Testing the method for surface air temperature refinement based on a complex of models of the atmospheric boundary layer and local heat and water budgets

2008 ◽  
Vol 33 (1) ◽  
pp. 9-14
Author(s):  
A. Yu. Mikhailov ◽  
K. G. Rubinshtein ◽  
A. B. Shmakin
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Local Heat ◽  
Water Budgets

Evaluating the response of the diurnal range of surface and air temperature to evaporative conditions across vegetation types in ERA5 and FLUXNET data

2021 ◽  
Author(s):  
Annu Panwar ◽  
Axel Kleidon
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Air Temperature ◽  
Extreme Events ◽  
Heat Storage ◽  
Vegetation Type ◽  
Diurnal Variations ◽  
Vegetation Types ◽  
Evaporative Fraction ◽  
Simple Boundary

<p>The diurnal variations of surface and air temperature are related but their different responses to evaporative conditions can inform us about land-atmosphere interactions, extreme events, and their response to global change. Here, we evaluate the sensitivity of the diurnal ranges of surface (DT<sub>s</sub>R) and air (DT<sub>a</sub>R) temperature to evaporative fraction, across short vegetation, savanna, and forests at 106 Fluxnet observational sites and in the ERA5 global reanalysis. We show that the sensitivity of DT<sub>s</sub>R to evaporative fraction depends on vegetation type, whereas for DT<sub>a</sub>R it does not. Using FLUXNET data we found that on days with low evaporative fraction, DT<sub>s</sub>R is enhanced by up to 20 °C (30 °C in ERA5) in short vegetation, whereas only by 8 °C (10 °C in ERA5) in forests. Particularly, in short vegetation, ERA5 shows stronger responses, which is attributable to a negative bias on days with the high evaporative fraction. ERA5 also tends to have lower shortwave and longwave radiation input when compared to FLUXNET data. Contrary to DT<sub>s</sub>R, DT<sub>a</sub>R responds rather similarly to evaporative fraction irrespective of vegetation type (8 °C in FLUXNET, 10 °C in ERA5). To explain this, we show that the DT<sub>a</sub>R response to the evaporative fraction is compensated for differences in atmospheric boundary layer height by up to 2000 m, which is similar across vegetation types. We demonstrate this with a simple boundary layer heat storage calculation, indicating that DT<sub>a</sub>R is primarily shaped by changes in boundary layer heat storage whereas DT<sub>s</sub>R mainly responds to solar radiation, evaporation, and vegetation.  Our study reveals some systematic biases in ERA5 that need to be considered when using its temperature products for understanding land-atmosphere interactions or extreme events. To conclude, this study demonstrates the importance of vegetation and the dynamics of the atmospheric boundary layer in regulating diurnal variations in surface and air temperature under different evaporative conditions.</p>

scholarly journals Estimation of Turbulent Heat Fluxes via Assimilation of Air Temperature and Specific Humidity into an Atmospheric Boundary Layer Model

2020 ◽  
Vol 21 (2) ◽  
pp. 205-225 ◽  
Author(s):  
E. Tajfar ◽  
S. M. Bateni ◽  
S. A. Margulis ◽  
P. Gentine ◽  
T. Auligne
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Air Temperature ◽  
Potential Temperature ◽  
Heat Fluxes ◽  
Specific Humidity ◽  
Turbulent Heat ◽  
Layer Model ◽  
Ground Heat Flux ◽  
Turbulent Heat Fluxes

AbstractA number of studies have used time series of air temperature and specific humidity observations to estimate turbulent heat fluxes. These studies require the specification of surface roughness lengths for heat and momentum (that are directly related to the neutral bulk heat transfer coefficient CHN) and/or ground heat flux, which are often unavailable. In this study, sequences of air temperature and specific humidity are assimilated into an atmospheric boundary layer model within a variational data assimilation (VDA) framework to estimate CHN, evaporative fraction (EF), turbulent heat fluxes, and atmospheric boundary layer (ABL) height, potential temperature, and humidity. The developed VDA approach needs neither the surface roughness parameterization (as it is optimized by the VDA approach) nor ground heat flux measurements. The VDA approach is tested over the First International Satellite Land Surface Climatology Project Field Experiment (FIFE) site in the summers of 1987 and 1988. The results indicate that the estimated sensible and latent heat fluxes agree fairly well with the corresponding measurements. For FIFE 1987 (1988), the daily sensible and latent heat fluxes estimates have a root-mean-square error of 25.72 W m−2 (27.77 W m−2) and 53.63 W m−2 (48.22 W m−2), respectively. In addition, the ABL height, specific humidity, and potential temperature estimates from the VDA system are in good agreement with those inferred from the radiosondes both in terms of magnitude and diurnal trend.

