Influence of shelter on night temperatures, frost damage, and bud break of white spruce seedlings

1996 ◽  
Vol 26 (9) ◽  
pp. 1531-1538 ◽  
Author(s):  
Arthur Groot ◽  
Derek W. Carlson
Keyword(s):  
Air Temperature ◽  
White Spruce ◽  
Frost Damage ◽  
Wave Radiation ◽  
View Factor ◽  
Bud Break ◽  
Long Wave ◽  
Forest Openings ◽  
Long Wave Radiation ◽  
Minimum Air Temperature

Measurements of frost damage and bud-break phenology were made during the spring of 1993 and 1994 on planted white spruce (Piceaglauca (Moench) Voss) seedlings and on trembling aspen (Populustremuloides Michx.) suckers in combination with measurements of minimum air temperature and long-wave radiation in forest openings of different sizes and configurations (1.5-ha clearcut, 9 and 18 m wide strips, 9 and 18 m diameter circular openings and intact forest) near Chapleau, Ontario. The average minimum air temperature during early summer (May–June) decreased linearly as the sky view factor of the forest openings increased. The average difference in minimum air temperature between the forest and clearcut opening was nearly 3 °C for the period, and during clear night sky conditions, this temperature difference approached 6 °C. The difference in minimum temperature between the forest and clearcut during cloudy night sky conditions was slightly greater than 1 °C. Differences in minimum air temperature between the forest and each of the openings increased with decreasing incoming long-wave radiation. The largest differences occurred between the forest and the clearcut with low incoming long-wave radiation (cloudless nights). Minimum air temperatures in the 9-m strip and 9-m circle differed little from minimums in the forest under all long-wave radiation regimes. Moderation of air temperature on clear nights would be best achieved with sky view factors of less than 0.3, implying a maximum strip width of 0.6 tree heights and a maximum patch diameter of 2.2 tree heights. Damage to white spruce seedlings after a frost in the spring of 1993 increased with increasing sky view factor. Nearly 75% of the seedlings in the clear-cut had medium or heavy frost damage, while only 2% of the seedlings in the 9-m circle and forest were frost damaged. Opening size and configuration had little influence on the timing of bud break in either the white spruce seedlings or the trembling aspen suckers.

Micro-Meteorological Conditions for Snow Melt

1987 ◽  
Vol 33 (113) ◽  
pp. 24-26 ◽  
Author(s):  
M. Kuhn
Keyword(s):  
Boundary Layer ◽  
Transfer Coefficient ◽  
Air Temperature ◽  
Short Wave ◽  
Wave Radiation ◽  
Free Atmosphere ◽  
Alpine Glacier ◽  
Long Wave ◽  
Air Temperatures ◽  
Long Wave Radiation

AbstractThe energy budget of a snow or ice surface is determined by atmospheric variables like solar and atmospheric long-wave radiation, air temperature, and humidity; the transfer of energy from the free atmosphere to the surface depends on the stability of the atmospheric boundary layer, where vertical profiles of wind speed and temperature determine stability, and on surface conditions like surface temperature (and thus surface humidity), roughness, and albedo.This paper investigates the conditions exactly at the onset or the end of melting using air temperature, humidity, and as the radiation term the sum of global and reflected short-wave plus downward long-wave radiation. For the turbulent exchange in the boundary layer, examples are computed with a transfer coefficient of 18.5 W m−2K−1which corresponds to the average over the ablation period on an Alpine glacier. Ways to estimate the transfer coefficient for various degrees of stability are indicated in the Appendix.It appears from such calculations that snow may melt at air temperatures as low as –10°C and may stay frozen at +10°C.

The Meteorological Impact to the Air Temperature on a Sub-Tropical City

2014 ◽  
Vol 905 ◽  
pp. 374-378
Author(s):  
Chih Hong Huang ◽  
John Cua Aganda
Keyword(s):  
Air Temperature ◽  
Minimum Temperature ◽  
Wave Radiation ◽  
Urban Air ◽  
Temperature Pattern ◽  
Long Wave ◽  
The Difference ◽  
Meteorological Impact ◽  
The City ◽  
Long Wave Radiation

