scholarly journals Quantitative Analysis of the Sub-Cloud Evaporation of Atmospheric Precipitation and Its Controlling Factors Calculated By D-Excess in an Inland River Basin of China

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2798
Author(s):  
Xinggang Ma ◽  
Wenxiong Jia ◽  
Guofeng Zhu ◽  
Shijin Wang
Keyword(s):  
Relative Humidity ◽  
River Basin ◽  
Sampling Site ◽  
Atmospheric Precipitation ◽  
Controlling Factors ◽  
Qilian Mountains ◽  
Cloud Base ◽  
Near Surface ◽  
Precipitation Decrease ◽  
Excess Value

Atmospheric precipitation is an important part of the water circle in an inland basin. Based on the analytical results of 149 precipitation samples and corresponding surface meteorological data collected at four sampling sites (Lenglong, Ningchang, Huajian and Xiying) at different elevations in the Xiying river basin on the north slope of Qilian Mountains from May to September 2017, the sub-cloud evaporation in precipitation and its controlling factors are analyzed by the Stewart model. The results show that sub-cloud evaporation led to d-excess value in precipitation decrease and d-excess variation from cloud-base to near surface (Δd) increase with decreasing altitude. The remaining evaporation fraction of raindrop (f) decreases with decreasing altitude. The difference of underlying surface led to a difference change of f and Δd in the Xiying sampling site. For every 1% increase in raindrop evaporation, d-excess value in precipitation decreased by about 0.99‰. In an environment of high relative humidity and low temperature, the slope of the linear relationship between f and Δd is less than 0.99. In contrast, in the environment of low relative humidity and high temperature, the slope is higher than 0.99. In this study, set constant raindrop diameter may affect the calculation accuracy. The Stewart model could have different parameter requirements in different study areas. This research is helpful to understand water cycle and land–atmosphere interactions in Qilian Mountains.

scholarly journals Influence of Below-Cloud Evaporation on Deuterium Excess in Precipitation of Arid Central Asia and Its Meteorological Controls

2016 ◽  
Vol 17 (7) ◽  
pp. 1973-1984 ◽  
Author(s):  
Shengjie Wang ◽  
Mingjun Zhang ◽  
Yanjun Che ◽  
Xiaofan Zhu ◽  
Xuemei Liu
Keyword(s):  
Relative Humidity ◽  
Central Asia ◽  
Air Temperature ◽  
Sampling Site ◽  
Heavy Precipitation ◽  
Cloud Base ◽  
Deuterium Excess ◽  
Arid Central Asia ◽  
Observation Network ◽  
The Difference

Abstract The deuterium excess is a second-order parameter linking water-stable oxygen and hydrogen isotopes and has been widely used in hydrological studies. The deuterium excess in precipitation is greatly influenced by below-cloud evaporation through unsaturated air, especially in an arid climate. Based on an observation network of isotopes in precipitation of arid central Asia, the difference in deuterium excess from cloud base to ground was calculated for each sampling site. The difference on the southern slope of the Tian Shan is generally larger than that on the northern slope, and the difference during the summer months is greater than that during the winter months. Generally, an increase of 1% in evaporation of raindrops causes deuterium excess to decrease by approximately 1‰. Under conditions of low air temperature, high relative humidity, heavy precipitation, and large raindrop diameter, a good linear correlation is exhibited between evaporation proportion and difference in deuterium excess, and a linear regression slope of <1‰ %−1 can be seen; in contrast, under conditions of high air temperature, low relative humidity, light precipitation, and small raindrop diameter, the linear relationship is relatively weak, and the slope is much larger than 1‰ %−1. A sensitivity analysis under different climate scenarios indicates that, if air temperature has increased by 5°C, deuterium excess difference decreases by 0.3‰–4.0‰ for each site; if relative humidity increases by 10%, deuterium excess difference increases by 1.1‰–10.3‰.

scholarly journals Modeling Insights into Precipitation Deuterium Excess as an Indicator of Raindrop Evaporation in Lanzhou, China

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 193
Author(s):  
Fenli Chen ◽  
Mingjun Zhang ◽  
Athanassios A. Argiriou ◽  
Shengjie Wang ◽  
Qian Ma ◽  
...  
Keyword(s):  
Arid Region ◽  
Quantitative Methods ◽  
Isotope Composition ◽  
Sampling Site ◽  
Western China ◽  
Cloud Base ◽  
Deuterium Excess ◽  
Semi Arid Region ◽  
Semi Arid

The deuterium excess in precipitation is an effective indicator to assess the existence of sub-cloud evaporation of raindrops. Based on the synchronous measurements of stable isotopes of hydrogen and oxygen (δ2H and δ18O) in precipitation for several sites in Lanzhou, western China, spanning for approximately four years, the variations of deuterium excess between the ground and the cloud base are evaluated by using a one-box Stewart model. The deuterium excess difference below the cloud base during summer (−17.82‰ in Anning, −11.76‰ in Yuzhong, −21.18‰ in Gaolan and −12.41‰ in Yongdeng) is greater than that in other seasons, and difference in winter is weak due to the low temperature. The variations of deuterium excess in precipitation due to below-cloud evaporation are examined for each sampling site and year. The results are useful to understand the modification of raindrop isotope composition below the cloud base at a city scale, and the quantitative methods provide a case study for a semi-arid region at the monsoon margin.

