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Peatlands store substantial amounts of carbon and are vulnerable to climate change. We present a modified version of the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) land surface model for simulating the hydrology, surface energy, and CO2 fluxes of peatlands on daily to annual timescales. The model includes a separate soil tile in each 0.5° grid cell, defined from a global peatland map and identified with peat-specific soil hydraulic properties. Runoff from non-peat vegetation within a grid cell containing a fraction of peat is routed to this peat soil tile, which maintains shallow water tables. The water table position separates oxic from anoxic decomposition. The model was evaluated against eddy-covariance (EC) observations from 30 northern peatland sites, with the maximum rate of carboxylation (Vcmax) being optimized at each site. Regarding short-term day-to-day variations, the model performance was good for gross primary production (GPP) (r2 Combining double low line 0.76; Nash-Sutcliffe modeling efficiency, MEF Combining double low line 0.76) and ecosystem respiration (ER, r2 Combining double low line 0.78, MEF Combining double low line 0.75), with lesser accuracy for latent heat fluxes (LE, r2 Combining double low line 0.42, MEF Combining double low line 0.14) and and net ecosystem CO2 exchange (NEE, r2 Combining double low line 0.38, MEF Combining double low line 0.26). Seasonal variations in GPP, ER, NEE, and energy fluxes on monthly scales showed moderate to high r2 values (0.57-0.86). For spatial across-site gradients of annual mean GPP, ER, NEE, and LE, r2 values of 0.93, 0.89, 0.27, and 0.71 were achieved, respectively. Water table (WT) variation was not well predicted (r2

A unique, highly time-resolved, and synchronous three-year dataset of near-surface atmospheric radon-222 as well as soil heat flux and air temperature measurements at two sites (rural and urban) in Central Poland are investigated. The recognition of temporal variability of Rn-222 and selected meteorological variables in the urban and rural areas served to create two statistical models for estimation of this radionuclide concentration at 2 m a.g.l. The description of the relationships between the variables for individual months was established on the basis of an exponential function and an exponential function with time derivative of predictor to account for the hysteresis issue. The model with time derivative provided better results. The weakest fitting of modelled data to empirical ones is observed for the winter months. During subsequent seasons, air temperature as well as QG-driven (soil heat flux) models exhibited very high agreement with the empirical data (MBE, RMSE, MAE, and ‘index of agreement’ by Willmott were used to evaluate the models). A restriction in the use of QG for Rn-222 concentration was observed only in winter in the case of snow cover occurrence, which reduces the daily QG variability.

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Northern peatland stores a large amount of organic soil carbon and is considered to be one of the most significant CH4 sources among wetlands. The default wetland CH4 emission scheme in JULES (land surface model of the UK Earth System model) only takes into account the CH4 emissions from inundated areas in a simple way. However, it is known that the processes for peatland CH4 emission are complex. In this work, we coupled the process-based peatland CH4 emission model HIMMELI (HelsinkI Model of MEthane buiLd-up and emIssion for peatlands) with JULES (JULES-HIMMELI) by taking the HIMMELI input data from JULES simulations. Firstly, the soil temperature, water table depth (WTD) and soil carbon simulated by JULES, as well as the prescribed maximum leaf area index (LAI) in JULES were evaluated against available datasets at the studied northern wetland sites. Then, the simulated CH4 emissions from JULES and JULES-HIMMELI simulations were compared against the observed CH4 emissions at these sites. Moreover, sensitivities of CH4 emissions to the rate of anoxic soil respiration (anoxic Rs), surface soil temperature and WTD were investigated. Results show that JULES can well represent the magnitude and seasonality of surface (5–10 cm) and relatively deep (34–50 cm) soil temperatures, whereas the simulated WTD and soil carbon density profiles show large deviations from the site observations. The prescribed maximum LAI in JULES was within one standard deviation of the maximum LAIs derived from the Sentinel-2 satellite data for Siikaneva, Kopytkowo and Degerö sites, but lower for the other three sites. The simulated CH4 emissions by JULES have much smaller inter-annual variability than the observations. However, no specific simulation setup of the coupled model can lead to consistent improvements in the simulated CH4 emissions for all the sites. When using observed WTD or modified soil decomposition rate, there were only improvements in simulated CH4 fluxes at certain sites or years. Both simulated and observed CH4 emissions at sites strongly depend on the rate of anoxic Rs, which is the basis of CH4 emission estimates in HIMMELI. By excluding the effect from the rate of anoxic Rs on CH4 emissions, it is found that the Rs-log-normalized CH4 emissions (log normalization of the ratio of CH4 emission to anoxic Rs rate) show similar increasing trends with increased surface soil temperature from both observations and simulations, but different trends with raised WTD which may due to the uncertainty in simulated O2 concentration in HIMMELI. In general, we consider the JULES-HIMMELI model is more appropriate in simulating the wetland CH4 emissions than the default wetland CH4 emission scheme in JULES. Nevertheless, in order to improve the accuracy of simulated wetland CH4 emissions with the JULES-HIMMELI model, it is still necessary to better represent the peat soil carbon and hydrologic processes in JULES and the CH4 production and transportation processes in HIMMELI, such as plant transportation of gases, seasonality of parameters controlling oxidation and production, and adding microbial activities. [ABSTRACT FROM AUTHOR]

