Scale up the influence of aerosols on deep convection derived from GoAmazon/CHUVA measurement to Amazon basin.

Abstract:

Although the effects of aerosol on clouds and precipitation have been shown extensively, whether we can detect them on climate and continental scale, especially on convective life cycle, and how can we isolate such effect from the influences of meteorological conditions, are still unclear. To address these challenges, we are analyzing both GoAmazon/CHUVA data and a large suite of instantaneously collocated geostationary and polar orbit satellite datasets over Amazon. The results show consistent increases of rainrate, number of convective cores, and radius of the mesoscale convective systems associated with the aerosols for relatively low and moderate vertical wind shears for various lower tropospheric relative humidity conditions. Our results also suggest that, while the vertical wind shear and lower tropospheric relative humidity dominate the variations of convective system radius and number of convective cores, especially during the growing and mature stage of the convective systems, aerosols dominate the reduction of small hydrometeors, the increase of large hydrometeors, and reduction of convective anvils, especially during the mature and decaying phase of the convective systems. These results derived from a large suite of independent measurements support the hypothesis that aerosols can reduce small hydrometeors and increase hydrometeors, and invigorate convective systems, as shown by their dominant effect during the mature and decay phase of the convection. The meteorological conditions dominate the size and number of convective cores of the convective systems, especially during the growing phase of the convection.

We analyze the DOE Atmospheric Radiation Measurement Mobile Facility (AMF) GoAmazon and Brazil led CHUVA field campaign data to evaluate these results from satellite data. Multiple regression analysis of the GoAmazon data generally suggest that aerosols have a comparable influence on cloud ice to those of the lower tropospheric relative humidity and vertical wind shear when the convections are in developing or steady stages in terms of convective top height. The influences also depend on the planetary boundary layer height. We will also report our comparison of the influence of aerosols on deep convection to those on convective congestus and shallow clouds.