Thanks Jim
Bob
K6UJ
> On Jan 22, 2022, at 9:45 AM, Lux, Jim <jim@luxfamily.com> wrote:
>
> On 1/22/22 9:21 AM, Robert Harmon wrote:
>> I love your perfect QTH description. A hill of salt water, sloping gently
>> in all directions. hihihi
> Calistoga has hot water under pressure, and I'll bet it's got plenty of
> dissolved minerals. So a big sprinkler fed from a hot spring at the top of
> your hill.
>>
>> I am having trouble finding ground conductivity fro my area in the north San
>> Francisco Bay Area. Napa county.
>> Looks like my area shows a number 8. Where is he chart to find out what
>> this means in conductivity ?
>
> millimhos per meter on the chart legend - that's milliSiemens/meter in SI
> units.
>
> Yes, that's not exactly averaged over large areas, it's more "interpolated
> from scattered measurements made in the 1930s and 1940s" for two purposes: LF
> and MF propagation estimates and powerline grounding.
>
> https://www.fcc.gov/media/radio/m3-ground-conductivity-map has a slightly
> newer version, and also has some references to tabular data.
>
>
>
>> Wish I could find a map that I could drill down closer to my QTH. I know it
>> is pretty good right now, we have had
>> lots of rain the last few weeks.
>
> There are some other datasets around, but they tend to be highly specific,
> because someone had a need to measure it. And there's not many needs.
> Munitions depots, electrical installations, etc. are most likely, along with
> some transmitter locations. And there's no particular reason why those
> measurements would be collected into a nice database, or even publicly
> available.
>
> You *might* be able to infer conductivity from a combination of geology and
> soil moisture. Soil Moisture *is* something for which there are datasets
> from satellite measurements. SMAP is a satellite specifically designed to do
> that measurement, and it's measuring in L band.
>
>
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