Peatlands have often been neglected in Earth System Models (ESMs). Where they are included, they are usually represented via a separate, prescribed grid cell fraction that is given the physical characteristics of a peat (highly organic) soil. However, in reality soils vary on a spectrum between purely mineral soil (no organic material), and purely organic soil, typically with an organic layer of variable thickness overlying mineral soil below. They are also dynamic, with organic layer thickness and its properties changing over time. Neither the spectrum of soil types nor their dynamic nature can be captured by current ESMs. Here we present a new version of an ESM land surface scheme (Joint UK Land Environment Simulator, JULES) where soil organic matter accumulation - and thus peatland formation, degradation and stability - is integrated in the vertically-resolved soil carbon scheme. We also introduce the capacity to track soil carbon age as a function of depth in JULES, and compare this to measured peat age-depth profiles. This scheme simulates dynamic feedbacks between the soil organic material and its thermal and hydraulic characteristics. We show that draining the peatlands can lead to significant carbon loss along with soil compaction and changes in peat properties. However, negative feedbacks can lead to the potential for peatlands to rewet themselves following drainage. These ecohydrological feedbacks can also lead to peatlands maintaining themselves in climates where peat formation would not otherwise initiate in the model, i.e. displaying some degree of resilience. The new model produces similar results to the original model for mineral soils, and realistic profiles of soil organic carbon for peatlands. In particular the best performing configurations had root mean squared error (RMSE) in carbon density for peat sites of 7.7-16.7 kgC m−3 depending on climate zone, when compared against typical peat profiles based on 216 sites from a global dataset of peat cores. This error is considerably smaller than the soil carbon itself (around 30-60 kgC m−3) and reduced by 35-80 % compared with standard JULES. The RMSE at mineral soil sites is also smaller in JULES-Peat than JULES itself (reduced by ~30-50 %). Thus JULES-Peat can be used as a complete scheme that simulates both organic and mineral soils. It does not require any additional input data and introduces minimal additional variables to the model. This provides a new approach for improving the simulation of organic and peatland soils, and associated carbon-cycle feedbacks in ESMs, which other land surface models could follow. [ABSTRACT FROM AUTHOR]

The work presents a historical outline and main achievements of Lodz researchers in the field of urban climate. Although regular meteorological measurements in Lodz began at the beginning of the 20th century, the development of urban climatology, understood as the city's influence on the field of meteorological elements, dates back to the 1950s. The last decade of the 20th century and the beginning of the present century brought a special intensification of activities in the field of urban climatology in Lodz. Apart from studies on the classic problems of the urban heat island or solar relations, unique measurements of the heat balance, surface exchange of greenhouse gases (CO2 and CH4) or radon concentration in the city were carried out during this period; the innovative measurement methods (scintillometry) were used and original numerical models were developed. [ABSTRACT FROM AUTHOR]

This paper contains the results of measurement of turbulent exchange of heat and mass in Łódź in the period 2013-2016. Measurement campaigns of sensible (QH) and latent (QE) heat fluxes as well as carbon dioxide and methane (FCO2 and FCH4) fluxes have been carried out on two urban sites characterized by different development and use. The first site has been located at the city center (artificial surfaces percentage ~60%) dominated by the net of urban canyons and 3-4 storey tenement buildings. The second site has been located at postindustrial district about 4.8 km to the north. This part of the city is characterized by lower development density (~40%) and dominated by big postindustrial buildings converted into warehouses and large stores. Turbulent fluxes QH, QE, FCO2, and FCH4 have been measured with eddy covariance technique. Both sites have been equipped with typical instrumentation set consisting of ultrasonic anemometers and water vapor, carbon dioxide and methane gas analyzers. According to eddy-covariance method principles, on both sites instruments have been mounted on the height double or more higher than mean surrounding urban canopy layer. The aim of this paper was to show variability of heat and mass fluxes registered during August, September and October 2016 in the postindustrial district and compare with the results obtained during the same months in the center of Łódź in the years 2013-2015. The results show that intensity of turbulent exchange is clearly related to land use and characteristics of urban surface. Turbulent exchange of sensible and latent heat on postindustrial area, covered by big buildings and wide market places has been smaller than in the center of Łódź, dominated by urban canyons and residential buildings. Moreover, turbulent fl uxes of greenhouse gases have been also smaller especially in the case of carbon dioxide. Diurnal courses of FCO2 and FCH4 fl uxes registered at the city center have been dominated by two maxima, related to diurnal rhythm of fossil fuel combustion during traffic rush hours and evening inhabitants activities (cooking, heating tec.). While traffic is much less intense in comparison with city center and there is a lack of residential buildings on postindustrial areas, carbon dioxide fluxes are much smaller there and methane fluxes have only one maximum a day. [ABSTRACT FROM AUTHOR]