Precipitation extremes over territory of Belarus under current climate change

The study presents an investigation of current and future changes in precipitation regime over territory of Belarus. An assessment of precipitation means and extremes and droughts indices was provided for period of 1948–2019 and more detailed analysis have been carried out for period of climate change in 1989–2019. The precipitation expected changes were studied for period of 2021–2099. It was established that precipitation growth up to 20–30 % in winter during 1989–2019 in comparison by 1948–1988, is connected with increase the number of days with weak precipitation and caused by growing duration of liquid precipitation falling. In summer the reducing of rain falling duration was noticed over territory of Belarus. At the same time the significant growth of precipitation maximal totals per day by 20–30 % was detected. The largest growth was found in the south of the country. Dry days number raised by 1–4 days and dry and hot days numbers raised by 1–2 days per decade. The repeatability of atmosphere droughts of different gradations increased up to 2–26 % by the majority of meteorological stations. According to climate projections based on the EURO-CORDEX-11, the growth of yearly and seasonal precipitation is expected over territory of Belarus. The precipitation increase is connected with growth of intense precipitation. At the same time, the dry periods duration is projected to rise in the warm part of the year. These tendencies are characterised the climate extremeness increase in the current century.

Corrections of Precipitation Particle Size Distribution Measured by a Parsivel OTT2 Disdrometer under Windy Conditions in the Antisana Massif, Ecuador

Monitoring precipitation in mountainous areas using traditional tipping-bucket rain gauges (TPB) has become challenging in sites with strong variations of air temperature and wind speed (Ws). The drop size distributions (DSD), amount, and precipitation-type of a Parsivel OTT2 disdrometer installed at 4730 m above sea level (close to the 0 °C isotherm) in the glacier foreland of the Antisana volcano in Ecuador are used to analyze the precipitation type. To correct the DSDs, we removed spurious particles and shifted fall velocities such that the mean value matches with the fall velocity–diameter relationship of rain, snow, graupel, and hail. Solid (SP) and liquid precipitation (LP) were identified through −1 and 3 °C thresholds and then grouped into low, medium, and high Ws categories by k-means approach. Changes in DSDs were tracked using concentration spectra and particle’s contribution by diameter and fall velocity. Thus, variations of concentration/dispersion and removed hydrometeors were linked with Ws changes. Corrected precipitation, assuming constant density (1 g cm−3), gives reliable results for LP with respect to measurements at TPB and overestimates SP measured in disdrometer. Therefore, corrected precipitation varying density models achieved fewer differences. These results are the first insight toward the understating of precipitation microphysics in a high-altitude site of the tropical Andes.

Assessment of the Climatic Variability of the Kunhar River Basin, Pakistan

Pakistan is water stressed, and its water resources are vulnerable due to uncertain climatic changes. Uncertainties are inherent when it comes to the modeling of water resources. The predicted flow variation in the Kunhar River Basin was modeled using the statistically decreased high-resolution general circulation model (GCM) as an input for the Hydrologiska Byråns Vattenbalansavdelning (HBV) model to assess the hydrological response of the Kunhar River Basin under prevailing climate changes. The model’s best performance during the calibration and validation stages was obtained with a regular 0.87 and 0.79 Nash–Sutcliffe efficiency in the basin, respectively. Under the high-end emission scenario, a 122% increase was expected in evapotranspiration in the rising season of months during the winter period 2059–2079, and such developments were attributed to an immense increase in liquid precipitation and temperature. The model’s output reflects a potential for basin stream flow in terms of increasing liquid precipitation up to 182% at the beginning of the monsoon season in the period 2059–2079 in the scenario of high-end emissions. Moreover, the study produced possible uncertainties in high-elevation zones, where the modeling of a catchment can lead to typical snow ablation and accumulation in future projections. This study revealed that the precipitation rate will increase annually, resulting in an increase in the summer stream flow over the basin, though snow is hardly expected to accumulate in the basin’s future climate.

