scholarly journals How Cold Can You Go? Frost and Winter Protection for Grape

HortScience ◽  
2008 ◽  
Vol 43 (7) ◽  
pp. 1966-1969 ◽  
Author(s):  
Joan R. Davenport ◽  
Markus Keller ◽  
Lynn J. Mills
Keyword(s):  
Snow Cover ◽  
Pacific Northwest ◽  
Site Selection ◽  
Growing Season ◽  
Recent Past ◽  
Warm Climate ◽  
Subzero Temperatures ◽  
Cold Events ◽  
Frost Protection

Although the inland Pacific Northwest has a warm climate during the growing season, grapes grown in this region may be exposed to colder than optimal temperatures at several times during the year. In addition to damage from spring and fall frosts, intermittent winters with little to no snow cover and subzero temperatures can cause vine dieback and death. Temperature patterns in the recent past indicate that both fall and midwinter are times when risk of bud damage from cold events is probable, making proper site selection and cultivar choice critical. Water is not used for frost protection in this climate, but wind machines have proven to be useful. In frost-prone sites, annual sucker growth with cane burying is practiced as an insurance strategy. Modifying pruning strategies has not been shown to be advantageous after fall cold events. If rootstocks are used, research has shown greater scion survival with higher graft positions.

scholarly journals Understanding Land-Atmosphere-Climate Coupling from the Canadian Prairie Dataset

2018 ◽  
Author(s):  
Alan K Betts ◽  
Raymond L Desjardins
Keyword(s):  
Snow Cover ◽  
Diurnal Cycle ◽  
Radiative Forcing ◽  
Potential Temperature ◽  
Warm Season ◽  
Growing Season ◽  
Cold Season ◽  
Maximum Temperature ◽  
Canadian Prairie ◽  
Cloud Forcing

Analysis of the hourly Canadian Prairie data for the past 60 years has transformed our quantitative understanding of land-atmosphere-cloud coupling. The key reason is that trained observers made hourly estimates of opaque cloud fraction that obscures the sun, moon or stars, following the same protocol for 60 years at all stations. These 24 daily estimates of opaque cloud data are of sufficient quality that they can be calibrated against Baseline Surface Radiation Network data to give the climatology of the daily short-wave, longwave and total cloud forcing (SWCF, LWCF and CF). This key radiative forcing has not been available previously for climate datasets. Net cloud radiative forcing reverses sign from negative in the warm season to positive in the cold season, when reflective snow reduces the negative SWCF below the positive LWCF. This in turn leads to a large climate discontinuity with snow cover, with a systematic cooling of 10°C or more with snow cover. In addition, snow cover transforms the coupling between cloud cover and the diurnal range of temperature. In the warm season, maximum temperature increases with decreasing cloud, while minimum temperature barely changes; while in the cold season with snow cover, maximum temperature decreases with decreasing cloud and minimum temperature decreases even more. In the warm season, the diurnal ranges of temperature, relative humidity, equivalent potential temperature and the pressure height of the lifting condensation level are all tightly coupled to opaque cloud cover. Given over 600 station-years of hourly data, we are able to extract, perhaps for the first time, the coupling between cloud forcing and the warm season imbalance of the diurnal cycle; which changes monotonically from a warming and drying under clear skies to a cooling and moistening under cloudy skies with precipitation. Because we have the daily cloud radiative forci, which is large, we are able to show that the memory of water storage anomalies, from precipitation and the snowpack, goes back many months. The spring climatology shows the memory of snowfall back through the entire winter, and the memory in summer goes back to the months of snowmelt. Lagged precipitation anomalies modify the thermodynamic coupling of the diurnal cycle to the cloud forcing, and shift the diurnal cycle of mixing ratio which has a double peak. The seasonal extraction of the surface total water storage is a large damping of the interannual variability of precipitation anomalies in the growing season. The large land-use change from summer fallow to intensive cropping, which peaked in the early 1990s, has led to a coupled climate response that has cooled and moistened the growing season, lowering cloud-base, increasing equivalent potential temperature, and increasing precipitation. We show a simplified energy balance of the Prairies during the growing season and its dependence on reflective cloud.

