The GMI imager scanned a developing cyclonein the central Pacific. Ku PR captured segmentsof the warm frontal/warm sector bands.

I.INTRODUCTION

NASAPrecipitationMeasurementMissions(PMM)ScienceTeamMeeting,Houston,Texas,24-28,October,2016

PrecipitationCharacteristicswithMid-latitudeFrontalSystems

MeiHan1,2,ScottA.Braun2,Chuntao Liu3

1GESTAR,MorganStateUniversity;2MesoscaleAtmosphericProcessLaboratory,NASA/GSFC;3TexasA&MUniversity-CorpusChristi

II.COLDFRONTAL

IV.OCCLUDED

Fig.2:Orbit10559

Table1:Precipitationbands/clusters(HHisHouze andHobbs;SKisShapiroandKeyser)

Fig.1:Orbit10466

Fig.4:Orbit10651

The GPM mission is designed to better quantifyprecipitation characteristics at middle and highlatitudes. During the cold season, precipitation isoften associated with frontal cyclones. Using radarobservations, precipitation is commonly categorizedas bands/clusters according to its location relative tofronts and cyclones. This study initiates aninvestigation to characterize the precipitationbands/clusters along the storm track in the NorthernPacific.

We use GPM IMERG and model reanalysis (MERRA2)data to identify different types of precipitation bands.Precipitation Feature (PF) data based on Ku PRreflectivity is applied to describe the precipitationcharacteristics.

GPM overpasses of occluded cyclones at higher latitudes, where precipitation is shallower and precipitationparticles appear smaller.

VII.SUMMARYObservations from the GPM core satellite were analyzed to characterize frontal precipitation bands/clustersin the Northern Pacific. 351 orbits in January 2016 were selected. During the study, we manually selectedcases that are representative of different types of precipitation bands/clusters, including cold frontal bands,warm frontal bands, warm sector bands/clusters, occlusion bands, and post-frontal bands/clusters. Frontalbands and warm sector bands appear to have higher vertical extent. Occlusion and post-frontalbands/clusters appear to have shallower vertical extent. The features appear to be consistent with theirdynamic causes. The mode of particle sizes (Dm) in most cases is within 1.0 – 1.5 mm.

The preliminary results demonstrate that precipitation sampled by the GPM satellite over the open oceanscan be classified into different categories of bands/clusters in a way relatively similar to their coastal/landcounter parts documented in the early literature. This study begins a comprehensive study of precipitationcharacteristics and hydrometeor properties associated with different types of precipitation bands/clusters.Future analysis will incorporate more objective measures derived from reanalysis data to describe therelationship between the precipitation bands/clusters and their dynamic and thermodynamic environment.

Fig.5:Orbit10477

Fig.6:Orbit10692

Fig.10:Orbit10721

VI.WESTERNANDEASTERNPACIFIC

V.POST-FRONTAL

Total351orbitsinNorthernPacificduringJanuary2016

ColdF(NCFR+WCFR) WarmF

WarmF+Warmsector Occlusion PostF

Coastal(N.America)

#oforbits 26 14 7 8 many 3

Type Subtype Definition References

Cold-frontalband

Wide(WCFR) AbandparalleltoandinthevicinityofthecoldfrontHH1982;Locatellietal.1994;Hanetal.2009

Narrow(NCFR) Aband(~10kmwide)withhighreflectivities collocatedwiththesurfacecoldfrontHH1982;Braunetal.1997;Hanetal.2009

Warm-frontalband − Abandinthevicinityofthewarmfront HH1982;Hanetal.2007

Warm-sectorband − Abandinthewarmsector

NozumiandArakawa1968;HH1982

Occlusionband −Abandclosetoalowandassociatedwithweaktemperaturegradients HH1982;SK1990

Post-frontalprecp.

−Agroupofopen- orclosed-cellularconvectivecells,ororganizedprecip.behindthecoldfront

Monteverdi1976;Reed1979;HH1982;ReedandBlier 1986;BraunandMonteverdi1991;Stevensetal.2005

Table2:KuPRorbitswithsufficientcoverage

IMERG and MERRA data show cyclones and frontal precipitation bands in the Northern Pacific. The Ku radarswaths captured the intense cold frontal bands. Histograms of reflectivity and mass spectrum meandiameter (Dm, melted) of PFs are shown. The cold frontal bands extended into the upper troposphere andproduce up to 50 dBZ intensities.

III.WARMFRONTAL/WARMSECTOR

Fig.3:Orbit10468

The GMI imager scanned a relatively weak cyclone in the central Pacific. The Ku PR captured a strong warmsector precipitation feature (PF). This PF has the largest Dm among all precipitation events in the NorthernPacific in January 2016.

GPM overpasses of an intense developing cyclone and an occluded cyclone on Jan 17th. A cold frontal bandwas captured by Ku PR in the western Pacific. In the eastern Pacific, an Atmospheric River in the warm sectorof an occluded cyclone transported a large amount of moisture to the California coast. The precipitationappears to be more intense within the developing cyclone in the western Pacific.

Fig.9:Orbit10716

Fig.7:FourlargestpostfrontalPFsinorbit10466(seeFig.1forthesynopticview)

Fig.8:Orbit10756

Post frontal precipitation cells/clusters produced in the cold sector of cyclones are commonly observed byGPM sensors.

Post frontal precipitation clusters produced by cold air outbreaks in the Sea of Japan.

Reflectivityhistograms Dm histograms

III.WARMFRONTAL/WARMSECTOR(continued) V.POST-FRONTAL(continued)