scholarly journals Climatic Controls on Mean and Extreme Streamflow Changes Across the Permafrost Region of Canada

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 626
Author(s):  
Rajesh R. Shrestha ◽  
Jennifer Pesklevits ◽  
Daqing Yang ◽  
Daniel L. Peters ◽  
Yonas B. Dibike
Keyword(s):  
Maximum Flow ◽  
Permafrost Region ◽  
Seasonal Temperature ◽  
Mean Flow ◽  
Positive Correlation ◽  
Temperature And Precipitation ◽  
Temperature Trends ◽  
Importance Analysis ◽  
Precipitation And Temperature ◽  
Precipitation Trends

Climatic change is affecting streamflow regimes of the permafrost region, altering mean and extreme streamflow conditions. In this study, we analyzed historical trends in annual mean flow (Qmean), minimum flow (Qmin), maximum flow (Qmax) and Qmax timing across 84 hydrometric stations in the permafrost region of Canada. Furthermore, we related streamflow trends with temperature and precipitation trends, and used a multiple linear regression (MLR) framework to evaluate climatic controls on streamflow components. The results revealed spatially varied trends across the region, with significantly increasing (at 10% level) Qmin for 43% of stations as the most prominent trend, and a relatively smaller number of stations with significant Qmean, Qmax and Qmax timing trends. Temperatures over both the cold and warm seasons showed significant warming for >70% of basin areas upstream of the hydrometric stations, while precipitation exhibited increases for >15% of the basins. Comparisons of the 1976 to 2005 basin-averaged climatological means of streamflow variables with precipitation and temperature revealed a positive correlation between Qmean and seasonal precipitation, and a negative correlation between Qmean and seasonal temperature. The basin-averaged streamflow, precipitation and temperature trends showed weak correlations that included a positive correlation between Qmin and October to March precipitation trends, and negative correlations of Qmax timing with October to March and April to September temperature trends. The MLR-based variable importance analysis revealed the dominant controls of precipitation on Qmean and Qmax, and temperature on Qmin. Overall, this study contributes towards an enhanced understanding of ongoing changes in streamflow regimes and their climatic controls across the Canadian permafrost region, which could be generalized for the broader pan-Arctic regions.

scholarly journals How Do We Define Climate Change? Considering the Temporal Resolution of Niveo-Meteorological Data

Hydrology ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 38 ◽  
Author(s):  
Steven R. Fassnacht ◽  
Glenn G. Patterson ◽  
Niah B.H. Venable ◽  
Mikaela L. Cherry ◽  
Anna K.D. Pfohl ◽  
...  
Keyword(s):  
Snow Water Equivalent ◽  
Meteorological Data ◽  
Snow Accumulation ◽  
Temperature Trends ◽  
Northern Colorado ◽  
Snow Water ◽  
Snow Telemetry ◽  
Precipitation And Temperature ◽  
Precipitation Trends ◽  
Cumulative Precipitation

Historically, snowpack trends have been assessed using one fixed date to represent peak snow accumulation prior to the onset of melt. Subsequent trend analyses have considered the peak snow water equivalent (SWE), but the date of peak SWE can vary by several months due to inter-annual variability in snow accumulation and melt patterns. A 2018 assessment evaluated monthly SWE trends. However, since the month is a societal construct, this current work examines daily trends in SWE, cumulative precipitation, and temperature. The method was applied to 13 snow telemetry stations in Northern Colorado, USA for the period from 1981 to 2018. Temperature trends were consistent among all the stations; warming trends occurred 63% of the time from 1 October through 24 May, with the trends oscillating from warming to cooling over about a 10-day period. From 25 May to 30 September, a similar oscillation was observed, but warming trends occurred 86% of the time. SWE and precipitation trends illustrate temporal patterns that are scaled based on location. Specifically, lower elevations stations are tending to record more snowfall while higher elevation stations are recording less. The largest SWE, cumulative precipitation, and temperature trends were +30 to −70 mm/decade, +30 to −30 mm/decade, and +4 to −2.8 °C/decade, respectively. Trends were statistically significance an average of 25.8, 4.5, and 29.4% of the days for SWE, cumulative precipitation, and temperature, respectively. The trend in precipitation as snow ranged from +/−2%/decade, but was not significant at any station.

