scholarly journals Weekly cycles in precipitation in a polluted region of Europe

2011 ◽  
Vol 11 (1) ◽  
pp. 1777-1801 ◽  
Author(s):  
C. W. Stjern
Keyword(s):  
Statistical Significance ◽  
Precipitation Amount ◽  
Cloud Amount ◽  
Heavy Precipitation ◽  
Potential Effect ◽  
Meteorological Variables ◽  
Precipitation Frequency ◽  
Total Period ◽  
Weekly Cycle ◽  
Weekly Cycles

Abstract. Weekly cycles in aerosol concentration and corresponding cycles in precipitation have been reported over Europe, but results are conflicting. To obtain a large potential effect of aerosols on precipitation we here focus on a highly polluted region on the borders between Germany, Poland and the Czech Republic. Meteorological parameters from 30 surface stations in a mix of urban, rural and remote locations were analyzed for the time period 1983–2008, using three different tests: the Kruskal-Wallis test, a spectral analysis and a comparison of the regular 7-day week to constructed 6- and 8-day weeks. We expect a clear and statistically significant weekly cycle to pass all three tests. Precipitation amount and meteorological variables associated with convective conditions, such as the frequency of heavy precipitation events and observations of rain showers, showed two-peak weekly cycles with maxima on Tuesdays and during weekends. The amplitude of the precipitation cycle increased with longitude towards the more polluted eastern part of the region, but the statistical significance of the cycles did not change correspondingly. The amplitudes of the weekly cycles were in many cases larger for the heavily polluted 1983–1987 period than for the cleaner 2004–2008 as well as the total period, but were equally often largest in the clean period. Moreover, of all the variables, periods and seasons investigated, the weekly cycles were statistically significant only for summertime values of light precipitation frequency and cloud amount, and only by one of the three tests applied. Conclusively, clear weekly cycles in meteorological variables were not found in this polluted region of Europe.

scholarly journals Weekly cycles in precipitation and other meteorological variables in a polluted region of Europe

2011 ◽  
Vol 11 (9) ◽  
pp. 4095-4104 ◽  
Author(s):  
C. W. Stjern
Keyword(s):  
Precipitation Amount ◽  
Cloud Amount ◽  
Heavy Precipitation ◽  
Potential Effect ◽  
Meteorological Variables ◽  
Precipitation Frequency ◽  
Weekly Cycle ◽  
Time Period ◽  
Urban Rural ◽  
Weekly Cycles

Abstract. Weekly cycles in aerosol concentration and corresponding cycles in precipitation have been reported over Europe, but results are conflicting. To obtain a large potential effect of aerosols on precipitation the focus will here be on a highly polluted region on the borders between Germany, Poland and the Czech Republic. Meteorological parameters from 30 surface stations in a mix of urban, rural and remote locations were analyzed for the time period 1983–2008, using three different tests: the Kruskal-Wallis test, a spectral analysis and a comparison of the regular 7-day week to constructed 6- and 8-day weeks. A clear and statistically significant weekly cycle will be expected to pass all three tests. Precipitation amount as well as meteorological variables associated with convective conditions, such as the frequency of heavy precipitation events and observations of rain showers, showed two-peak weekly cycles with maxima on Tuesdays and during weekends. The amplitudes of the weekly cycles were in many cases larger for the heavily polluted 1983–1987 period than for the cleaner 2004–2008 period, but were equally often largest in the cleaner period. Moreover, of all the variables, periods and seasons investigated, the weekly cycles were statistically significant only for summertime values of light precipitation frequency and cloud amount, and only by one of the three tests applied (the Kruskal-Wallis test). Conclusively, clear weekly cycles in meteorological variables were not found in this polluted region of Europe.

How Often Will It Rain?

