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. Wea. Forecasting , 12 , 78 – 107 . 10.1175/1520-0434(1997)012<0078:NCAFSS>2.0.CO;2 Bevis, M. , Businger S. , Herring T. A. , Rocken C. , Anthes R. A. , and Ware R. H. , 1992 : GPS meteorology: Remote sensing of atmospheric water vapor using the global positioning system. J. Geophys. Res. , 97 , 15787 – 15801 . 10.1029/92JD01517 Bevis, M. , Businger S. , Chriswell S. , Herring T. A. , Anthes R. A. , Roken C. , and Ware R. H. , 1994 : GPS meteorology: Mapping zenith
. Wea. Forecasting , 12 , 78 – 107 . 10.1175/1520-0434(1997)012<0078:NCAFSS>2.0.CO;2 Bevis, M. , Businger S. , Herring T. A. , Rocken C. , Anthes R. A. , and Ware R. H. , 1992 : GPS meteorology: Remote sensing of atmospheric water vapor using the global positioning system. J. Geophys. Res. , 97 , 15787 – 15801 . 10.1029/92JD01517 Bevis, M. , Businger S. , Chriswell S. , Herring T. A. , Anthes R. A. , Roken C. , and Ware R. H. , 1994 : GPS meteorology: Mapping zenith
1. Introduction The observations from the global positioning system (GPS) radio occultation (RO) limb sounding technique have been proven to be a valuable source of atmospheric data for numerical weather prediction (NWP) and climate research ( Kuo et al. 1998 ; Zou et al. 1999 ; Zou et al. 2000 ; Liu and Zou 2003 ; Healy et al. 2005 ; Huang et al. 2005 ; Cucurull et al. 2006 ; Cucurull and Derber 2008 ; Healy and Thepaut 2006 ). GPS RO data have several advantages, such as no need for
1. Introduction The observations from the global positioning system (GPS) radio occultation (RO) limb sounding technique have been proven to be a valuable source of atmospheric data for numerical weather prediction (NWP) and climate research ( Kuo et al. 1998 ; Zou et al. 1999 ; Zou et al. 2000 ; Liu and Zou 2003 ; Healy et al. 2005 ; Huang et al. 2005 ; Cucurull et al. 2006 ; Cucurull and Derber 2008 ; Healy and Thepaut 2006 ). GPS RO data have several advantages, such as no need for
, between low earth-orbiting satellites and satellites of the Global Positioning System (GPS), are independent of both weather and surface conditions. The sounding of upper-tropospheric humidity by GPS radio occultations is of high accuracy but the accuracy decreases in the lower troposphere (e.g., Marquardt et al. 2001 ; Wickert et al. 2002 ; Beyerle et al. 2002 , 2004 ; Hajj et al. 2004 ; Liou et al. 2005 ; Larsen et al. 2005 ). However, the lowest 5-km layer of the troposphere includes about
, between low earth-orbiting satellites and satellites of the Global Positioning System (GPS), are independent of both weather and surface conditions. The sounding of upper-tropospheric humidity by GPS radio occultations is of high accuracy but the accuracy decreases in the lower troposphere (e.g., Marquardt et al. 2001 ; Wickert et al. 2002 ; Beyerle et al. 2002 , 2004 ; Hajj et al. 2004 ; Liou et al. 2005 ; Larsen et al. 2005 ). However, the lowest 5-km layer of the troposphere includes about
1. Introduction The National Centers for Environmental Prediction (NCEP) has been assimilating observations from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) mission ( Cheng et al. 2006 ; Anthes et al. 2008 ) into their operational global data assimilation ( Kleist et al. 2009 ) system since 1 May 2007. The use of global positioning system (GPS) radio occultation (RO) data required the coding of new numerical algorithms and the implementation of quality
1. Introduction The National Centers for Environmental Prediction (NCEP) has been assimilating observations from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) mission ( Cheng et al. 2006 ; Anthes et al. 2008 ) into their operational global data assimilation ( Kleist et al. 2009 ) system since 1 May 2007. The use of global positioning system (GPS) radio occultation (RO) data required the coding of new numerical algorithms and the implementation of quality
efforts to improve the usage of radiance data over the Antarctic area are continuing [e.g., improved modeling of surface emissivity ( English 2008 ; Bouchard et al. 2010 ) and enhanced detection of clouds ( McNally and Watts 2003 )], new sources of observation are also receiving attention. One promising data source is the global positioning system (GPS) radio occultation (RO) technique; this approach utilizes a GPS receiver on board a low Earth-orbiting (LEO) satellite that measures the GPS signal
efforts to improve the usage of radiance data over the Antarctic area are continuing [e.g., improved modeling of surface emissivity ( English 2008 ; Bouchard et al. 2010 ) and enhanced detection of clouds ( McNally and Watts 2003 )], new sources of observation are also receiving attention. One promising data source is the global positioning system (GPS) radio occultation (RO) technique; this approach utilizes a GPS receiver on board a low Earth-orbiting (LEO) satellite that measures the GPS signal