Seasonal Climate Variability and Change in the Pacific Northwest of the United States

2014 ◽  
Vol 27 (5) ◽  
pp. 2125-2142 ◽  
Author(s):  
John T. Abatzoglou ◽  
David E. Rupp ◽  
Philip W. Mote
Keyword(s):  
Climate Variability ◽  
Pacific Northwest ◽  
Time Scales ◽  
Potential Evapotranspiration ◽  
Seasonal Precipitation ◽  
Seasonal Temperature ◽  
Temperature Trends ◽  
The Pacific ◽  
Precipitation Trends

Abstract Observed changes in climate of the U.S. Pacific Northwest since the early twentieth century were examined using four different datasets. Annual mean temperature increased by approximately 0.6°–0.8°C from 1901 to 2012, with corroborating indicators including a lengthened freeze-free season, increased temperature of the coldest night of the year, and increased growing-season potential evapotranspiration. Seasonal temperature trends over shorter time scales (<50 yr) were variable. Despite increased warming rates in most seasons over the last half century, nonsignificant cooling was observed during spring from 1980 to 2012. Observations show a long-term increase in spring precipitation; however, decreased summer and autumn precipitation and increased potential evapotranspiration have resulted in larger climatic water deficits over the past four decades. A bootstrapped multiple linear regression model was used to better resolve the temporal heterogeneity of seasonal temperature and precipitation trends and to apportion trends to internal climate variability, solar variability, volcanic aerosols, and anthropogenic forcing. The El Niño–Southern Oscillation and the Pacific–North American pattern were the primary modulators of seasonal temperature trends on multidecadal time scales: solar and volcanic forcing were nonsignificant predictors and contributed weakly to observed trends. Anthropogenic forcing was a significant predictor of, and the leading contributor to, long-term warming; natural factors alone fail to explain the observed warming. Conversely, poor model skill for seasonal precipitation suggests that other factors need to be considered to understand the sources of seasonal precipitation trends.

Trend analysis in Icelandic discharge, temperature and precipitation series by parametric methods

2008 ◽  
Vol 39 (5-6) ◽  
pp. 425-436 ◽  
Author(s):  
Jóna Finndís Jónsdóttir ◽  
Cintia B. Uvo ◽  
Robin T. Clarke
Keyword(s):  
Mean Annual Temperature ◽  
Positive Trend ◽  
Seasonal Temperature ◽  
Parametric Methods ◽  
Broad Agreement ◽  
Temperature And Precipitation ◽  
Discharge Temperature ◽  
Annual Means ◽  
Seasonal Discharge ◽  
Precipitation Trends

This paper presents results of analyses by parametric methods of annual means of temperature, precipitation and discharge, and of seasonal maximum precipitation at 17, 28 and 10 Icelandic stations, respectively, for the period 1961–2000. Trends in mean seasonal temperature and precipitation are in broad agreement with results found by other authors using other methods. A positive trend appears in both mean annual temperature and mean temperatures in most seasons. Annual mean precipitation trends are positive in most seasons except for negative trends in the September–November season in the south. Additionally, positive trends appear in maximum one-, three- and five-day precipitation, both during the spring and autumn, except at a group of stations in central Iceland. Some of the positive trends in mean annual and seasonal precipitation may, however, be attributed to the positive trend in temperature which may have influenced gauge catch. Trends in mean annual and seasonal discharge are small and statistically insignificant; the trends found in temperature and precipitation do not all relate directly to trends in discharge but suggest hypotheses for further study of the relationships between them.

scholarly journals Investigation of The Long-Term Seasonal Variability of Precipitation And Temperature Across Turkey

2021 ◽  
Author(s):  
Nida Doğan Çiftçi ◽  
Ahmet Duran Şahin
Keyword(s):  
Climate Change ◽  
The Black Sea ◽  
Daily Maximum ◽  
Time Interval ◽  
Seasonal Temperature ◽  
Total Precipitation ◽  
Temperature And Precipitation ◽  
Increasing Trend ◽  
Precipitation And Temperature