This study will center on the meteorological impact of clouds and its influence to the urban air temperature. Quantitative assessment over the behavior and temperature pattern was done using a five-year data of meteorological parameters obtain from the local weather and climate bureau. Urban heat island (UHI) is defined as the increased air temperature of the city over its surrounding sub-urban and rural areas and in this case of a five-year summer period of Taipei, Taiwan were heat temperatures are higher and can go beyond 39°C, acting dominant meteorological cloud cover factor is observe for its effect in temperature pattern. Analysis of local heat characteristics suggests the possibility of the believed theory Urban-scaled greenhouse effect that maybe affecting the patterns of the urban air temperature. An urban-scaled greenhouse effect is a theory that implies; when dense cloud covers the city, most of the supposed released long wave radiation or heat energy is trapped and reflected back by the dense clouds, creating a body of conserved heat that is prolonged in the area. The duration of conserved heat (DCH) is measured by the difference of the diurnal maximum and minimum temperature. To assess the value of the theory the daily cloud amount (CA) and its relationship with the DCH was tested with regression analysis. Calm days with the complete cycle of maximum and minimum temperature accordingly were selected and tested. The five-year average (2008 – 2012) resulted in a regression value of R2 = 0.072. Although the years 2011 & 2012 showed a higher regression value of R2 = 0.265 and R2 = 0.104 respectively, certainly enough the data of years 2011 and 2012 revealed a higher ratio of days with less combination of high wind speed and rainfall which created less fluctuations. Trend pattern for the five summers showed similarities. Some days showed fluctuation but no negative trend of correlation was detected. The heat intensity (HI) is another type of temperature pattern that was observed against CA and DCH, it is characterized by the difference of maximum and minimum diurnal temperature. Suggestive with our analysis, all five-year summertime data of HI showed negative correlation with the CA and DCH, attesting a faster release of long wave radiation when clouds are less.

scholarly journals Micro-Meteorological Conditions for Snow Melt

1987 ◽  
Vol 33 (113) ◽  
pp. 24-26 ◽  
Author(s):  
M. Kuhn
Keyword(s):  
Boundary Layer ◽  
Transfer Coefficient ◽  
Air Temperature ◽  
Short Wave ◽  
Wave Radiation ◽  
Free Atmosphere ◽  
Alpine Glacier ◽  
Long Wave ◽  
Air Temperatures ◽  
Long Wave Radiation

AbstractThe energy budget of a snow or ice surface is determined by atmospheric variables like solar and atmospheric long-wave radiation, air temperature, and humidity; the transfer of energy from the free atmosphere to the surface depends on the stability of the atmospheric boundary layer, where vertical profiles of wind speed and temperature determine stability, and on surface conditions like surface temperature (and thus surface humidity), roughness, and albedo.This paper investigates the conditions exactly at the onset or the end of melting using air temperature, humidity, and as the radiation term the sum of global and reflected short-wave plus downward long-wave radiation. For the turbulent exchange in the boundary layer, examples are computed with a transfer coefficient of 18.5 W m−2 K−1 which corresponds to the average over the ablation period on an Alpine glacier. Ways to estimate the transfer coefficient for various degrees of stability are indicated in the Appendix.It appears from such calculations that snow may melt at air temperatures as low as –10°C and may stay frozen at +10°C.

Performance Characteristics of Sanborn Rod Thermistors

1952 ◽  
Vol 33 (2) ◽  
pp. 67-72 ◽  
Author(s):  
Raymond C. Staley
Keyword(s):  
Air Temperature ◽  
Temperature Compensation ◽  
Performance Characteristics ◽  
Wave Radiation ◽  
Long Wave ◽  
Accuracy Of Measurement ◽  
Long Wave Radiation

One type of Sanborn rod thermistor is studied with respect to the accuracy of measurement of air temperature. Compensation techniques are reviewed and inaccuracies, uncertainties, and lag coefficients are evaluated. Shielding of thermistors from solar and long-wave radiation is examined. With yearly calibration and proper shielding, temperatures may be measured with an accuracy of at least 0.4C°.

scholarly journals Spatiotemporal Patterns and Trends of Precipitation and Their Correlations with Related Meteorological Factors by Two Sets of Reanalysis Data in China

2018 ◽  
Author(s):  
Jinhui Jeanne Huang ◽  
Nan Zhang ◽  
Gyewoon Choi ◽  
Edward Arthur McBean ◽  
Qian Zhang
Keyword(s):  
Tibetan Plateau ◽  
Latent Heat ◽  
Air Temperature ◽  
Surface Pressure ◽  
Strong Correlation ◽  
Meteorological Factors ◽  
Wave Radiation ◽  
Monsoon Region ◽  
Long Wave ◽  
Long Wave Radiation