scholarly journals Understanding Land–Atmosphere–Climate Coupling from the Canadian Prairie Dataset

Environments ◽  
2018 ◽  
Vol 5 (12) ◽  
pp. 129 ◽  
Author(s):  
Alan Betts ◽  
Raymond Desjardins
Keyword(s):  
Snow Cover ◽  
Diurnal Cycle ◽  
Radiative Forcing ◽  
Potential Temperature ◽  
Warm Season ◽  
Growing Season ◽  
Cold Season ◽  
Maximum Temperature ◽  
Canadian Prairie ◽  
Cloud Forcing

Analysis of the hourly Canadian Prairie data for the past 60 years has transformed our quantitative understanding of land–atmosphere–cloud coupling. The key reason is that trained observers made hourly estimates of the opaque cloud fraction that obscures the sun, moon, or stars, following the same protocol for 60 years at all stations. These 24 daily estimates of opaque cloud data are of sufficient quality such that they can be calibrated against Baseline Surface Radiation Network data to yield the climatology of the daily short-wave, long-wave, and total cloud forcing (SWCF, LWCF and CF, respectively). This key radiative forcing has not been available previously for climate datasets. Net cloud radiative forcing changes sign from negative in the warm season, to positive in the cold season, when reflective snow reduces the negative SWCF below the positive LWCF. This in turn leads to a large climate discontinuity with snow cover, with a systematic cooling of 10 °C or more with snow cover. In addition, snow cover transforms the coupling between cloud cover and the diurnal range of temperature. In the warm season, maximum temperature increases with decreasing cloud, while minimum temperature barely changes; while in the cold season with snow cover, maximum temperature decreases with decreasing cloud, and minimum temperature decreases even more. In the warm season, the diurnal ranges of temperature, relative humidity, equivalent potential temperature, and the pressure height of the lifting condensation level are all tightly coupled to the opaque cloud cover. Given over 600 station-years of hourly data, we are able to extract, perhaps for the first time, the coupling between the cloud forcing and the warm season imbalance of the diurnal cycle, which changes monotonically from a warming and drying under clear skies to a cooling and moistening under cloudy skies with precipitation. Because we have the daily cloud radiative forcing, which is large, we are able to show that the memory of water storage anomalies, from precipitation and the snowpack, goes back many months. The spring climatology shows the memory of snowfall back through the entire winter, and the memory in summer, goes back to the months of snowmelt. Lagged precipitation anomalies modify the thermodynamic coupling of the diurnal cycle to the cloud forcing, and shift the diurnal cycle of the mixing ratio, which has a double peak. The seasonal extraction of the surface total water storage is a large damping of the interannual variability of precipitation anomalies in the growing season. The large land-use change from summer fallow to intensive cropping, which peaked in the early 1990s, has led to a coupled climate response that has cooled and moistened the growing season, lowering cloud-base, increasing equivalent potential temperature, and increasing precipitation. We show a simplified energy balance of the Prairies during the growing season, and its dependence on reflective cloud.

Mapping “At Risk” Snow in the Pacific Northwest

2006 ◽  
Vol 7 (5) ◽  
pp. 1164-1171 ◽  
Author(s):  
Anne W. Nolin ◽  
Christopher Daly
Keyword(s):  
At Risk ◽  
Snow Cover ◽  
Pacific Northwest ◽  
Climate Warming ◽  
The United States ◽  
Cold Climate ◽  
Temperature Threshold ◽  
Precipitation Regime ◽  
The Pacific ◽  
Northwest Region

Abstract One of the most visible and widely felt impacts of climate warming is the change (mostly loss) of low-elevation snow cover in the midlatitudes. Snow cover that accumulates at temperatures close to the ice-water phase transition is at greater risk to climate warming than cold climate snowpacks because it affects both precipitation phase and ablation rates. This study maps areas in the Pacific Northwest region of the United States that are potentially at risk of converting from a snow-dominated to a rain-dominated winter precipitation regime, under a climate-warming scenario. A data-driven, climatological approach of snow cover classification is used to reveal these “at risk” snow zones and also to examine the relative frequency of warm winters for the region. For a rain versus snow temperature threshold of 0°C the at-risk snow class covers an area of about 9200 km2 in the Pacific Northwest region and represents approximately 6.5 km3 of water. Many areas of the Pacific Northwest would see an increase in the number of warm winters, but the impacts would likely be concentrated in the Cascade and Olympic Ranges. A number of lower-elevation ski areas could experience negative impacts because of the shift from winter snows to winter rains. The results of this study point to the potential for using existing datasets to better understand the potential impacts of climate warming.

