Grantville Gazette 37

higher than the average daytime one.

A shorter averaging period will be needed to filter out chaotic fluctuations in temperature, which is a parameter directly driven by (non-chaotic) solar radiation, than that needed to address precipitation, sea level pressure and wind speed, which are heavily dependent on 'turbulent atmospheric dynamics' (Zorita).

Climate is predictable because some of the major forcings (solar radiation) and components (the ocean, soil) are mostly of a slowly varying nature, and thus impart 'memory.'

'Seasonal anomalies and longer-term climate anomalies tend to be controlled by other processes whose predictability is not necessarily limited to 2 weeks.' (Buontempo 41).

****

Now, let's talk about the size of the perturbation created by the RoF. The air mass may differ in temperature and pressure, and certainly in composition, from the air that it replaced.

Eric has acknowledged that the Ring of Fire took place, up-time, on April 2, 2000. We also know it occurred around noon; a few minutes after the event, Frank pointed out to Mike that the sun was in the wrong place, that it should be to the south (Flint, 1632, chapter 3).

Determining what those differences are isn't that easy. You would think that we could at least fix the characteristics of the year 2000 hemisphere. And you would be wrong. While the Mannington 8 WNW weather station was in business in 2000, the April 2000 records are not available from NCDC. March yes, May yes, April no.

According to the Farmers' Almanac, the closest available weather station, HARRISON MARION RGN, WV, reported on that day a high of 62.6^oF, a low of 48.2, an average of 55.7, a dewpoint of 45, a wind speed of 3.9 knots, and 0.01 inches precipitation (essentially, a drizzle). The mean temperature and dewpoint correspond to a relative humidity of 67%. Another nearby station, MORGANTOWN HART FIELD, WV, reported high 61, low 48.9, average 56.9, dewpoint 39.9, wind speed 4.7 knots, and precipitation 0.09 inches.

I took a look at the 24-hour graphs for the station KWVFAIRM17 in Fairmont for April 2 in 2007-2010. In 2010, noon temperature was almost 5^oC below the peak, reached at 6 pm. In 2009, the peak was at 3 pm and the noon temperature was only about 2.5°C less. In 2008, the noon-to-peak spread was similar but the peak was at 5 pm. And 2007 was similar.

So I am going to estimate that on the day of the RoF, the high was 62°F (16.7°C) and that at the time of the RoF, the temperature had only reached about 57.6°F (14.2°C). The saturation vapor density of water is 12.15 grams/cubic meter at 14.2°C. I am estimating a relative humidity of 60%, there's 7.3 grams/cubic meter of water in the air.

I have no idea what the air pressure was that day. There is no reference to rain on RoF day in the novel, so the pressure was probably average (29.92 inches mercury, 1013.25 mbar) or a little above.

We know even less about the conditions on May 25, 1631 near Rudolstadt, Germany. Presently, the average max and min temperatures are 13 and 4^oC for April and 18 and 8 for May (www.holidaycheck.com), i.e., a 9-10 degree spread. For 1766-1850, climate reconstructions yield an average of 12.10°C (standard deviation 1.51) for May, and 15.35^oC for June (s.d. 1.24). May 25 is one-third of the way from May 15 to June 15, so the mean temperature for May 25 was probably something like 13.18^oC (55.7°F).

The sun in the new timeline sky is in the east, so it's morning. Indeed, in the mid-latitudes, temperatures tending to be coolest just before sunrise and warmest at 4-6 pm. I think it reasonable to expect the mean to be hit around 9 am.

The principal atmospheric gases are nitrogen and oxygen. The trace gases that are significant from a climatic standpoint are water vapor, carbon dioxide, methane, and the nitrogen and sulfur oxides. Besides gases, the atmosphere also contains aerosols (airborne particles) , including desert dust, droplets of sulfuric acid produced by the reaction of volcanic sulfur dioxide with water, carbon from smoke, and sulfates from the combustion of fossil fuel.

My summary as to the likeliest size of the perturbation caused by the Ring of Fire, as measured by meteorological variables, is in Table 3-1.

*1631 and 1997 values (Robertson),2000, estimated from graph for Mauna Loa: http://www.esrl.noaa.gov/gmd/ccgg/trends/

**.2000 sulfur dioxide concentration for Marshall county (which is near Marion).(WVDEP).

Because the RoF occurred suddenly, it's probably most comparable to a volcanic eruption. There is no doubt that an eruption can have a profound effect on climate, as well as weather, for up to several years, at least if it injects material into the stratosphere.

So the question is, how does the RoF rate, compared to various eruptions, as a source of heat, carbon dioxide, and aerosols?

Since the diameter of the RoF hemisphere is six miles, its maximum height above the earth's surface is three miles. The stratosphere begins at about 6-31 miles above the ground in temperate latitudes, so the immediate meteorological effect of the RoF is limited to the troposphere.

There's something called the Volcanic Explosivity Index. It's based on plume height and volume. The three mile height of the RoF hemisphere corresponds to a plume height of just under five kilometers; VEI 2 ('explosive') is 1-5 km. However, the volume (236 km³) ranks as VEI 7 ('super-colossal'), 100-1000 km³.

However, that's quite misleading because the temperature difference between a volcanic plume and the 'background air' is likely to be much higher than that between the Grantville and Thuringian hemispheres. And the volcanic plume is going to differ in composition from 'background air' more than the two hemispheres do, too.

At the temperature of the Grantville hemisphere, the heat capacity of air is 1.005 kJ/kg-^oC, and the density is about 1.225 kg/m³. Since the temperature difference between the Grantville and Thuringian hemispheres is most likely one degree Celsius, that means that the heat energy introduced by the RoF is about 2.9*10¹¹ kJ. That's a bit less than the amount of energy released when the water in a typical thunderstorm condenses.

For a volcanic plume measured on March 19, 2002 at Miyake Island, the temperature initially was 34^oC, but the temperature dropped to 20 when the plume rose to 3 km and to 19 at 6 km. Such a plume would have been carrying at least an order of magnitude more heat energy than that attributable to the air temperature difference caused by RoF.

The RoF also resulted in an injection of greenhouse gases and aerosols, but it was small.

Even if there were no sulfate aerosol already in the Thuringian air that it replaced, the effective injection was only about ten tons sulfate, as a one-shot deal. In comparison, during the Miyake 2002 eruption, that volcano was emitting 10,000 tons SO₂per day, for months. Yet it had a VEI of only 2.

Thus, it seems fair to conclude that the effect of the RoF on climate is mostly likely to be smaller than even that of an eruption of VEI 2.

****

I consulted with climatologist James Annan (Senior Scientist, Research Institute for Global Change, Yokohama Institute for Earth Sciences) about the possible effect of the RoF (without providing the specifics of the size of the perturbation because I hadn't yet calculated it at the time of our email exchange). Here's his reply:

'Generally speaking, changing the initial conditions (atmosphere) will, as you say, scramble the weather. It will not affect the response to temporally-varying forcing such as solar output, or volcanoes, which probably drive a large part of the large-scale climate changes. However, it's not obvious to me (and perhaps anyone) to what extent the observed seasonal climate variation is simply due to internal variability, versus a forced response.

'On the assumption that the important external forcing factors are greenhouse gases and solar output you could probably consider swapping the climates around from roughly consecutive years-e.g. use the seasonal means from 1632, then 1631, then 1634 . . . and so on shuffling the years around a little. The daily weather would not match in any case. If there's a volcano (I haven't checked) then that would have to affect the particular year of course.'

I have since checked the volcanic activity. While there was an active eruption somewhere in the world for