2007 ◽  
Vol 20 (19) ◽  
pp. 4801-4818 ◽  
Author(s):  
Ying Sun ◽  
Susan Solomon ◽  
Aiguo Dai ◽  
Robert W. Portmann
Keyword(s):  
Climate Change ◽  
Daily Precipitation ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Precipitation Intensity ◽  
First Century ◽  
Simultaneous Increase ◽  
Percentage Increase ◽  
Precipitation Frequency ◽  
Twenty First Century

Abstract Daily precipitation data from climate change simulations using the latest generation of coupled climate system models are analyzed for potential future changes in precipitation characteristics. For the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) B1 (a low projection), A1B (a medium projection), and A2 (a high projection) during the twenty-first century, all the models consistently show a shift toward more intense and extreme precipitation for the globe as a whole and over various regions. For both SRES B1 and A2, most models show decreased daily precipitation frequency and all the models show increased daily precipitation intensity. The multimodel averaged percentage increase in the precipitation intensity (2.0% K−1) is larger than the magnitude of the precipitation frequency decrease (−0.7% K−1). However, the shift in precipitation frequency distribution toward extremes results in large increases in very heavy precipitation events (>50 mm day−1), so that for very heavy precipitation, the percentage increase in frequency is much larger than the increase in intensity (31.2% versus 2.4%). The climate model projected increases in daily precipitation intensity are, however, smaller than that based on simple thermodynamics (∼7% K−1). Multimodel ensemble means show that precipitation amount increases during the twenty-first century over high latitudes, as well as over currently wet regions in low- and midlatitudes more than other regions. This increase mostly results from a combination of increased frequency and intensity. Over the dry regions in the subtropics, the precipitation amount generally declines because of decreases in both frequency and intensity. This indicates that wet regions may get wetter and dry regions may become drier mostly because of a simultaneous increase (decrease) of precipitation frequency and intensity.

scholarly journals Assessing large-scale weekly cycles in meteorological variables: a review

2012 ◽  
Vol 12 (13) ◽  
pp. 5755-5771 ◽  
Author(s):  
A. Sanchez-Lorenzo ◽  
P. Laux ◽  
H.-J. Hendricks Franssen ◽  
J. Calbó ◽  
S. Vogl ◽  
...  
Keyword(s):  
Statistical Methods ◽  
Large Scale ◽  
Anthropogenic Activities ◽  
Statistical Significance ◽  
Meteorological Variables ◽  
Future Research ◽  
Scientific Debate ◽  
The Us ◽  
The World ◽  
Weekly Cycles

Abstract. Several studies have claimed to have found significant weekly cycles of meteorological variables appearing over large domains, which can hardly be related to urban effects exclusively. Nevertheless, there is still an ongoing scientific debate whether these large-scale weekly cycles exist or not, and some other studies fail to reproduce them with statistical significance. In addition to the lack of the positive proof for the existence of these cycles, their possible physical explanations have been controversially discussed during the last years. In this work we review the main results about this topic published during the recent two decades, including a summary of the existence or non-existence of significant weekly weather cycles across different regions of the world, mainly over the US, Europe and Asia. In addition, some shortcomings of common statistical methods for analyzing weekly cycles are listed. Finally, a brief summary of supposed causes of the weekly cycles, focusing on the aerosol-cloud-radiation interactions and their impact on meteorological variables as a result of the weekly cycles of anthropogenic activities, and possible directions for future research, is presented.

How Often Does It Rain?

2006 ◽  
Vol 19 (6) ◽  
pp. 916-934 ◽  
Author(s):  
Ying Sun ◽  
Susan Solomon ◽  
Aiguo Dai ◽  
Robert W. Portmann
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Global Climate Models ◽  
Annual Precipitation ◽  
Precipitation Frequency ◽  
Daily Precipitation Data ◽  
Precipitation Total ◽  
Rainy Days

Abstract Daily precipitation data from worldwide stations and gridded analyses and from 18 coupled global climate models are used to evaluate the models' performance in simulating the precipitation frequency, intensity, and the number of rainy days contributing to most (i.e., 67%) of the annual precipitation total. Although the models examined here are able to simulate the land precipitation amount well, most of them are unable to reproduce the spatial patterns of the precipitation frequency and intensity. For light precipitation (1–10 mm day−1), most models overestimate the frequency but produce patterns of the intensity that are in broad agreement with observations. In contrast, for heavy precipitation (>10 mm day−1), most models considerably underestimate the intensity but simulate the frequency relatively well. The average number of rainy days contributing to most of the annual precipitation is a simple index that captures the combined effects of precipitation frequency and intensity on the water supply. The different measures of precipitation characteristics examined in this paper reveal region-to-region differences in the observations and models of relevance for climate variability, water resources, and climate change.

