Phil Arkin, ESSICPhil Arkin, ESSIC

University of MarylandUniversity of Maryland

Satellite Observations in Satellite Observations in Support of NAME Diagnostic Support of NAME Diagnostic

StudiesStudies

OutlineOutline

•Mean seasonal cycle in Mean seasonal cycle in precipitation in the NAME regionprecipitation in the NAME region

•Seasonal and diurnal variability Seasonal and diurnal variability in precipitation in the NAME in precipitation in the NAME region during the 2003 monsoon region during the 2003 monsoon seasonseason

• Issues for NAME Diagnostic Issues for NAME Diagnostic StudiesStudies

Seasonal variability in Seasonal variability in precipitation in the NAME precipitation in the NAME

region from CMAPregion from CMAP

• CMAP is composite product using CMAP is composite product using several satellite-derived estimates several satellite-derived estimates and gauge observations (Xie and and gauge observations (Xie and Arkin, 1997)Arkin, 1997)

• Monthly, 2.5Monthly, 2.5ºx ºx 2.52.5º used hereº used here

• Averaged over 1987 – 1997 (full Averaged over 1987 – 1997 (full dataset is 1979-2003)dataset is 1979-2003)

CMAP Precipitation1987 - 1997

April – June

July - August

Ratio – percentage increase from AMJ to JA

CMAP precipitation (1987-1997) for AMJ (top) and JA (bottom)

Tip of Baja California goes from <0.2 to 2-3 mm/day; coastal point to the south goes from 1 to >6 mm/day

Ratio (JA/AMJ)

Annual cycle of precipitation averaged over the two boxes

Details of the diurnal cycle Details of the diurnal cycle during the 2003 monsoon during the 2003 monsoon

season using CMORPHseason using CMORPH• CMORPH is composite product using all CMORPH is composite product using all

available passive microwave-derived available passive microwave-derived estimates with interpolation by advection estimates with interpolation by advection inferred from geostationary IR (Joyce et al., inferred from geostationary IR (Joyce et al., 2003, submitted)2003, submitted)

• Basic dataset is 30 minute/8 km – 3 hour Basic dataset is 30 minute/8 km – 3 hour totals for 0.25totals for 0.25ºx 0.ºx 0.2525º areas used hereº areas used here

• Pingping Xie made the figures I will show Pingping Xie made the figures I will show here; thanks also to Robert Joyce, John here; thanks also to Robert Joyce, John Janowiak, Mingyue Chen and Yelena YaroshJanowiak, Mingyue Chen and Yelena Yarosh

Conclusions: Part 4Conclusions: Part 4• CMORPH allows us to visualize details of the CMORPH allows us to visualize details of the

influence of the terrain of the diurnal cycle of influence of the terrain of the diurnal cycle of precipitation that probably have not been seen precipitation that probably have not been seen beforebefore

• Precipitation dies away quickly to the west of Precipitation dies away quickly to the west of the Sierra Madre Occidental; only a little rain the Sierra Madre Occidental; only a little rain makes it offshoremakes it offshore

• ITCZ south of Mexico has weak diurnal cycle ITCZ south of Mexico has weak diurnal cycle with peak just after midnight; sharp with peak just after midnight; sharp demarcation right at coastlinedemarcation right at coastline

• Over the U.S., CMORPH exhibits clear eastward Over the U.S., CMORPH exhibits clear eastward propagation from the Rockies, quite similar to propagation from the Rockies, quite similar to Carbone et al. findings from several years of Carbone et al. findings from several years of radar dataradar data

Issues for NAME Diagnostic Issues for NAME Diagnostic StudiesStudies

• Precipitation products that utilize Precipitation products that utilize satellite observations (such as, but not satellite observations (such as, but not limited to, CMAP and CMORPH) will be limited to, CMAP and CMORPH) will be very useful for NAME diagnostics very useful for NAME diagnostics studies:studies:

• However, the link to surface-based However, the link to surface-based observations (gauges, radars) is still to observations (gauges, radars) is still to be made for fine scalesbe made for fine scales

• The (likely) loss of TRMM and AMSR The (likely) loss of TRMM and AMSR (on ADEOS-2) is a significant handicap(on ADEOS-2) is a significant handicap