Seasonal and interannual variability of atmospheric convergence zones in the tropical Pacific observed with ERS‐1 scatterometer

Zheng, Quanan; Yan, Xiao-Hai; Liu, W. Timothy; Tang, Wenqing; Kurz, Dragan

doi:10.1029/97gl00033

Cited by 27 publications

(32 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…OLR shows that the ITCZ is a meandering narrow band of cloudiness close to the equator. As discussed in the introduction section, an alternative method for the identification of the ITCZ is from convergence of winds (Žagar et al, 2011;Zheng et al, 1997), which is later related to vertical wind. Therefore, we plotted the vertical wind obtained from NCEP reanalysis data at 850 hPa as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, the ITCZ can be identified by using visible and infrared satellite observations of high reflective cloud cover , by locating the convergence of wind fields (e.g., Žagar, Skok, & Tribbia, 2011;Zheng, Yan, Liu, Tang, & Kurz, 1997), by calculating the relative vorticity structures (e.g., Magnusdottir & Wang, 2008), or by using multiple variable criteria (e.g., Bain et al, 2010). Despite the availability of a number of methods for its identifications, some discrepancies in identifying the ITCZ are mentioned in the literature.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Vertical and latitudinal variation of the intertropical convergence zone derived using GPS radio occultation measurements

Basha¹,

Kishore²,

Ratnam

et al. 2015

Remote Sensing of Environment

View full text Add to dashboard Cite

Using GPS radio occultation refractivity data collected over the period of 2002-2013, we present a new method for identification of the intertropical convergence zone (ITCZ). The ITCZ is identified by estimating the maximum in the monthly meridional refractivity and specific humidity field by applying a Gaussian fit at each longitude. The interannual variability and climatology of the ITCZ is presented from 12 years of refractivity data. This new method captures all the general features of ITCZ extent and its variability. We also examine the effects of the ITCZ vertically during different seasons. The ITCZ is observed mostly at eastern Pacific in May month, and it is zonally distributed in the September and October months of each year. The zonal variability is large between lower and higher levels, particularly over the Indian monsoon and western Pacific. The latitudinal difference in the vertical extent between 850 hPa and higher levels is larger during the northern hemisphere (NH) summer than NH winter.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vertical and latitudinal variation of the intertropical convergence zone derived using GPS radio occultation measurements

Basha¹,

Kishore²,

Ratnam

et al. 2015

Remote Sensing of Environment

View full text Add to dashboard Cite

show abstract

“…QuikSCAT even clearly depicts the broad double-ITCZ structures (Fig. 9) often observed over the eastern Pacific during boreal spring (e.g., Zheng et al 1997;Lietzke et al 2001).…”

Section: B Intertropical Convergence Zonementioning

confidence: 99%

The Operational Use of QuikSCAT Ocean Surface Vector Winds at the National Hurricane Center

Brennan

Hennon

Knabb

2009

Weather and Forecasting

109

View full text Add to dashboard Cite

The utility and shortcomings of near-real-time ocean surface vector wind retrievals from the NASA Quick Scatterometer (QuikSCAT) in operational forecast and analysis activities at the National Hurricane Center (NHC) are described. The use of QuikSCAT data in tropical cyclone (TC) analysis and forecasting for center location/identification, intensity (maximum sustained wind) estimation, and analysis of outer wind radii is presented, along with shortcomings of the data due to the effects of rain contamination and wind direction uncertainties. Automated QuikSCAT solutions in TCs often fail to show a closed circulation, and those that do are often biased to the southwest of the NHC best-track position. QuikSCAT winds show the greatest skill in TC intensity estimation in moderate to strong tropical storms. In tropical depressions, a positive bias in QuikSCAT winds is seen due to enhanced backscatter by rain, while in major hurricanes rain attenuation, resolution, and signal saturation result in a large negative bias in QuikSCAT intensity estimates.QuikSCAT wind data help overcome the large surface data void in the analysis and forecast area of NHC's Tropical Analysis and Forecast Branch (TAFB). These data have resulted in improved analyses of surface features, better definition of high wind areas, and improved forecasts of high-wind events. The development of a climatology of gap wind events in the Gulf of Tehuantepec has been possible due to QuikSCAT wind data in a largely data-void region.The shortcomings of ocean surface vector winds from QuikSCAT in the operational environment at NHC are described, along with requirements for future ocean surface vector wind missions. These include improvements in the timeliness and quality of the data, increasing the wind speed range over which the data are reliable, and decreasing the impact of rain to allow for accurate retrievals in all-weather conditions.

show abstract

“…Different authors have used different parameters to examine these convergence zones: visible images of cloudiness (Hubert et al, 1969;Saha, 1971), atmospheric circulation (Sadhuram et al, 1989), highly reflective clouds (Waliser and Gautier, 1993), rainfall (Zhang, 2001), surface wind convergence (Zheng et al, 1997), and integrated cloud liquid water content (Ferraro et al, 1996). Earlier studies (Levy and Battisti, 1995;Tomas and Webster, 1997;Levy and Dunkerton, 2004;Toma and Webster, 2009;Levy and Patoux, 2010) suggested that the circulation of the lower troposphere is symmetrically unstable equator-ward of the ITCZ in regions where it is displaced off the equator, and such instability may interact with convection in the ITCZ.…”

Section: Introductionmentioning

confidence: 99%

A multi-sensor climatological view of double ITCZs over the Indian Ocean

Kumar

Devasthale

Levy

et al. 2011

International Journal of Remote Sensing

View full text Add to dashboard Cite

We characterize climatological features of Double Inter Tropical Convergence Zones (DITCZs) over the western Indian Ocean during November-December by a synergistic analysis of the Satellite Application (1997, 2002 and 2006), in sharp contrast to the DITCZs in the eastern Pacific Ocean, where they are absent during ENSOs. Further, these convergence zones on either side of the equator are of short duration, approximately 3-6 pentads during November and December. All satellite sensors data sets consistently capture major features of DITCZ. As an accurate simulation of DITCZs in coupled global climate models remains a challenge, results from the present study would provide platform for evaluating these models.

show abstract

Seasonal and interannual variability of atmospheric convergence zones in the tropical Pacific observed with ERS‐1 scatterometer

Abstract: where the coordinate system is the same as the geographic coordinate system; u and v are the zonal and meridional components of the wind field.

Cited by 27 publications

References 4 publications

Vertical and latitudinal variation of the intertropical convergence zone derived using GPS radio occultation measurements

Vertical and latitudinal variation of the intertropical convergence zone derived using GPS radio occultation measurements

The Operational Use of QuikSCAT Ocean Surface Vector Winds at the National Hurricane Center

A multi-sensor climatological view of double ITCZs over the Indian Ocean

Contact Info

Product

Resources

About