Questions tagged [measurements]

Questions related to acquiring, processing and interpreting field measurements of any kind. Including instrumentation and data analysis.

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35
votes
9answers
56k views

What does a mm of rain mean?

Lots of people have explained it over many sites but I still can not confidently say that I know what it means when they say Hong Kong experienced 3mm of rainfall last Friday. Does it mean that 3mm ...
22
votes
1answer
310 views

Estimating the permeability tensor of an oil field by remote sensing

I work a lot with numerical methods to solve multiphase flow in porous media for oil applications. In our field, we often use Darcy's law which states that the flux is negatively proportional to the ...
21
votes
5answers
4k views

Is there a database of global rainfall time series?

Is there any institute out there collecting time series data of precipitation, and making them accessible online? I need data for a few different locations, but: Low spatial resolution is fine. For ...
17
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3answers
9k views

If 75% of radioactive material remains, how many half-lives have elapsed?

Radioactive element A radioactively decays into material B. If 75% of A and 25% of ...
17
votes
1answer
578 views

Why are weather kites no longer used (much) operationally?

Figure 1.12 from the IPCC AR5 WG1 report (reproduced below) illustrates the different instruments that have been used for weather forecasting. Most of the methods have been in continuous use since ...
15
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5answers
4k views

How are barometric pressure measurements traceable over centuries to 100 parts per million accuracy?

The BBC News item Barometric pressure in London 'highest in 300 years' at least begins with Overnight, Sunday into Monday, London's Heathrow Airport recorded a barometric pressure of 1,049.6 ...
14
votes
2answers
345 views

How are subsurface wave speeds determined without subsurface sensors?

This is something I've never quite understood from a geology class I took years ago: Consider the following picture (courtesy of wikipedia) Obviously, we can't possibly have sensors deep in the ...
14
votes
2answers
1k views

How can odor travel be tracked

Odd question, but what data would be needed to to calculate how far winds will carry a strong odor (such as the smells of a restaurant, pizza parlor or burning wood/building? There is wind direction ...
14
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2answers
2k views

Characterizing earthquakes using accelerometer data

Is there a way to use accelerometer data to characterize earthquake intensity, e.g., on Richter scale?
14
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1answer
183 views

What kinds of remote sensing required to observe methanogenic life on Titan?

Inspired by Chris McKay's Possibilities for methanogenic life in liquid methane on the surface of Titan. In the paper, the PI's found that the consumed acetylene, ethane, and other organic solids ...
14
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1answer
150 views

Have there been any attempts to measure profiles through deep convective systems using dropsondes?

In-situ measurements in deep convective systems, tropical cyclones, etc., are difficult to perform. Few if any people would like to fly a small aircraft close to its core, and radiosondes or larger ...
13
votes
1answer
604 views

Where can I obtain ocean wave data of the Southeast Asian region?

I am interested in obtaining ocean wave data (preferably from actual measurements), such as wave height, period, and direction, in the Southeast Asian region. Where can I obtain them?
13
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1answer
2k views

How do you calculate the depth of penetration in a Schlumberger array?

In a resistivity survey, how do we calculate the depth of penetration for a Schlumberger array?
12
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2answers
3k views

What exactly is wind velocity

How exactly do we define wind velocity? Obviously, I suppose this is something like "speed of displacement of a quantity of air", but this seems to be too imprecise. For example, a cup anemometer ...
12
votes
2answers
951 views

From where do weather radar maps get their data?

I see maps like this one all the time online and in the news. A moving map that shows clouds and stuff moving around with time. Where do they get the data from? Is it from a single source location or ...
12
votes
2answers
1k views

Width of strata in stratigraphic column

I am trying to understand whether there is one "standard" meaning of the width of represented strata in stratigraphic columns, but I can find nothing online or in my geology books. I notice that, ...
12
votes
3answers
652 views

How much does COVID-19 affect weather forecasts?

The World Meteorological Organization (WMO) is concerned about the impact of the COVID-19 pandemic on the quantity and quality of weather observations and forecasts, as well as atmospheric and climate ...
11
votes
2answers
52k views

What was the highest temperature ever recorded on the surface of Earth?

