scholarly journals Bias Corrections of Precipitation Measurements across Experimental Sites in Different Ecoclimatic Regions of Western Canada

2016 ◽  
Author(s):  
Xicai Pan ◽  
Daqing Yang ◽  
Yanping Li ◽  
Alan Barr ◽  
Warren Helgason ◽  
...  
Keyword(s):  
Regional Climate ◽  
Western Canada ◽  
Monthly Precipitation ◽  
Seasonal Precipitation ◽  
Balance Assessment ◽  
Precipitation Regime ◽  
Western Cordillera ◽  
Operational Networks ◽  
Precipitation Gauge ◽  
Bias Corrections

Abstract. This study assesses a filtering procedure on accumulating precipitation gauge measurements, and quantifies the effects of bias corrections for wind-induced undercatch across four ecoclimatic regions in western Canada, including the permafrost regions of the Sub-arctic, the Western Cordillera, the Boreal Forest, and the Prairies. The bias corrections increased monthly precipitation by up to 163 % at windy sites with short vegetation, and sometimes modified the seasonal precipitation regime, whereas the increases were less than 13 % at sites shielded by forest. On a yearly basis, the increase of total precipitation ranged from 8 to 20 mm (3–4 %) at sites shielded by vegetation, and 60 to 384 mm (about 15–34 %) at open sites. In addition, the bias corrections altered the seasonal precipitation patterns at some windy sites with high snow percentage (> 50 %). This study highlights the need and importance of precipitation bias corrections at both research sites and operational networks for water balance assessment and the validation of global/regional climate/hydrology models.

scholarly journals Bias corrections of precipitation measurements across experimental sites in different ecoclimatic regions of western Canada

2016 ◽  
Vol 10 (5) ◽  
pp. 2347-2360 ◽  
Author(s):  
Xicai Pan ◽  
Daqing Yang ◽  
Yanping Li ◽  
Alan Barr ◽  
Warren Helgason ◽  
...  
Keyword(s):  
Regional Climate ◽  
Western Canada ◽  
Monthly Precipitation ◽  
Seasonal Precipitation ◽  
Balance Assessment ◽  
Precipitation Regime ◽  
Western Cordillera ◽  
Operational Networks ◽  
Precipitation Gauge ◽  
Bias Corrections

Abstract. This study assesses a filtering procedure on accumulating precipitation gauge measurements and quantifies the effects of bias corrections for wind-induced undercatch across four ecoclimatic regions in western Canada, including the permafrost regions of the subarctic, the Western Cordillera, the boreal forest, and the prairies. The bias corrections increased monthly precipitation by up to 163 % at windy sites with short vegetation and sometimes modified the seasonal precipitation regime, whereas the increases were less than 13 % at sites shielded by forest. On a yearly basis, the increase of total precipitation ranged from 8 to 20 mm (3–4 %) at sites shielded by vegetation and 60 to 384 mm (about 15–34 %) at open sites. In addition, the bias corrections altered the seasonal precipitation patterns at some windy sites with high snow percentage ( > 50 %). This study highlights the need for and importance of precipitation bias corrections at both research sites and operational networks for water balance assessment and the validation of global/regional climate–hydrology models.

scholarly journals Quantifying rainfall in Greenland: a combined observational and modelling approach

2021 ◽  
Author(s):  
Baojuan Huai ◽  
Michiel R. van den Broeke ◽  
Carleen H. Reijmer ◽  
John Cappellen
Keyword(s):  
Climate Model ◽  
Regional Climate ◽  
Correction Method ◽  
Horizontal Resolution ◽  
Spatial And Temporal Variability ◽  
Monthly Precipitation ◽  
Dynamic Correction ◽  
Correction Model ◽  
Precipitation Gauge

