Evaluation Question 4

Question 4

Why do coastlines often appear very blocky or with gaps in the data for POES microwave products? (Check the boxes for all answers that apply, and leave those that do not apply unchecked. Then click DONE.)

a) Data along coastlines is often screened out during the retrieval process due to the large changes in the surface properties from ocean to land.

b) Data is screened out of the retrieval process when subpixel effects result in false signatures that resemble precipitation.

c) Coastlines appear blocky only where the instrument field-of-view is very large, like near the edges of an AMSU swath.

d) Data along certain portions of a coastline may be removed if surface winds are strong and the ocean roughness is dramatically increased.

Discussion

Data along coastlines is typically screened out during the retrieval process because of the large changes in brightness temperature associated with the large ocean/land contrast in emissivity. Answer c) is incorrect since it is the screening process which determines which pixels are eliminated from the final product. Answer d) is incorrect since ocean surface winds and changing ocean emissivity are not factors in the screening process.

	a) Data along coastlines is often screened out during the retrieval process due to the large changes in the surface properties from ocean to land.
	b) Data is screened out of the retrieval process when subpixel effects result in false signatures that resemble precipitation.
	c) Coastlines appear blocky only where the instrument field-of-view is very large, like near the edges of an AMSU swath.
	d) Data along certain portions of a coastline may be removed if surface winds are strong and the ocean roughness is dramatically increased.