Temporal Trends in Snow Water Equivalent in New England from 1960 to Present

Author(s):  
Stephen R. Kissock
Author(s):  
Benjamin Hatchett

Snowpack seasonality in the conterminous United States (U.S.) is explored using a daily,14 km horizontal resolution gridded snow water equivalent and snow depth reanalysis product. I2calculated seasonal snowpacks using two established methods: (1) the classic Sturm approach that3requires 60 days of snow cover with a peak depth >50 cm and (2) the snow seasonality metric (SSM)4that only requires 60 days of continuous snow cover. The latter approach yields continuous values5from -1 to +1, where -1 (+1) indicates an ephemeral (seasonal) snowpack. Both approaches identify6seasonal snowpacks in western mountains and the northernmost central and eastern U.S. By relaxing7the depth constraint and providing continuous values, the SSM identifies greater areas of seasonal8snowpacks compared to the Sturm method, particularly in the upper Midwest, New England, and the9Intermountain West. Ephemeral snowpacks are identified throughout lower elevation regions of the10western U.S. and across a broad swath centered near 35°N spanning the lee of the Rocky Mountains11to the Atlantic coast. Because it lacks a depth constraint, the SSM approach is sensitive to interannual12variability, indicating it may inform the location of shallow but long-duration snowpacks at risk13of transitioning to becoming ephemeral with climatic change. A case study in Oregon during an14extreme snow drought year highlights seasonal to ephemeral snowpack transitions.


2016 ◽  
Author(s):  
Mustafa Gokmen

Abstract. We present a regional assessment of the spatiotemporal trends in several hydro-climate variables from 1979 to 2010 in Turkey, one of the vulnerable countries of the Eastern Mediterranean to climate change, using the two reanalysis products of ECMWF: ERA-Interim and ERA-Interim/Land, namely. The trend analysis revealed that an average warming of 1.26 °C occurred in Turkey from 1979 to 2010, with high confidence intervals (95 to 99 %) mostly. Geographically, the largest warming (up to 1.8 °C) occurred in the Western coastal areas next to Aegean Sea and in the South-East regions. The increasing trend of air temperature was confirmed by the comparisons with the measurements from several meteorological stations. With respect to the regional trends in hydrological variables, ERA-Interim and ERA-Interim/Land revealed quite different pictures: the ERA-Interim dataset indicated that there have been significant decreasing trends of precipitation, snow water equivalent and runoff in some parts of inner/South-eastern Anatolia (up to 250 mm decrease totally in the upstream of Euphrates, Kizilirmak and Seyhan basins), while ERA-Interim/Land showed none or minor trends in the same areas. Comparison of the precipitation trends by the two datasets with some rain gauge data distributed over Turkey revealed that none of the products is consistently closer to the observations. Based on the trend assessment of the hydrological trends by the two datasets and the comparisons with the observation data and other trend studies in the study area we can conclude that, except for some evapotranspiration trends over Mediterranean and Black Sea, there have not been clear and considerable trends of precipitation, snow water equivalent and runoff quantities over Turkey from 1979 to 2010, despite the considerable warming for the same period throughout the country. In this respect, we can suggest that, the impacts of global warming on the water cycle are rather unpredictable especially at regional scale.


2021 ◽  
Vol 13 (4) ◽  
pp. 616
Author(s):  
Rafael Alonso ◽  
José María García del Pozo ◽  
Samuel T. Buisán ◽  
José Adolfo Álvarez

Snow makes a great contribution to the hydrological cycle in cold regions. The parameter to characterize available the water from the snow cover is the well-known snow water equivalent (SWE). This paper presents a near-surface-based radar for determining the SWE from the measured complex spectral reflectance of the snowpack. The method is based in a stepped-frequency continuous wave radar (SFCW), implemented in a coherent software defined radio (SDR), in the range from 150 MHz to 6 GHz. An electromagnetic model to solve the electromagnetic reflectance of a snowpack, including the frequency and wetness dependence of the complex relative dielectric permittivity of snow layers, is shown. Using the previous model, an approximated method to calculate the SWE is proposed. The results are presented and compared with those provided by a cosmic-ray neutron SWE gauge over the 2019–2020 winter in the experimental AEMet Formigal-Sarrios test site. This experimental field is located in the Spanish Pyrenees at an elevation of 1800 m a.s.l. The results suggest the viability of the approximate method. Finally, the feasibility of an auxiliary snow height measurement sensor based on a 120 GHz frequency modulated continuous wave (FMCW) radar sensor, is shown.


Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 404
Author(s):  
Tong Heng ◽  
Xinlin He ◽  
Lili Yang ◽  
Jiawen Yu ◽  
Yulin Yang ◽  
...  

To reveal the spatiotemporal patterns of the asymmetry in the Tianshan mountains’ climatic warming, in this study, we analyzed climate and MODIS snow cover data (2001–2019). The change trends of asymmetrical warming, snow depth (SD), snow coverage percentage (SCP), snow cover days (SCD) and snow water equivalent (SWE) in the Tianshan mountains were quantitatively determined, and the influence of asymmetrical warming on the snow cover activity of the Tianshan mountains were discussed. The results showed that the nighttime warming rate (0.10 °C per decade) was greater than the daytime, and that the asymmetrical warming trend may accelerate in the future. The SCP of Tianshan mountain has reduced by 0.9%. This means that for each 0.1 °C increase in temperature, the area of snow cover will reduce by 5.9 km2. About 60% of the region’s daytime warming was positively related to SD and SWE, and about 48% of the region’s nighttime warming was negatively related to SD and SWE. Temperature increases were concentrated mainly in the Pamir Plateau southwest of Tianshan at high altitudes and in the Turpan and Hami basins in the east. In the future, the western and eastern mountainous areas of the Tianshan will continue to show a warming trend, while the central mountainous areas of the Tianshan mountains will mainly show a cooling trend.


Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 363
Author(s):  
George Duffy ◽  
Fraser King ◽  
Ralf Bennartz ◽  
Christopher G. Fletcher

CloudSat is often the only measurement of snowfall rate available at high latitudes, making it a valuable tool for understanding snow climatology. The capability of CloudSat to provide information on seasonal and subseasonal time scales, however, has yet to be explored. In this study, we use subsampled reanalysis estimates to predict the uncertainties of CloudSat snow water equivalent (SWE) accumulation measurements at various space and time resolutions. An idealized/simulated subsampling model predicts that CloudSat may provide seasonal SWE estimates with median percent errors below 50% at spatial scales as small as 2° × 2°. By converting these predictions to percent differences, we can evaluate CloudSat snowfall accumulations against a blend of gridded SWE measurements during frozen time periods. Our predictions are in good agreement with results. The 25th, 50th, and 75th percentiles of the percent differences between the two measurements all match predicted values within eight percentage points. We interpret these results to suggest that CloudSat snowfall estimates are in sufficient agreement with other, thoroughly vetted, gridded SWE products. This implies that CloudSat may provide useful estimates of snow accumulation over remote regions within seasonal time scales.


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