scholarly journals Assessment of the underestimation of snowfall accumulation by tipping bucket gauges used operationally by the Spanish national weather service

2016 ◽  
Author(s):  
Samuel T. Buisan ◽  
Michael E. Earle ◽  
José Luís Collado ◽  
John Kochendorfer ◽  
Javier Alastrué ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Weather Conditions ◽  
Test Site ◽  
Environmental Variable ◽  
State Agency ◽  
Mountain Range ◽  
Northern Spain ◽  
Wind Speeds ◽  
Precipitation Gauge ◽  
Average Catch

Abstract. Within the framework of the WMO-SPICE (Solid Precipitation Intercomparison Experiment) at the Formigal-Sarrios test site located in the Pyrenees mountain range of Spain, the Thies tipping bucket precipitation gauge was assessed against the SPICE reference. The Thies gauge is the most widely-used precipitation gauge by the Spanish Meteorological State Agency (AEMET) for the measurement of all precipitation types, including snow. It is therefore critical that its performance be characterized. The first objective of this study is to derive transfer functions based on the relationships between catch ratio and wind speed and temperature. Multiple linear regression was applied to 1 h and 3 h accumulation periods, confirming that wind is the most dominant environmental variable affecting the gauge catch efficiency, especially during snowfall events. At wind speeds of 1.5 m s−1 the average catch ratio was 0.7. At 3 m s−1, the average catch ratio was 0.5, and was even lower for temperatures below −2 ºC and decreased to 0.2 or less for higher wind speeds. Following this, this study outlines two areas in Northern Spain that exhibit different catch ratios under weather conditions leading to snowfall events, highlighting the importance of how the precipitation gauge behaves in various conditions.

scholarly journals Assessment of snowfall accumulation underestimation by tipping bucket gauges in the Spanish operational network

2017 ◽  
Vol 10 (3) ◽  
pp. 1079-1091 ◽  
Author(s):  
Samuel T. Buisán ◽  
Michael E. Earle ◽  
José Luís Collado ◽  
John Kochendorfer ◽  
Javier Alastrué ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Test Site ◽  
Environmental Variable ◽  
State Agency ◽  
Mountain Range ◽  
Northern Spain ◽  
Wind Speeds ◽  
Solid Precipitation ◽  
The World ◽  
Precipitation Gauge

Abstract. Within the framework of the World Meteorological Organization Solid Precipitation Intercomparison Experiment (WMO-SPICE), the Thies tipping bucket precipitation gauge was assessed against the SPICE reference configuration at the Formigal–Sarrios test site located in the Pyrenees mountain range of Spain. The Thies gauge is the most widely used precipitation gauge by the Spanish Meteorological State Agency (AEMET) for the measurement of all precipitation types including snow. It is therefore critical that its performance is characterized. The first objective of this study is to derive transfer functions based on the relationships between catch ratio and wind speed and temperature. Multiple linear regression was applied to 1 and 3 h accumulation periods, confirming that wind is the most dominant environmental variable affecting the gauge catch efficiency, especially during snowfall events. At wind speeds of 1.5 m s−1 the tipping bucket recorded only 70 % of the reference precipitation. At 3 m s−1, the amount of measured precipitation decreased to 50 % of the reference, was even lower for temperatures colder than −2 °C and decreased to 20 % or less for higher wind speeds.The implications of precipitation underestimation for areas in northern Spain are discussed within the context of the present analysis, by applying the transfer function developed at the Formigal–Sarrios and using results from previous studies.

scholarly journals Testing and Development of Transfer Functions for Weighing Precipitation Gauges in WMO-SPICE

2017 ◽  
Author(s):  
John Kochendorfer ◽  
Rodica Nitu ◽  
Mareile Wolff ◽  
Eva Mekis ◽  
Roy Rasmussen ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Precipitation Amount ◽  
Wind Speeds ◽  
Small Manufacturer ◽  
Lower Porosity ◽  
Precipitation Gauge ◽  
Reference Amount ◽  
First Time ◽  
High Winds ◽  
Better Than

