SPEI calculated based on the TH model is overestimated globally, whereas the more accurate ET derived from the Penman–Monteith (PM) model recommended by the Food and Agriculture Organization of the United Nations is unavailable due to the lack of a large amount of meteorological data at most places. Therefore, how to improve the accuracy of ET calculated by the TH model becomes the focus of this study. Here, a revised TH (RTH) model is proposed using the temperature (T) and precipitable water vapor (PWV) data. The T and PWV data are derived from the reanalysis data and the global navigation satellite system (GNSS) observation, respectively. The initial value of ET for the RTH model is calculated based on the TH model, and the time series of ET residual between the TH and PM models is then obtained. Analyzed results reveal that ET residual is highly correlated with PWV and T, and the correlate coefficient between PWV and ET is −0.66, while that between T and ET for cases of T larger or less than 0 °C are −0.54 and 0.59, respectively. Therefore, a linear model between ET residual and PWV/T is established, and the ET value of the RTH model can be obtained by combining the TH-derived ET and estimated ET residual. Finally, the SPEI calculated based on the RTH model can be obtained and compared with that derived using PM and TH models. Result in the Loess Plateau (LP) region reveals the good performance of the RTH-based SPEI when compared with the TH-based SPEI over the period of 1979–2016. A case analysis in April 2013 over the LP region also indicates the superiority of the RTH-based SPEI at 88 meteorological and 31 GNSS stations when the PM-based SPEI is considered as the reference.

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Airborne water vapor DIAL estimation of humidity fluxes and atmospheric boundary-layer parameters

10.1117/12.275140 ◽

1997 ◽

Author(s):

Christoph Kiemle ◽

Gerhard Ehret ◽

K. J. Davis ◽

Donald H. Lenschow

Keyword(s):

Boundary Layer ◽

Water Vapor ◽

Atmospheric Boundary Layer

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Penman and Priestley-Taylor approaches in Atmospheric Boundary-Layer Dynamics

10.5194/egusphere-egu2020-9216 ◽

2020 ◽

Author(s):

Jun Yin ◽

Amilcare Porporato

Keyword(s):

Boundary Layer ◽

Water Vapor ◽

Surface Temperature ◽

Atmospheric Boundary Layer ◽

Slab Model ◽

Unified Framework ◽

Surface Evaporation ◽

Analytical Approximations ◽

Taylor Approximation ◽

Boundary Layer Dynamics

<p>By linearizing the saturation water vapor curve, Penman (1948) not only found the famous explicit approximation of wet-surface evaporation but also obtained a less well-known expression of surface temperature. Here the latter has been taken into the slab model of Atmospheric Boundary Layer (ABL) to derive multiple analytical approximations of ABL dynamics, which share the features of the Penman equation with evaporation driven by energy and drying power of the air. Noticing that these two parts of evaporation are proportional to each other within the Priestley-Taylor approximation at sub-daily timescale, a unified framework is obtained that links the Penman approach and Priestley-Taylor method to the diurnal behaviors of ABL. The resulting model is useful for diagnosing the land-atmosphere interactions.</p>

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Temperature profiling of the atmospheric boundary layer with rotational Raman lidar during the HD(CP)<sup>2</sup> Observational Prototype Experiment

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-2867-2015 ◽

2015 ◽

Vol 15 (5) ◽

pp. 2867-2881 ◽

Cited By ~ 44

Author(s):

E. Hammann ◽

A. Behrendt ◽

F. Le Mounier ◽

V. Wulfmeyer

Keyword(s):