Abstract. This paper investigates the spatial-temporal characteristics of the changes in precipitation for China and the influence of other meteorological factors on precipitation. Two reanalysis datasets at monthly scale, namely, the GLDAS2 phase 2 forcing data 0.5 × 0.5 (1948 ~ 2008) and National Centers for Environmental Prediction (NCEP) data were employed. The Mann-Kendall trend test identified the annual and seasonal changes in four meteorological factors for precipitation, air temperature, long wave radiation and surface pressure. Confidence levels of 95 % were taken as thresholds to classify the significance of positive and negative trends. The trend analysis was conducted in three storm zones (I-Eastern Monsoon Region, II-Northern Inland Region and III-Qinghai-Tibetan Plateau Region) specified by Wang (2002). The findings indicate: 1) Air temperature, specific humidity and downward long wave radiation, have strong correlation with precipitation, especially for the eastern monsoon region of China; while surface pressure has very weak correlation with precipitation. 2) Latent heat shows very strong correlation with precipitation throughout China except for a small, extremely arid area in north China where large portions of the area are deserts. 3) The correlation between the volumetric soil moisture with precipitation and latent heat are controlled by precipitation with the characteristics of high annual precipitation and high correlations. 4) For precipitation, an increasing tendency in precipitation for the southeastern monsoon region and a decreasing tendency for the northeastern monsoon region (the drier region) were observed. 5) Strong increasing tendencies for air temperature and downward long wave radiation, were observed in the northeastern monsoon region and the western area of Qinghai-Tibetan Plateau. 6) Due to changes in precipitation and air temperature and downward long wave radiation, the scarcity of water resources in northeastern monsoon region and flooding problems in southeastern monsoon region may become more severe. 7) The study shows that agricultural development in China may require a shift between northern and western areas to adapt to the shift in precipitation patterns.

scholarly journals Spring Frost Damage to Tea Plants Can Be Identified with Daily Minimum Air Temperatures Estimated by MODIS Land Surface Temperature Products

2021 ◽  
Vol 13 (6) ◽  
pp. 1177
Author(s):  
Peijuan Wang ◽  
Yuping Ma ◽  
Junxian Tang ◽  
Dingrong Wu ◽  
Hui Chen ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Frost Damage ◽  
Estimation Model ◽  
Spring Frost ◽  
Tea Plants ◽  
Elevation Model ◽  
Minimum Air Temperature

Tea (Camellia sinensis) is one of the most dominant economic plants in China and plays an important role in agricultural economic benefits. Spring tea is the most popular drink due to Chinese drinking habits. Although the global temperature is generally warming, spring frost damage (SFD) to tea plants still occurs from time to time, and severely restricts the production and quality of spring tea. Therefore, monitoring and evaluating the impact of SFD to tea plants in a timely and precise manner is a significant and urgent task for scientists and tea producers in China. The region designated as the Middle and Lower Reaches of the Yangtze River (MLRYR) in China is a major tea plantation area producing small tea leaves and low shrubs. This region was selected to study SFD to tea plants using meteorological observations and remotely sensed products. Comparative analysis between minimum air temperature (Tmin) and two MODIS nighttime land surface temperature (LST) products at six pixel-window scales was used to determine the best suitable product and spatial scale. Results showed that the LST nighttime product derived from MYD11A1 data at the 3 × 3 pixel window resolution was the best proxy for daily minimum air temperature. A Tmin estimation model was established using this dataset and digital elevation model (DEM) data, employing the standard lapse rate of air temperature with elevation. Model validation with 145,210 ground-based Tmin observations showed that the accuracy of estimated Tmin was acceptable with a relatively high coefficient of determination (R2 = 0.841), low root mean square error (RMSE = 2.15 °C) and mean absolute error (MAE = 1.66 °C), and reasonable normalized RMSE (NRMSE = 25.4%) and Nash–Sutcliffe model efficiency (EF = 0.12), with significantly improved consistency of LST and Tmin estimation. Based on the Tmin estimation model, three major cooling episodes recorded in the "Yearbook of Meteorological Disasters in China" in spring 2006 were accurately identified, and several highlighted regions in the first two cooling episodes were also precisely captured. This study confirmed that estimating Tmin based on MYD11A1 nighttime products and DEM is a useful method for monitoring and evaluating SFD to tea plants in the MLRYR. Furthermore, this method precisely identified the spatial characteristics and distribution of SFD and will therefore be helpful for taking effective preventative measures to mitigate the economic losses resulting from frost damage.