Abstract. Adjustments for the undercatch of solid precipitation caused by wind were developed for different weighing gauge/wind shield combinations tested in WMO-SPICE. These include several different manufacturer-provided unshielded and single-Alter shielded weighing gauges, a MRW500 precipitation gauge within a small, manufacturer-provided shield, and host-provided precipitation gauges within double-Alter, Belfort double-Alter, and small Double-Fence Intercomparison Reference (SDFIR) shields. Previously-derived adjustments were also tested on measurements from each weighing gauge/wind shield combination. The transfer functions developed specifically for each of the different types of unshielded and single-Alter shielded weighing gauges did not perform significantly better than the more generic and universal transfer functions developed previously using measurements from eight different WMO-SPICE sites. This indicates that wind shield type (or lack thereof) is more important in determining the magnitude of wind-induced undercatch than the type of weighing precipitation gauge. It also demonstrates the potential for widespread use of the previously-developed, multi-site single-Alter shielded and unshielded transfer functions. In addition, corrections for the lower-porosity Belfort double-Alter shield and a standard double-Alter shield were developed and tested using measurements from two separate sites for the first time. Among all of the manufacturer-provided shields tested, with an average undercatch of about 5 %, the Belfort double Alter shield required the least amount of correction, and caught ~ 80 % of the reference amount of precipitation even in snowy conditions with wind speeds greater than 5 m  s−1. The SDFIR-shielded gauge accumulated 98 % of the Double-Fence Automated Reference (DFAR) precipitation amount on average, accumulated 90 % of the DFAR accumulation in high winds, and was almost indistinguishable from the full-sized DFAR used as a reference. In general, the more effective wind shields, that were associated with smaller unadjusted errors, also produced more accurate measurements after adjustment.

scholarly journals Derivation of a new continuous adjustment function for correcting wind-induced loss of solid precipitation: results of a Norwegian field study

2014 ◽  
Vol 11 (9) ◽  
pp. 10043-10084 ◽  
Author(s):  
M. A. Wolff ◽  
K. Isaksen ◽  
A. Petersen-Øverleir ◽  
K. Ødemark ◽  
T. Reitan ◽  
...  
Keyword(s):  
Land Surface ◽  
Test Site ◽  
Cold Season ◽  
Winter Precipitation ◽  
Wind Speeds ◽  
Solid Precipitation ◽  
Extensive Test ◽  
Precipitation Loss ◽  
Southern Norway ◽  
Precipitation Gauge

Abstract. Precipitation measurements exhibit large cold-season biases due to under-catch in windy conditions. These uncertainties affect water balance calculations, snowpack monitoring and calibrations of remote sensing algorithms and land surface models. More accurate data would improve the ability to predict future changes in water resources and mountain hazards in snow-dominated regions. In 2010, an extensive test-site for precipitation measurements was established at a mountain plateau in Southern Norway. Precipitation data of automatic gauges were compared with a precipitation gauge in a Double Fence Intercomparison Reference (DFIR) wind shield construction which served as the reference. Additionally, a large number of sensors were monitoring supportive meteorological parameters. In this paper, data from three winters were used to study and determine the wind-induced under-catch of solid precipitation. Qualitative analyses and Bayesian statistics were used to evaluate and objectively choose the model that is describing the data best. A continuous adjustment function and its uncertainty were derived for measurements of all types of winter precipitation (from rain to dry snow). A regression analysis did not reveal any significant misspecifications for the adjustment function, but showed that the chosen model uncertainty is slightly insufficient and can be further optimized. The adjustment function is operationally usable based only on data available at standard automatic weather stations. Our results show a non-linear relationship between under-catch and wind speed during winter precipitation events and there is a clear temperature dependency, mainly reflecting the precipitation type. The results allowed for the first time to derive an adjustment function with a data-tested validity beyond 7 m s−1 and proved a stabilisation of the wind-induced precipitation loss for higher wind speeds.

scholarly journals Derivation of a new continuous adjustment function for correcting wind-induced loss of solid precipitation: results of a Norwegian field study

2015 ◽  
Vol 19 (2) ◽  
pp. 951-967 ◽  
Author(s):  
M. A. Wolff ◽  
K. Isaksen ◽  
A. Petersen-Øverleir ◽  
K. Ødemark ◽  
T. Reitan ◽  
...  
Keyword(s):  
Land Surface ◽  
Test Site ◽  
Cold Season ◽  
Winter Precipitation ◽  
Wind Speeds ◽  
Solid Precipitation ◽  
Comprehensive Test ◽  
Precipitation Loss ◽  
Southern Norway ◽  
Precipitation Gauge