Boundary Layer ◽

Water Vapor ◽

Temperature Gradient ◽

Atmospheric Boundary Layer ◽

Average Power ◽

Mixing Ratio ◽

Raman Lidar ◽

Backscatter Signal ◽

Low Background ◽

Water Vapor Mixing Ratio

Abstract. The temperature measurements of the rotational Raman lidar of the University of Hohenheim (UHOH RRL) during the High Definition of Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observation Prototype Experiment (HOPE) in April and May 2013 are discussed. The lidar consists of a frequency-tripled Nd:YAG laser at 355 nm with 10 W average power at 50 Hz, a two-mirror scanner, a 40 cm receiving telescope, and a highly efficient polychromator with cascading interference filters for separating four signals: the elastic backscatter signal, two rotational Raman signals with different temperature dependence, and the vibrational Raman signal of water vapor. The main measurement variable of the UHOH RRL is temperature. For the HOPE campaign, the lidar receiver was optimized for high and low background levels, with a novel switch for the passband of the second rotational Raman channel. The instrument delivers atmospheric profiles of water vapor mixing ratio as well as particle backscatter coefficient and particle extinction coefficient as further products. As examples for the measurement performance, measurements of the temperature gradient and water vapor mixing ratio revealing the development of the atmospheric boundary layer within 25 h are presented. As expected from simulations, a reduction of the measurement uncertainty of 70% during nighttime was achieved with the new low-background setting. A two-mirror scanner allows for measurements in different directions. When pointing the scanner to low elevation, measurements close to the ground become possible which are otherwise impossible due to the non-total overlap of laser beam and receiving telescope field of view in the near range. An example of a low-level temperature measurement is presented which resolves the temperature gradient at the top of the stable nighttime boundary layer 100 m above the ground.

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3D Water Vapor Field in the Atmospheric Boundary Layer Observed with Scanning Differential Absorption Lidar

10.5194/amt-2015-393 ◽

2016 ◽

Cited By ~ 1

Author(s):

F. Späth ◽

A. Behrendt ◽

S. K. Muppa ◽

S. Metzendorf ◽

A. Riede ◽

...

Keyword(s):

Boundary Layer ◽

Water Vapor ◽

Atmospheric Boundary Layer ◽

Elevation Angle ◽

Three Dimensions ◽

Dimensional Structure ◽

Differential Absorption ◽

Differential Absorption Lidar ◽

3 Dimensional ◽

Western Germany

Abstract. The scanning differential absorption lidar (DIAL) of the University of Hohenheim (UHOH) determines fields of the atmospheric water vapor number density with a temporal resolution of a few seconds and spatial resolution of up to a few tens of meters. We present three case studies which show that this high resolution combined with 2- and 3-dimensional scans allows for new insights in the 3-dimensional structure of the water vapor field in the atmospheric boundary layer (ABL). In spring 2013, the UHOH DIAL was operated within the scope of the HD(CP)2 Observational Prototype Experiment (HOPE) in western Germany. HOPE was part of the project High Definition of Clouds and Precipitation for advancing Climate Prediction (HD(CP)2). Range-height indicator (RHI) scans of the UHOH DIAL show the water vapor heterogeneity within a range of a few kilometers and its impact on the formation of clouds at the ABL top. The uncertainty of the measured data was assessed by extending a technique, which was formerly applied to vertical time series, to scanning data. Typically, even during daytime, the accuracy of the DIAL measurements is between 0.5 and 0.8 g m−3 (or < 6 %) within the ABL, so that now the performance of an RHI scan from the surface to an elevation angle of 90 degrees becomes possible within 10 min. In summer 2014, the UHOH DIAL participated in the Surface-Atmosphere-Boundary-Layer-Exchange (SABLE) campaign in south-western Germany. Volume scans show the water vapor field in three dimensions. In this case, multiple humidity layers were present. Differences in their heights in different directions can be attributed to different surface elevation. With low elevation scans in the surface layer, the humidity profiles and gradients related to different land use and surface stabilities were also revealed.

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A Raman Lidar with a Deep Ultraviolet Laser for Continuous Water Vapor Profiling in the Atmospheric Boundary Layer

EPJ Web of Conferences ◽

10.1051/epjconf/202023703001 ◽

2020 ◽

Vol 237 ◽

pp. 03001

Author(s):

Masanori Yabuki ◽

Yuya Kawano ◽

Yusaku Tottori ◽

Makoto Tsukamoto ◽

Eiji Takeuchi ◽

...

Keyword(s):

Boundary Layer ◽

Water Vapor ◽

Atmospheric Boundary Layer ◽

Environmental Conditions ◽

Raman Lidar ◽

Backscatter Signal ◽

Ultraviolet Laser ◽

Deep Ultraviolet ◽

Temperature Controlled

A Raman lidar with a deep ultraviolet laser was constructed to continuously monitor water vapor distributions in the atmospheric boundary layer for twenty-four hours. We employ a laser at a wavelength of 266 nm and detects the light separated into an elastic backscatter signal and vibrational Raman signals of oxygen, nitrogen, and water vapor. The lidar was encased in a temperature-controlled and vibration-isolated compact container, resistant to a variety of environmental conditions. Water vapor profile observations were made for twelve months from November 24, 2017, to November 29, 2018. These observations were compared with collocated radiosonde measurements for daytime and nighttime conditions.

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