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The article offers information on the multiscale modeling framework (MMF) for parameterizing convective clouds and cloud systems by the U.S. National Aeronotics and Space Administration (NASA), Goddard Space Flight Center (GSFC). The Goddard finite-volume MMF is based on the NASA Goddard finite-volume Generic Circulation Model (GCM) and the Goddard Cumulus Ensemble model (GCE). The Goddard MMF has been evaluated against observations at interannual, intraseasonal, and diurnal time scales using a two year long simulation representing different climate scenarios. MMFs can bridge the gap between traditional Cloud Resolving Models (CRM) simulations, regional weather forecast models, and current and future non hydrostatic global cloud-resolution models.

This study compares instantaneous rainfall estimates provided by the current generation of retrieval algorithms for passive microwave sensors using retrievals from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) and merged surface radar and gauge measurements over the continental United States as references. The goal is to quantitatively assess surface rain retrievals from cross-track scanning microwave humidity sounders relative to those from conically scanning microwave imagers. The passive microwave sensors included in the study are three operational sounders—the Advanced Microwave Sounding Unit-B (AMSU-B) instruments on the NOAA-15, -16, and -17 satellites—and five imagers: the TRMM Microwave Imager (TMI), the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) instrument on the Aqua satellite, and the Special Sensor Microwave Imager (SSM/I) instruments on the Defense Meteorological Satellite Program (DMSP) F-13, -14, and -15 satellites. The comparisons with PR data are based on “coincident” observations, defined as instantaneous retrievals (spatially averaged to 0.25° latitude and 0.25° longitude) within a 10-min interval collected over a 20-month period from January 2005 to August 2006. Statistics of departures of these coincident retrievals from reference measurements as given by the TRMM PR or ground radar and gauges are computed as a function of rain intensity over land and oceans. Results show that over land AMSU-B sounder rain retrievals are comparable in quality to those from conically scanning radiometers for instantaneous rain rates between 1.0 and 10.0 mm h-1. This result holds true for comparisons using either TRMM PR estimates over tropical land areas or merged ground radar/gauge measurements over the continental United States as the reference. Over tropical oceans, the standard deviation errors are comparable between imager and sounder retrievals for rain intensities above 5 mm h-1, below which the imagers are noticeably better than the sounders; systematic biases are small for both imagers and sounders. The results of this study suggest that in planning future satellite missions for global precipitation measurement, cross-track scanning microwave humidity sounders on operational satellites may be used to augment conically scanning microwave radiometers to provide improved temporal sampling over land without degradation in the quality of precipitation estimates. [ABSTRACT FROM AUTHOR]

This study attempts to explore a comprehensive and compact approach for delineating the multiscale and multivariate characteristics of the ITCZ over the western–central Pacific based on daily satellite observations of precipitation, SSTs, and surface winds. Essentially six distinct ITCZ spatial patterns—namely, the north, south, equator, double, full, and weak—are identified according to the daily percentage coverage of deep convection within different latitudinal bands on and off the equator over the western–central Pacific. The evolving structure of the ITCZ over the western–central Pacific is investigated with a focus on the transient statistical characteristics. The relationship between these daily ITCZ patterns and SSTs, and near-surface winds, is also examined. The north (37%), south (24%), and weak (24%) ITCZs represent the three major ITCZ daily patterns over the western–central Pacific, and combined they account for almost 85% of the total number of days within a 10-yr period. The other three ITCZ patterns, namely, the equator (3%), double (6%), and full (5%) ITCZs, occur infrequently. The climatology of the ITCZ, such as monthly, seasonal, and annual means, can be approximately determined by how often and intense these ITCZ daily spatial patterns occur within a specified period. Taking the long-term mean statistics for each ITCZ daily type into account, the double ITCZ deep convection typically observed over the western–central Pacific in monthly, seasonal, and annual mean plots appears to be mainly associated with the frequent occurrence of the north and south ITCZ patterns, instead of the double ITCZ pattern in which an ITCZ appears on each side of the equator simultaneously on a daily basis. Consistent with the strong seasonality in their frequency of occurrence, the three major ITCZ patterns indicate a dominant correspondence with the seasonal meridional migration of warm SSTs. In contrast, the three less frequent ITCZ patterns show a close relationship with the positive or negative SST anomaly over the equatorial central and eastern Pacific, namely, the extension and retraction of the equatorial cool tongue and its strength. Surface wind divergence/convergence does not show any distinct patterns for these ITCZ spatial patterns, suggesting that little relationship between low-level convergence and precipitation can be discerned from daily data. As an application of the method proposed, the frequency distribution of daily ITCZ patterns, as derived from a recent version of the National Aeronautics and Space Administration (NASA) Goddard Earth Observing System (GEOS) general circulation model (GCM), is evaluated against observations. Preliminary comparisons indicate that the GEOS-5 GCM is capable of simulating the correct ITCZ spatial patterns, but their occurrence frequencies can be further improved, in particular, the weak ITCZ and the patterns with fewer occurrences, which may be associated with significantly different control mechanisms and/or feedbacks. [ABSTRACT FROM AUTHOR]

The structure and genetic diversity of a California Cucumber mosaic virus (CMV) population was assessed by single-strand conformation polymorphism and nucleotide sequence analyses of genomic regions 2b, CP, MP, and the 3' nontranslated region of RNA3. The California CMV population exhibited low genetic diversity and was composed of one to three predominant haplotypes and a large number of minor haplotypes for specific genomic regions. Extremely low diversity and close evolutionary relationships among isolates in a subpopulation suggested that founder effects might play a role in shaping the genetic structure. Phylogenetic analysis indicated a naturally occurring reassortant between subgroup IA and IB isolates and potential reassortants between subgroup IA isolates, suggesting that genetic exchange by reassortment contributed to the evolution of the California CMV population. Analysis of various population genetics parameters and distribution of synonymous and nonsynonymous mutations revealed that different coding regions and even different parts of coding regions were under different evolutionary constraints, including a short region of the 2b gene for which evidence suggests possible positive selection. [ABSTRACT FROM AUTHOR]