Statistics of air temperature inversions in the atmospheric boundary layer

2021 ◽  
Author(s):  
Andrey P. Kamardin ◽  
Irina V. Nevzorova ◽  
Sergey L. Odintsov
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Air Temperature ◽  
Temperature Inversions

scholarly journals Evaluation of urban surface parameterizations in the WRF model using measurements during the Texas Air Quality Study 2006 field campaign

2011 ◽  
Vol 11 (5) ◽  
pp. 2127-2143 ◽  
Author(s):  
S.-H. Lee ◽  
S.-W. Kim ◽  
W. M. Angevine ◽  
L. Bianco ◽  
S. A. McKeen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Air Temperature ◽  
Urban Areas ◽  
Surface Air Temperature ◽  
Urban Vegetation ◽  
Galveston Bay ◽  
Near Surface ◽  
Field Campaign ◽  
Quality Study

Abstract. The performance of different urban surface parameterizations in the WRF (Weather Research and Forecasting) in simulating urban boundary layer (UBL) was investigated using extensive measurements during the Texas Air Quality Study 2006 field campaign. The extensive field measurements collected on surface (meteorological, wind profiler, energy balance flux) sites, a research aircraft, and a research vessel characterized 3-dimensional atmospheric boundary layer structures over the Houston-Galveston Bay area, providing a unique opportunity for the evaluation of the physical parameterizations. The model simulations were performed over the Houston metropolitan area for a summertime period (12–17 August) using a bulk urban parameterization in the Noah land surface model (original LSM), a modified LSM, and a single-layer urban canopy model (UCM). The UCM simulation compared quite well with the observations over the Houston urban areas, reducing the systematic model biases in the original LSM simulation by 1–2 °C in near-surface air temperature and by 200–400 m in UBL height, on average. A more realistic turbulent (sensible and latent heat) energy partitioning contributed to the improvements in the UCM simulation. The original LSM significantly overestimated the sensible heat flux (~200 W m−2) over the urban areas, resulting in warmer and higher UBL. The modified LSM slightly reduced warm and high biases in near-surface air temperature (0.5–1 °C) and UBL height (~100 m) as a result of the effects of urban vegetation. The relatively strong thermal contrast between the Houston area and the water bodies (Galveston Bay and the Gulf of Mexico) in the LSM simulations enhanced the sea/bay breezes, but the model performance in predicting local wind fields was similar among the simulations in terms of statistical evaluations. These results suggest that a proper surface representation (e.g. urban vegetation, surface morphology) and explicit parameterizations of urban physical processes are required for accurate urban atmospheric numerical modeling.

scholarly journals Effect of Evaporating Sea Spray on Heat Fluxes in a Marine Atmospheric Boundary Layer

2019 ◽  
Vol 49 (7) ◽  
pp. 1927-1948 ◽  
Author(s):  
Yevgenii Rastigejev ◽  
Sergey A. Suslov
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Air Temperature ◽  
Weather Prediction ◽  
Heat Fluxes ◽  
Total Heat ◽  
Vertical Profiles ◽  
Marine Atmospheric Boundary Layer ◽  
Wide Range ◽  
Vertical Distributions

AbstractA detailed analysis of the evaporating ocean spray effect on the vertical latent and sensible heat fluxes in a marine atmospheric boundary layer (MABL) for different droplet sizes, vertical distributions of air temperature, humidity, and turbulent intensity is presented. For our analysis we have employed a two-temperature nonequilibrium MABL model developed in our previous work. The obtained analytical and numerical solutions show that the latent and total heat fluxes are significantly enhanced by large droplets because these droplets produce steep vertical gradients of moisture and air temperature in a MABL. Small droplets, however, do not noticeably change the total heat flux but rather redistribute the energy between its sensible and latent components. It has been shown that evaporating spray affects the turbulent kinetic energy (thus the intensity of the vertical turbulent transport) mostly mechanically by altering the vertical distribution of the mass density of the air–spray mixture rather than thermodynamically by changing vertical profiles of the air temperature and moisture. Furthermore, we have found that the vertical profiles of heat fluxes are approximately self-similar for a wide range of defining parameters, that is, can be approximately scaled to a reference heat profile for a wide range of vertical distributions of the temperature, humidity, and turbulence intensity. The obtained analytical expressions for the vertical heat fluxes affected by the spray presence enable their quick and efficient calculations. This will allow for the future construction of a computationally efficient spray and accurate parameterization to be used in global weather prediction models.

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