The article entitled "54 Celsius degrees in Iran, the highest temperature ever recorded?" says 56,6 Celsius may be the highest temperature ever recorded, in Death Valley, California, and it also ...
11
votes
1answer
465 views

What does the term “Snow Interval” mean?

When looking Weather Station readings from the National Weather Service website, what does the term "Snow Interval (inches)" actually mean? 6 hr and 24 hr readings are obvious, but I can't seem to ...
11
votes
1answer
244 views

Turbidity/clarity vs optical depth

Are measurements for clarity (secchi disk) or turbidity (nephelometer) made for water quality related in any way to measurements made for optical or aerosol optical depth in meteorology?
11
votes
2answers
3k views

Standardized scale for coastline length or mapping in general?

Measuring the length of a coastline depends on the scale of the measuring tool. The smaller the scale of your tool, the longer will your measured coastline be. The reason for this is the fractal ...
11
votes
1answer
2k views

Intuitive explanation of precipitation amount

I'm trying to learn how to make sense of numbers in a forecast. I can interpret temperature and wind speed, but I don't know what to make of rainfall. What does it mean, for a human, that there will ...
11
votes
1answer
168 views

How do we determine subsurface composition?

Let's assume that a seismogram $s(t)$ is the convolution $s(t)=r(t)g(t)$ between a source signal $r(t)$ and propagation effects $g(t)$. If the source signal $r(t)$ is known, then we can obtain the ...
11
votes
1answer
264 views

What happens to the higher frequency content of the tremors associated with a volcanic eruption?

From [1]: The main characteristics of volcanic tremor depend strongly on whether a volcano is erupting explosively and on the intensity of the event. Long before an eruption, tremor is ‘narrow-band’ (...
10
votes
2answers
872 views

How can daily brightness be quantified or measured?

It occurred to me that there might very will be a metric out there that measures and quantifies "daily brightness". Meaning, how bright any given day is, taking weather conditions and cloud coverage ...
10
votes
1answer
252 views

How to determine the transmissivity of a system of rocks and faults from the stationary drawdown pattern?

I have a dataset containing high frequency measurements of the hydraulic head at different locations in a 5x6km area. Also known are the precipitation, evaporation, and pumped discharges from a number ...
10
votes
1answer
114 views

What methods exist for remote profiling of oceanic columns?

Remote sounding of the atmosphere is a well-established method used extensively used extensively for operational weather forecasting and scientific research. Active or passive instruments carried on ...
10
votes
1answer
259 views

What principles do we consider when selecting an air pollution monitor location?

I'm working on a project aiming at finding some potential point as a new air pollutant monitor site for a city to measure $SO_2$, $NO_2$, $PM_{2.5}$, etc. After modeling the surface concentration of ...
9
votes
3answers
1k views

How deep could the surface of the Earth's crust get?

In theory, how deep can a natural formation on the surface of the Earth's crust be? What are the limits to this depth?
9
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2answers
3k views

How much distance does $0.001^\circ$ in latitude or longitude represent?

If I'm standing at a lat of 30.000$^\circ$ and a long of 30.000$^\circ$ and I move to a lat of 30.001$^\circ$ and a long 30.000$^\circ$, how far have I gone? Is there a relationship between decimal ...
9
votes
1answer
92 views

How is the distribution of Argo floats managed over the Earth's oceans?

The BBC News article Climate change: Oceans 'soaking up more heat than estimated' mentions Argo floats as one technology to measure the temperature of the oceans, and links to argo.ucsd.edu where ...
9
votes
1answer
705 views

How are data from tiltmeters used to monitor volcanic activity?

I've just learned in this answer that tiltmeters (which I assume measure changes in tilt) are used near active volcanos. (Saw a mention in item 4. here also.) What kind of geological (volcanological?)...
9
votes
1answer
59 views

Lab procedure for analyzing/assessing the presence of semi-volatile solids

I'm looking for a lab experiment design that shows how to measure the presence of semi-volatile solids in water (and not sludge or soil or solids). All I have found so far are chromotography/mass ...
9
votes
0answers
79 views

What field studies have developed or supported the Penman-Monteith equations for estimating evapotranspiration?

