The NOAA IR serves as an archival repository of NOAA-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by NOAA or funded partners.
As a repository, the NOAA IR retains documents in their original published format to ensure public access to scientific information.
i
Satellite-estimated rainfall in GATE
-
1979
-
[PDF-101.53 MB]
Details:
-
Personal Author:
-
Corporate Authors:
-
NOAA Program & Office:
-
Description:Quartitative precipitation estimates have been made for the GRIP (Global Atmospheric Research Program) Rtlartic Tropical Experiment (GATE) from geosynchronous, irfrared satellite imagery and a computer-automated technique that ns described in this memorandum. Isohystal maps and volumetric estimates vere made for tie GATE A scale (1.43 x 10 tof) and for a 3° square (1.10 x ia tot) that enclosed the B scale for time frames ranging all of GATE (27 June through 20 September 1974) dam to 6-hr segments. The estivates for the square are compared with independent rain measurements made by four C-band digital radars that vere complemented by shipboard rain gages. The A-scale estimates are compared to rainfall estimates generated by NASA using Nimbus 5 m microwave imagery. Other analyses presented include: (1) comparisons of the satellite rain estimates ewer Africa with rain gage measurements, (2) maps c£ satellite-inferred locations a frequencies cf new cloud formation, cloud mergers, and cloid dissipations, (3) latitudinal precipitation cross sections along several longitudes, and (4) diurnal rairfall patterns. The satellite-generated B-scale rairfall patterning is similar to, and the rain volumes are within 10% of, those provided by radar for phases 1 and 3. The isohyetal pattens are similar in phase 2, hit the satellite estimates are lew, relative to the radar, by 73%. The reasons for this B-scale disparity m phase 2 are unknown, but the analyses presented suggest that it does net cany over tot A scale. Comparison cf NASA Electronically Scanning Microwave Radiormter (E&R) rain estimates with airs for several areas within the A scale for all GATE suggests that the former is lew relative to the latter by 50%. The satellite estimates cf rainfall in Africa are similar to measurements by rain gages in all phases cf GATE up to 11° N and progressively greater than the gage measurements north cf this latitude toward the Sahara desert. Tie diurnal rainfall studies suggest a midday (abort 1200 GMT) maximum of rainfall over the water areas and a late e/ening maximum (about 0000 GMT) over Africa and the north part of South America. The latitudinal rainfall cress sections along several longitudes by phase clearly show the weste-sortlwest/ eastnortheast orientation cf the Intertropical Convergence Tone (ITCZ), the dirnmnutnon cf the rainfall west-soutlwesiwavd from Africa into the Atlantic, and the northward progression cf the ITCZ from phase 1 into phases 2 and 3. The center of action for clcud formation, merger and dissipation, and the area cf maximum rainfall (exceeding 1600 mm for all cf GATE) occurs along the sothest African coast near 11° N. This agrees with past climatologies for this region, anpenpositnon cf tie sateLlite-gererated rairfall mops and sea surface temperature mops by phase suggests a strong relationship between the two. Almost all cf the rairfall occurs within the 26° C sea surface temperature envelope. The mean daily coverage of rainfall and the mean rainfall in the areas with rain for the A scale for all GATE are 20% and 14.1 mm d'1, respectively. These and ether results are discussed.
-
Keywords:
-
Series:
-
Document Type:
-
Place as Subject:
-
License:
-
Rights Information:CC0 Public Domain
-
Compliance:Library
-
Main Document Checksum:
-
Download URL:
-
File Type:
