Deep Freeze R6 Delayed

[Giorgio Aguilar]

Asidefrom the regular preventive measures that I used to give to tenants, ie., wrapping up outdoor faucets, dripping kitchen faucets, turning on ice-maker, setting thermostat to at least 70F, keeping cabinet doors open, etc., I am also thinking of asking them to turn on dishwasher before they go to sleep, setting it to 4-hour-delay start. I hope this will induce more water flow during midnight.

Turning the dishwasher on it shouldn't make a difference as long as they leave their kitchen tap run a little stream of water. This should keep the main service from freezing. Inside the house as long as you have a heater (which you said setting the thermostat to 70F) which is what I keep my house around at all winter. They will not freeze inside the house.

It has been -40 here for a couple weeks now. As long as you have a slow stream of water the lines should not freeze. I do live in Canada and most of our water and services lines are 8 feet or deeper outside however. I cannot attest to how or where your water and sewer services are ran inside or outside of your home and how much insulation is in your houses.

We have had to run garden hoses across lawns in the middle of winter to supply houses with water when their main services get frozen. As long as the water flows it should not freeze. DO NOT turn it off however.

Depending on the depth of your sewer lines and where they run you could possibly freeze them up. (Like I said ours are usually deep in the ground when they leave the basement of the house). A larger stream of water would prevent this but would use more water.

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Arctic sea ice is rapidly decreasing during the recent period of global warming. One of the significant factors of the Arctic sea ice loss is oceanic heat transport from lower latitudes. For months of sea ice formation, the variations in the sea surface temperature over the Pacific Arctic region were highly correlated with the Pacific Decadal Oscillation (PDO). However, the seasonal sea surface temperatures recorded their highest values in autumn 2018 when the PDO index was neutral. It is shown that the anomalous warm seawater was a rapid ocean response to the southerly winds associated with episodic atmospheric blocking over the Bering Sea in September 2018. This warm seawater was directly observed by the R/V Mirai Arctic Expedition in November 2018 to significantly delay the southward sea ice advance. If the atmospheric blocking forms during the PDO positive phase in the future, the annual maximum Arctic sea ice extent could be dramatically reduced.

Near-surface Arctic air temperatures have warmed faster than the global average by a factor of two or more in recent decades, which is a robust phenomenon known as Arctic amplification1,2,3. Global consequences of the rapid Arctic warming are anticipated because Arctic warming influences the general atmospheric and oceanic circulations and extreme weather events at mid-latitudes2,4,5,6,7. Despite the remarkable signal of Arctic warming, understanding of its mechanisms remains incomplete4. The recent rapid reduction of the Arctic sea ice extent is also concerning because of the wide-ranging impacts such as changes in the air-sea interactions8,9,10. Their adverse effects on marine mammals and other species that depend on the presence of sea ice for their survival were also reported11,12.

This study focuses on the Pacific water inflow to the Arctic Ocean in relation to the Arctic sea ice advance. The area of interest is the Chukchi Sea where significant seawater warming trends, reductions of the seasonal sea ice cover, and high primary production including massive phytoplankton blooms under the sea ice were previously reported15,35,36,37,38,39,40,41,42. The sea ice covered period over the Chukchi Sea was recently found to be highly correlated with the oceanic heat inflow from the Pacific Ocean through the Bering Strait43,44. The heat transport through the Bering Strait is highly variable and complex as it depends on both the volume transport and the Pacific water temperature45. The volume transport depends on local winds in the Bering Strait and pressure head difference between the Arctic and the Pacific Ocean. A recent study found that the pressure difference is largely driven from the Arctic side, specifically by the zonal winds in the East Siberian Sea46. Serreze et al.45 conducted case studies for selected months and demonstrated that each factor above contributes to the Bering Strait heat inflow.

The present study uses various types of information to comprehensively evaluate the interannual variation of the Pacific Arctic Ocean for months of sea ice formation. The possible factors and consequences associated with the highest sea surface temperature (SST) in autumn 2018 are next investigated in detail. Satellite observations of SST made by the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) and the Advanced Microwave Scanning Radiometer 2 (AMSR2) since 2002 (hereafter abbreviated as AMSR) were used to analyze the interannual variation of the Pacific Arctic SST. Atmospheric reanalysis data from ERA547 since 1979 was then used to investigate causal factors of positive SST anomalies in autumn 2018. Direct observations near the marginal ice zone (MIZ) in the Chukchi Sea during the R/V Mirai Arctic Expedition were then combined with the other types of information to show that the warm seawater delayed the sea ice advance.