Abstract. Precipitation measurements exhibit large cold-season biases due to under-catch in windy conditions. These uncertainties affect water balance calculations, snowpack monitoring and calibration of remote sensing algorithms and land surface models. More accurate data would improve the ability to predict future changes in water resources and mountain hazards in snow-dominated regions. In 2010, a comprehensive test site for precipitation measurements was established on a mountain plateau in southern Norway. Automatic precipitation gauge data are compared with data from a precipitation gauge in a Double Fence Intercomparison Reference (DFIR) wind shield construction which serves as the reference. A large number of other sensors are provided supporting data for relevant meteorological parameters. In this paper, data from three winters are used to study and determine the wind-induced under-catch of solid precipitation. Qualitative analyses and Bayesian statistics are used to evaluate and objectively choose the model that best describes the data. A continuous adjustment function and its uncertainty are derived for measurements of all types of winter precipitation (from rain to dry snow). A regression analysis does not reveal any significant misspecifications for the adjustment function, but shows that the chosen model does not describe the regression noise optimally. The adjustment function is operationally usable because it is based only on data available at standard automatic weather stations. The results show a non-linear relationship between under-catch and wind speed during winter precipitation events and there is a clear temperature dependency, mainly reflecting the precipitation type. The results allow, for the first time, derivation of an adjustment function based on measurements above 7 m s−1. This extended validity of the adjustment function shows a stabilization of the wind-induced precipitation loss for higher wind speeds.

scholarly journals Improvement of solid precipitation measurements using a hotplate precipitation gauge

2021 ◽  
Author(s):  
Julie M. Thériault ◽  
Nicolas R. Leroux ◽  
Roy Rasmussen
Keyword(s):  
Wind Speed ◽  
Transfer Functions ◽  
Collection Efficiency ◽  
Meteorological Conditions ◽  
Speed Limit ◽  
Mean Square ◽  
Wind Speeds ◽  
Solid Precipitation ◽  
Precipitation Measurement ◽  
Precipitation Gauge

AbstractAccurate snowfall measurement is challenging because it depends on the precipitation gauge used, meteorological conditions, and the precipitation microphysics. Upstream of weighing gauges, the flow field is disturbed by the gauge and any shielding used usually creates an updraft, which deflects solid precipitation from falling in the gauge resulting in significant undercatch. Wind shields are often used with weighing gauges to reduce this updraft and transfer functions are required to adjust the snowfall measurements to consider gauge undercatch. Using these functions reduce the bias in precipitation measurement but not the Root Mean Square Error (RMSE) (Kochendorfer et al. 2017a, b). The analysis performed in this study shows that the hotplate precipitation gauge bias after wind correction is near zero and similar to wind corrected weighing gauges but improves on the RMSE or scatter of the collection efficiency of weighing gauges for a given wind speed. To do this, the accuracy of the hotplate was compared to standard unshielded and shielded weighing gauges collected during the WMO SPICE program. The RMSE of the hotplate measurements is lower than weighing gauges (with or without an Alter shield) for wind speeds up to 5 m s-1; the wind speed limit at which sufficient data were available. This study shows that the hotplate precipitation measurement has a low bias and RMSE due to its aerodynamic shape, making its performance mostly independent of the type of solid precipitation.

scholarly journals The quantification and correction of wind-induced precipitation measurement errors

2017 ◽  
Vol 21 (4) ◽  
pp. 1973-1989 ◽  
Author(s):  
John Kochendorfer ◽  
Roy Rasmussen ◽  
Mareile Wolff ◽  
Bruce Baker ◽  
Mark E. Hall ◽  
...  
Keyword(s):  
Measurement Errors ◽  
Transfer Functions ◽  
Climate Change Research ◽  
Wind Speeds ◽  
Solid Precipitation ◽  
Precipitation Measurement ◽  
Single Function ◽  
Safety Work ◽  
The Usa ◽  
Precipitation Gauge

