The Proceedings of the Eighth International Conference on Creationism (2018)

most intense precipitation. When the jet stream is strong (WO, AM and AP), the precipitation occurs primarily on the United States’ coast. There is also higher precipitation near the exit zones of the jet streaks. Since the jet’s exit zone is shifted further south and east in Figure 7f (AP), the precipitation maximum also occurs further south in Figure 8f. At first it is surprising that the precipitation in Figure 8e (AM) is weaker than in Figure 8f. However, with mid- latitude aerosols in the AM simulation, the surface temperature of the continent is colder than the AP simulation. As a result, there is a land/ocean thermal circulation that weakens the onshore surface winds. When a uniform aerosol layer is used, the jet stream weakens and is split. As a result, Figures 8c and d show precipitation maxima shifted northward to the coast of Canada. All of the warm ocean simulations show an increased precipitation rate over the Great Lakes region and north to Hudson Bay. There does not appear to be a pattern in the surface winds for this region, but the land/ocean temperature difference is smaller thus reducing the thermal circulation. The AP simulation, Figure 8f, shows the largest increase in Ontario, Canada with a precipitation rate of 4 mm/day. This is an order of magnitude less than the maximum precipitation rate recorded by Spelman (1996). To some extent this is an unfair comparison since Spelman’s maximum occurred over the Arctic Ocean. DISCUSSION Six simulations were compared to determine factors that influence the location of precipitation patterns needed to grow an ice sheet over the North American continent. It is clear that warmer oceans increase the precipitation rate in arctic regions, but this precipitation primarily falls on open water. The ice sheet over Greenland hinders precipitation over land due to a strong thermal circulation. This is lessened when it is removed. However, this illustrates the challenge of maintaining high precipitation rates over a continental ice sheet once it is formed. Uniformly distributed stratospheric aerosols offset the higher surface temperatures generated by warm oceans. However, a uniform equator to pole aerosol distribution reduces the north/ south temperature contrast and likewise reduces the strength of the jet stream. Aerosols restricted to the mid-latitudes or Polar Regions restore the temperature contrast and strength of the jet stream, but these two distributions have only a small impact on the location of the jet stream. In the Ferrel cell winds are westerlies. These winds along with a strong jet stream and a weak land/ocean thermal circulation result in strong precipitation along the western coast of the United States. This result is compatible with results reported by Vardiman and Brewer (2010a, b, c). In the North Atlantic the polar easterlies do not penetrate into Eastern Canada. There is a weak thermal circulation that keeps most of the precipitation over the ocean. Although the Icelandic low could potentially affect surface winds in North America, it is shifted east and has a more significant effect on Western Europe. Aerosols restricted to the Polar Regions have the largest impact on precipitation near the Great Lakes and southeast Canada; however, the rates are an order of magnitude smaller than desired for a rapid growth of an ice sheet. Because surface temperatures are higher due to the warm oceans, these simulations give marginal conditions for snowfall. Most likely it would be a mix of snow and rain. Since this is the heart of winter, precipitation the rest of the year would be rain. Although aerosol distribution has an effect on the jet stream, surface winds and precipitation; this is minor compared to the global circulation and land/ocean thermal circulations. If an ice sheet is to form, the most significant factor is surface temperature. A non-uniform aerosol distribution is preferable over a uniform distribution, but to control temperature it is necessary to consider even thicker aerosol layers. In addition, water temperature in the Arctic Ocean needs to be cooler to reduce the strength of the thermal circulation. This might make it possible for circulation in the polar cell to draw humid air into the Hudson Bay region. A longer simulation would allow considerable cooling of the Arctic Ocean and test this hypothesis. Future work needs to focus on reducing surface temperature in the presence of warm oceans. Thicker aerosol layers can be tried, but it appears that cooler surface temperatures in the Arctic Ocean are a reasonable next step. Since the GISS ModelE2 has a dynamic ocean, the next simulation should run for a century or more to study how the temperature profile of the ocean changes with time. Since the time constant for a deeply circulating ocean is about 40 years, this simulation should transition the ocean from a uniform temperature of 24 ˚C to a temperature distribution that is within 10% of modern day equilibrium values. Such a simulation would also reveal how circulation patterns shift with oceanic cooling. CONCLUSION The GISS ModelE2 was used to study the impact of aerosol location on precipitation patterns. Six simulations were compared to determine what factors might contribute to the development of an ice sheet over the North American continent. As seen in other studies, warmer oceans result in increased precipitation in arctic regions. However, this precipitation primarily falls on open water. Although aerosol distribution has an effect on precipitation patterns, this is minor compared to the global circulation and land/ ocean thermal circulations. Non-uniform aerosol distributions are advantageous for a strong jet stream since they maintain a larger temperature contrast between the equator and the North Pole. It is clear that a combination of thicker aerosol layers and a cooler Arctic Ocean is needed to establish surface air temperatures cold enough for snow accumulation. ACKNOWLEDGMENTS A number of people and organizations have been instrumental to the success of this work. Central to this work is the GISS ModelE2. Development of this code is ongoing and coordinated through the NASAGoddard Institute for Space Studies. When resolving issues related to changed boundary conditions, the GISS data archive and personal communication with Dr. Gavin Schmidt were invaluable. Data plots were generated using the Panoply Data Viewer, which is under continued development by Dr. Robert Schmunk. Computer resources were provided by Cedarville University and the Ohio Supercomputer Center. The Creation Geological Society provided a forum for presenting preliminary work leading to this publication. REFERENCES Agassiz, L. 1840. Etudes sur les glaciers, Reissue edition (2012) . Gollmer ◀ Post-Flood Ice Age precipitation ▶ 2018 ICC 705