# Tag Info

29

The clouds can be seen moving but of course it's subtle at first glance. Frame 16: Frame 20:

27

They are moving, but not fast enough to notice at the distance shown. From the NASA page: These images were taken between 3:50 p.m. and 8:45 p.m. EDT on July 16, showing the moon moving over the Pacific Ocean near North America. The North Pole is in the upper left corner of the image, reflecting the orbital tilt of Earth from the vantage point of the ...

23

In a nutshell: The instrument measures microwave radiances (after calibration) If we know the sea surface temperature, we can use radiances to calculate emissivity. The emissivity at 1.4 GHz is itself a function of near-surface ocean salinity. However, in reality, it's more complicated, because there are other factors that come into the equation, such as ...

13

I'm not familiar with land-based methods, but for global measurements, one method is to use satellite altimetry (I'm more familiar with the geodesy side, but many of the same satellites are used). I think many of the current methods interpolate global or regional currents from a sparse network of buoys. As more radar satellites are launched, however, ...

13

Neither. The Sahara Desert is heterogenous. It’s yellow, red, orange, brown, black, and even green in certain places and at certain times of year. Slightly less cheeky answer: neither. Both examples are both approximations of human vision, displayed on computer screens that can be highly variable. The 2002 version of the Blue Marble is a composite of 4 ...

12

Remember from school when you learned that light is actually photons oscillating at specific frequencies, and we happen to perceive some of these frequencies as specific colors? Technically, satellites measure reflected light in spectral bands, where each band is actually a range of wavelengths or light frequencies. The raw data that is sent back to earth ...

11

The image is real, and the clouds are moving, they just move slow, as clouds do. The unnatural appearance arise because they are taken by DSCOVR at an extraordinarily large distance, from a place called L1, more than one million kilometers away!!!. The rotation of the Earth in the animation makes it difficult to distinguish the movement of the clouds, but ...

10

The structure looks similar to this photograph of a "Japanese land retention system" mentioned in passing towards the bottom of this webpage. From the linked page: Land retention systems in Japan, for example, are often designed as heavy waffle grids which are molded to the topography and cover it to a uniform structural depth. This seems to correspond ...

10

One way to approach this is to treat the Earth as an oblate ellipsoid. This would mean the errors arise from the uncertainties in the Earth's equatorial radius and the flattening. From Groten, "Fundamental Parameters and Current (2004) Best Estimates of the Parameters of Common Relevance to Astronomy, Geodesy, and Geodynamics," Journal of Geodesy 77:10-11, ...

10

Civilian earth observing SAR satellites do not always operate over empty swaths of oceans (specially in the middle of Indian Ocean) in order to save power. They are not designed to track a fast moving target and have repeat cycle of at least a few days. Then there is the issue of resolution. High res acquisitions modes (with satellites like TerraSAR-X) are ...

10

The WMO report Instruments and Methods of Observation has a chapter on Measurement of humidity and a separate chapter on Measurement of upper-air pressure, temperature, humidity. The first deals with instruments used for surface measurements. The second deals with instruments used for measuring vertical profiles, which have to deal with a larger range of ...

9

The Tropical Rainfall Measuring Mission (TRMM) satellite is a single satellite, carrying multiple instruments on board, as described here. It makes a total of 16 orbits/day at a low altitude of 400 km, with different swath widths for each instrument. Thus, the measurement product that you get is not a "continuous" measurement of a single atmospheric ...

8

As casey said, the satellite isn't an instrument in itself, it is a platform hosting many instruments. What you're talking about the discovery of oceans on Titan and Europa, you're referring to the the Cassini-Huygens mission aimed at, among other things : Determine the composition of the satellites surfaces (such as Titan) Prove or disprove the existence ...

8

First OLR map is usually graded in flux units (W/m2) thus it is quantitative data, not just a visual picture. Clouds themselves are not a very reliable indicator of high convection and thunderstorm activity. They could form elsewhere and get blown into a dry region. Also with an OLR map students would not be distracted with the shapes of the clouds. AIRS ...

8

Weather stations and airports around the world almost always include an anemometer. Because of ground friction, the wind speed varies with height, so instrumental deployment is set at a standard height of 10 metres in open rural areas. This may require some adjustment in urban or forested areas. In fact, measuring accurate wind speeds above tree canopies is ...

8

I can engage in some educated speculation about what you think you see, but I'm confident you were fooled by the shadows in the image, which are caused by a low sun angle and distorted by the terrain. These are not inuksuit (which is the correct plural of inuksuk). They are all natural, not man-made. Let's point out a few things we know and can see on the ...

