lst_filter: lst_filter

In RichardLemoine/LSTtools: LSTtools: An R package to process thermal data derived from Landsat and MODIS images

Description

Filter pixels of MODIS LST products based on the LST error and angle layers.

Usage

lst_filter(x, time = "day", flag, angle, conv = TRUE)

Arguments

x	.hdf MODIS file corresponding to a LST product.
time	A character specifying the time of the data to filter. Possible values are "day" or "night".
flag	LST error bit flag or accuracy tolerance from 1-4.
angle	Viewing zenith angle tolerance to filter pixels (in degrees).
conv	Logical; if TRUE, units are converted to Celsius degrees.

Details

Filter the pixels of a day or night data of a MODIS LST product, based on tolerance values of LST error and zenith viewing angle defined by the user. If parameter conv = TRUE, temperature units are convert to Celsius degrees. This is the default. Products MXD11_L2 and MYD21_L2 are not supported.

LST error bit flag to filter pixels must be defined as an integer from 0-3 corresponding to: 0=00, 1=01, 2=10 and 3=11 in the 7 & 6 bit flags for 8 bit QC layers and 15 & 14 bit flags for 16 bit QC layers. LST error flags differ between MXD11 and MXD21 products. In MXD11 products, the flag represents average LST error values in Kelvin degrees, with an increase of 1 degree. In MXD21 products, the level of error is represented as accuracy in Kelvin degrees, with increases of 0.5 degrees. See table 13 (MXD11; Wan, 2013) and table 10 (MXD21; Hulley et al., 2016) in the MXD11 and MXD21 user guides, respectively.

A negative sign of the viewing angle means MODIS viewing the grid from east. The view zenith angle itself is always a positive number, the zenith angle from nadir. The information of MODIS viewing the grid from east or west may be important in understanding the view angle effect in the temporal variations in LST, especially in rugged regions.

Value

List of three raster layers: LST layer in Kelvin or Celsius degrees, error or accuracy layer and viewing zenith angle layer. Only pixels that are not NA in the original LST layer are included in the error and view zenith angle layers.

References

Hulley, G., Freepartner, R., Malakar, N. & Sarkar, S. (2016), Moderate Resolution Imaging Spectroradiometer (MODIS) - Land Surface Temperature and Emissivity Product (MxD21) User Guide Collection-6. Pasadena, EUA, 29.

Hulley, G., Hook, S., & Hughes, C. (2012). MODIS MxD21 Land Surface Temperature and Emissivity Algorithm Theoretical Basis Document. In: Jet Propulsion Laboratory, California Institute of Technology, JPL Publication 12-17, August, 2012.

Z. Wan, & Z.-L. Li. (2011), Chapter 25, MODIS land surface temperature and emissivity. In B. Ramachandran, C. O. Justice, & M. J. Abrams (Eds.), Land remote sensing and global environmental change, NASA's Earth observing system and the science of ASTER and MODIS, NASA's Earth observing system and the science of ASTER and MODIS. New York Dordrecht Heidelberg London: Springer, http://dx.doi.org/10.1007/978-1-4419-6749-7.

Z. Wan. (2013), Collection-6 MODIS Land Surface Temperature Products User's guide. Santa Barbara, USA, 33.

Z. Wan, Y. Zhang, Q. Zhang, and Z.-L. Li. (2002), "Validation of the land-surface temperature products retrieved from Terra Moderate Resolution Imaging Spectroradiometer data", Remote Sens. Environ., 83, 163-180.

Gawuc, L., & Struzewska, J. (2016). Impact of MODIS quality control on temporally aggregated urban surface temperature and long-term surface urban heat island intensity. Remote Sensing, 8(5). https://doi.org/10.3390/rs8050374

Hu, L., Brunsell, N. A., Monaghan, A. J., Barlage, M., & Wilhelmi, O. V. (2014). How can we use MODIS land surface temperature to validate long-term urban model simulations? Journal of Geophysical Research, 119(6), 3185-3201. https://doi.org/10.1002/2013JD021101

Examples

## Not run: # For LST day MXD11 product, filtering pixels with LST error
# <= 1 and view zenith angle <= 35
x <- "MOD11A1.A2019305.h14v09.006.2019306084028.hdf"
lstfiltered  <- lst_filter(x, time = "day", flag  = 1, angle = 35, conv = TRUE)
## End(Not run)

RichardLemoine/LSTtools documentation built on Oct. 19, 2020, 12:50 a.m.