Hot answers tagged

13 votes
Accepted

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

The equal-area projection used to create the continental U.S. grid for weather forecasting does not represent lines of latitude and longitude as straight lines. Instead, they are curved (note the ...
user avatar
  • 12.7k
10 votes

What is the distance between the tropics?

Let's start by the quick rule of thumb, I'll follow the way I do it mentally as I think the mnemonics I use could help you too. First, the tropics are at 23.5° of latitude. And remembering that the ...
user avatar
8 votes
Accepted

What is the distance between the tropics?

Both the tropics of Capricorn and Cancer are 23.43692 degrees from the equator. So the angular distance between the two is 46.8738 degrees (2 x 23.437) of latitude. One nautical mile is defined as ...
user avatar
  • 20.3k
8 votes
Accepted

Confusion with precipitation values in CORDEX MPI-ESM rcp data

TLDR; The precipitation values (and possibly some other variables; see below) need to be divided by 24. Background The global attributes of the netCDF file in the question provide an URL to a ...
user avatar
8 votes
Accepted

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

Yes. current climate change will most likely increase the amount of cultivable lands on Earth. However, it will at a high social cost and at the expense of biodiversity, and I can't emphasize enough ...
user avatar
7 votes
Accepted

High-resolution georeferenced population data

For "historical" population data, you can refer to the Gridded Population of the World (GPW), version 4. This dataset makes available estimates of population at ~1 km resolution (30 arc second) for ...
user avatar
  • 1,248
6 votes
Accepted

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

As Boston and Rhode Island are whole areas more than points, the question is easier to answer the other way around: From which mountain you can see Boston and Rhode Island? To answer the question I'...
user avatar
4 votes
Accepted

Software for spatial interpolation of temperature and relative humidity data from weather stations

I am presently working on exactly this. I am using climate reanalysis data, to fill in the 'empties' since my climate stations are far away from each other. Or, sometime, I have N/A's in my series ...
user avatar
  • 2,623
3 votes
Accepted

How can smartphones help geologists in the field?

I know a young geologist using his smartphone as a compass. When we were in the field doing structural measurements together, I would: Record a waypoint using my hiking GPS Take the measurement with ...
user avatar
3 votes

How can smartphones help geologists in the field?

Part of the answer lies in where the geologist will be working and if there will be coverage by cellular/mobile telephone networks. It is my experience that a number of geologists, particularly ...
user avatar
  • 20.3k
3 votes

convert .srtm to xyz ord grd

NOTE: This is not the solution to the question in the title but it solves the problem described in the question's text. Alternative solution I would download the ...
user avatar
3 votes

Code for DEM based flow routing in R

Take a look at the RSAGA package on CRAN, or the rgdal package. Many of the GIS methods can be done in R but basically act as a wrapper for saga or gdal. RSAGA is likely your best bet for processing ...
user avatar
  • 751
3 votes

Great circle in UTM coordinates

The UTM coordinate system, is a kind of Transverse Mercator projection separated in longitude bands and restricted in latitud extent such that the distortions associated with the projection remain ...
user avatar
3 votes
Accepted

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

The latitude and longitude of each pixel is not stored in the HDF file. But using metadata=hdfinfo('file_name.hdf'); You can get the info to generate those latitudes and longitudes. In metadata....
user avatar
2 votes

Looking for global cloud cover animations or videos

That kind of "moving clouds animation" is a very common one, as it is used routinely to aid in weather forecasting. However, it is not very common to see it in a whole-world geographic projection as ...
user avatar
2 votes
Accepted

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

I think there are a few things to consider. First, a drainage basin is defined as the area upstream of the point to which all precipitation converges. Flow does not converge at the outlet - flow ...
user avatar
  • 422
2 votes
Accepted

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

The problem (if there is only one) is in the way you are importing the data into .mat file. If with the files you provided I do ...
user avatar
2 votes
Accepted

where to download NASA-NEX daily downscaled datasets?

Google Earth Engine's NASA NEX dataset (or this) might be of interest to you. It is an online repository, where you can do your analysis using the GEE platform without having the need to download to ...
user avatar
  • 146
2 votes
Accepted

When calculating a precipitation index, should it be constrained to a basin?

Normally you could calculate a precipitation index for any location with a long-term record. A basin will have nearly the same index, regardless of which station location you use, so it can be ...
user avatar
  • 12.7k
1 vote

convert .srtm to xyz ord grd

QGIS does it easily. open the NETCDF (or whatever format the SRTM sits in) by add raster right click on the menu item and select export choose the file format as .xyz DONE!
user avatar
1 vote
Accepted

Rainfall Anomaly Index using satellite data

I think Standardized Precipitation Index (SPI) is good fit with your objective. The SPI value is spanning from -3 to +3, positive SPI values indicate greater than median precipitation (Wet) and ...
user avatar
  • 146
1 vote
Accepted

download NASA Earth Exchange Global Daily Downscaled Projections for single lat lon

I did download and process some of the NEX files a year or so ago. Maybe there is a more efficient way to do that now, but what I used is this R script to download the files: ...
user avatar
  • 1,248
1 vote

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

I would recommend looking at automatic stream network delineation and/or known stream locations features, and overlaying those as a check on the final watersheds created through whatever procedure you ...
user avatar
  • 751
1 vote
Accepted

What divides Hydrological Unit Code areas of the same level?

I'm confused about your misunderstanding as the answer to your question is in the Wikipedia link you posted: Regions receive a two-digit code. The following levels are designated by the addition ...
user avatar
1 vote

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

Exciting question... it's something I've wondered as well, both for interest purposes and for utility in programs like you mention (I posed a fairly related question in the cartography SE site ...
user avatar

Only top scored, non community-wiki answers of a minimum length are eligible