Soil Moisture-Boundary Layer Feedbacks on the Loess Plateau in China Using Radiosonde Data with 1-D Atmospheric Boundary Layer Model

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.

Download Full-text

On the turbulent structure of the marine atmospheric boundary layer from CBLAST Nantucket measurements

Global NEST Journal ◽

10.30955/gnj.000439 ◽

2013 ◽

Vol 10 (3) ◽

pp. 210-217

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Land Surface ◽

Atmospheric Stability ◽

Heat Fluxes ◽

Turbulent Structure ◽

Atmospheric Conditions ◽

Turbulent Characteristics ◽

Momentum Fluxes

In this work preliminary results on the characteristics of the turbulent structure of the Marine Atmospheric Boundary Layer (MABL) are presented. Measurements used here were conducted in the framework of the Coupled Boundary Layers Air-Sea Transfer Experiment in Low Wind (CBLAST-Low) project. A number of in situ (fast and slow sensors) and remote sensing (SODAR) instruments were deployed on the coast of Nantucket Island, MA, USA. Measurements of the mean wind, the variances of the three wind components, the atmospheric stability and the momentum fluxes from the acoustic radar (SODAR) revealed the variation of the depth, the turbulent characteristics, and the stability of the MABL in response to the background flow. More specifically, under light south-southwesterly winds, which correspond to the MABL wind directions, the atmosphere was very stable and low values of turbulence were observed. Under moderate to strong southwesterly flow, less stable and neutral atmospheric conditions appeared and the corresponding turbulent quantities were characterized by higher values. The SODAR measurements, with high temporal and spatial resolution, also indicated large magnitude of momentum fluxes at higher levels, presumably associated with the shear forcing near the developed low-level jet. The measurements from the in-situ instrumentation confirmed that the MABL typically has small negative momentum and sensible heat fluxes consistent with stable to neutral stratification while strong diurnal variations were typical for the land surface Atmospheric Boundary Layer (ABL). The developed internal ABL at the experimental site was in general less than 10m during the night and could reach 15m heights during the day, particularly under low-wind conditions.

Download Full-text

Impact of revegetation of the Loess Plateau of China on the regional growing season water balance

10.5194/egusphere-egu2020-3877 ◽

2020 ◽

Author(s):

Weidong Guo ◽

Andrew Pitman ◽

Jun Ge ◽

Beilei Zan ◽

Congbin Fu

Keyword(s):

Soil Moisture ◽

Loess Plateau ◽

Wrf Model ◽

Growing Season ◽

Weather Research And Forecasting ◽

The Loess Plateau ◽

Deep Soil ◽

Bare Land ◽

Biophysical Changes ◽

The Impact

<p>To resolve a series of ecological and environmental problems over the Loess Plateau, the was initiated at the end of 1990s. Following the conversion of croplands and bare land on hillslopes to forests, the Loess Plateau has displayed a significant greening trend with soil erosion being reduced. However, the GFGP has also affected the hydrology of the Loess Plateau which has raised questions whether the GFGP should be continued in the future. We investigated the impact of revegetation on the hydrology of the Loess Plateau using high resolution simulations and multiple realisations with the Weather Research and Forecasting (WRF) model. Results suggests that land cover change since the launch of the GFGP has reduced runoff and soil moisture due to enhanced evapotranspiration. Further revegetation associated with the GFGP policy is likely to increase evapotranspiration further, and thereby reduce runoff and soil moisture. The increase in evapotranspiration is associated with biophysical changes, including deeper roots that deplete deep soil moisture stores. However, despite the increase in evapotranspiration our results show no impact on rainfall. Our study cautions against further revegetation over the Loess Plateau given the reduction in water available for agriculture and human settlements, without any significant compensation from rainfall.</p>

Download Full-text

Impact of revegetation of the Loess Plateau of China on the regional growing season water balance

10.5194/hess-2019-397 ◽

2019 ◽

Cited By ~ 1

Author(s):

Jun Ge ◽

Andrew J. Pitman ◽

Weidong Guo ◽

Beilei Zan ◽

Congbin Fu

Keyword(s):