Abstract The variability of temperature and precipitation is the main subject of climate change. Globally, since the last century, climate change leads to an increase in the occurrence of weather extremes along with mean values of climate parameters. In this study, long term changes in seasonal temperature and precipitation extremes are investigated based on daily maximum, minimum, mean temperature, and daily total precipitation data assessing the trends for the winter (DJF), spring (MAM), summer (JJA) and fall (SON) seasons across Turkey during 1960 – 2019 period. The first aim of the paper is to evaluate changes on warming/cooling trends of temperature, increasing/decreasing trends of precipitation, and variability of seasonal averages over Turkey. Extreme value and relative value indices are used for evaluating both precipitation and temperature trends of the seasons by dividing into two sequential periods and each time interval has 30 years’ data. Seasonal distribution of Probability Density Function (PDF) for air temperature anomalies are shown for the first (1960–1989), the second (1990–2019) halves of the whole period. For a comprehensive data quality assessment, Mann-Kendall (MK) trend test, Sen’s slope estimator, and the Pettit test, indices analyses have been performed [significant<0.05]. Hence, the data interval completely includes two thirty years’ periods, the results of this study could be interpreted as a significant summary of climatological seasonal changes in climate zones over Turkey. There has been a significant increasing trend on temperature over Turkey during 1960-2019, at TXn indices, 13 out of 61 stations has 2 °C decades−1 increasing, moreover, except for 5 stations, 1 °C decades−1 increasing trend is observed between the halves. Warming trends both extreme and relative indices are observed on the majority of stations. While there has been a gradually increasing trend on temperature indices over the zones, variable results are gotten on precipitation indices. Continental -b, Continental- c and the Black Sea climate have shown approximately 50 mm increasing on PRCPTOT index, Continental-a, Transition and Mediterranean climate annual total precipitation value have decreased. The features of PDFs clearly show that there has been a significant increase in the prevalence of extreme precipitation in the second halves across Turkey.

scholarly journals Correlation Analysis of Seasonal Temperature and Precipitation in a Region of Southern Italy

Geosciences ◽  
2018 ◽  
Vol 8 (5) ◽  
pp. 160 ◽  
Author(s):  
Ennio Ferrari ◽  
Roberto Coscarelli ◽  
Beniamino Sirangelo
Keyword(s):  
Correlation Analysis ◽  
Southern Italy ◽  
Seasonal Temperature ◽  
Temperature And Precipitation

scholarly journals Climate Dynamics of the Spatiotemporal Changes of Vegetation NDVI in Northern China from 1982 to 2015

2021 ◽  
Vol 13 (2) ◽  
pp. 187
Author(s):  
Rui Sun ◽  
Shaohui Chen ◽  
Hongbo Su
Keyword(s):  
Solar Radiation ◽  
Vegetation Index ◽  
Global Climate ◽  
Regional Scale ◽  
Northern China ◽  
Climate Dynamics ◽  
High Coverage ◽  
Vegetation Growth ◽  
Temperature And Precipitation ◽  
Precipitation And Temperature

As an important part of a terrestrial ecosystem, vegetation plays an important role in the global carbon-water cycle and energy flow. Based on the Global Inventory Monitoring and Modeling System (GIMMS) third generation of Normalized Difference Vegetation Index (NDVI3g), meteorological station data, climate reanalysis data, and land cover data, this study analyzed the climate dynamics of the spatiotemporal variations of vegetation NDVI in northern China from 1982 to 2015. The results showed that growth season NDVI (NDVIgs) increased significantly at 0.006/10a (p < 0.01) in 1982–2015 on the regional scale. The period from 1982 to 2015 was divided into three periods: the NDVIgs increased by 0.026/10a (p < 0.01) in 1982–1990, decreased by −0.002/10a (p > 0.1) in 1990–2006, and then increased by 0.021/10a (p < 0.01) during 2006–2015. On the pixel scale, the increases in NDVIgs during 1982–2015, 1982–1990, 1990–2006, and 2006–2015 accounted for 74.64%, 85.34%, 48.14%, and 68.78% of the total area, respectively. In general, the dominant climate drivers of vegetation growth had gradually switched from solar radiation, temperature, and precipitation (1982–1990) to precipitation and temperature (1990–2015). For woodland, high coverage grassland, medium coverage grassland, low coverage grassland, the dominant climate drivers had changed from temperature and solar radiation, solar radiation and precipitation, precipitation and solar radiation, solar radiation to precipitation and solar radiation, precipitation, precipitation and temperature, temperature and precipitation. The areas controlled by precipitation increased significantly, mainly distributed in arid, sub-arid, and sub-humid areas. The dominant climate drivers for vegetation growth in the plateau climate zone or high-altitude area changed from solar radiation to temperature and precipitation, and then to temperature, while in cold temperate zone, changed from temperature to solar radiation. These results are helpful to understand the climate dynamics of vegetation growth, and have important guiding significance for vegetation protection and restoration in the context of global climate change.