scholarly journals Schrenk spruce leaf litter decomposition varies with snow depth in the Tianshan Mountains

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Lu Gong ◽  
Xin Chen ◽  
Xueni Zhang ◽  
Xiaodong Yang ◽  
Yanjiang Cai
Keyword(s):  
Soil Properties ◽  
Snow Cover ◽  
Litter Decomposition ◽  
Growing Season ◽  
Temporal Variations ◽  
Tianshan Mountains ◽  
Cover Depth ◽  
C And N ◽  
Thaw Period ◽  
Snow Cover Depth

Abstract Seasonal snowfall, a sensitive climate factor and the main form of precipitation in arid areas, is important for forest material circulation and surface processes and profoundly impacts litter decomposition and element turnover. However, how the thickness and duration of snow cover affect litter decomposition and element release remain unclear. Thus, to understand the effects of snow on litter decomposition, fiber degradation and their relationships with soil properties, a field litterbag experiment was conducted under no, thin, medium, and thick snow cover in a Schrenk spruce (Picea schrenkiana) forest gap in the Tianshan Mountains. The snow cover period exhibited markedly lower rates of decomposition than the snow-free period. The litter lignin, cellulose and N concentrations in the pregrowing season and middle growing season were significantly higher than those in the deep-freeze period, and the litter C and P concentrations were significantly higher during the onset of the freeze–thaw period, deep-freeze period and thaw period than in the late growing season. The litter cellulose, C and N concentrations were significantly higher under thick snow cover than under no snow cover in most stages. Moreover, the correlations among litter mass, cellulose, lignin/cellulose and soil bulk density varied with snow cover depth. The temporal variations and snow cover depth affected the decomposition process significantly. The former affected lignin, cellulose and P, and the latter affected cellulose, C and N and changed the litter-soil properties relationship. These differences provide references for understanding how winter conditions affect material cycling and other ecological processes under climate change.

scholarly journals Florida Subtropical Peaches: Production Practices

EDIS ◽  
2013 ◽  
Vol 2013 (8) ◽  
Author(s):  
Mercy Olmstead ◽  
Jose Chaparro ◽  
Jeffrey G. Williamson ◽  
Robert Rouse ◽  
Russell Mizell ◽  
...  
Keyword(s):  
Site Selection ◽  
Growing Season ◽  
Subtropical Climate ◽  
Insect Management ◽  
Fact Sheet ◽  
Production Practices ◽  
Recommended Practices

Subtropical peach production includes many practices, such as site selection, orchard design, and disease, weed, and insect management through to harvest. Florida’s subtropical climate allows growers to harvest their crops early, but it creates challenges for the long postharvest growing season. This 14-page fact sheet covers the breadth of topics related to subtropical peach production, including a monthly timeline of recommended practices. Written by M. Olmstead, J. Chaparro, J. G. Williamson, R. Rouse, R. Mizell, P. Harmon, and J. Ferguson, and published by the UF Department of Horticultural Sciences, August 2013. http://edis.ifas.ufl.edu/hs348

scholarly journals Loss of Total Phenol in Two Shrub Leaf Litter Species: The Dual Role of Alpine Forest Gap Disturbance

2019 ◽  
Author(s):  
Wei He ◽  
Wanqin Yang
Keyword(s):  
Snow Cover ◽  
Growing Season ◽  
Dual Role ◽  
Total Phenol ◽  
First Year ◽  
Forest Gap ◽  
Cover Depth ◽  
Forest Gaps ◽  
Alpine Forest ◽  
Snow Cover Depth