Soil Moisture ◽

Loess Plateau ◽

Wrf Model ◽

Weather Research And Forecasting ◽

The Loess Plateau ◽

Deep Soil ◽

Grain For Green ◽

Bare Land ◽

Biophysical Changes ◽

The Impact

Abstract. To resolve a series of ecological and environmental problems over the Loess Plateau, the Grain for Green Program (GFGP) was initiated at the end of 1990s. Following the conversion of croplands and bare land on hillslopes to forests, the Loess Plateau has displayed a significant greening trend with soil erosion being reduced. However, the GFGP has also affected the hydrology of the Loess Plateau which has raised questions whether the GFGP should be continued in the future. We investigated the impact of revegetation on the hydrology of the Loess Plateau using high resolution simulations and multiple realisations with the Weather Research and Forecasting (WRF) model. Results suggests that land cover change since the launch of the GFGP has reduced runoff and soil moisture due to enhanced evapotranspiration. Further revegetation associated with the GFGP policy is likely to increase evapotranspiration further, and thereby reduce runoff and soil moisture. The increase in evapotranspiration is associated with biophysical changes, including deeper roots that deplete deep soil moisture stores. However, despite the increase in evapotranspiration our results show no impact on rainfall. Our study cautions against further revegetation over the Loess Plateau given the reduction in water available for agriculture and human settlements, without any significant compensation from rainfall.

Download Full-text

Impact of revegetation of the Loess Plateau of China on the regional growing season water balance

Hydrology and Earth System Sciences ◽

10.5194/hess-24-515-2020 ◽

2020 ◽

Vol 24 (2) ◽

pp. 515-533 ◽

Cited By ~ 9

Author(s):

Jun Ge ◽

Andrew J. Pitman ◽

Weidong Guo ◽

Beilei Zan ◽

Congbin Fu

Keyword(s):

Soil Moisture ◽

Loess Plateau ◽

Wrf Model ◽

Weather Research And Forecasting ◽

The Loess Plateau ◽

Deep Soil ◽

Grain For Green ◽

Bare Land ◽

Biophysical Changes ◽

The Impact

Abstract. To resolve a series of ecological and environmental problems over the Loess Plateau, the “Grain for Green Program” (GFGP) was initiated at the end of 1990s. Following the conversion of croplands and bare land on hillslopes to forests, the Loess Plateau has displayed a significant greening trend, which has resulted in soil erosion being reduced. However, the GFGP has also affected the hydrology of the Loess Plateau, which has raised questions regarding whether the GFGP should be continued in the future. We investigated the impact of revegetation on the hydrology of the Loess Plateau using relatively high-resolution simulations and multiple realizations with the Weather Research and Forecasting (WRF) model. Results suggest that revegetation since the launch of the GFGP has reduced runoff and soil moisture due to enhanced evapotranspiration. Further revegetation associated with the GFGP policy is likely to further increase evapotranspiration, and thereby reduce runoff and soil moisture. The increase in evapotranspiration is associated with biophysical changes, including deeper roots that deplete deep soil moisture stores. However, despite the increase in evapotranspiration, our results show no impact on rainfall. Our study cautions against further revegetation over the Loess Plateau given the reduction in water available for agriculture and human settlements and the lack of any significant compensation from rainfall.

Download Full-text

Comparisons of Planetary Boundary Layer Height from Ceilometer with ARM Radiosonde Data

10.5194/amt-2021-292 ◽

2021 ◽

Author(s):

Damao Zhang ◽

Jennifer Comstock ◽

Victor Morris

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Richardson Number ◽

Value Added ◽

Department Of Energy ◽

Radiosonde Data ◽

Polar Regions ◽

Atmospheric Conditions ◽

Bulk Richardson Number ◽

Stable Atmospheric Boundary Layer

Abstract. Ceilometer measurements of aerosol backscatter profiles have been widely used to provide continuous PBLHT estimations. To investigate the robustness of ceilometer-estimated PBLHT under different atmospheric conditions, we compared ceilometer- and radiosonde-estimated PBLHTs using long term U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) ceilometer and balloon-borne sounding data at three ARM fixed-location atmospheric observatories and from three ARM mobile observatories deployed around the world for various field campaigns, which cover from Tropics to Polar regions and over both ocean and land surfaces. Statistical comparisons of ceilometer-estimated PBLHTs from the Vaisala CL31 ceilometer data with radiosonde-estimated PBLHTs from the ARM PBLHT-SONDE Value-added Product (VAP) are performed under different atmospheric conditions including stable and unstable atmospheric boundary layer, low-level cloud-free, and cloudy conditions at these ARM observatories. Under unstable atmospheric boundary layer conditions, good comparisons are found between ceilometer- and radiosonde-estimated PBLHTs at ARM low- and mid-latitude land observatories. However, it is still challenging to obtain reliable PBLHT estimations over ocean surfaces even using radiosonde data. Under stable atmospheric boundary layer conditions, ceilometer- and radiosonde-estimated PBLHTs have weak correlations. Among different PBLHT estimations utilizing the Heffter, the Liu-Liang, and the bulk Richardson number methods in the ARM PBLHT-SONDE VAP, ceilometer-estimated PBLHTs have better comparisons with the Liu-Liang method under unstable and with the bulk Richardson number method under stable atmospheric boundary layer conditions.