scholarly journals Assessing large-scale weekly cycles in meteorological variables: a review

2012 ◽  
Vol 12 (1) ◽  
pp. 1451-1491 ◽  
Author(s):  
A. Sanchez-Lorenzo ◽  
P. Laux ◽  
H.-J. Hendricks-Franssen ◽  
J. Calbó ◽  
S. Vogl ◽  
...  
Keyword(s):  
Statistical Methods ◽  
Large Scale ◽  
Anthropogenic Activities ◽  
Statistical Significance ◽  
Meteorological Variables ◽  
Future Research ◽  
Scientific Debate ◽  
The Us ◽  
The World ◽  
Weekly Cycles

Abstract. Several studies have claimed to have found significant weekly cycles of meteorological variables appearing over large domains, which can hardly be related to urban effects exclusively. Nevertheless, there is still an ongoing scientific debate whether these large-scale weekly cycles exist or not, and some other studies fail to reproduce them with statistical significance. In addition to the lack of the positive proof for the existence of these cycles, their possible physical explanations have been controversially discussed during the last years. In this work we review the main results about this topic published during the recent two decades, including a summary of the existence or non-existence of significant weekly weather cycles across different regions of the world, mainly over the US, Europe and Asia. In addition, some shortcomings of common statistical methods for analyzing weekly cycles are listed. Finally, a brief summary of supposed causes of the weekly cycles, focusing on the aerosol-cloud-radiation interactions and their impact on meteorological variables as a result of the weekly cycles of anthropogenic activities, and possible directions for future research, is presented.

scholarly journals On the aerosol weekly cycle spatiotemporal variability over Europe

2011 ◽  
Vol 11 (10) ◽  
pp. 4611-4632 ◽  
Author(s):  
A. K. Georgoulias ◽  
K. A. Kourtidis
Keyword(s):  
Eastern Europe ◽  
Statistical Significance ◽  
Spatiotemporal Variability ◽  
Spatial And Temporal Variability ◽  
Dust Transport ◽  
Weekly Cycle ◽  
The North ◽  
Synoptic Wind ◽  
Terra Modis ◽  
Weekly Cycles

Abstract. In this work, we focus on the spatial and temporal variability of the aerosol weekly cycle over Europe as these were recorded from TERRA MODIS and AQUA MODIS satellite instruments. Aerosol optical properties retrieved from MODIS TERRA (February 2000–February 2009) and AQUA (July 2002–December 2008) were used to produce an aerosol weekly cycle index. First, the general aerosol optical depth (AOD550 nm) weekly patterns were defined at a 1° × 1° resolution using the satellite-based index and six regions of interest were selected. To remove episodic dust transport events, two different aerosol flags, employing fine mode ratio (FMR550 nm) and AOD550 nm data, were applied diagnostically, showing that the observed weekly cycles over Europe are due to continental aerosols. A second spatial averaging method was then used for the investigation of the weekly variability and the statistical significance of the weekly cycle over each of the previously selected regions. Three major weekly cycle plumes are observed over Europe. A strong positive (higher values during midweek) weekly cycle plume appears over Central Europe, while a strong negative (higher values during weekend) weekly plume appears over the Iberian Peninsula and the North-eastern Europe. The temporal examination of the weekly cycles shows that in some areas there are seasonal differences in the sign of the weekly cycle. The aerosol weekly variability over different regions in Europe was examined in conjunction with the dominating synoptic wind patterns from the NCEP/NCAR reanalysis, showing that the seasonal weekly cycle plumes over regions situated in the eastern Europe and the Mediterranean Sea could be partly attributed to the westerly transport of continental aerosols.

scholarly journals Contrasting Daytime and Nighttime Precipitation Variability between Observations and Eight Reanalysis Products from 1979 to 2014 in China