Alpine forest gaps can distribute snowfall, solar radiation and rainfall, thus inducing a heterogeneous hydrothermal microenvironment between the inside and outside areas of forest gaps. Additionally, the characteristics of the heterogeneous microenvironment could vary greatly across the gap location properties during winter and the growing season. To determine the response of total phenol loss (TPL) from the litter to alpine forest gap disturbance during decomposition, we conducted a field litterbag experiment within a representative fir (Abies faxoniana Rehd.) forest based on the gap location properties. The TPL and abundances of fungi and bacteria from two typical shrub species (willow, Salix paraplesia Schneid., and bamboo, Fargesia nitida (Mitford) Keng f.) were measured during the following periods over two years: snow formation (SF), snow cover (SC) snow melting (ST), the early growing season (EG) and the later growing season (LG). At the end of the study, we found that the snow cover depth, frequencies of the freeze-thaw cycle and the fungal copy g-1 to bacterial copy g-1 ratio had significant effects on the litter TPL. The abundances of fungi and bacteria decreased from the gap center to the closed canopy during the two SF, SC, ST and LG periods and reversed during the two EG periods. The TPL closely followed the same trend as the microbial abundance during the first year of incubation. In addition, both species had larger TPLs in the gap center during the first winter, first year and entire two years. These findings suggest that alpine forest gap formation accelerates litter TPL and plays a dual role during specific critical periods by distributing abiotic and biotic factors directly and indirectly. In conclusion, reduced snow cover depth and duration during winter warming under current climate change scenarios or as gaps vanish may slow litter TPL in alpine biomes.

scholarly journals Convergent evolution of seasonal camouflage in response to reduced snow cover across the snowshoe hare range

2019 ◽  
Author(s):  
Matthew R. Jones ◽  
L. Scott Mills ◽  
Jeffrey D. Jensen ◽  
Jeffrey M. Good
Keyword(s):  
Gene Flow ◽  
Snow Cover ◽  
Pacific Northwest ◽  
Deep Structure ◽  
Low Frequency ◽  
Masking Effect ◽  
Snowshoe Hare ◽  
Changing Environments ◽  
Range Edge ◽  
History Of

AbstractDetermining how different populations adapt to similar environments is fundamental to understanding the limits of adaptation under changing environments. Snowshoe hares (Lepus americanus) typically molt into white winter coats to remain camouflaged against snow. In some warmer climates, hares have evolved brown winter camouflage – an adaptation that may spread under climate change. We used extensive range-wide genomic data to 1) resolve broad-scale patterns of population structure and gene flow and 2) investigate the factors shaping the origins and distribution of winter-brown camouflage variation. In coastal Pacific Northwest (PNW) populations, winter-brown camouflage is known to be determined by a recessive haplotype at the Agouti pigmentation gene. Our phylogeographic analyses revealed deep structure and limited gene flow between PNW and more northern Boreal populations, where winter-brown camouflage is rare along the range edge. Genome sequencing of a winter-brown snowshoe hare from Alaska shows that it lacks the winter-brown PNW haplotype, reflecting a history of convergent phenotypic evolution. However, the PNW haplotype does occur at low frequency in a winter-white population from Montana, consistent with the spread of a locally deleterious recessive variant that is masked from selection when rare. Simulations show that if annual snow cover dramatically declined in the same population, then the predicted selective increase in frequency of the now beneficial winter-brown Agouti allele is likely to be extremely slow due to the same masking effect. Our findings underscore how allelic dominance can shape the geographic extent and rate of convergent adaptation in response to rapidly changing environments.

scholarly journals Basics of Frost and Freeze Protection for Horticultural Crops

1998 ◽  
Vol 8 (1) ◽  
pp. 10-15 ◽  
Author(s):  
Katharine B. Perry
Keyword(s):  
Heat Transfer ◽  
Site Selection ◽  
Energy Exchange ◽  
Transfer Energy ◽  
Horticultural Crops ◽  
Frost Protection ◽  
Freeze Protection

