Reliablemicrostructuremeasurement of snow is a requirement for microwave radiative transfer model validation.Snow specific surface area(SSA)can be measured using stereological methods,in which snow samples are cast in...Reliablemicrostructuremeasurement of snow is a requirement for microwave radiative transfer model validation.Snow specific surface area(SSA)can be measured using stereological methods,in which snow samples are cast in the field and photographed in the laboratory.Processing stereology photographs manually by counting intersections of test cycloids with air-ice boundaries reduces the problems in binary segmentation.This paper is a case study to evaluate the repeatability of the manually stereology interpretation by two independent research groups.We further assessed how uncertainty in snow SSA influences simulated brightness temperature(TB)driven by the Microwave Emission Model of Layered Snowpacks(MEMLS),and how stereology compares to Near Infrared(NIR)camera and hand lens.Data was obtained from two alpine snow profiles from Steamboat Springs,Colorado.Results showed that stereological SSA values measured by two groups are highly consistent,and the ground radiometer measured T_(B)at 19 and 37 GHz was successfully predicted(RMSE<3.8 K);simulations using NIR SSA and hand-lens geometric grain size(Dg)measurements have larger errors.This conclusion was not sensitive to uncertainty in the free parameters of TB modeling.展开更多
On 18 January 2017 a catastrophic avalanche destroyed the Rigopiano Gran Sasso Resort&Wellness(Rigopiano Hotel)in the Gran Sasso National Park in Italy,with 40 people trapped and a death toll of 29.This article de...On 18 January 2017 a catastrophic avalanche destroyed the Rigopiano Gran Sasso Resort&Wellness(Rigopiano Hotel)in the Gran Sasso National Park in Italy,with 40 people trapped and a death toll of 29.This article describes the location of the disaster and the general meteorological scenario,with field investigations to provide insight on the avalanche dynamics and its interaction with the hotel buildings.The data gathered in situ suggest that the avalanche was a fluidized dry snow avalanche,which entrained a sligthtly warmer snow cover along the path and reached extremely long runout distances with braking effect from mountain forests.The avalanche that reached the Rigopiano area was a‘‘wood-snow’’avalanche—a mixture of snow and uprooted and crushed trees,rocks,and other debris.There were no direct eyewitnesses at the event,and a quick post-event survey used a numerical model to analyze the dynamics of the event to estimate the pressure,velocity,and direction of the natural flow and the causes for the destruction of the hotel.Considering the magnitude and the damage caused by the event,the avalanche was at a high to very high intensity scale.展开更多
基金supported by NASA Terrestrial Hydrology Program[grant number NNX09AM10G]Strategic Priority Research Program of Chinese Academy of Sciences[grant number XDA20100300].
文摘Reliablemicrostructuremeasurement of snow is a requirement for microwave radiative transfer model validation.Snow specific surface area(SSA)can be measured using stereological methods,in which snow samples are cast in the field and photographed in the laboratory.Processing stereology photographs manually by counting intersections of test cycloids with air-ice boundaries reduces the problems in binary segmentation.This paper is a case study to evaluate the repeatability of the manually stereology interpretation by two independent research groups.We further assessed how uncertainty in snow SSA influences simulated brightness temperature(TB)driven by the Microwave Emission Model of Layered Snowpacks(MEMLS),and how stereology compares to Near Infrared(NIR)camera and hand lens.Data was obtained from two alpine snow profiles from Steamboat Springs,Colorado.Results showed that stereological SSA values measured by two groups are highly consistent,and the ground radiometer measured T_(B)at 19 and 37 GHz was successfully predicted(RMSE<3.8 K);simulations using NIR SSA and hand-lens geometric grain size(Dg)measurements have larger errors.This conclusion was not sensitive to uncertainty in the free parameters of TB modeling.
文摘On 18 January 2017 a catastrophic avalanche destroyed the Rigopiano Gran Sasso Resort&Wellness(Rigopiano Hotel)in the Gran Sasso National Park in Italy,with 40 people trapped and a death toll of 29.This article describes the location of the disaster and the general meteorological scenario,with field investigations to provide insight on the avalanche dynamics and its interaction with the hotel buildings.The data gathered in situ suggest that the avalanche was a fluidized dry snow avalanche,which entrained a sligthtly warmer snow cover along the path and reached extremely long runout distances with braking effect from mountain forests.The avalanche that reached the Rigopiano area was a‘‘wood-snow’’avalanche—a mixture of snow and uprooted and crushed trees,rocks,and other debris.There were no direct eyewitnesses at the event,and a quick post-event survey used a numerical model to analyze the dynamics of the event to estimate the pressure,velocity,and direction of the natural flow and the causes for the destruction of the hotel.Considering the magnitude and the damage caused by the event,the avalanche was at a high to very high intensity scale.