AbstractThis paper estimates rainfall totals at 17 Greenland meteorological stations, subjecting data from in-situ precipitation gauge measurements to seven different precipitation phase schemes to separate rain- and snowfall amounts. To correct the resulting snow/rain fractions for undercatch, we subsequently use a Dynamic Correction Model (DCM) for Automatic Weather Stations (AWS, Pluvio gauges) and a regression analysis correction method for staffed stations (Hellmann gauges). With observations ranging from 5% to 57% for cumulative totals, rainfall accounts for a considerable fraction of total annual precipitation over Greenland’s coastal regions, with the highest rain fraction in the south (Narsarsuaq). Monthly precipitation and rainfall totals are used to evaluate the regional climate model RACMO2.3. The model realistically captures monthly rainfall and total precipitation (R=0.3-0.9), with generally higher correlations for rainfall for which the undercatch correction factors (1.02-1.40) are smaller than those for snowfall (1.27-2.80), and hence the observations more robust. With a horizontal resolution of 5.5 km and simulation period from 1958-present, RACMO2.3 therefore is a useful tool to study spatial and temporal variability of rainfall in Greenland, although further statistical downscaling may be required to resolve the steep rainfall gradients.

scholarly journals Air temperature and precipitation regime in Ukraine in 2021-2050 by CORDEX model ensemble

2020 ◽  
pp. 17-27
Author(s):  
M. S. Zamfirova ◽  
V. M. Khokhlov
Keyword(s):  
Air Temperature ◽  
Climate Models ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Monthly Precipitation ◽  
Precipitation Regime ◽  
Maximum Increase ◽  
Temperature And Precipitation ◽  
Maximum Temperatures ◽  
Southern Ukraine

Global temperatures over the period of 2081–2100 are expected to rise by 0.3–4.8 °C compared to the period of 1986–2005. According to the previous studies, the average annual air temperature in all regions of Ukraine will keep increasing in the near future and the maximum increase in precipitation is expected mainly in the western and northern regions during winter and spring, whereas the decrease in precipitation will be registered in the central, eastern and southern regions during summer and autumn. This article aims to identify the features of changes in air temperature and precipitation for different regions of Ukraine in 2021–2050 based on the modelling results of the ensemble of CORDEX models as per the RCP4.5 scenario. 16 simulation runs for 7 regional climate models were selected for the analysis and the results were presented for five regional centers of Ukraine: Kyiv, Lviv, Kropyvnytskyi, Kharkiv and Odesa. It is shown that future monthly precipitation in all regions tends to increase by an average of 20–40 mm during autumn, winter and spring, whereas the decrease is expected to occur in summer. According to some models, the monthly precipitation will be close to zero in the Southern Ukraine in July and August, which is typical for the Mediterranean climate. Compared to the period of 1961–1990, the average monthly temperature will undergo small changes (up to 1 °C) in spring and autumn, while the temperature in summer and winter will increase by 2.5–3.5 °C. In Odesa, in contrast to the present-day situation, a positive average monthly air temperature will be expected to be recorded throughout the whole year, and only 25% of the runs show negative average monthly minimum temperatures. In the Northern Ukraine, the average monthly minimum and maximum temperatures in winter will increase by 2.0–2.5 °C, and in summer only the maximum air temperature will increase significantly. Thus, we can assume a change in the regime of moisture supply in Ukraine over the next thirty years. One can also assume a high probability of snow cover absence throughout the whole winter in the Southern Ukraine as a result of positive temperatures.

The influence of seasonal precipitation and temperature regimes on lake levels in the northeastern United States during the Holocene

2006 ◽  
Vol 65 (1) ◽  
pp. 44-56 ◽  
Author(s):  
Bryan Shuman ◽  
Jeffrey P. Donnelly
Keyword(s):  
Sediment Cores ◽  
Summer Precipitation ◽  
Water Levels ◽  
Monthly Precipitation ◽  
Seasonal Precipitation ◽  
Lake Levels ◽  
Precipitation Regime ◽  
The Holocene ◽  
Temperature Regimes ◽  
Precipitation Regimes