An Assessment of Observed and Simulated Temperature Variability in Sierra de Guadarrama (Spain)

2021 ◽  
Author(s):  
Cristina Vegas Cañas ◽  
J. Fidel González Rouco ◽  
Jorge Navarro Montesinos ◽  
Elena García Bustamante ◽  
Etor E. Lucio Eceiza ◽  
...  
Keyword(s):  
Western Europe ◽  
Climate Model ◽  
Regional Climate ◽  
Monitoring Network ◽  
Horizontal Resolution ◽  
Temperature Variability ◽  
Added Value ◽  
Seasonal Temperature ◽  
Temperature Trends ◽  
Highly Correlated

&lt;p&gt;This work provides a first assessment of temperature variability from interannual to multidecadal timescales in Sierra de Guadarrama, located in central Spain, from observations and regional climate model (RCM) simulations. Observational data are provided by the Guadarrama Monitoring Network (GuMNet; www.ucm.es/gumnet) at higher altitudes, up to 2225 masl, and by the Spanish Meteorological Agency (AEMet) at lower sites. An experiment at high horizontal resolution of 1 km using the Weather Research and Forecasting (WRF) RCM, feeding from ERA Interim inputs, is used. Through model-data comparison, it is shown that the simulations are annually and seasonally highly representative of the observations, although there is a tendency in the model to underestimate observational temperatures, mostly at high altitudes. Results show that WRF provides an added value in relation to the reanalysis, with improved correlation and error metrics relative to observations.&lt;/p&gt;&lt;p&gt;The analysis of temperature trends shows a warming in the area during the last 20 years, very significant in autumn. When spanning the analysis to the whole observational period, back to the beginning of the 20th century at some sites, significant annual and seasonal temperature increases of 1&amp;#8451;/decade develop, most of them happening during de 1970s, although not as intense as during the last 20 years.&lt;/p&gt;&lt;p&gt;The temporal variability of temperature anomalies in the Sierra de Guadarrama is highly correlated with the temperatures in the interior of the Iberian Peninsula. This relationship can be extended broadly over south-western Europe.&lt;/p&gt;

scholarly journals The Fingerprint of Climate Change and Urbanization in South Korea

Atmosphere ◽  
2018 ◽  
Vol 9 (7) ◽  
pp. 273 ◽  
Author(s):  
Won-Ho Nam ◽  
Guillermo Baigorria ◽  
Eun-Mi Hong ◽  
Taegon Kim ◽  
Yong-Sang Choi ◽  
...  
Keyword(s):  
Climate Change ◽  
South Korea ◽  
Urban Areas ◽  
Temporal Trends ◽  
Weather Data ◽  
Maximum Temperature ◽  
Island Effect ◽  
Temperature Trends ◽  
Agricultural Areas ◽  
Precipitation And Temperature

Understanding long-term changes in precipitation and temperature patterns is important in the detection and characterization of climate change, as is understanding the implications of climate change when performing impact assessments. This study uses a statistically robust methodology to quantify long-, medium- and short-term changes for evaluating the degree to which climate change and urbanization have caused temporal changes in precipitation and temperature in South Korea. We sought to identify a fingerprint of changes in precipitation and temperature based on statistically significant differences at multiple-timescales. This study evaluates historical weather data during a 40-year period (1973–2012) and from 54 weather stations. Our results demonstrate that between 1993–2012, minimum and maximum temperature trends in the vicinity of urban and agricultural areas are significantly different from the two previous decades (1973–1992). The results for precipitation amounts show significant differences in urban areas. These results indicate that the climate in urbanized areas has been affected by both the heat island effect and global warming-caused climate change. The increase in the number of rainfall events in agricultural areas is highly significant, although the temporal trends for precipitation amounts showed no significant differences. Overall, the impacts of climate change and urbanization in South Korea have not been continuous over time and have been expressed locally and regionally in terms of precipitation and temperature changes.

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