Sea ice normally freezes up in November over the Chukchi Sea, but in 2018, the seawater was anomalously warm and there was less sea ice (Fig. 1). Based on satellite measurements of SST between 2002 and 2018, the November monthly SST over the Chukchi and Bering seas were their highest recorded values in 2018. Most of seawater in the Chukchi Sea originates from the Pacific Ocean, so the significant factors associated with the interannual variations of the Pacific Ocean were investigated. The November monthly SSTs varied to some extent in phase with the Pacific Decadal Oscillation (PDO) (Fig. 2). For both the Chukchi and the Bering seas, the correlation coefficients between the November monthly SST and annual PDO index were approximately 0.7 with the p-values less than 0.05 (Fig. 2b). The PDO index represents the large-scale and long-term SST variation in the North Pacific, and its positive phase corresponds to the warming in the study area48,49. However, the PDO is unlikely to be the cause of the exceptionally high SST in November 2018, because the PDO index was close to zero in 2018. The correlation coefficient between the PDO and SST becomes even higher if 2018 is removed (Fig. 2b), which indicates the high monthly SST in November 2018 was likely caused by other factors.

Interannual variation of November SST in the Chukchi and Bering seas and their relationships with the PDO. (a) November SST in the Chukchi (blue) and Bering (red) seas from AMSR satellite measurements. The black circles show the values for 2018. The SST values were spatially averaged over the areas as defined in Fig. 1b. The data in 2011 are missing because neither AMSR-E nor AMSR2 operated from September 2011 to October 2012. (b) November SST values plotted with the corresponding annual mean PDO index values of each year. The solid lines show the linear regression with the r2 values. The values in parenthesis are the cases excluding 2018.

AMSR satellite measurements captured rare monthly SST conditions in the Chukchi and Bering seas in 2018 (Fig. 3). The monthly SST values were almost unchanged from August to September in 2018, although the historical SST values usually decrease by several degrees during that time of the year (Fig. 3). The stable temperature was also recorded by an Argo float that was operating in the central Chukchi Sea at that time in 2018 (Supplementary Fig. 1). Previous studies indicated that the Pacific water takes at least three months to travel from the Bering Strait to the mouth of the Barrow canyon.50,51 This indicates that the warm Chukchi Sea observed in November 2018 can be linked to the high seawater temperatures that were present in September 2018.

Interannual variation of the monthly sea surface temperature over the Pacific Arctic region for August to November. Panel (a) is for the Chukchi Sea, and (b) is for the Bering Sea. The black circles indicate the 2018 values. The areas for the spatial average of the Chukchi and Bering seas are shown in Fig. 1b.

A possible relation between the atmospheric blocking high system over the Bering Sea and the PDO was also investigated. We calculated the point correlations between the monthly z500 and PDO and found the maximum value was at most 0.42 (Supplementary Fig. 2). In addition, the spatial distribution would not explain the southerly wind pattern near the Bering Strait in September 2018. These results are consistent with the previous study that reported the Alaskan blocking is not in phase with PDO52. It is reasonable to think that the atmospheric blocking high system formed independently from the PDO.

The anomalous warm and open Chukchi Sea in late autumn 2018 was studied in the context of interannual variation using a variety of data. We found that seawater temperature in the Chukchi Sea in the sea ice freezing season was highly correlated with the PDO index in the last two decades. However, the highest autumn seasonal values of SST in the Chukchi Sea were recorded in 2018 when the PDO index was close to zero. The primary factor causing the anomalous warm conditions in the Chukchi Sea was found to be the episodic blocking high pressure system over the Bering Sea in September 2018. The blocking high caused an unusual near-surface southerly wind pattern near the Bering Strait. As a result, warm Pacific seawater intruded into the Chukchi Sea in September 2018 and subsequently delayed sea ice advance in November 2018.

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