AbstractAMS–dated sediment cores combined with ground–penetrating radar profiles from two lakes in southeastern Massachusetts demonstrate that regional water levels rose and fell multiple times during the Holocene when the known climatic controls (i.e., ice extent and insolation) underwent unidirectional changes. The lakes were lowest between 10,000 and 9000 and between 5500 and 3000 cal yr B.P. Using a heuristic moisture-budget model, we explore the hypothesis that changes in seasonal precipitation regimes, driven by monotonic trends in ice extent and insolation, plausibly explain the multiple lake-level changes. Simulated lake levels resulting from low summer precipitation rates match observed low lake levels of 10,000–9000 cal yr B.P., whereas a model experiment that simply shifts the seasonality of the modern Massachusetts precipitation regime (i.e., moving the peak monthly precipitation from winter to summer) produces levels that are ∼2 m lower than today as observed for 5500–3000 cal yr B.P. The influence of the Laurentide ice sheet could explain dry summers before ca. 8000 cal yr B.P. A later shift from a summer-wet to a winter-wet moisture-balance regime could have resulted from insolation-driven changes in the influence of the Bermuda subtropical high. Temperature changes probably further modified lake levels by affecting snowmelt and transpiration.

scholarly journals Cool season precipitation projections for California and the Western United States in NA-CORDEX models

2021 ◽  
Author(s):  
Kelly Mahoney ◽  
James D. Scott ◽  
Michael Alexander ◽  
Rachel McCrary ◽  
Mimi Hughes ◽  
...  
Keyword(s):  
United States ◽  
Climate Models ◽  
Snow Water Equivalent ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Western United States ◽  
Monthly Precipitation ◽  
Wet Season ◽  
Cool Season ◽  
Projected Change

AbstractUnderstanding future precipitation changes is critical for water supply and flood risk applications in the western United States. The North American COordinated Regional Downscaling EXperiment (NA-CORDEX) matrix of global and regional climate models at multiple resolutions (~ 50-km and 25-km grid spacings) is used to evaluate mean monthly precipitation, extreme daily precipitation, and snow water equivalent (SWE) over the western United States, with a sub-regional focus on California. Results indicate significant model spread in mean monthly precipitation in several key water-sensitive areas in both historical and future projections, but suggest model agreement on increasing daily extreme precipitation magnitudes, decreasing seasonal snowpack, and a shortening of the wet season in California in particular. While the beginning and end of the California cool season are projected to dry according to most models, the core of the cool season (December, January, February) shows an overall wetter projected change pattern. Daily cool-season precipitation extremes generally increase for most models, particularly in California in the mid-winter months. Finally, a marked projected decrease in future seasonal SWE is found across all models, accompanied by earlier dates of maximum seasonal SWE, and thus a shortening of the period of snow cover as well. Results are discussed in the context of how the diverse model membership and variable resolutions offered by the NA-CORDEX ensemble can be best leveraged by stakeholders faced with future water planning challenges.

scholarly journals Climatic changes and their influence on air temperature and precipitation in Ukraine during transitional seasons

2020 ◽  
pp. 60-67
Author(s):  
V. M. Khokhlov ◽  
H. O. Borovska ◽  
M. S. Zamfirova
Keyword(s):  
Air Temperature ◽  
Meteorological Parameters ◽  
Regional Climate ◽  
Monitoring Network ◽  
Climatic Changes ◽  
Precipitation Regime ◽  
Runoff Water ◽  
The West ◽  
Temperature And Precipitation ◽  
Dynamic Methods

      Since modern research indicates climatic changes in all regions of our planet, including on the territory of Ukraine (in particular, the deviation of temperature and other meteorological parameters from the values of the climatic norm), their study is extremely important. After all, they can lead to changes in the nature of precipitation distribution, the length of the growing season, a decrease in the duration of the stable snow cover, local runoff water resources, etc. Most scientific works in recent years describe changes in the distribution of temperature characteristics and precipitation regime, because they are one of the main indicators of the state of the climate system. Therefore, the purpose of this article is to identify the features of changes in air temperature and precipitation for the entire territory of Ukraine from 2021 to 2050 based on the results of 16 simulations of the ensemble of CORDEX models based on the RCP4.5 scenario. The CORDEX project is a modern simulation of the future climate and has a resolution of ~ 12.5 km in the horizontal plane, which makes it possible to better simulate the characteristics under study. It integrates regional climate predictions that are generated using statistical and dynamic methods. The results obtained are presented for 177 cities of Ukraine, which currently form the basis of a modern monitoring network. It was found that the number of days with precipitation ≥ 5 mm in transitional seasons increases on average by 1-3 days per month, depending on the region. The maximum values of the frequency of occurrence of the number of days with precipitation ≥ 5 mm are observed in the west and gradually decrease in the south. Compared to 1961-1990, the most significant changes occur with the number of frosty days with an air temperature of ≤ 0°С, which noticeably decreases during the study period from north to south. In April and October, for the southern regions of Ukraine, the considered parameter is equal to 0, which means that in these months the air temperature for these regions will have positive values. From the above, there is a tendency towards warming in transitional seasons and a change in the nature of moisture supply to the territory of Ukraine in the next thirty years.

