Microwave Radiometer) was compared with those of the BOBMEX-GPS Radiosonde (Vaisala) data. The root mean square error between Vaisala and MSMR data is of the order of 0.30 gm/cm2 after bias correction.
The other geophysical parameters like SST and wind speed derived from IRS-P4/MSMR were also compared. SST difference was of the order of 1.5°C and wind speed difference was of 2 m/sec when compared to in-situ data.
9. Results of marine atmospheric aerosol optical depth, total ozone and precipitable water content obtained during BOBMEX-99
K.K. Dani, R.S. Mahesh Kumar and P.C.S. Devara, Indian Institute of Tropical Meteorology, Pune
Analysis of multi-band solar radiometric data collected onboard ORV Sagar Kanya (cruise 147-B) during BOBMEX-99 was presented.
Two distinct maxima were seen in total column ozone (TCO)- one around 0700 hrs and the other around 1500 hrs (IST)- which could be due to strong wind speed during these times.
Time variation of TCO appeared to be inversely related (may be with some time lag) with that of Precipitable Water Content (PWC). Increasing trends in both PWC and TCO were seen during 20-22 August.
Aerosol optical depth (AOD) decreased with an increase in wave length. The inverted aerosol size distribution from the spectral variation of AOD exhibited power-law type distribution with more number of accumulation-mode particles and less concentration of coarse-mode particles. Markable spectral dependence of AOD, i.e. greater AOD at smaller wavelengths and vice versa was noticed. Sharp fall in AOD (almost 3 times) from the beginning to the middle of the study period was due to cloud-scavenging and rain & wash out processes.
During the cruise period, the values of the wave length exponent (a) and Angstrom turbidity coefficient (b) suggested abundance of larger particles with greater extinction property.
Composite data during the entire cruise period showed bi-modal aerosol size distribution with maximum concentration of particles at primary mode of 0.02mm radius and secondary mode around 1.0mm radius particles of fairly high concentration.
Good agreement between (correlation coefficient =0.87) radiometer derived TCO and satellite derived TCO was found during the entire period. This agreement seemed to be better when TCO values were smaller during the second half of the observational period.
10 Aitken Nuclei and precipitation chemistry over the Bay of Bengal during BOBMEX-99.