Occurrence, Variability and Trends in Snowfall and Rainfall under the background of air temperature and Atmospheric Circulation in Poland

<p>The reaction of precipitation on current warming is ambiguous and differs depending on the region. Particular precipitation phases were found to respond more significantly to recent climate change in many areas located in North America, Asia, Europe and mountains. Since precipitation is an important factor in many environmental processes, trends in its occurrence and totals may trigger various changes in the Earth system and affect life.</p><p>This study aims to recognize the influence of air temperature and atmospheric circulation on the occurrence, variability and trends in precipitation phase indices. We used sub-daily data (every 3h) on air temperature, precipitation totals, notation of weather phenomena in the form of a current (ww) and past weather (W1W2) and cloud types from 38 synoptic stations located in Poland. Moreover, we used various teleconnection patterns to describe macroscale circulation and circulation types to describe regional circulation. Unlike in most studies, precipitation phase was identified based on notation of weather phenomena. Such an approach allowed us to assess a real range of surface air temperature (2m above ground) where snowfall and rainfall occur. Both frequency, totals and quotient of particular precipitation phases were analysed over the period of 1966-2020.  </p><p>Our preliminary results showed that each precipitation phase occurred over a wide range of temperatures; however, most snowfall registered during air temperatures far above freezing point (even 6°C) fell during the existence of cumulonimbus, which indicates strong convection. The highest probability of solid precipitation was linked to air advection from the north-eastern sector under the influence of cyclone (ca.15-20%). Mixed precipitation could be most expected during days with a cyclone centre located over Poland (ca. 20%). The highest probability of liquid precipitation (ca. 70%) was most characteristic of the west and north-west advection under the influence of cyclone and during the cyclone centre or trough over Poland.  </p><p>High year-to-year variability in the indices of precipitation phases impacted their trends. However, liquid precipitation tended to increase in winter over most of the stations. Mixed precipitation exhibited various trend directions depending on the region in winter and decreasing spring and autumn trends. In transitional seasons, a significant decrease was also found in solid precipitation. Most of these changes were significantly related to changes in air temperature except for solid precipitation in winter. Variability in precipitation phases was also correlated with teleconnection patterns, including NAO (negative correlation with solid precipitation in spring and autumn and liquid precipitation in summer, positive correlation with mixed pre in winter), EA (negative correlation with mixed precipitation in autumn) and SCAND (negative correlation with mixed precipitation in winter).</p><p> </p><p>The research performed within the project No. 2017/27/B/ST10/00923, financed by National Science Centre,</p>

Projected changes in Rhine River flood seasonality under global warming

Climatic change alters the frequency and intensity of natural hazards. In order to assess potential future changes in flood seasonality in the Rhine River basin, we analyse changes in streamflow, snowmelt, precipitation and evapotranspiration at 1.5, 2.0 and 3.0 ∘C global warming levels. The mesoscale hydrological model (mHM) forced with an ensemble of climate projection scenarios (five general circulation models under three representative concentration pathways) is used to simulate the present and future climate conditions of both pluvial and nival hydrological regimes. Our results indicate that future changes in flood characteristics in the Rhine River basin are controlled by increases in antecedent precipitation and diminishing snowpacks. In the pluvial-type sub-basin of the Moselle River, an increasing flood potential due to increased antecedent precipitation encounters declining snowpacks during winter. The decrease in snowmelt seems to counterbalance increasing precipitation, resulting in only small and transient changes in streamflow maxima. For the Rhine Basin at Basel, rising temperatures cause changes from solid to liquid precipitation, which enhance the overall increase in precipitation sums, particularly in the cold season. At the gauge at Basel, the strongest increases in streamflow maxima show up during winter, when strong increases in liquid precipitation encounter almost unchanged snowmelt-driven runoff. The analysis of snowmelt events for the gauge at Basel suggests that at no point in time during the snowmelt season does a warming climate result in an increase in the risk of snowmelt-driven flooding. Snowpacks are increasingly depleted with the course of the snowmelt season. We do not find indications of a transient merging of pluvial and nival floods due to climate warming. To refine attained results, next steps need to be the representation of glaciers and lakes in the model set-up, the coupling of simulations to a streamflow component model and an independent validation of the snow routine using satellite-based snow cover maps.