Preliminary analysis and main problems of instrumental measurement complex at the Vernadsky Antarctic Station

2021 ◽  
Author(s):  
Denys Pishniak ◽  
Svitlana Krakovska ◽  
Anastasia Chyhareva ◽  
Sergii Razumnyi
Keyword(s):  
Measurement Data ◽  
Bias Reduction ◽  
Small Scale ◽  
High Temporal Resolution ◽  
Monthly Precipitation ◽  
Polar Regions ◽  
Indirect Methods ◽  
Precipitation Measurement ◽  
Precipitation Gauge ◽  
The Antarctic

<p>Measurements of precipitation has always had well known difficulties that caused inaccuracies. This is especially acute in Polar regions where prevailing solid precipitation is accomplished with strong winds. Alternatively some indirect methods of precipitation measurements still in development and numerous meteorological instruments have been created on their basis.</p><p>The Akademik Vernadsky station is located in the Antarctic Peninsula region with a large amount of precipitation and  the problem of its measuring has always been relevant here. Although the data of monthly precipitation have been found for Vernadsky (Faraday) station since 1964, the first standard Tretyakov precipitation gauge was set up there only in 1997. But in recent years, several new instruments for indirect precipitation measurement have been installed at the meteorological site. The consistency of their data are the subject for this study. </p><p>Direct comparison of all measurement devices as well as investigation of their estimations dependencies from other meteorological parameters are analysed and will be presented for the period 2019-2020. Originally various instruments showed huge differences in precipitation estimates. Deep analysis and correction of the measurement results according to weather conditions is obviously needed for bias reduction. But the local features of the extremely heterogeneous underlying surface of the region affect the vertical component of the wind, and can cause the natural small scale precipitation variability. </p><p>The advantages of indirect methods for precipitation measuring is a high sensitivity to registering even individual falling precipitation particles and, hence, the really high temporal resolution of the data. Therefore, it can be used for investigation of physical atmospheric processes. As an example, the case study of a cyclone with precipitation phase transition over Vernadsky station on December 5-6, 2020 is investigated and will be presented. A comparison of the measurement data of various devices (Tretyakov Precipitation Gauge, Snow Stick, Vaisala PWD22, Lufft WS100, METEK MRR-PRO) and the ERA-5 reanalysis was carried out. A vertical radar MRR-PRO is of special interest as a measuring instrument for polar regions because it can ignore surface snow transport and has proved reliability in the Antarctic environment recently. In Marine Antarctica this device can identify the height of precipitation melting and also show a number of other useful parameters. This complex of precipitation measurement instruments is planned to be used in the frames of the forthcoming YOPP-SH field campayne.</p>

scholarly journals Downscaling Atmosphere-Ocean Global Climate Model Precipitation Simulations over Africa Using Bias-Corrected Lateral and Lower Boundary Conditions

Atmosphere ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 493 ◽  
Author(s):  
Leonard Druyan ◽  
Matthew Fulakeza
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Regional Climate ◽  
Lower Boundary ◽  
Climate Projections ◽  
African Easterly Jet ◽  
Modèle Simulation ◽  
Goddard Institute ◽  
Bias Corrections

