Particle morphology and elemental compositions are among the crucial parameters of aerosols required for accurate understanding of the climatic effect of aerosols in the earth-atmosphere system; yet their vertical distributions and region specific properties are poorly characterised due to sparse in-situ measurements. This is the first study to classify and quantify the vertical distributions of the morphological characteristics and elemental composition of aerosols based on single particle as well as bulk chemical analysis over seven geographically diverse regions of northern and central parts of India during spring (April–May, 2013), carried out as a part of Regional Aerosol Warming Experiment (RAWEX). Significant regional distinctiveness in shapes (non-sphericity), sizes and elemental compositions of the airborne particles were conspicuous, having dominance of highly irregular granular aggregates over the north Indian sites. The non-spherical coarse mode particles dominated the lower free tropospheric regions (> 2 km) of the Indo-Gangetic Plains (IGP). These particles could be responsible for enhanced spring time aerosol absorption in the elevated region of the atmosphere. Elemental compositions of the single particle analysis indicate that the free tropospheric layer over the IGP and central India is enriched with Na and Ca compounds mixed with Fe or Al (soil particles), indicating long range transport of crustal aerosols. This finding is very well supported by the bulk particle analysis indicating abundance of Ca²⁺ in the free troposphere with low contribution of ssNa⁺. Particles with irregular rough surfaces having dominance of SiO₂ were observed over all the study sites. The percentage share of spherical (either smooth or rough) particles to the total morphological characteristics of the particles was found to be highly subdued (< 10%). The present study thus critically assesses the relevant knowledge pertaining to the morphological features of aerosols over the IGP during spring for the accurate estimation of aerosol radiative properties. More such efforts are required in future to study the connections and dependencies between morphological and radiative properties of aerosols in different seasons.

颗粒形态和元素组成是准确了解气溶胶对地球-大气系统的气候影响所需的关键气溶胶参数；然而，由于现场测量稀疏，它们的垂直分布和区域特定特性很难被表征。这是第一项基于单颗粒和批量化学分析对印度北部和中部七个地理不同地区春季（四月至五月， 2013），作为区域气溶胶变暖实验（RAWEX）的一部分进行。空气中颗粒的形状（非球形）、尺寸和元素组成具有显着的区域独特性，在印度北部地区以高度不规则的粒状聚集体为主。非球形粗模粒子主导印度恒河平原（IGP）的较低自由对流层区域（> 2 km）。这些颗粒可能是春季大气高海拔区域气溶胶吸收增强的原因。单颗粒分析的元素组成表明，IGP 和印度中部上空的自由对流层富含与 Fe 或 Al（土壤颗粒）混合的 Na 和 Ca 化合物，表明地壳气溶胶的长距离传输。这一发现得到了散装粒子分析的充分支持，表明自由对流层中Ca ^{2+丰度较高，而ssNa +}的贡献较低。在所有研究地点均观察到具有以SiO ₂为主的不规则粗糙表面的颗粒。发现球形（光滑或粗糙）颗粒占颗粒总形态特征的百分比非常低（< 10%）。因此，本研究批判性地评估了春季IGP气溶胶形态特征的相关知识，以准确估计气溶胶辐射特性。未来需要更多的努力来研究不同季节气溶胶形态和辐射特性之间的联系和依赖性。