The Gravel Parameterization Schemes on Tibetan Plateau and Its Assessment Using RegCM4

<p>In this paper, the impact of gravel is taken into account in regional simulations on the Tibetan Plateau (TP). The differences of ground surface and soil hydrological processes in the TP are compared when the gravel parameterization schemes and the original soil hydrothermal parameterization schemes are respectively adopted in the regional climate model version 4.7 (RegCM4.7), which is driven by the EIN15. Moreover, the performances in simulating the liquid soil moisture (LSM) by using the two schemes are also assessed. When the impact of gravel is considered, the changes of ground hydrological processes are consistent with those of liquid precipitation and snow meltwater except the infiltration, indicating the dominance of liquid precipitation and snow meltwater in ground hydrological processes. The lower gravel content will facilitate the downward transportation of LSM. However, in the case of high gravel content, the roles of gravel content are completely opposite in the western and central TP. The most obvious change is that the simulated LSM by the gravel schemes is lower at most soil depths compared with that by the original schemes, which is beneficial in most cases. For instance, the mean absolute errors of the reference data with the simulations by the gravel schemes and original schemes at the soil depth of 0.1 m in the southeastern TP are 0.026 and 0.101, respectively. Besides the southeastern TP, the performance in simulating the temporal variation of the LSM below the middle soil layers still needs to be improved.</p>

GuMNet – The Guadarrama Monitoring Network initiative (Spain)

<p>GuMNet is a facility that operates continuous observation of the atmosphere, surface and subsurface at the Sierra de Guadarrama, located 50 km north-northwest of Madrid. It is composed of 10 real–time automatic stations and attempts to promote research on weather, soil thermodynamics, boundary layer physics, impacts of climate change on climate and ecosystems and air pollution in Sierra de Guadarrama. This infrastructure represents a first step into providing a unique observational network in a high protected environment that can serve a wide range of scientific and educational interests and also management.</p><p>The stations are located at heights ranging from 900 m.a.s.l. to 2225 m.a.s.l. Every station has been settled in open areas, except for one that can be found in a forested zone. High altitude sites are focused on periglacial areas, while low elevation sites are placed in pasture environments. The atmospheric instrumentation includes sensors used for the measurement of air temperature, air humidity, 4-component radiation, solid and liquid precipitation, snow depth, wind speed and wind direction. For the subsurface measurements, soil temperature and humidity sensors have been placed in 9 trenches up to 1 m depth and 12 boreholes up to 2 m and 20 m depth. One of the lowest stations has been equipped with a 3D sonic anemometer that includes a CO2/H2O analyzer. Wind profiles and eddy-covariance will be sampled, which is important for energy and water vapor exchanges. A portable station has also been equipped with a 3D sonic anemometer, which will enable the comparison between measurements at both sites. The entire network is connected via general packet radio service (GPRS) to the management software at the central laboratory located at the Campus of Excellence of Moncloa (Madrid, Spain).</p><p>The database generated by GuMNet is accessible through request and allows for developing studies concerning environmental and climate change in middle and high mountain areas. This valuable source of data aims at generating a space for scientific collaboration with other national and international institutions. The diversity of potential uses of the GuMNet observational network will be very useful in education at every level.</p><p>Website and contact: http://www.ucm.es/gumnet/</p>

Trends and spatial variation in rain-on-snow events over the Arctic Ocean during the early melt season

Rain-on-snow (ROS) events can accelerate the surface ablation of sea ice, thus greatly influencing the ice–albedo feedback. However, the variability of ROS events over the Arctic Ocean is poorly understood due to limited historical station data in this region. In this study early melt season ROS events were investigated based on four widely used reanalysis products (ERA-Interim, JRA-55, MERRA, and ERA5) in conjunction with available observations at Arctic coastal stations. The performance of the reanalysis products in representing the timing of ROS events and the phase change of precipitation was assessed. Our results show that ERA-Interim better represents the onset date of ROS events in spring, and ERA5 better represents the phase change of precipitation associated with ROS events. All reanalyses indicate that ROS event timing has shifted to earlier dates in recent decades (with maximum trends up to −4 to −6 d per decade in some regions in ERA-Interim) and that sea ice melt onset in the Pacific sector and most of the Eurasian marginal seas is correlated with this shift. There has been a clear transition from solid to liquid precipitation, leading to more ROS events in spring, although large discrepancies were found between different reanalysis products. In ERA5, the shift from solid to liquid precipitation phase during the early melt season has directly contributed to a reduction in spring snow depth on sea ice by more than −0.5 cm per decade averaged over the Arctic Ocean since 1980, with the largest contribution (about −2.0 cm per decade) in the Kara–Barents seas and Canadian Arctic Archipelago.