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Questions tagged [gis]

For questions related to Geographic Information Systems: any digital tool that is designed to obtain, edit, analyze, and present spatially organized data.

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2
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1answer
70 views

Code for DEM based flow routing in R

I have a DEM as shown for which I have determined flow paths using D8 algorithm (My own code) in R. The resulting DEM with the flow paths is also shown. The flow paths are generated in the form of ...
3
votes
1answer
85 views

Great circle in UTM coordinates

I've got a question about calculation of great circles in Cartesian coordinates: Is it possible to compute points along a great circle in UTM coordinates, i.e. given two points P1(easting1, northing1)...
6
votes
1answer
101 views

Which mountains (or hills) are visible from both Boston and Rhode Island?

In the description of the Norse exploration of America, there are two places mentioned, "Hop" and "Straumfjord", with some relationship to the same mountains. E.g. The finding of Wineland the Good, p....
1
vote
1answer
207 views

How to extract lat-lon from MOD10C2 hdf data in matlab?

We can import and read all given bands/parameters of MOD10C2, lat and lon is not given as separate band rather embedded with other bands. How we can extract from MOD10C2 hdf data in matlab. Similar ...
1
vote
1answer
85 views

How to figure the MODIS snow cover against different elevation zones?

I am working on MOD10C2 (8days snow cover), when I clip the MODIS snow cover against different zones of elevation the results was against general trend .i.e. the higher elevation was showing lower ...
6
votes
1answer
193 views

Would more or less land be usable if global temperatures rose?

I think a large portion of the earth's land is unusable from being too cold and land that is too hot does not have enough water and dries out which could be fixed by diverging water to those areas. ...
2
votes
2answers
87 views

where to download NASA-NEX daily downscaled datasets?

I'm looking to download a small geographic area of the CMIP5 models part of NASA-NEX dataset. Previously I relied on the Planet OS OpenNEX GDDP website which had a great tool for selecting geographic ...
4
votes
1answer
82 views

how to know the correct results in watershed delineation in ArcGIS?

When I use one DEM in my study area to delineate watersheds, the results are different from when I mosaic 4 DEM layers adjacent to each other. After the mosaic process, 3 of the basins were merged in ...
2
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1answer
166 views

Looking for global cloud cover animations or videos

I am looking for a video of global cloud cover. Something like an animated version of this image: (Originally presented at http://naturalearth.springercarto.com/ne3_data/8192/clouds/africa_clouds_8k....
5
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2answers
4k views

What is the distance between the tropics?

What is the distance between the tropic of cancer and the tropic of capricorn here on Earth? Now this would seem like I could simply google the answer to it and know the exact distance in miles (...
2
votes
0answers
75 views

Approaches for estimating potential evapotranspiration for non agricultural landuse classes

We are studying the water balance of a small catchment close to Jaipur, Rajasthan India in a semiarid climate. About a quarter of the landuse within the catchment is agriculture, the rest is divided ...
8
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1answer
357 views

Confusion with precipitation values in CORDEX MPI-ESM rcp data

I want to analyze climate projection data for the different RCPs for a region in north western India, which has an arid climate. I chose MPI-ESM data downscaled with CORDEX. An example filename looks ...
4
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1answer
57 views

Is there a measure for the “dominance” of a city's population?

since there are topological isolation as well as prominence as measures to describe how "dominant" a summit is in comparison to the ones surrounding it, I was thinking about a similar measure to ...
2
votes
1answer
282 views

To delineate the drainage basin for a lake, would the pour point be the inlet or the outlet?

I am interested in the area draining into and affecting a particular lake. Delineating this drainage basin, should I use the lake's inlet or outlet to best capture the relevant drainage basin? I think ...
1
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0answers
18 views

Categories for supervised classification, wildlife analysis

I am using GIS to undertake a small research on the loss of natural habitat in north England. I will be using Supervised Classification where I train the system on a few examples, e.g. shallow water ...
1
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0answers
25 views

Has there been loss of natural habitat in north England?

Has there been loss of natural habitat in north England or Britain in general over the past years? If there was, what is the loss in percentage? A reference would be highly appreciated
2
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0answers
226 views

How to determine associated USGS stream gauges with a watershed HUC?

USGS stream gauges have an associated drainage area, but the associated hydrologic unit listed by USGS is often different than the actual drainage area. How can one determine what hydrologic unit ...
2
votes
1answer
197 views

What divides Hydrological Unit Code areas of the same level?

I'm trying to better understand the Hydrological Unit Code (HUC) system of the United States. I understand the basic hierarchy of it (HUC4, 6, 8, 12) and watersheds/drainage areas. Here's what I want ...
6
votes
1answer
166 views

Why do forecast areas on weather.gov appear as twisted squares?

I get my weather forecasts from good ol' NOAA's weather.gov site. On the detailed site weather pages, there's a map that shows the forecast area as a green square (for Boston at least, the square is ...