Raindrop Size Distribution and Radar Parameters at Cape Verde

Nzeukou, Armand; Sauvageot, Henri; Ochou, Abé Delfin; Kébé, Cheikh Mouhamed Fadel

doi:10.1175/1520-0450(2004)043<0090:rsdarp>2.0.co;2

Cited by 74 publications

(66 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Most rainy events are tropical squall lines (a special kind of mesoscale convective system), going from land toward sea, observed only during the rainy season, between early July and late September, when the intertropical convergence zone is higher than 13°N. The conditional mean rain rate (i.e., when R > 0) is 5.1 mm h À1 [Nzeukou et al, 2004]. Figure 2 presents the gauge-based mean annual cumulative rainfall for West Senegal computed and interpolated over a period of 39 years .…”

Section: Datasupporting

confidence: 77%

“…The mean is 2.41, that is very close to 2.24 found for CV R in many place in the world [Sauvageot, 1994;Nzeukou et al, 2004;NS].…”

Section: Rain Rate Distributionmentioning

confidence: 99%

“…These values corroborate the climatic observations on rain. For example the mean conditional point rain rate m R in West Senegal is around 5.1 mm h À1 [Nzeukou et al, 2004;NS]. The cumulative annual rainfall along East is around 600 mm.…”

Section: Rain Rate Distributionmentioning

confidence: 99%

See 2 more Smart Citations

Rain rate and attenuation statistics along paths in a tropical coastal area from radar data

2006

Self Cite

View full text Add to dashboard Cite

[1] A data set on rain rate distribution was collected by radar from a coastal site located at tropical latitude in West Africa where the rain field is strongly heterogeneous. It is used to compute rain rate (R) and microwave attenuation (A) statistics integrated along four paths located onshore, offshore, and perpendicularly to the coast, that is, north and south of the radar. These statistics are analyzed in order to see if coastal effects on rain fields induce significant differences between the conditions of microwave propagation along the four paths. R and A averaged along the paths are found to be mixed lognormal distributions with parameters m and s (mean and standard deviation, respectively) almost constant for the four paths, which shows that locally, the rain field is approximately ergodic. The probability of rain occurrence is found to be lower for the paths located offshore and north with respect to onshore and south. These differences are linked to the presence of positive gradients of rainfall occurrences between sea and land areas and between north and south areas. The magnitude of these differences is about 100%. The statistical variation coefficient, that is, CV = m/s, is found to be close to 2.24, a value observed in many other sites. For the attenuation, CV is found to be dependent on the exponential coefficient of the relation between the specific attenuation and the rain rate. For attenuation, the parameters of the probability density function are given for nine frequencies between 3 and 94 GHz.Citation: Nzeukou, A., H. Sauvageot, and L. Féral (2006), Rain rate and attenuation statistics along paths in a tropical coastal area from radar data, Radio Sci., 41, RS2005,

show abstract

Section: Datasupporting

confidence: 77%

“…The mean is 2.41, that is very close to 2.24 found for CV R in many place in the world [Sauvageot, 1994;Nzeukou et al, 2004;NS].…”

Section: Rain Rate Distributionmentioning

confidence: 99%

See 1 more Smart Citation

Rain rate and attenuation statistics along paths in a tropical coastal area from radar data

2006

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is important to understand whether the observed DSD variability is random or associated with any complex microphysical process. Several earlier studies have shown that the DSDs are not random, but can be reproduced under homogeneous environmental conditions (Jameson and Kostinski, 2001), and have investigated the variability of DSD and statistics of DSD parameters as a function of R (Sauvageot and Lacaux, 1995;Tokay et al, 2001;Nzeukou et al, 2004;Kozu et al, 2006). Therefore, the DSDs stratified based on R should look similar, unless they are fundamentally different.…”

Section: Discussionmentioning

confidence: 99%

Differences in raindrop size distribution from southwest monsoon to northeast monsoon at Gadanki

Rao

Radhakrishna

Nakamura

et al. 2009

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

Characteristics of raindrop size distribution (DSD) are studied during the southwest (SW) and northeast (NE) monsoon seasons using 4 1/2 years of DSD measurements made at Gadanki (13.5 • N, 79.2 • E) by an impact-type disdrometer. The observed DSD is found to be distinctly different in the NE monsoon from that of the SW monsoon. The stratified DSD (based on rain rate) shows more small drops and fewer bigger drops in the NE monsoon than in the SW monsoon, particularly in the low rain rate regime. This feature is not an anomalous one, rather observed consistently in all the years. The diurnal variation of DSD (in terms of mass-weighted mean diameter, D m ) plots in both monsoons show large values of D m in the evening hours. Several possible reasons, from instrumental problems to geophysical mechanisms, for the observed DSD differences are examined. The wind field and the range of D m values indicate that the DSDs in the SW and NE monsoons are continental and oceanic in nature, respectively. Further, high temperature and intense convective activity (vigorous updraughts) in the SW monsoon modify the DSD through evaporation, drop sorting, and collision-coalescence processes.

show abstract

“…Several previous studies (Ochou et al, 2007;Nzeukou et al, 2004) have compared radar reflectivity data with dropsize distribution estimates from disdrometer data to produce Z-R relations for West Africa. After discussion with AMMA scientists working in this area, it was decided to use the Z−R relation of Z = 400R 1.3 (Gosset, personal communication, 2008).…”

Section: Radar Rain-rate Data From Niamey Nigermentioning

confidence: 99%

The TAMORA algorithm: satellite rainfall estimates over West Africa using multi-spectral SEVIRI data

et al. 2010

View full text Add to dashboard Cite

Abstract.A multi-spectral rainfall estimation algorithm has been developed for the Sahel region of West Africa with the purpose of producing accumulated rainfall estimates for drought monitoring and food security. Radar data were used to calibrate multi-channel SEVIRI data from MSG, and a probability of rainfall at several different rain-rates was established for each combination of SEVIRI radiances. Radar calibrations from both Europe (the SatPrecip algorithm) and Niger (TAMORA algorithm) were used. 10 day estimates were accumulated from SatPrecip and TAMORA and compared with kriged gauge data and TAMSAT satellite rainfall estimates over West Africa. SatPrecip was found to produce large overestimates for the region, probably because of its non-local calibration. TAMORA was negatively biased for areas of West Africa with relatively high rainfall, but its skill was comparable to TAMSAT for the low-rainfall region climatologically similar to its calibration area around Niamey. These results confirm the high importance of local calibration for satellite-derived rainfall estimates. As TAMORA shows no improvement in skill over TAMSAT for dekadal estimates, the extra cloud-microphysical information provided by multi-spectral data may not be useful in determining rainfall accumulations at a ten day timescale. Work is ongoing to determine whether it shows improved accuracy at shorter timescales.

show abstract

Raindrop Size Distribution and Radar Parameters at Cape Verde

Cited by 74 publications

References 41 publications

Rain rate and attenuation statistics along paths in a tropical coastal area from radar data

Rain rate and attenuation statistics along paths in a tropical coastal area from radar data

Differences in raindrop size distribution from southwest monsoon to northeast monsoon at Gadanki

The TAMORA algorithm: satellite rainfall estimates over West Africa using multi-spectral SEVIRI data

Contact Info

Product

Resources

About