Long-term measurements of carbon dioxide flux (F_c) and the latent and sensible heat fluxes were performed using the eddy covariance (EC) method in Beijing, China over a 4-yr period in 2006–2009. The EC setup was installed at a height of 47 m on the Beijing 325-m meteorological tower in the northwest part of the city. Latent heat flux dominated the energy exchange between the urban surface and the atmosphere in summer, while sensible heat flux was the main component in the spring. Winter and autumn were two transition periods of the turbulent fluxes. The source area of F_c was highly heterogeneous, which consisted of buildings, parks, and highways. It was of interest to study of the temporal and spatial variability of F_c in this urban environment of a developing country. Both on diurnal and monthly scale, the urban surface acted as a net source for CO₂ and downward fluxes were only occasionally observed. The diurnal pattern of F_c showed dependence on traffic and the typical two peak traffic patterns appeared in the diurnal cycle. Also F_c was higher on weekdays than on weekends due to the higher traffic volumes on weekdays. On seasonal scale, F_c was generally higher in winter than during other seasons likely due to domestic heating during colder months. Total annual average CO₂ emissions from the neighborhood of the tower were estimated to be 4.90 kg C m⁻² yr⁻¹ over the 4-yr period. Total vehicle population was the most important factor controlling the inter-annual variability of F_c in this urban area.

Evaluation of the Weather Research and Forecasting Model version 3.7.1 lake model performance on lake physical processes and lake‐atmosphere interaction at Erhai Lake was conducted with in situ observation data sets over the lake to verify the model results. The lake model with default parameters presented significant negative bias during the day and positive bias during the night on lake surface temperature. Calibrations of water absorption and extinction coefficients, surface roughness length, and eddy diffusion coefficient were carried out to correct this bias. The added absorption and extinction coefficients increased solar radiation in upper water layer, leading to a little higher surface temperature. Compared to constant surface roughness lengths, parameterization of roughness lengths as functions of friction velocity and fetch length significantly improved simulations of lake surface temperature and sensible heat flux. In Erhai Lake, eddy diffusion coefficient of the Henderson‐Sellers parameterization is smaller than that in deep lakes. The eddy diffusion coefficient was reduced by a factor of 0.05 in dry season and 0.02 in wet season, respectively, to restrict mixing strength, generating a reasonable diurnal range with observed surface temperature. The adjusted parameter simulations matched better with in situ observations in diurnal cycle of temperature and surface heat fluxes but still overestimated wind speed. Topographic correction is effective to correct the bias, indicating that topographic correction over complex terrain was necessary.

Seasonal and interannual variations of evapotranspiration (ET) and energy exchange were estimated over degraded grassland and cropland land surfaces in a semiarid region of northeastern China using the eddy covariance technique from 2003 to 2008. The peak daily ET, which occurred in August, was 1.5–4.5 mm day⁻¹for the degraded grassland and 1.5–5.5 mm day⁻¹for the cropland land surface. Annual cumulative ET was roughly equal to annual precipitation at both sites. However, the annual cumulative ET at the cropland site was slightly larger (about 10–30 mm) than it was at the grassland at the end of each year. More water might come from irrigation at seedtime and from the soil. With the factor analysis technique, the results revealed that the atmospheric water demand was the most important factor in the ET process on a half-hour time scale in this semiarid area. On a seasonal time scale, ET was greatly constrained by surface conductance and precipitation; on an annual time scale, ET was greatly constrained by the total amount of precipitation at both sites. The accuracy of ET estimation using the Penman–Monteith formula in this semiarid area was also discussed.

Interactions between lakes and the atmosphere are poorly understood, especially for lakes in highland areas. A better understanding of the physical processes controlling turbulent exchange dynamics over lakes is crucial to improve the numerical modelling of the lake–climate interaction. Four years of continuous measurements of energy and CO₂ fluxes are conducted over a shallow highland lake (Lake Erhai) in China using eddy covariance (EC) technique from 2012 to 2015. It is found that the latent heat flux (LE) and sensible heat flux (H) has distinct diurnal and seasonal variations. The diurnal H and LE ranges from −31 to 21 W/m² and from 31 to 171 W/m², respectively. The heat is stored in the lake from January to June and released from July to the end of the year. The annual total evaporation of Lake Erhai varies from 1120.8 to 1228.5 mm/a, which is always higher than the annual total precipitation. On diurnal scale, the CO₂ uptake is observed during most of the midday period. On an annual scale, the Lake Erhai behaves as a net CO₂ source, with an annual CO₂ budget ranging from 117.5 to 161.7 g C m⁻² a⁻¹. The temperature difference (ΔT) between the water surface (T _s) and the air temperature (T _a), and the product of ΔT and wind speed (U) are the major drivers of H from half‐hourly to monthly scale. The main factors controlling LE are U and the product of U and the vapour pressure difference (VPD) on half‐hourly and daily scales, the total cloud cover, and net radiation (R _n) on the monthly scale. Photosynthetic active radiation (PAR) and U has a close relationship with half‐hourly and daily CO₂ fluxes, respectively, while annual precipitation and T _s has a larger effect on annual CO₂ fluxes.