2017 ◽  
Vol 30 (16) ◽  
pp. 6443-6464 ◽  
Author(s):  
Chunlüe Zhou ◽  
Kaicun Wang
Keyword(s):  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Precipitation Intensity ◽  
Southeastern China ◽  
Precipitation Frequency ◽  
Climate Forecast System Reanalysis ◽  
Negative Center ◽  
Significant Downward Trend ◽  
Light Precipitation ◽  
Positive Center

Daytime (0800–2000 Beijing time) and nighttime (2000–0800 Beijing time) precipitation at approximately 2100 stations in China from 1979 to 2014 was used to evaluate eight current reanalyses. Daytime, nighttime, and nighttime–daytime contrast of precipitation were examined in aspects of climatology, seasonal cycle, interannual variability, and trends. The results show that the ECMWF interim reanalysis (ERA-Interim), ERA-Interim/Land, Japanese 55-year Reanalysis (JRA-55), and NCEP Climate Forecast System Reanalysis (CFSR) can reproduce the observed spatial pattern of nighttime–daytime contrast in precipitation amount, exhibiting a positive center over the eastern Tibetan Plateau and a negative center over southeastern China. All of the reanalyses roughly reproduce seasonal variations of nighttime and daytime precipitation, but not always nighttime–daytime contrast. The reanalyses overestimate drizzle and light precipitation frequencies by greater than 31.5% and underestimate heavy precipitation frequencies by less than −30.8%. The reanalyses successfully reproduce interannual synchronizations of daytime and nighttime precipitation frequencies and amounts with an averaged correlation coefficient r of 0.66 against the observed data but overestimate their year-to-year amplitudes by approximately 64%. The trends in nighttime, daytime, and nighttime–daytime contrast of the observed precipitation amounts are mainly dominated by their frequencies ( r = 0.85). Less than moderate precipitation frequency has exhibited a significant downward trend (−2.5% decade−1 during nighttime and −1.7% decade−1 during daytime) since 1979, which is roughly captured by the reanalyses. However, only JRA-55 captures the observed trend of nighttime precipitation intensity (2.4% decade−1), while the remaining reanalyses show negative trends. Overall, JRA-55 and CFSR provide the best reproductions of the observed nighttime–daytime contrast in precipitation intensity, although they have considerable room for improvement.

Temporal Changes in the Areal Coverage of Daily Extreme Precipitation in the Northeastern United States Using High-Resolution Gridded Data

2020 ◽  
Vol 59 (3) ◽  
pp. 551-565
Author(s):  
Arthur T. DeGaetano ◽  
Griffin Mooers ◽  
Thomas Favata
Keyword(s):  
United States ◽  
Extreme Precipitation ◽  
Daily Precipitation ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Northeastern United States ◽  
Precipitation Frequency ◽  
Polygon Area ◽  
Areal Precipitation ◽  
Grid Points

AbstractTime-dependent changes in extreme precipitation occurrence across the northeastern United States are evaluated in terms of areal extent. Using gridded precipitation data for the period from 1950 to 2018, polygons are defined that are based on isohyets corresponding to extreme daily precipitation accumulations. Across the region, areal precipitation is characterized on the basis of the annual and seasonal number of extreme precipitation polygons and the area of the polygons. Using the subset of grid points that correspond to station locations in the northeastern United States, gridded precipitation replicates the observed trends in extreme precipitation based on station observations. Although the number of extreme precipitation polygons does not change significantly through time, there is a marked increase in the area covered by the polygons. The median annual polygon area nearly doubles from 1950 to 2013. Consistent results occur for percentiles other than the median and a range of extreme precipitation amount thresholds, with the most pronounced changes observed in spring and summer. Like trends in station data, outside the northeastern United States trends in extreme precipitation polygon area are negative, particularly in the western United States, or they are not statistically significant. Collectively, the results suggest that the increases in heavy precipitation frequency and amount observed at stations in the northeastern United States are a manifestation of an expansion of the spatial area over which extreme precipitation occurs rather than a change in the number of unique extreme precipitation polygons.

scholarly journals A Novel Multi-Input Multi-Output Recurrent Neural Network Based on Multimodal Fusion and Spatiotemporal Prediction for 0–4 h Precipitation Nowcasting