8

This is an interesting and common question, so I'll try to give a good answer here, that I think is a good place, as well as GIS and Open Data SE. First, regarding the format, you will never find data natively stored in text or tabular form, because the large data volume would lead to huge files very difficult to handle. Data is usually stored in binary ...

7

Earthquake prediction have been discussed before in this forum and is rather dispiriting. Distortion in transmitted signals could be an early indication of earthquake, but seismometers (geophones) are still a far better instrument to detect vibrations. In future satellites could be an option in remote areas. However, damage from an earthquake can be ...

7

Talking about the volume of the Earth, we have to ignore that it is not static but in fact highly dynamic. The tides alone make the height differ by up to 50 cm. The information I take is from a 2003 article from esri by Witold Fraczek. As you said, we have different understandings of the Earth. Approximations are made to make calculations easier (and ...

7

You ask, How to remove these abnormal value for more precise data? The short answer is that you might be able to make your data look more representative of the natural 'truth', but you will probably have to pay for this with some precision. The problem is that the measurement itself is imperfect: this looks like an artifact of the data collection method. ...

7

Short answer Different plants reflect light at different wavelengths with specific patterns. If you know the reflection pattern of a broad-leaved forest and that of a needle-leaved forest, you can compare them with the pattern observed with a satellite and conclude to which forest it is more similar. Long answer Optical remote sensing Optical sensors ...

7

$\rm \frac{mol}{m^2}$ shows the amount of $\rm{NO_2}$ in the atmosphere over a square meter of surface area - in mols. The molar mass of the $\rm{NO_2}$ is $14+2\cdot 16=46$. It means, the mass of 1 mol of $\rm{NO_2}$ is $\rm{46g}$. The surface area of the Earth is 510million $\rm{km^2}$. Thus, 1 $\rm \frac{mol}{m^2} \rm{NO_2}$ translates to \$\rm{46 \frac{...

6

Hydrosource Associates (no personal relation) claims to use the following: HSA’s use of geophysical instruments and methods includes seismic, electrical resistivity, ground penetrating radar, electromagnetic, magnetic, gravimetric, self-potential, and magnetotelluric. Since you're looking for a list, you could investigate each of those technologies above....

6

From what @Richard and @JoeKington said in their answers, it seems that the usual way of finding water is through a hydrological map. However, for the sake of completeness, I'll include here a bit about what geophysical methods could be used to find water. I'll not comment on the practical issue of cost-benefit as that was nicely explained by @JoeKington in ...

6

Joe Kington has provided an excellent answer re sensing from space. Torbjørn T. pointed out in a comment that the site that I linked for context actually has a good explanation... so after blushing slightly, I shall summarise it here. People with more specialist knowledge are, of course, welcome to elaborate or correct any misunderstanding. Incidentally, it ...

6

I found a natural-color image of the same area: 68.28 South, 60.47 East, North is up, resolution is 130m/px, which makes the whole image about 100 km x 100 km. Looking at the image i'd say that: sea ice is water with pieces of ice in it, the boundary between the two regions is clear water, probably caused by winds and currents moving the floating ice away ...

6

I can't imagine a moving object more suitable for remote sensing tracking than Iceberg A-68, with such slow displacement and huge size. So I don't think it will be particularly useful to install any instrumentation to track its position on site. However, there would be plenty of other measurements that can be done, about mass balance, stress fields, etc. I'...

6

Water molecules do interact with microwaves and in microwave ovens that operate at 900MHZ- 2.5GHz. This Radar instrument operates using Very High Freq Radio Waves at 193MHz [1]. At lower-than-microwave frequencies, the loss factor is much lower, and as a result the wave can penetrate deeper into the ice sheet with minimal absorption. The difference in ...

6

We use something like an Onset HOBO electronic sensor. They've got logging (and in some cases, networking) built in. They'll typically log both temperature and relative humidity at regular intervals specified by the user. Humidity sensors have a tendency to wander off calibration, so you will need to take that into account when designing your monitoring ...

6

The unit mole / m² has dimensions count per area; the unit µg / m³ has dimensions mass per volume. To go from a quantity per area to a quantity per volume, you need to understand some properties of the instrument. The spectrometer on Sentinel-5P is TROPOMI. TROPOMI is an imaging spectrometer, meaning it measures the spectrum of top-of-atmosphere ...

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