scholarly journals Climate pattern-scaling set for an ensemble of 22 GCMs – adding uncertainty to the IMOGEN version 2.0 impact system

2018 ◽  
Vol 11 (2) ◽  
pp. 541-560 ◽  
Author(s):  
Przemyslaw Zelazowski ◽  
Chris Huntingford ◽  
Lina M. Mercado ◽  
Nathalie Schaller
Keyword(s):  
Climate Change ◽  
Relative Humidity ◽  
Land Surface ◽  
Land Surface Model ◽  
Individual Performance ◽  
Balance Model ◽  
Surface Model ◽  
Near Surface ◽  
Global Circulation Models ◽  
Version 2.0

Abstract. Global circulation models (GCMs) are the best tool to understand climate change, as they attempt to represent all the important Earth system processes, including anthropogenic perturbation through fossil fuel burning. However, GCMs are computationally very expensive, which limits the number of simulations that can be made. Pattern scaling is an emulation technique that takes advantage of the fact that local and seasonal changes in surface climate are often approximately linear in the rate of warming over land and across the globe. This allows interpolation away from a limited number of available GCM simulations, to assess alternative future emissions scenarios. In this paper, we present a climate pattern-scaling set consisting of spatial climate change patterns along with parameters for an energy-balance model that calculates the amount of global warming. The set, available for download, is derived from 22 GCMs of the WCRP CMIP3 database, setting the basis for similar eventual pattern development for the CMIP5 and forthcoming CMIP6 ensemble. Critically, it extends the use of the IMOGEN (Integrated Model Of Global Effects of climatic aNomalies) framework to enable scanning across full uncertainty in GCMs for impact studies. Across models, the presented climate patterns represent consistent global mean trends, with a maximum of 4 (out of 22) GCMs exhibiting the opposite sign to the global trend per variable (relative humidity). The described new climate regimes are generally warmer, wetter (but with less snowfall), cloudier and windier, and have decreased relative humidity. Overall, when averaging individual performance across all variables, and without considering co-variance, the patterns explain one-third of regional change in decadal averages (mean percentage variance explained, PVE, 34.25±5.21), but the signal in some models exhibits much more linearity (e.g. MIROC3.2(hires): 41.53) than in others (GISS_ER: 22.67). The two most often considered variables, near-surface temperature and precipitation, have a PVE of 85.44±4.37 and 14.98±4.61, respectively. We also provide an example assessment of a terrestrial impact (changes in mean runoff) and compare projections by the IMOGEN system, which has one land surface model, against direct GCM outputs, which all have alternative representations of land functioning. The latter is noted as an additional source of uncertainty. Finally, current and potential future applications of the IMOGEN version 2.0 modelling system in the areas of ecosystem modelling and climate change impact assessment are presented and discussed.

scholarly journals Evaluation of the AMPS Boundary Layer Simulations on the Ross Ice Shelf, Antarctica, with Unmanned Aircraft Observations

2017 ◽  
Vol 56 (8) ◽  
pp. 2239-2258 ◽  
Author(s):  
Jonathan D. Wille ◽  
David H. Bromwich ◽  
John J. Cassano ◽  
Melissa A. Nigro ◽  
Marian E. Mateling ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Relative Humidity ◽  
High Wind ◽  
Ice Shelf ◽  
High Wind Speed ◽  
Near Surface ◽  
Ross Ice Shelf ◽  
Low Cloud ◽  
The Antarctic

AbstractAccurately predicting moisture and stability in the Antarctic planetary boundary layer (PBL) is essential for low-cloud forecasts, especially when Antarctic forecasters often use relative humidity as a proxy for cloud cover. These forecasters typically rely on the Antarctic Mesoscale Prediction System (AMPS) Polar Weather Research and Forecasting (Polar WRF) Model for high-resolution forecasts. To complement the PBL observations from the 30-m Alexander Tall Tower! (ATT) on the Ross Ice Shelf as discussed in a recent paper by Wille and coworkers, a field campaign was conducted at the ATT site from 13 to 26 January 2014 using Small Unmanned Meteorological Observer (SUMO) aerial systems to collect PBL data. The 3-km-resolution AMPS forecast output is combined with the global European Centre for Medium-Range Weather Forecasts interim reanalysis (ERAI), SUMO flights, and ATT data to describe atmospheric conditions on the Ross Ice Shelf. The SUMO comparison showed that AMPS had an average 2–3 m s−1 high wind speed bias from the near surface to 600 m, which led to excessive mechanical mixing and reduced stability in the PBL. As discussed in previous Polar WRF studies, the Mellor–Yamada–Janjić PBL scheme is likely responsible for the high wind speed bias. The SUMO comparison also showed a near-surface 10–15-percentage-point dry relative humidity bias in AMPS that increased to a 25–30-percentage-point deficit from 200 to 400 m above the surface. A large dry bias at these critical heights for aircraft operations implies poor AMPS low-cloud forecasts. The ERAI showed that the katabatic flow from the Transantarctic Mountains is unrealistically dry in AMPS.