Download Full-text

Evaluating the Impacts of Climate Change and Vegetation Restoration on the Hydrological Cycle over the Loess Plateau, China

Water ◽

10.3390/w11112241 ◽

2019 ◽

Vol 11 (11) ◽

pp. 2241 ◽

Cited By ~ 4

Author(s):

Yang ◽

Kang ◽

Bu ◽

Chen ◽

Gao

Keyword(s):

Climate Change ◽

Soil Moisture ◽

Land Cover ◽

Loess Plateau ◽

Hydrological Cycle ◽

Management Strategies ◽

The Loess Plateau ◽

Infiltration Capacity ◽

Deep Soil ◽

The Impact

In recent decades, both observation and simulation data have demonstrated an obvious decrease in runoff and soil moisture, with increasing evapotranspiration, over the Loess Plateau. In this study, we employed a Variable Infiltration Capacity model coupled with scenario simulation to explore the impact of change in climate and land cover on four hydrological variables (HVs) over the Loess Plateau, i.e., evapotranspiration (ET), runoff (Runoff), shallow soil moisture (SM1), and deep soil moisture (SM2). Results showed precipitation, rather than temperature, had the closest relationship with the four HVs, with r ranging from 0.76 to 0.97 (p < 0.01), and this was therefore presumed to be the dominant climate-based driving factor in the variation of hydrological regimes. Vegetation conversion, from cropland and grassland to woodland, significantly reduced runoff and increased soil moisture consumption, to sustain an increased ET, and, assuming that the reduction of SM2 is entirely evaporated, we can attribute 71.28% ± 18.64%, 65.89% ± 24.14% of the ET increase to the water loss of SM2 in the two conversion modes, respectively. The variation in HVs, induced by land cover change, were higher than the expected climate change with respect to SM1, while different factors were selected to determine HVs variation in six catchments, due to differences in the mode and intensity of vegetation conversion, and the degree of climate change. Our findings are critical for understanding and quantifying the impact of climate change and vegetation conversions, and provide a further basis for the design of water resources and land-use management strategies with respect to climate change, especially in the water-limited Loess Plateau.

Download Full-text

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

SOLA ◽

10.2151/sola.2008-009 ◽

2008 ◽

Vol 4 ◽

pp. 33-36 ◽

Cited By ~ 10

Author(s):

Atsuhiro Takahashi ◽

Tetsuya Hiyama ◽

Masanori Nishikawa ◽

Hatsuki Fujinami ◽

Atsushi Higuchi ◽

...

Keyword(s):

Boundary Layer ◽

Water Vapor ◽

Atmospheric Boundary Layer ◽

Diurnal Variation ◽

Loess Plateau ◽

The Loess Plateau ◽

Free Atmosphere

Download Full-text

Impact of Lateral Groundwater Flow and Subsurface Lower Boundary Conditions on Atmospheric Boundary Layer Development over Complex Terrain

Journal of Hydrometeorology ◽

10.1175/jhm-d-19-0029.1 ◽

2020 ◽

Vol 21 (6) ◽

pp. 1133-1160 ◽

Cited By ~ 1

Author(s):

Mary M. Forrester ◽

Reed M. Maxwell

Keyword(s):

Boundary Layer ◽

Soil Moisture ◽

Atmospheric Boundary Layer ◽

Soil Layer ◽

Lower Boundary ◽

Hydrologic Model ◽

Water Model ◽

Moist Convection ◽

One Dimensional ◽

The Impact

AbstractCredible soil moisture redistribution schemes are essential to meteorological models, as lower boundary moisture influences the balance of surface turbulent fluxes and atmospheric boundary layer (ABL) development. While land surface models (LSMs) have vastly improved in their hydrologic representation, several commonly held assumptions, such as free-draining lower boundary, one-dimensional moisture flux, and lack of groundwater representation, can bias the terrestrial water balance. This study explores the impact of LSM hydrology representation on ABL development in the Weather Research and Forecasting (WRF) meteorological model. The results of summertime WRF simulations with Noah LSM, characterized by 2-m-thick soil and one-dimensional flow, are shown for a domain in the Colorado Rocky Mountain headwaters region. A reference WRF simulation is compared to 1) the same model with soil moisture initialized by the hydrologic model ParFlow; 2) a deep, free-draining simulation; and 3) WRF coupled to ParFlow, a three-dimensional, integrated groundwater-surface water model. Results show that both lateral transport of groundwater and the rate of drainage from the lower soil layer can weaken or reverse the coupling strength between evaporative fraction and ABL over a 5-month summer period. The resulting shifts in low-level moist convection in river valleys and thermally driven airflows yield strengthened anabatic upslope winds and perturbations to regional precipitation.

Download Full-text