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Kenneth D. Leppert II
and
Daniel J. Cecil

1. Introduction Previous work (e.g., Gray and Jacobson 1977 ; Yang and Slingo 2001 ; Nesbitt and Zipser 2003 ; Bowman et al. 2005 ) has shown a consistent diurnal cycle in rainfall and/or deep convection over tropical oceanic regions with a maximum in the morning. In particular, Bowman et al. (2005) used data from rain gauges on buoys and the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and Precipitation Radar (PR) to better understand the characteristics of the

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George R. Alvey III
,
Jonathan Zawislak
, and
Edward Zipser

-oriented quadrant-based analyses. In particular, more in situ and remote sensing observations (airborne radar) are needed in the early stages of intensification, when intense convection is often more transient, to help fill the gaps between passive microwave overpasses. Observations during these preintensification periods could help give a better understanding of convective bursts and their transition to symmetry often seen during rapid intensification. Acknowledgments The authors thank Dan Cecil and an

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Andrea Skow
,
Michael Poellot
,
David Delene
,
Mark Askelson
,
Kirk North
, and
Mariko Oue

considered to be in cloud. The Oklahoma Mesonet is a network of automated surface stations covering the state of Oklahoma that record observations every 5 min ( McPherson et al. 2007 ; Brock et al. 1995 ). The network consists of 120 stations, with at least one station in every county in Oklahoma. Observed variables include air temperature, wind speed and direction, precipitation, and relative humidity. Mesonet temperature and station pressure data are used to calculate the potential temperature at a

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Aurélie Bouchard
,
Florence Rabier
,
Vincent Guidard
, and
Fatima Karbou

, improvements in the representation of surface emissivity and temperature are necessary to decrease the number of observations rejected during the assimilation system. In the following, studies toward a better estimation of surface emissivity at microwave frequencies will be presented as well as feasibility studies undertaken to assimilate as many relevant infrared and microwave observations as possible over Antarctica. b. Microwave observations Satellite instruments measure the top

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Maziar Bani Shahabadi
and
Mark Buehner

standard deviation (stddev) as a function of the cloud amount for assimilation of cloud-affected radiances. All-sky assimilation of observations from four Microwave Humidity Sounder (MHS) satellites and one SSMIS satellite improved the dynamical forecasts in tropical and midlatitude regions up to 6 days in the 4D-Var system at ECMWF ( Geer et al. 2014 ). All-sky assimilation of cloud-affected MHS observations in the 4D-Var system at the Met Office improved forecasts of humidity and wind fields in the

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Gerald M. Heymsfield
and
Richard Fulton

) ABSTRACT Observations of an isolated group of Oklahoma thunderstorms from NASA's high altitude ER-2 aircraft arepresented. These observations include passive radiometric measurements at frequencies in the microwave (92,183 GHz), infrared (10.7 ~m) and visible portion of the spectrum from a perspective above the storm top.Direct measurements of cloud top height were also collected using a pulsed lidar instrument. These remoteobservations are discussed and compared with coincident radar data from the

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Yunji Zhang
,
Xingchao Chen
, and
Yinghui Lu

). Microwave (MW) observations also show great potential for improving the TC structure forecast ( Wu et al. 2019 ; Sieron 2020 ). IR observations can provide knowledge about the environmental thermodynamics, the height of the clouds, and can infer synoptic-scale motions implicitly through their temporal evolutions. MW observations can provide information about the hydrometeors in addition to moisture. Therefore, they provide complementary information on different aspects of the TCs. However, both IR and

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Daniel J. Cecil
and
Edward J. Zipser

°–1° radius latent heat release. Would other microwave channels that are more intimately tied to latent heat release, but have lower resolution than the 85 GHz 13 km × 15 km footprint, likewise produce such high correlations? The lack of a relationship between indicators of intense convection (such as lightning) and tropical cyclone deepening seems to be in conflict with previous reports. Would a more detailed dataset (such as lightning observations from a geostationary satellite) resolve this conflict

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Xin Lin
,
Sara Q. Zhang
, and
Arthur Y. Hou

on the temporal sampling and spatial coverage of observations. The Global Precipitation Measurement (GPM) mission being planned for the beginning of the next decade is based on the concept of providing frequent global precipitation measurements using a spaceborne precipitation radar as a calibrator of a constellation of passive microwave radiometers. GPM is designed to extend the successful Tropical Rainfall Measuring Mission (TRMM; Simpson et al. 1988 ) in the Tropics to higher latitudes, but

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M. A. Filiberti
,
L. Eymard
, and
B. Urban

486 MONTHLY WEATHER REVIEW VOLUME122Assimilation of Satellite Precipitable Water in a Meteorological Forecast ModelM. A. FILIBERTI AND L. EYMARD CRPE I CNET / CNRS Vdlizy, France B. URBANMdMo-France, Toulouse, France(Manuscript received 15 February 1993, in final form 30 July 1993) The lack of local humidity observations over a large portion of the globe hinders any

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