A prequel study showed that dynamic downscaling using a regional climate model (RCM) over Africa improved the Goddard Institute for Space Studies Atmosphere-Ocean Global Climate Model (GISS AOGCM: ModelE) simulation of June–September rainfall patterns over Africa. The current study applies bias corrections to the lateral and lower boundary data from the AOGCM driving the RCM, based on the comparison of a 30-year simulation to the actual climate. The analysis examines the horizontal pattern of June–September total accumulated precipitation, the time versus latitude evolution of zonal mean West Africa (WA) precipitation (showing monsoon onset timing), and the latitude versus altitude cross-section of zonal winds over WA (showing the African Easterly Jet and the Tropical Easterly Jet). The study shows that correcting for excessively warm AOGCM Atlantic sea-surface temperatures (SSTs) improves the simulation of key features, whereas applying 30-year mean bias corrections to atmospheric variables driving the RCM at the lateral boundaries does not improve the RCM simulations. We suggest that AOGCM climate projections for Africa should benefit from downscaling by nesting an RCM that has demonstrated skill in simulating African climate, driven with bias-corrected SST.

scholarly journals Modelling long-term blanket peatland development in eastern Scotland

2019 ◽  
Vol 16 (20) ◽  
pp. 3977-3996 ◽  
Author(s):  
Ward Swinnen ◽  
Nils Broothaerts ◽  
Gert Verstraeten
Keyword(s):  
Dynamic Equilibrium ◽  
Carbon Sink ◽  
Regional Climate ◽  
Growth Potential ◽  
Peat Bogs ◽  
Mean Annual Temperature ◽  
Monthly Precipitation ◽  
Peatland Development ◽  
Blanket Peatlands

Abstract. Blanket peatlands constitute a rare ecosystem on a global scale, but blanket peatland is the most important peatland type on the British Isles. Most long-term peatland development models have focussed on peat bogs and high-latitude regions. Here, we present a process-based 2-D hillslope model to simulate long-term blanket peatland development along complex hillslope topographies. To calibrate the model, the peatland architecture was assessed along 56 hillslope transects in the headwaters of the river Dee (633 km2) in eastern Scotland, resulting in a dataset of 866 soil profile descriptions. The application of the calibrated model using local pollen-based land cover and regional climate reconstructions (mean annual temperature and mean monthly precipitation) over the last 12 000 years shows that the Early Holocene peatland development was largely driven by a temperature increase. An increase in woodland cover only has a slight positive effect on the peat growth potential contradicting the hypothesis that blanket peatland developed as a response to deforestation. Both the hillslope measurements and the model simulations demonstrate that the blanket peatland cover in the study area is highly variable both in extent and peat thickness stressing the need for spatially distributed peatland modelling. At the landscape scale, blanket peatlands were an important atmospheric carbon sink during the period 9.5–6 kyr BP. However, during the last 6000 years, the blanket peatlands were in a state of dynamic equilibrium with minor changes in the carbon balance.

scholarly journals Spatial and temporal characteristics in streamflow-related hydroclimatic variables over western Canada. Part 2: future projections

2016 ◽  
Vol 48 (4) ◽  
pp. 932-944 ◽  
Author(s):  
H. C. L. O'Neil ◽  
T. D. Prowse ◽  
B. R. Bonsal ◽  
Y. B. Dibike
Keyword(s):  
Snow Depth ◽  
Climate Models ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Cold Season ◽  
Maximum Temperature ◽  
Western Canada ◽  
The North ◽  
Spring Freshet ◽  
Hydroclimatic Variables

Much of the freshwater in western Canada originates in the Rocky Mountains as snowpack. Temperature and precipitation patterns throughout the region control the amount of snow accumulated and stored throughout the winter, and the intensity and timing of melt during the spring freshet. Therefore, changes in temperature, precipitation, snow depth, and snowmelt over western Canada are examined through comparison of output from the current and future periods of a series of regional climate models for the time periods 1971–2000 and 2041–2070. Temporal and spatial analyses of these hydroclimatic variables indicate that minimum temperature is likely to increase more than maximum temperature, particularly during the cold season, possibly contributing to earlier spring melt. Precipitation is projected to increase, particularly in the north. In the coldest months of the year snow depth is expected to increase in northern areas and decrease across the rest of study area. Snowmelt results indicate increases in mid-winter melt events and an earlier onset of the spring freshet. This study provides a summary of potential future climate using key hydroclimatic variables across western Canada with regard to the effects these changes may have on streamflow and the spring freshet, and thus water resources, throughout the study area.

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