I'm trying to understand transpiration estimation methods. The FAO recommends a standard Penman-Monteith methodology for modeling evapotranspiration based on meteorological and vegetation parameters (...
8
votes
2answers
126 views

Measurement of groundwater levels

There are numerous measurement systems available for measuring groundwater levels (head / stage). What period of time should measurements be collected in order to draw solid conclusions about the ...
8
votes
2answers
227 views

TRMM rainfall measurement for synoptic systems

I have gone through the website of TRMM that explains how the TRMM satellite gather precipitation data- http://pmm.nasa.gov/node/158. During the Indian Summer Monsoon (ISM), we have synoptic systems ...
8
votes
1answer
1k views

Are average daily temperatures affected by DST?

To calculate the average daily temperatures, do meteo professionals still use the Mannheim procedure with twice weighted measurement in the evening? (It could be obsolete by automated weather stations....
8
votes
2answers
1k views

How accurate is a tipping-bucket rain gauge?

My question is simple - how accurate is a tipping-bucket rain gauge? I have read about what causes the errors (wind, bucket mechanics for extreme events, ...) and I know the accuracy is strictly ...
8
votes
2answers
326 views

Is seismology really the only way to measure the thickness of Earth's layers?

Answers from these two questions: How can we guess the size of the earths inner core? & How can we measure the thickness of the earths mantle? use seismic waves as the method for detirmining ...
8
votes
1answer
86 views

Are there measurement techniques that can help determine the exact geometry of a volcanic vent?

In a previous question What happens to the higher frequency content of the tremors associated with a volcanic eruption?, I asked about the high(er) frequency content of a volcanic eruption. In the ...
8
votes
1answer
115 views

Checking the bedrock with radiowaves - how does it work?

I've heard long ago that the rock material deeply below surface are checked by a device that acts like radar - it sends radiowaves into the ground, and geologists find out from reflections that what ...
8
votes
1answer
140 views

Do humans cause a DST-related shift in average daily temperatures?

Inspired by the title to this question, is there a shift in average daily temperatures caused by the DST change in human activities? I can picture any number of mechanisms by which a shift could ...
8
votes
1answer
135 views

Direct measurments of vertical ocean mixing?

What kinds of vertical ocean mixing measuring instruments are available? This answer How to measure ocean vertical velocity? tells about the measurement of vertical velocity by ADCP, but they give ...
7
votes
3answers
171 views

How do the pros measure humidity?

I have used a wet/dry bulb setup to estimate humidity, and it appears that the Argentinian meteorological service uses one in Antarctica as well. Wikipedia sez: Humidity measurement is among the ...
7
votes
2answers
498 views

How does ice-penetrating radar “see” through kilometers of ice without being absorbed?

The BBC News article Isolated lakes found beneath Canadian ice sheet links to the open access Science Advances article Discovery of a hypersaline subglacial lake complex beneath Devon Ice Cap, ...
7
votes
2answers
1k views

How do I represent wind direction on a UTM (Universal Transverse Mercator) map projection?

What does it mean when I say "the wind direction is 50o" on a UTM map? Which direction is the 0o reference? For example, if I draw a wind vector V as seen in the ...
7
votes
2answers
614 views

Relationship between illuminance and cloud cover

Is there a clear formula or table relating the illuminance in (lux) to status of the sky in terms of cloud cover? For example, mostly cloudy would be 2000-3000 lux.
7
votes
1answer
370 views

What are the advantages in looking at an OLR map versus looking at IR satellite imagery?

Conceptually they seem to be showing the same information. But in the context of a Madden Julien Oscillation (MJO) or equatorial waves especially over the equatorial oceanic layers which one is more ...
7
votes
2answers
260 views

What mechanism is used to measure ocean currents from cables?

The volume transport of the Florida Current (one of the parts of the Gulf Stream) is measured using an underwater cable. What are the processes that allow for these measurements? How can we obtain ...
7
votes
1answer
2k views

How to count lightning in a thunderstorm?

Is there an accurate way to count the amount of lightning happening in a thunderstorm? How is lightning measured? Is there a special unit for this?