Basic meteorology as it applies to frost-freeze events and a discussion of the methods of frost protection are included in this article. The presentation of basic meteorology includes descriptions of heat transfer, energy exchange, inversion, frost, freeze, microclimate, air versus crop temperature, and forecasts and warnings in the context of how each of these in involved in frost-freeze events. The second part of the paper describes the major methods of frost protection for commercial crops. The methods included are site selection, irrigation (overhead, undercanopy, man-made fog, flooding), wind machines, heaters, covers, and sprayable materials.

scholarly journals Impact of snow cover on CO<sub>2</sub> dynamics in Antarctic pack ice

2014 ◽  
Vol 8 (3) ◽  
pp. 3263-3295
Author(s):  
N.-X. Geilfus ◽  
J.-L. Tison ◽  
S. F. Ackley ◽  
S. Rysgaard ◽  
L. A. Miller ◽  
...  
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Dissolved Inorganic Carbon ◽  
Ice Cover ◽  
Snow Accumulation ◽  
Total Alkalinity ◽  
Partial Pressures ◽  
Pack Ice ◽  
Cold Events

Abstract. Temporal evolution of pCO2 profiles in sea ice in the Bellingshausen Sea, Antarctica, in October 2007 shows that the CO2 system in the ice was primarily controlled by physical and thermodynamic processes. During the survey, a succession of warming and cold events strongly influenced the physical, chemical and thermodynamic properties of the ice cover. Two sampling sites with contrasting characteristics of ice and snow thickness were sampled: one had little snow accumulation (from 8 to 25 cm) and larger temperature and salinity variations than the second site, where the snow cover was up to 38 cm thick and therefore better insulated the underlying sea ice. We confirm that each cooling/warming event was associated with an increase/decrease in the brine salinity, total alkalinity (TA), total dissolved inorganic carbon (TCO2), and in situ brine and bulk ice CO2 partial pressures (pCO2). Thicker snow covers muted these changes, suggesting that snow influences changes in the sea ice carbonate system through its impact on the temperature and salinity of the sea ice cover. During this survey, pCO2 was undersaturated with respect to the atmosphere both in situ, in the bulk ice (from 10 to 193 μatm), and in the brine (from 65 to 293 μatm), and the ice acted as a sink for atmospheric CO2 (up to 2.9 mmol m−2 d−1), despite the underlying supersaturated seawater (up to 462 μatm).

scholarly journals Analysis of viticulture region climate structure and suitability in New Zealand

OENO One ◽  
2012 ◽  
Vol 46 (3) ◽  
pp. 149 ◽  
Author(s):  
Jon D. Anderson ◽  
Gregory V. Jones ◽  
Andrew Tait ◽  
Andrew Hall ◽  
Michael C.T. Trought
Keyword(s):  
New Zealand ◽  
Growing Season ◽  
Climate Indices ◽  
Growing Degree Days ◽  
Methodological Issues ◽  
Warm Climate ◽  
Degree Days ◽  
Average Temperature ◽  
Climate Suitability ◽  
Two Indices

<p style="text-align: justify;"><strong>Aims</strong>: This research analyzes four climate indices derived from gridded, interpolated data to assess New Zealand’s climate structure and variation among wine regions.</p><p style="text-align: justify;"><strong>Methods and results</strong>: High resolution gridded data based on 1971-2000 climate normals was used to characterize climate indices depicting viticultural suitability in a geographic information system. The statistical properties of each index were assessed over 21 New Zealand viticulture regions. The results show predominately cool to moderately warm climate suitability in New Zealand, comparable to many European and United States regions. While many viticulture regions have one primary class of suitability, variability of climate within regions can be significant, with some regions containing two to four climate classes, making them suitable for a greater range of cultivars.</p><p style="text-align: justify;"><strong>Conclusion</strong>: While the indices depict broad patterns expected over New Zealand, both within and between region variations can be substantial among the indices. However, two indices, Growing Season Average Temperature (GST) and Growing Degree-Days (GDD), are functionally identical, but GST is easier to calculate and overcomes many methodological issues in GDD.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This research provides the basis for evaluating general suitability for viticulture in New Zealand, assists comparisons between viticulture regions in New Zealand and worldwide, and offers growers measures of assessing appropriate cultivars and sites.</p>

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