, increasing precision and widespread adoption of global positioning system (GPS) technology has opened new avenues for airborne research. Differential GPS (DGPS), which use one or more GPS base stations at fixed reference sites whose locations have been determined precisely, is used to refine the vertical position of the aircraft. Here, we describe the measurement of pressure perturbations associated with evolving cumulus clouds over horizontal scales ranging from <1 to ~20 km. Such measurements can
, increasing precision and widespread adoption of global positioning system (GPS) technology has opened new avenues for airborne research. Differential GPS (DGPS), which use one or more GPS base stations at fixed reference sites whose locations have been determined precisely, is used to refine the vertical position of the aircraft. Here, we describe the measurement of pressure perturbations associated with evolving cumulus clouds over horizontal scales ranging from <1 to ~20 km. Such measurements can
for the Pacific Ocean. Having a set of properly constructed initial vortices to include into the background field is likely sufficient in TC satellite data assimilation for generating a long-term reanalysis and/or analysis for HU forecasts. Specifically, historic global positioning system (GPS) radio occultation (RO) data will be used to first create a vortex background. GPS RO and other meteorological observations around the initial times of HU forecasts will then be assimilated to generate model
for the Pacific Ocean. Having a set of properly constructed initial vortices to include into the background field is likely sufficient in TC satellite data assimilation for generating a long-term reanalysis and/or analysis for HU forecasts. Specifically, historic global positioning system (GPS) radio occultation (RO) data will be used to first create a vortex background. GPS RO and other meteorological observations around the initial times of HU forecasts will then be assimilated to generate model
a tornado outbreak in the Midwest, for which the operational model was compared against one that assimilated global positioning system (GPS) precipitable water. The operational model underestimated the convective available potential energy (CAPE) of the situation, while the model that assimilated GPS precipitable water had higher CAPE, which more accurately portrayed the severe storm threat. With the advent of GPS, people realized that atmospheric water vapor could affect measurements, and in
a tornado outbreak in the Midwest, for which the operational model was compared against one that assimilated global positioning system (GPS) precipitable water. The operational model underestimated the convective available potential energy (CAPE) of the situation, while the model that assimilated GPS precipitable water had higher CAPE, which more accurately portrayed the severe storm threat. With the advent of GPS, people realized that atmospheric water vapor could affect measurements, and in
1. Introduction In recent years, real-time kinematic global positioning systems (RTK GPS), and by extension postprocessed kinematic (PPK) positioning, have played an increasingly important role in the study of marine and riverine environments. Aboard survey vessels or mounted on buoys, kinematic GPS record any motion of the water surface and measurement platform across the whole frequency spectrum. Relying on differential carrier-phase measurements, they are capable of subdecimeter accuracy in
1. Introduction In recent years, real-time kinematic global positioning systems (RTK GPS), and by extension postprocessed kinematic (PPK) positioning, have played an increasingly important role in the study of marine and riverine environments. Aboard survey vessels or mounted on buoys, kinematic GPS record any motion of the water surface and measurement platform across the whole frequency spectrum. Relying on differential carrier-phase measurements, they are capable of subdecimeter accuracy in
Kinematic GNSS Estimation of Zenith Wet Delay over a Range of Altitudes-sparse areas where NWP model precipitation performance is limited, such as deserts, mountains, and oceans. Previous studies ( Baker et al. 2001 ; Karabatić et al. 2011 ; Smith et al. 2007 ) have suggested a total precipitable water vapor (PWV) measurement accuracy approaching 1–2 mm is desirable for improving NWP models. Meteorological applications of using static ground-based global positioning system (GPS) receivers have developed, since the conception of GPS as a PWV sensor in the early 1990s, to now
-sparse areas where NWP model precipitation performance is limited, such as deserts, mountains, and oceans. Previous studies ( Baker et al. 2001 ; Karabatić et al. 2011 ; Smith et al. 2007 ) have suggested a total precipitable water vapor (PWV) measurement accuracy approaching 1–2 mm is desirable for improving NWP models. Meteorological applications of using static ground-based global positioning system (GPS) receivers have developed, since the conception of GPS as a PWV sensor in the early 1990s, to now