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1596
Author(s):  
Fuhan Zhang ◽  
Xiaodong Wang ◽  
Jiping Guan
Keyword(s):  
Neural Network ◽  
Recurrent Neural Network ◽  
Input Data ◽  
Learning Strategy ◽  
Meteorological Data ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Precipitation Intensity ◽  
Multimodal Fusion ◽  
Grid Data

Multi-source meteorological data can reflect the development process of single meteorological elements from different angles. Making full use of multi-source meteorological data is an effective method to improve the performance of weather nowcasting. For precipitation nowcasting, this paper proposes a novel multi-input multi-output recurrent neural network model based on multimodal fusion and spatiotemporal prediction, named MFSP-Net. It uses precipitation grid data, radar echo data, and reanalysis data as input data and simultaneously realizes 0–4 h precipitation amount nowcasting and precipitation intensity nowcasting. MFSP-Net can perform the spatiotemporal-scale fusion of the three sources of input data while retaining the spatiotemporal information flow of them. The multi-task learning strategy is used to train the network. We conduct experiments on the dataset of Southeast China, and the results show that MFSP-Net comprehensively improves the performance of the nowcasting of precipitation amounts. For precipitation intensity nowcasting, MFSP-Net has obvious advantages in heavy precipitation nowcasting and the middle and late stages of nowcasting.

scholarly journals Long-term phenoclimatic averages of the Yuganskiy Nature Reserve territory and changes for 1961-2016

2018 ◽  
Vol 9 (2) ◽  
pp. 28-39
Author(s):  
Elena A. Zvyagina ◽  
Tatiana S. Pereyzslovets
Keyword(s):  
Nature Reserve ◽  
Linear Trend ◽  
Statistical Significance ◽  
Precipitation Amount ◽  
Positive Temperature ◽  
Leaf Fall ◽  
Least Squares Regression ◽  
Sap Flux ◽  
Climate Data ◽  
Average Maximum

In light of the observed global climate changes in recent decades, we studied the local climate indicators and explored the possible links between the spring and autumn phenophases and climate data changes in the Yuganskiy nature reserve (N 600 17’; E74054’ – N590 23’; E74000’) in 1982-2016. The collected climate data include daily average, maximum and minimum temperatures, daily precipitation amount and intensity, and number of days with precipitation of 0.1mm or more, monthly average of snow depths, dates of first and last occurrence of daily mean temperatures 0, +5, +10°С through the year. Timing of sap movement and leaf fall start were used as the spring and autumn indicators of birch (Bétula péndula ) phenology. The mean value of weather averages in the 30-year period of 1961-1990 was used as reference. Trends were calculated using linear least squares regression. Statistical significance was determined by calculating the standard error of the trend estimate. We found that the annual mean temperature has increased from –1.9°С (1961-1990) to –0.8° С (1982-2016), with corroborating indicators including increased temperature of the coldest night of the year from –53°С (1961-1990) to –51.3° С (1982-2016) and increased frequency of significant positive temperature anomalies from 21% (1961-1990) to 37% (1982-2016). May, June, August and October nights have become successively warmer. The air temperature increase was not accompanied by a corresponding increase in precipitation. Statistically significant trends toward earlier onset of spring and summer from 1982 to 2016 were observed. The date of the last spring freeze has been advancing by 6.1 days per decade since 1982. A freeze-free season has lengthened by 7.7 days per decade. Linear trend of the snowmelt timing was –3.7 days per decade. Permanent snow cover period has been shortening by 7.7 days per decade. The date of the first occurrence of the daily mean temperatures of +10° С has been advancing by 5.1 days per decade. However, the 0 -+5° С lag has been lengthening significantly by 9.2 days per decade, and the number of biologically effective degree days (base +5C) has not statistically changed. Sap flux and leaf fall timing of B. pendula have been advancing almost simultaneously by 4.0 and 4.2 days per decade since 1985. Sap flux beginning and last spring freeze date have been found to be linearly correlated (r=0.904). The average lag of them was 5±1 days and has been lengthening by 3 days per decade (1985–2016).

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