RETROSPECTIVE ASSESSMENT OF UNREGULATED LATERAL INFLOWS OF THE KUIBYSHEVSKY (NOW ZHIGULYOVSKAYA HYDROPOWER PLANT) HYDRAULIC UNIT OF THE VOLGA RIVER BASIN

2021 ◽  
pp. 87-99
Author(s):  
G. KH. ISMAIYLOV ◽  
◽  
N. V. MURASCHENKOVA ◽  
I. G. ISMAIYLOVA
Keyword(s):  
River Basin ◽  
Air Temperature ◽  
Atmospheric Precipitation ◽  
Total Precipitation ◽  
Volga River ◽  
Hydraulic Unit ◽  
Seasonal Characteristics ◽  
Lateral Inflow ◽  
Increasing Trend

The results of the analysis and assessment of changes in annual and seasonal characteristics of hydrometeorological processes in a private catchment area of the Kuibyshev hydroelectric complex of the Volga river are presented. To analyze the temporal dynamics of the variability of the annual and seasonal characteristics of the hydrometeorological processes in the considered territory of the river basin we used more than 100 years of observations of annual and seasonal fluctuations of lateral inflow, total atmospheric precipitation and air temperature regimes on the Volgariver. Relationship equations for annual and seasonal changes in hydrometeorological characteristics in time are obtained. It was found that long-term fluctuations of hydrometeorological processes (lateral inflow, total atmospheric precipitation and air temperature) are characterized by tendencies (trends). The analysis of these trends showed that the non-standard climatic situation, starting from the 70s of the last century, had a very significant impact on the distribution of annual and especially on the seasonal (low-water and winter) characteristics of hydrometeorological processes. It has been established that non-standard unidirectional changes are found in the fluctuations in the total atmospheric precipitation. If the winter total precipitation is characterized over the 100-year period in question by a continuously decreasing trend,the summer-autumn period is an increasing trend. This leads to the fact that long-term fluctuations in total precipitation during the period of low water are formed as a stationary process. At the same time, the total precipitation of the spring flood and inflowing to the Kuibyshev hydroelectric unit is characterized by a constantly increasing trend.

scholarly journals Brief communication: Rare ambient saturation during drifting snow occurrences at a coastal location of East Antarctica

2019 ◽  
Vol 13 (12) ◽  
pp. 3405-3412 ◽  
Author(s):  
Charles Amory ◽  
Christoph Kittel
Keyword(s):  
Relative Humidity ◽  
Meteorological Data ◽  
Ice Sheet ◽  
Ambient Air ◽  
East Antarctica ◽  
Strong Increase ◽  
Katabatic Wind ◽  
Strong Wind ◽  
Near Surface ◽  
Drifting Snow

Abstract. Sublimation of snow particles during transport has been recognized as an important ablation process on the Antarctic ice sheet. The resulting increase in moisture content and cooling of the ambient air are thermodynamic negative feedbacks that both contribute to increase the relative humidity of the air, inhibiting further sublimation when saturation is reached. This self-limiting effect and the associated development of saturated near-surface air layers in drifting snow conditions have mainly been described through modelling studies and a few field observations. A set of meteorological data, including drifting snow mass fluxes and vertical profiles of relative humidity, collected at site D17 in coastal Adélie Land (East Antarctica) during 2013 is used to study the relationship between saturation of the near-surface atmosphere and the occurrence of drifting snow in a katabatic wind region that is among the most prone to snow transport by wind. Atmospheric moistening by the sublimation of the windborne snow particles generally results in a strong increase in relative humidity with the magnitude of drifting snow and a decrease in its vertical gradient, suggesting that windborne-snow sublimation can be an important contributor to the local near-surface moisture budget. Despite a high incidence of drifting snow at the measurement location (60.1 % of the time), saturation, when attained, is however most often limited to a thin air layer below 1 m above ground. The development of a near-surface saturated air layer up to the highest measurement level of 5.5 m is observed in only 8.2 % of the drifting snow occurrences or 6.3 % of the time and mainly occurs in strong wind speed and drift conditions. This relatively rare occurrence of ambient saturation is explained by the likely existence of moisture-removal mechanisms inherent to the katabatic and turbulent nature of the boundary-layer flow that weaken the negative feedback of windborne-snow sublimation. Such mechanisms, potentially quite active in katabatic-generated windborne-snow layers all over Antarctica, may be very important in understanding the surface mass and atmospheric moisture budgets of the ice sheet by enhancing windborne-snow sublimation.

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