scholarly journals The Influence of Cloudiness on The Net Radiation Balance of A Snow Surface with High Albedo

1974 ◽  
Vol 13 (67) ◽  
pp. 73-84 ◽  
Author(s):  
W. Ambach
Keyword(s):  
Greenland Ice Sheet ◽  
Short Wave ◽  
Mean Value ◽  
Wave Radiation ◽  
Radiation Balance ◽  
Net Radiation ◽  
Long Wave ◽  
Energy Excess ◽  
Overcast Sky ◽  
Long Wave Radiation

The short-wave and long-wave radiant fluxes measured in the accumulation area of the Greenland ice sheet during a mid-summer period are discussed with respect to their dependence on cloudiness. At a cloudiness of 10/10, a mean value of 270 J/cm2 d is obtained for the daily totals of net radiation balance, whereas a mean value of only 75 J/cm2 d is observed at 0/10. The energy excess of the net radiation balance with overcast sky is due to the significant influence of the incoming long-wave radiation and the high albedo of the surface (average of 84%). High values of net radiation balance are therefore correlated with high values of long-wave radiation balance and low values of short-wave radiation balance.

scholarly journals Prediction of Radiation Frost Using Support Vector Machines Based on Micrometeorological Data

2019 ◽  
Vol 10 (1) ◽  
pp. 283
Author(s):  
Yongzong Lu ◽  
Yongguang Hu ◽  
Pingping Li ◽  
Kyaw Tha Paw U ◽  
Richard L. Snyder
Keyword(s):  
Yangtze River ◽  
Prediction Accuracy ◽  
Short Wave ◽  
Yangtze River Delta ◽  
Wave Radiation ◽  
Support Vector ◽  
Short Wave Radiation ◽  
Long Wave ◽  
Vector Machines ◽  
Long Wave Radiation

Radiation frost happens frequently in the Yangtze River Delta region, which causes high economic loss in agriculture industry. It occurs because of heat losses from the atmosphere, plant and soil in the form of radiant energy, which is strongly associated with the micrometeorological characteristics. Multidimensional and nonlinear micrometeorological data enhances the difficulty in predicting the radiation frost. Support vector machines (SVMs), a type of algorithms, can be supervised learning which widely be employed for classification or regression problems in research of precision agriculture. This paper is the first attempt of using SVMs to build prediction models for radiation frost. Thirty-two kinds of micrometeorological parameters, such as daily mean temperature at six heights (Tmean0.5, Tmean1.5, Tmean2.0, Tmean3.0, Tmean4.5 and Tmean6.0), daily maximum and minimum temperatures at six heights (Tmax0.5, Tmax1.5, Tmax2.0, Tmax3.0, Tmax4.5 and Tmax6.0, and Tmin0.5, Tmin1.5, Tmin2.0, Tmin3.0, Tmin4.5 and Tmin6.0), daily mean relative humidity at six heights (RH0.5, RH1.5, RH2.0, RH3.0, RH4.5 and RH6.0), net radiation (Rn), downward short-wave radiation (Rsd), downward long-wave radiation (Rld), upward long-wave radiation (Rlu), upward short-wave radiation (Rsu), soil temperature (Tsoil) and soil heat flux (G) and daily average wind speed (u) were collected from November 2016 to July 2018. Six combinations inputs were used as the basis dataset for testing and training. Three types of kernel functions, such as linear kernel, radial basis function kernel and polynomial kernel function were used to develop the SVMs models. Five-fold cross validation was conducted for model fitting on training dataset to alleviate over-fitting and make prediction results more reliable. The results showed that an SVM with the radial basis function kernel (SVM-BRF) model with all the 32 micrometeorological data obtained high prediction accuracy in training and testing sets. When the single type of data (temperature, humidity and radiation data) was used for the SVM without any functions, prediction accuracy was better than that with functions. The SVM-BRF model had the best prediction accuracy when using the multidimensional and nonlinear micrometeorological data. Considering the complexity level of the model and the accuracy of prediction, micrometeorological data at the canopy height with the SVM-BRF model has been recommended for radiation frost prediction in Yangtze River Delta and probably could be applied in elsewhere with the similar terrains and micro-climates.

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