Abstract. Hydrologic measurements are important for both the short- and long-term management of water resources. Of the terms in the hydrologic budget, precipitation is typically the most important input; however, measurements of precipitation are subject to large errors and biases. For example, an all-weather unshielded weighing precipitation gauge can collect less than 50 % of the actual amount of solid precipitation when wind speeds exceed 5 m s−1. Using results from two different precipitation test beds, such errors have been assessed for unshielded weighing gauges and for weighing gauges employing four of the most common windshields currently in use. Functions to correct wind-induced undercatch were developed and tested. In addition, corrections for the single-Alter weighing gauge were developed using the combined results of two separate sites in Norway and the USA. In general, the results indicate that the functions effectively correct the undercatch bias that affects such precipitation measurements. In addition, a single function developed for the single-Alter gauges effectively decreased the bias at both sites, with the bias at the US site improving from −12 to 0 %, and the bias at the Norwegian site improving from −27 to −4 %. These correction functions require only wind speed and air temperature as inputs, and were developed for use in national and local precipitation networks, hydrological monitoring, roadway and airport safety work, and climate change research. The techniques used to develop and test these transfer functions at more than one site can also be used for other more comprehensive studies, such as the World Meteorological Organization Solid Precipitation Intercomparison Experiment (WMO-SPICE).

scholarly journals The Quantification and Correction of Wind-Induced Precipitation Measurement Errors

2016 ◽  
Author(s):  
John Kochendorfer ◽  
Roy Rasmussen ◽  
Mareile Wolff ◽  
Bruce Baker ◽  
Mark E. Hall ◽  
...  
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Measurement Errors ◽  
Transfer Functions ◽  
Universal Function ◽  
Climate Change Research ◽  
Wind Speeds ◽  
Solid Precipitation ◽  
The Us ◽  
Precipitation Gauge

Abstract. Hydrologic measurements are becoming increasingly important for both the short and long term management of water resources. Of all the terms in the hydrologic budget, precipitation is the typically most important input. However, measurements of precipitation are still subject to large errors and biases. For example, a high-quality but unshielded weighing precipitation gauge can collect less than 50 % of the actual amount of solid precipitation when wind speeds exceed 5 ms−1. Using results from two different precipitation testbeds, such errors have been assessed for unshielded weighing gauges and for four of the most common windshields currently in use. Functions used to correct wind-induced undercatch were developed and tested. In addition, corrections for the single Altar weighing gauge were developed using the combined results of two separate sites, one of which was in Norway and other in the US. In general the results indicate that corrections described as a function of air temperature and wind speed effectively remove the undercatch bias that affects such precipitation measurements. In addition, a single ‘universal’ function developed for the single Altar gauges effectively removed the bias at both sites, with the bias at the US site improved from −12 % to 0 %, and the bias at the Norwegian site improved from −27 % to −3 %. These correction functions require only wind speed and air temperature, and were developed for use in national and local precipitation networks, hydrological monitoring, roadway and airport safety work, and climate change research. The techniques used to develop and test these transfer functions at more than one site can also be used for other more comprehensive studies, such as the WMO Solid Precipitation Intercomparison Experiment.

Retrofit of Aerodynamic Cable Instability on a Cable-Stayed Bridge: Case Study

2000 ◽  
Vol 1740 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Niket M. Telang ◽  
Charles M. Minervino ◽  
Paul G. Norton
Keyword(s):  
Large Amplitude ◽  
Weather Conditions ◽  
Mitigation Measures ◽  
Mobile Bay ◽  
Department Of Transportation ◽  
Light Rain ◽  
Wind Speeds ◽  
Cable Stays ◽  
Large Amplitude Vibrations

Elegantly poised over the Mobile River, the twin pylons and the semi-harped cable stays of the Cochrane Bridge subtly complement the vast and undulating landscape of the Mobile Bay as the bridge carries US Route 90 over the Mobile River in Alabama. In February 1998, light rain drizzled on the bridge, and a weather station nearby recorded wind speeds of about 48 km/h (30 mph). Under these seemingly mild weather conditions, the normally immobile cable stays started to vibrate, and within moments, these nascent vibrations reached amplitudes of more than 1.2 m (4 ft). Alarmed by this event, the Alabama Department of Transportation (ALDOT) took immediate action to ensure the continued safety and serviceability of the bridge. A team of consultants was selected by ALDOT to investigate mitigation measures for the large-amplitude cable-stay vibrations. The fast-tracked comprehensive program planned and implemented to inspect, test, document, and evaluate the effects of the large-amplitude vibrations and the recommendation of retrofit measures that would limit future occurrences of such cable-stay vibrations on the Cochrane Bridge are described in detail.

