Characteristics of land-atmosphere interaction parameters in hinterland of the Taklimakan Desert

Abstract

The importance of the energy exchange between the land surface and the atmosphere can be characterized by bulk transfer coefficients for momentum, C d , and heat, C h. The diurnal and monthly variations of both bulk transfer coefficients and lengths of surface roughness are analyzed. Based on observed data from January to December 2009 in hinterland of the Taklimakan Desert, the characteristics of aerodynamic roughness length, z 0m , and thermal roughness length, z 0h , are discussed. It should be noted that the diurnal and monthly variations of the parameters are fundamentally different from those reported in vegetated areas. Specifically, four unique features can be identified in the surface layer. First, in Taklimakan Desert, z 0m does not vary with seasons; however, it significantly depends on wind speed. Second, z 0h is higher in the daytime and lower at night, showing obvious diurnal characteristics. The high values appear at sunrise and sunset. Third, both C d and C h have two peaks, one peak at sunrise, and another one at noon. Fourth, both C d and C h have larger values in winter season and smaller values in summer season. The vast Taklimakan Desert (TD) significantly influences the climate formation in Northwestern China 1-4 , and the energy exchange at the interface of land and the atmosphere drives the climate system 5,6. The energy exchange is dependent on several important parameters, including the surface albedo (α), the surface emissivity (ε), the aerodynamic and thermal roughness lengths (z 0m and z 0h), and the bulk transfer coefficients for momentum C d and heat C h. Thus, to study these parameters is of great importance. Many field experiments, such as HAPEX/ MOBILMY 7 , FIFE 8 , HEIFE 9 , EFEDA 10 , BOREAS 11 , IMGRASS 12 , NOPEX 13 , GAME 14 , NWC-ALIEX 15 , EBEX-2000 16 , LOPEX 17 and others, have focused on the interactions between the surface of land and the atmosphere. In the TD, many studies have been performed about the land surface key parameters, atmospheric boundary layer and its stability. Liu et al. 18 calibrated some key parameters by in-situ observed data of the hinterland of TD, including the averaged surface albedo (α), surface emissivity (ε), soil thermal conductivity (λ s), and aerodynamic roughness lengths (z 0m). In addition, several formulas or schemes for the thermal roughness length (z 0h) in the common land model were assessed. Liu et al. 19 investigated two completely different methods for the calculation of surface emissivity. Jin et al. 20 analyzed the above important parameters (e.g., α, ε, z 0m , z 0h , C d and C h) in the hinterland of TD, which was located in the northern edge of TD and spatially inhomogeneous. Aynigar et al. 21 re-estimated the global terrestrial satellite broadband emissivity and moderate-resolution imaging spectrometer broadband emissivity in the TD regions. Wang et al. 22 investigated the vertical structures of the convective boundary layer during the day and the stable boundary layer at night. In addition, they also explored the effects of ...

Effects of Summer Rainfall on the Soil Thermal Properties and Surface Energy Balances in the Badain Jaran Desert

“…Figure 5(b) shows the variations in the surface albedo with the solar elevation angle in the desert area. According to the calculations, when the solar elevation angle was greater than 25°, the effect on the surface albedo was very limited, which is somewhat different from the results obtained in the Taklimakan Desert [41]. is difference was caused mainly by the latitude difference between the two locations.…”

“…Figure 6(a) shows that the soil thermal capacity before the rainfall event was 1.09 × 10 6 J•m − 3 •K − 1 , which is close to the measured value of 1.12 × 10 6 J•m − 3 •K − 1 [42] in Dunhuang and slightly lower than the result of 1.56 × 10 6 J•m − 3 •K − 1 in the Taklimakan Desert [41]. After rainfall (Figure 6(b)), the soil thermal capacity increased to 1.54 × 10 6 J•m − 3 •K − 1 due to the increase in the VWC and a lower air content between sand particles, which resulted in an increase in the soil thermal capacity.…”

Parameterization and Remote Sensing Retrieval of Land Surface Processes in the Gurbantunggut Desert, China

“…The overall dynamic roughness of Shiquanhe Station on the Qinghai-Tibet Plateau is 5.8 × 10 −2 m. Wang et al [12] calculated and compared the dynamic roughness of different types of underlying surfaces in different regions of the Qinghai-Tibet Plateau and found that they were related to the vegetation, topography, soil state, and seasonal differences of the underlying surface. The annual aerodynamic roughness of the KLML station was 1.1 × 10 −2 m, which was higher than that obtained by Liu et al [17] in the hinterland of the Taklimakan Desert of 3.1 × 10 −3 m. He Qing et al [21] calculated the average roughness of Xiaotang Station to be 6.05 × 10 −5 m, Chen et al [22] calculated the aerodynamic roughness of Gansu Jinta Oasis Desert Station to be 2.8 × 10 −2 m, and Yang Xinhua et al [23] calculated the roughness of Hade Station in the northern edge of the Taklimakan Desert to be 2.70 × 10 −5 m, which is lower than that of Zhao et al [24]. The overall dynamic roughness of Shiquanhe Station on the Qinghai-Tibet Plateau is 5.8 × 10 −2 m. Wang et al [12] calculated and compared the dynamic roughness of different types of underlying surfaces in different regions of the Qinghai-Tibet Plateau and found that they were related to the vegetation, topography, soil state, and seasonal differences of the underlying surface.…”

“…Several researchers used the wind speed profile method and wind tunnel simulation to study the dynamic roughness of a flat sandy bed and flat sand [13][14][15][16]. Liu et al [17] calculated multiple surface parameters in the hinterland of the Taklamakan Desert and found that the dynamic roughness in the region did not vary seasonally, mainly depending on wind speed. The C H is higher in winter and lower in summer.…”

Turbulent Mechanisms for the Deep Convective Boundary Layer in the Taklimakan Desert

“…Recently, extreme precipitation events have occurred frequently (Wang et al., 2020; Zhang et al., 2012; Zhou et al., 2019). With the construction of the environment and climate observation network (Yang et al., 2021), it has been found that the land‐surface processes and the vertical structures of the atmospheric boundary layer are unique (Liu & Meng et al., 2020; Wang & Lu et al., 2016; Wei et al., 2019). Contrary to the typical 1,000–2,000 m over land, the convective boundary layer (CBL) can reach 5,000 m in summer (Wang & Wei et al., 2016).…”