Trends and Variability of North American Cool-Season Extratropical Cyclones: 1979–2019

2021 ◽  
Author(s):  
Robert Fritzen ◽  
Victoria Lang ◽  
Vittorio A. Gensini
Keyword(s):  
North American ◽  
Research Question ◽  
Weather Conditions ◽  
Extratropical Cyclones ◽  
Mountain Range ◽  
Cool Season ◽  
The North ◽  
Primary Driver ◽  
Regional Reanalysis ◽  
Log Linear

AbstractExtratropical cyclones are the primary driver of sensible weather conditions across the mid-latitudes of North America, often generating various types of precipitation, gusty non-convective winds, and severe convective storms throughout portions of the annual cycle. Given ongoing modifications of the zonal atmospheric thermal gradient due to anthropogenic forcing, analyzing the historical characteristics of these systems presents an important research question. Using the North American Regional Reanalysis, boreal cool-season (October–April) extratropical cyclones for the period 1979–2019 were identified, tracked, and classified based on their genesis location. Additionally, bomb cyclones—extratropical cyclones that recorded a latitude normalized pressure fall of 24 hPa in 24-hr—were identified and stratified for additional analysis. Cyclone lifespan across the domain exhibits a log-linear relationship, with 99% of all cyclones tracked lasting less than 8 days. On average, ≈ 270 cyclones were tracked across the analysis domain per year, with an average of ≈ 18 year−1 being classified as bomb cyclones. The average number of cyclones in the analysis domain has decreased in the last 20 years from 290 year−1 during the period 1979–1999 to 250 year−1 during the period 2000–2019. Spatially, decreasing trends in the frequency of cyclone track counts were noted across a majority of the analysis domain, with the most significant decreases found in Canada’s Northwest Territories, Colorado, and east of the Graah mountain range. No significant interannual or spatial trends were noted with bomb cyclone frequency.

Meteorological study for Gangotri Glacier and its comparison with other high altitude meteorological stations in central Himalayan region

2007 ◽  
Vol 38 (1) ◽  
pp. 59-77 ◽  
Author(s):  
Pratap Singh ◽  
Umesh K. Haritashya ◽  
Naresh Kumar
Keyword(s):  
High Altitude ◽  
Meteorological Data ◽  
Weather Conditions ◽  
Meteorological Station ◽  
Himalayan Region ◽  
Valley Wind ◽  
Maximum Rainfall ◽  
Garhwal Himalayas ◽  
Wind Speeds ◽  
Gangotri Glacier

In spite of the vital role of high altitude climatology in melting of snow and glaciers, retreat or advancement of glaciers, flash floods, erosion and sediment transport, etc., weather conditions are not much studied for the high altitude regions of Himalayas. In this study, a comprehensive meteorological analysis has been made for the Gangotri Meteorological Station (Bhagirathi Valley, Garhwal Himalayas) using data observed for four consecutive melt seasons (2000–2003) covering a period from May to October for each year. The collected meteorological data includes rainfall, temperature, wind speed and direction, relative humidity, sunshine hours and evaporation. The results and their distribution over the different melt seasons were compared with available meteorological records for Dokriani Meteorological Station (Dingad Valley, Garhwal Himalayas) and Pyramid Meteorological Station (Khumbu Valley, Nepal Himalayas). The magnitude and distribution of temperature were found to be similar for different Himalayan regions, while rainfall varied from region to region. The influence of the monsoon was meagre on the rainfall in these areas. July was recorded to be the warmest month for all the regions and, in general, August had the maximum rainfall. For all the stations, daytime up-valley wind speeds were 3 to 4 times stronger than the nighttime down-valley wind speeds. It was found that the Gangotri Glacier area experienced relatively low humidity and high evaporation rates as compared to other parts of the Himalayas. Such analysis reveals the broad meteorological characteristics of the high altitude areas of the Central Himalayan region.

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